Dissertations / Theses on the topic 'Supramolecular sensing'

Cette thèse explore l’utilisation des principes de la chimie supramoléculaire afin de fabriquer des dispositifs senseurs de gaz novateurs et à haute performance, avec une lecture (opto)-électronique. Parmi les différentes sections, divers échafaudages tels que des réseaux hybrides bi- et tridimensionnels de particules d’or et des nanofibres supramoléculaires sont utilisés comme matériaux actifs pour la détection quantitative de l’humidité. Au sein de la dernière section, des couches 2D d’oxyde de graphène sont fabriquées par exposition à un laser IR, puis comme validation de principe, exploitées comme matériau actif pour la détection d’ozone à une concentration ppm. Chacun des échafauds présentés est basé sur un mécanisme de transduction différent, mais dans tous les cas, les interactions entre récepteurs et analytes sont basés sur des liaisons dynamiques non covalentes
This thesis explores the use of supramolecular chemistry principles to fabricate novel and high performances gas sensing devices, featuring (opto)-electronic readouts. Within the different sections, diverse scaffolds such as 2D and 3D hybrid networks of gold nanoparticles and 1D supramolecular nanofibers are exploited as active materials for the quantitative detection of environmental humidity. In the last section, 2D layers of reduced graphene oxide are fabricated by IR laser exposure and, as a proof-of-concept application, they are exploited as active materials for the detection of ozone in ppm concentration. Each of the presented scaffolds rely on a different transduction mechanism but, in all the cases, the interactions between the receptors and the analytes are based on dynamic non-covalent bonds

Supramolecular chemistry is an emerging field of chemistry which has attracted much attention in recent years as a result of its broad applicability in many areas. Thus, the design of functional supramolecular systems is strongly in demand in this field. For this purpose, we have developed ratiometric fluorescent chemosensors for ion sensing and mechanically interlocked structures for their application in molecular logic. In the first part, we report a novel dimeric boradiazaindacene dye which can be converted in one step to an efficient resonance energy transfer (RET) dyad. In addition, if this modification is done with appropriate ligands, RET can be coupled to ion sensing. The utility of this approach is demonstrated in a highly selective, emission ratiometric chemosensor for Ag(I). In the second part, boradiazaindacene dyads designed as energy transfer casettes were modified to signal cation concentrations ratiometrically. If the energy transfer efficiency is increased by changing spectral overlap on cation binding, an enhancement of emission signal ratios can be obtained. A larger range of ratios results in highly improved sensitivity to analyte concentrations. We demonstrate this approach in a de novo design of a novel and highly selective ratiometric chemosensor for Hg(II) ions. In the last part, we synthesized a two-station [2]catenane composed of an &
#960
-electron rich bis-1,5-dihydroxynapthalene[38]-crown-10 (1/5DNPC10) ring interlocked with a second macrocycle containing two &
#960
-electron deficient unit, namely, napthodiimide (NpI) and bipyridinium (BIPY)2+ unit using the Cu(I)-catalyzed Huisgen 1,3-cycloaddition reaction. The resulting bistable [2]catenane is isolated as a single co-conformation which is comprised of the 1/5DNP[38]C10 ring around the NpI unit. Thermal activation of the pure NpI-isomer at 70&
#730
C for 60 h leads to the formation of the BIPY2+-isomer by virtue of the circumrotation of the crown-ether ring along the backbone of the other macrocycle over the steric barrier of the tetra-aryl methane units. The energy barrier for the circumrotation is 28.5±
0.3 kcal/mol. Electrochemistry of a 1:1 mixture of the two possible isomers shows that the [2]catenane cannot be switched mechanically on account of the large steric barriers presented by the tetra-aryl methane groups on the electron-accepting ring.

Thesis (S.M. in Inorganic Chemistry)--Massachusetts Institute of Technology, Dept. of Chemistry, 2013.
Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Generating metabolic profiles of tumors provides a spatiotemporal map of the concentration of key species to assess and quantify tumor growth, metabolism, and response to therapy. Because the tumor microenvironment is characterized by hypoxia, the concentration of oxygen is an important indicator of tumor health. Understanding how this parameter changes as a function of disease progression is critical to develop novel targeted therapeutics. New non-invasive sensors must be developed that are small enough to penetrate into the tumor and monitor dynamic changes with high resolution. To this end, this thesis presents new oxygen sensors that are a supramolecular assemblies of a quantum dot (QD) and a palladium(II) porphyrin. High spectral overlap between QD emission and porphyrin absorption results in efficient Förster resonance energy transfer (FRET) for signal transduction in these sensors. Porphyrins with meso pyridyl substituents bind to the surface of the QD to produce self-assembled nanosensors. Since these macrocycles are sensitive in the 0-160 torr range, they are ideal phosphors for in vivo biological oxygen quantification. The QD serves as a two-photon antenna to enable sensing under two-photon excitation. Multiphoton imaging is a powerful technique that is nondestructive to tissue and provides high-resolution images of live tissue at depths of several hundred microns with submicron spatial resolution. Having studied the photohysical properties of these sensors under both one- and two-photon excitation in organic solvents, these sensors were then encapsulated in lipid micelles to quantify oxygen in aqueous media. In these constructs, the quantum dot also serves as an internal intensity standard, furnishing a ratiometric oxygen sensor. Preliminary in vivo multiphoton imaging and oxygen measurements were conducted using mice with chronic dorsal skinfold chambers or cranial windows. Together, the properties of this sensor establish a ratiometric two-photon oxygen sensor for applications in probing biological microenvironments.
by Christopher M. Lemon.
S.M.in Inorganic Chemistry

Conjugated polyelectrolytes (CP) show interesting electrical and optical properties for organic electronics as well as for life science applications. Their possibilities of supramolecular assembly with nanowire like misfolded proteins, amyloids, as well as synthetic polypeptides or DNA forming conducting or luminescent nano composites is highly interesting as being a truly bottom up approach for fabrication of OLEDs, photovoltaic’s as well as logic devices. The conformation and aggregation dependent luminescence properties from the special class of CPs, Luminescent conjugated polyelectrolytes (LCP), have been utilised and developed as sensors to follow and study biomolecular interactions, DNA hybridisation, protein-protein interactions and staining of living cell cultures and tissue slides. In this thesis we are bringing the evolution a few steps further by applying new types of experimental techniques, such as light scattering and fluorescence correlation spectroscopy, combined with standard techniques as soft lithography and different spectroscopy techniques, to gain better knowledge of the optical behaviour of LCPs and their interactions with biomolecules. We explore the optical properties and vibronic transitions of LCPs; their ability of resonance energy transfer with LCPs indicating super lightning behaviour; the opposite fluorescence shift when interacting with α-helical rich polypeptides compared to earlier reports of interactions upon staining of β-rich amyloids; and the possibility of LCPs to influence protein aggregation as well as the possibility of fabricating biochips based on LCPs and soft lithography. Here we also show fundamental limitations to patterning using macromolecular fluids, of general relevance to soft lithography and nanoimprint lithography with low viscosity polymers.

Surface-enhanced Raman scattering (SERS) spectroscopy is a powerful analytical technique for ultrasensitive detection of chemicals and biomolecules. As the high sensitivity of SERS requires analytes to be in close contact with a plasmonic substrate, the detectionof analyte molecules with low chemical affinity towards the substrate is thus limited. Cucurbit[n]uril (CB[n]) exhibits strong and selective encapsulation of various guest molecules into its barrel-shaped cavity. In addition, it can function as a precise rigid spacer between metallic nanoparticles (NPs). The larger homologue CB[8] can simultaneously sequester two guest molecules to form ternary complexes, allowing for tailoring of the chemical environment of its cavity to trap specific analytes. CB[n] aggregated metallic NPs provide a powerful platform for the detection of a wide variety of molecules. However, the colloidal instability of this system requires the measurement to be finished within 60 min after the preparation of the substrate. In addition, in situ measurements may involve environments that affect such self-assembly processes. For example, the possible displacement of analytes in the nanogap by non-analyte moieties can give rise to fluctuating backgrounds. Therefore, a SERS substrate that can provide the same levels of detection and functionality but eliminates the need for aggregation is of great demand. This thesis mainly focuses on the preparation and characterisation of CB[n]-engineered nanostructures as SERS substrates with great colloidal stability, high SERS enhancements and sensitivities. Other applications of the prepared nanostructures such as peptide separation and high-performance catalysis are also discussed. In the first chapter, the historical development and the remaining challenges in the field of SERS are discussed. Three types of the most commonly used SERS substrates are introduced, followed by the introduction of rationally designed nanoplatforms for molecules with low chemical affinity towards metallic surfaces. In addition, CB[n] host guest complexation, examples of CB[n]-engineered nanostructures and the application of these nanostructures in SERS sensing are also discussed. The second chapter demonstrates the preparation of surface-bound CB[8] catenanes on silica NPs, where CB[8] is employed as a tethered supramolecular "receptor" to selectively capture target guest molecules. More specifically, CB[8] is threaded onto a methyl viologen (MV2+) axle and immobilised onto silica NPs with a surface density up to 0.56 nm$^{−2}$. Its use as an efficient and recyclable nanoplatform for peptide separation is demonstrated. The peptides captured by the catenanes can be released by reversible single-electron reduction of MV$^{2+}$. The entire process demonstrates high recoverability. Continued in the third chapter, a highly stable free-standing molecular sensor that exploits a catenane-engineered nanostructure is described. CB[8] is tethered onto spiky γ-Fe2O3@Au NPs in a similar approach, to collect target analytes from aqueous media. These target analytes can be detected with high sensitivities, on account of the high SERS enhancement (on the order of 10$^{8}$) of the spiky NPs. This CB[8] catenane-based molecular sensor provides a powerful SERS substrate that shows great promise in the detection of versatile chemicals, biomolecules, controlled substances and auxiliary diagnostics of various diseases. The fourth chapter introduces a facile preparation of monodispersed γ-Fe2O3@Au magnetic nanoraspberry NPs using a one-pot seeded growth method. The obtained nanoraspberry NPs show excellent colloidal stability and high SERS enhancement factors (on the order of 10$^{10}$). By immobilising a dense layer of CB[n]s onto the surface of nanoraspberry NPs, a new type of CB/Au NP SERS substrate is obtained. CB[n]s are located perpendicularly to the NP surface and their cavity maintain the capability to sequester guest molecules from aqueous media. More versatile molecules (both electron rich and electron deficient molecules) can thus be detected with high sensitivities. We envisage that this nanoraspberry-based molecular sensor will provide a powerful platform for SERS detection in various fields, such as chemical and biomolecule analysis, illegal drug detectionand pre-clinical/clinical diagnosis. The fifth chapter focuses on the preparation of CB[7]-based catalytic microreactors, where metallic NPs are immobilised onto microchannels via supramolecular interaction of methyl viologen@CB[7]. This microreactor exhibits remarkable catalytic activity on account of the high surface area to volume ratio of the microchannels and metallic NPs. Superior to most conventional heterogeneous catalytic reactions, separation post reaction and complicated recycling steps of the catalysts are not required. Moreover, CB[7] can complex a variety of metallic NPs onto its portal (e.g. gold, silver, palladium, quantum dot), providing a multifunctional in situ catalysis platform. In the end, a concluding chapter summarises the presented work, also giving a brief outlook of the potential future work.

Recognition and sensing of ions is an important front in supramolecular organic chemistry. One remarkable extension of this kind of work is the application of selective switching processes to logic gate operations. In this study, we have designed selective metal ion chelators for zinc and cadmium ions based on dansylamide fluorophores and dipicolylamine chelators. The zinc complex of a previously reported difluoroboradiazaindacene-bipyridyl derivative was shown to respond anions by an increase in emission intensity. We also discovered a hitherto unknown reaction of difluoroboradiazaindacenes and showed that this reaction can be exploited in a very selective sensing of fluoride ions in acetone solutions. The remarkable chemistry of these boradiazaindacene dyes, especially the bipyridyl derivative, allowed us to propose the first example of a unimolecular &ldquo
molecular subtractor&rdquo
. A single molecule can carry out substraction of binary inputs, when these inputs are fluoride anion and zinc cation.

The common thread of this thesis is the will of investigating properties and behavior of assemblies. Groups of objects display peculiar properties, which can be very far from the simple sum of respective components’ properties. This is truer, the smaller is inter-objects distance, i.e. the higher is their density, and the smaller is the container size. “Confinement” is in fact a key concept in many topics explored and here reported. It can be conceived as a spatial limitation, that yet gives origin to unexpected processes and phenomena based on inter-objects communication. Such phenomena eventually result in “non-linear properties”, responsible for the low predictability of large assemblies. Chapter 1 provides two insights on surface chemistry, namely (i) on a supramolecular assembly based on orthogonal forces, and (ii) on selective and sensitive fluorescent sensing in thin polymeric film. In chapters 2 to 4 confinement of molecules plays a major role. Most of the work focuses on FRET within core-shell nanoparticles, investigated both through a simulation model and through experiments. Exciting results of great applicative interest are drawn, such as a method of tuning emission wavelength at constant excitation, and a way of overcoming self-quenching processes by setting up a competitive deactivation channel. We envisage applications of these materials as labels for multiplexing analysis, and in all fields of fluorescence imaging, where brightness coupled with biocompatibility and water solubility is required. Adducts of nanoparticles and molecular photoswitches are investigated in the context of superresolution techniques for fluorescence microscopy. In chapter 5 a method is proposed to prepare a library of functionalized Pluronic F127, which gives access to a twofold “smart” nanomaterial, namely both (i)luminescent and (ii)surface-functionalized SCSSNPs. Focus shifts in chapter 6 to confinement effects in an upper size scale. Moving from nanometers to micrometers, we investigate the interplay between microparticles flowing in microchannels where a constriction affects at very long ranges structure and dynamics of the colloidal paste.

Supramolecular chemistry (chemistry beyond the molecule) is the study and synthesis of complex molecular architectures from simple subunits using non-covalent interactions. The types of non-covalent interactions that are used for the self-assembly of these complex molecular architectures include electrostatic interactions (e.g. ionic, halogen, and hydrogen bonding), π-effects, van der Waals interactions, metal coordination, and hydrophobic effects. While these interactions are often used in concert, some of the most successful and ubiquitous approaches for the design and construction of new host–guest architectures are the incorporation of hydrogen bonding motifs. A popular class of molecules capable of making strong, highly directional hydrogen bonds is barbiturates. Barbiturates have a well-known reputation as potent hypnotics, anticonvulsants, and anxiolytics but recent years have seen a renewed interest in these molecules due to their unique, symmetric acceptor-donor-acceptor hydrogen bonding motif. In addition, receptors with complementary hydrogen bonding motifs capable of binding barbiturates have also been reported, namely those based on the work of Hamilton et al. Collectively, barbiturates and their receptors have seen widespread use in a variety of applications including sensing, optoelectronics, catalysis, and the design of soft materials. The work presented in this dissertation describes the development of novel Hamilton receptors for supramolecular catalysis and barbiturate sensing, as well as the design of new synthetic barbiturates. Together this body of research aims to extend the utility of these types of host–guest systems as well as continue to develop and refine the supramolecular design principles that govern the binding interactions between barbiturates and a variety of Hamilton-type receptors. This dissertation includes both previously published/unpublished and co-authored material.

A series of multidentate N-donor ligands have been synthesised all containing pyridyl and pyridyl/thiazole units and their coordination behaviour is described. The ligands are classified into four types; i) terpyridine containing pyridyl/thiazole ligands (L1-3); ii) pyridyl/thiazole ligands containing a 3,3′-disubstituted bipyridine core. (L4-8); iii) 2,2′-bipyridine containing a crown ether moiety (L9-11); and iv) a 2,2′- bipyridine derived ligand containing a urea functional group in the 3,3′-positions (L12). Chapter II describes terpyridyl/pyridyl/thiazole ligands: - the synthesis of (L1-3) is described and the complexes ([Cu(L1)][ClO4]2, [Ni(L2)][ClO4]2, [Co(L2)][ClO4]2, [Cd3(L3)2][ClO4]6) structurally characterised. Partitioning of the ligands (L1-3) is dependant on the position of the thiazole ring within the ligand chain. This partitioning is found to occur at a position adjacent to that of the thiazole ring in all but the L2 ligand complexes, where it is partitioned preferentially at a position creating favourable coordination geometry for the metal ion. Chapter III describes 3,3′-disubstituted pyridyl/thiazole ligands (L4-8): - the novel potentially hexadentate ligands (L4, 5), the potentially octadentate ligand (L6) and the potentially tetradentate ligands (L7, 8) have been synthesized and structurally characterised. All ligands are found to partition at the central pyridine unit due to unfavourable steric interactions to form a pyridyl/thiazole/pyridyl-binding domain (L4-6) and the pyridyl/thiazole-binding domain (L7,8). The substituents are found to dominate the control of the formation of complexes produced ([Zn(L4)][ClO4]2, [Cd(L5)][ClO4]2, [Cd2(L6)2][ClO4]2, [Cd2(L8)2][ClO4]2). Chapter IV, Section 1 describes ditopic bipyridine/crown ether ligands: - the synthesis of (L9-11) is described and the Ru (II) complexes (L9-11) structurally characterised. The Ru(II) complexes of these 3,3′-disubstituted crown ether species were found to luminesce. Modulation of the luminescent properties of the ruthenium complex was investigated with a selection of common cations but resulted in little or no response. Chapter IV: - Section 2- Ditopic bipyridine/urea ligands: - the novel ligand containing urea substituent side chains (L12) has been synthesised and a ligand containing both pyridine and urea substituents has been synthesised and characterised. A ruthenium complex (X) was synthesised with ligand (L12) and (bipy)2RuCl2, the resulting structure confirmed via 1H & 13C NMR as well as electrospray mass spectrometry (ESI-MS). Unfortunately no complexes have been structurally characterised due to the instability and decomposition of the complex after a short period of time. The ruthenium complex however was found to luminesce; ligand/anion recognition studies with complex (X) and a selection of common anions showed a marked change, a ten fold increase in the luminescence was observed with the addition of H2PO4 - when in a non-aqueous solvent.

Dentro del campo de la óptica y de la optoelectrónica, los radicales orgánicos se están convirtiendo en prometedores materiales gracias a su configuración de capa abierta. En este marco, el objetivo de esta tesis ha sido el desarrollo de radicales tritilo fotoestables y altamente luminiscentes. En el capítulo I, tras una introducción sobre la luminiscencia, se describirán las propiedades ópticas de los radicales libres de carbono central, centrándose en las capacidades y perspectivas que ofrecen estas moléculas en la microscopía de fluorescencia y en dispositivos electroluminiscentes. En el capítulo II, se presentarán las propiedades ópticas de los radicales tris(2,4,6-triclorofenil)metilo (TTM) y perclorotrifenilmetilo (PTM) cuando se emplean como especies emisoras en nanopartículas orgánicas (ONPs) y en películas poliméricas. Además, a pesar de que existe un amplio conocimiento sobre las propiedades luminiscentes de estos radicales en solución, no hay estudios acerca del efecto del confinamiento de estos radicales en matrices rígidas orgánicas. Como sistemas huéspedes, se han escogido el tris(2,4,6 triclorofenil)metano (TTM-αH) y el poli(metilmetacrilato) para nanopartículas orgánicas y películas, respectivamente. De especial interés resulta el caso del TTM dopado con nanopartículas orgánicas (TTMd-ONPs) en el que se observa, por primera vez, la formación de excímeros en radicales libres de carbono central. Ambos sistemas resultan de gran interés ya que, por primera vez, se observan emisiones de excímeros desde radicales libres de carbono central debido a la formación de pares de radicales supramoleculares estables y persistentes. Gracias a su emisión en la zona NIR-roja (650-800 nm), estos materiales basados en excímeros de radicales libres se han convertido en materiales moleculares muy prometedores para la bioimagen y en aplicaciones optoelectrónicas. En el capítulo III, se estudiarán los procesos de asociación y disociación de los excímeros de TTM (estructura molecular, naturaleza del receptor, efectos térmicos). En particular, se ha encontrado que el TTMd-ONPs ofrece la posibilidad de ser utilizado como nanotermómetro rentable y radiométrico. En este marco, se ha estudiado la salida ratiométrica de la suspensión acuosa de TTMd-ONPs al 20% en diferentes condiciones de polaridad, fuerza iónica y pHs, con el objetivo de probar su posible aplicación como biosensor térmico. Finalmente, en el capítulo IV, se presentará la síntesis del primero ejemplo de polibromotrifenilmetil radical. Esta nuevo radical constituye un componente prometedor para la síntesis de radicales tritilo altamente luminiscentes y fotoestables. De hecho, gracias a la triple funcionalización de bromo en las posiciones para, este nuevo radical permite fácilmente superar la poca versatilidad sintética de los radicales policlorotrifenilmetilo. Además, en comparación con su especie análoga clorada, el radical tris (2,4,6 tribromofenil)metilo (TTBrM) presenta una absorción y emisión desplazados hacia el rojo , alta fotoestabilidad, y es capaz de formar excímeros NIR cuando se dispersa en nanopartículas orgánicas, transformándose en un radical muy prometedor para aplicaciones en bioimagen.
Organic radicals are emerging as promising materials in optics and optoelectronics thanks to their open-shell configuration. In this framework, the aim of this Thesis is the development of highly luminescent and photostable trityl radicals. In Chapter I, after an overview on luminescence, the unique optical properties of carbon-centred free-radicals will be introduced, focusing on the strengths and perspectives offered by these molecules in fluorescence microscopy and electroluminescence devices. In Chapter II, a study on the optical properties of the tris(2,4,6-trichlorophenyl)methyl radical (TTM) and perchlorotriphenylmethyl radical (PTM) when used as emitting specie in organic nanoparticles (ONPs) and polymeric films will be presented. Indeed, despite the good knowledge about the luminescence properties of trityl radicals in solution, no systematic studies are reported about the effect of the confinement of radicals in organic rigid matrices. As host systems the optically neutral tris(2,4,6-trichlorophenyl)methane (TTM-αH) and poly(methylmethacrylate) for ONPs and films respectively, have been chosen. Particularly interesting is the case of TTM doped ONPs (TTMd-ONPs) in which, for the first time for a carbon-centred free-radical, it has been observed the formation of excimers. Both systems become particularly interesting because for the first time, excimeric emissions from carbon centered free-radicals will be observed due to the formation of stable and persistent supramolecular radical-pairs. Thanks to their emission in the red-NIR region (650-800 nm), these free-radical excimer-forming materials become promising molecular materials for bioimaging and optoelectronics applications In Chapter III, the processes which explain the association and dissociation of TTM excimers (molecular structure, nature of the host, thermal effects) will be studied. In particular, it will be found that TTMd-ONPs offer the possibility to be employed as cost-effective, ratiometric nanothermometer. In this framework, the ratiometric output of 20% TTMd-ONPs water suspension has been studied in different conditions of polarity, ionic strength and pHs, in order to test its possible applicability as bio thermal sensor. Finally, in Chapter IV it will be presented the synthesis of a new class of radicals, i.e. polybromotriphenylmethyl radicals. This new molecule constitutes the perfect building block for the synthesis of highly luminescent and photostable trityl radicals. In fact, thanks to its three para bromine functionalizations, this new radical allows to easily overcome the poor synthetic versatility of polychlorotriphenylmethyl radicals. Moreover, compared to the analogous chlorinated specie, the tris(2,4,6-tribromophenyl)methyl radical (TTBrM) exhibits a red-shifted absorption and emission, a higher photostability, and it is able to form NIR-excimers when dispersed in ONPs, constituting a promising radical for bio-imaging applications.

The aim of this thesis was to study the phenomenon of supramolecular gelation of urea-based gelators and their application as sensors for neutral organophosphorus species such as nerve agents. The work was therefore naturally divided into two major parts. The first part consisted in an investigation of the structure-gelation relationship of a series of urea gelators, in an effort to overcome the serendipitous approach that is widely applied to their discovery. Among the components of the common gelator scaffold that were optimised to deliver the best gelation performance, particular attention was given to the role of the head substituent on its benzene ring. Crystal structure prediction calculations together with liquid- and solid-state NMR were used to understand the molecular reasons behind the observed macroscopic properties of supramolecular gels formed either by nitro- or methoxy-substituted gelators. Remarkably, this approach demonstrated that, rather than electronic effects, it was the nitro substituent’s ability to interfere with the urea hydrogen bond network to cause the differences observed in the gel formation experiments, when compared to the methoxy-analogue. The second part focused on the possible application of bis/tris(urea)-based supramolecular gels as organophosphorus warfare agents’ sensors. After the development of a fast and easily interpretable in-house test, it was possible to observe the effectiveness of different candidates in responding to the presence of either the nerve agent Soman or its simulant dimethyl methyl phosphonate. It was observed that in the presence of the guest molecules gelation could be delayed or even suppressed, suggesting the formation of hydrogen bonds between guest and host that were interfering with the self-assemble of the gelator molecules. Conversely it was also found that, if present in lower amount, dimethyl methyl phosphonate could instead induce a detectable thermo-mechanical reinforcement of the gel network, as confirmed by rheology and calorimetry results, which was ascribed to solvophobic effects.

This thesis is concerned with the synthesis and study of novel anion templated rotaxanes and catenanes for electrochemical anion sensing, as well as interlocked structures that possess different anion binding properties, higher-order topologies and the ability to undergo molecular motion. Chapter One provides an introduction to anion recognition and the preparation of interlocked structures. A short summary of fundamental aspects of supramolecular chemistry is followed by detailed surveys of current approaches to anion binding and sensing, as well as the templated synthesis of rotaxanes and catenanes. Chapter Two describes the preparation of rotaxanes and catenanes appended with ferrocene to allow for electrochemical anion sensing. The anion recognition properties of a [2]rotaxane and a [2]catenane, as investigated by ¹H NMR spectroscopy and electrochemical methods, are presented. The utilization of a ferrocene-appended macrocycle in the construction of surface confined anion templated rotaxanes and catenanes is also discussed. Chapter Three reports the work carried out to achieve electrochemical anion sensing by the incorporation of redox-active groups into the integral structures of interlocked structures. The syntheses of a bis-stoppered 1, 2, 3, 4, 5-pentaphenylferrocene [2]rotaxane and a ferrocene containing [3]rotaxane are presented, along with their subsequent anion recognition studies. In addition, attempts to incorporate ferrocene into the macrocyclic components of rotaxanes and catenanes are outlined. Chapter Four details further investigations into the use of interlocked structures to achieve anion recognition. Doubly-charged [2]catenanes able to bind anions in aqueous solvent media, as well as the incorporation of alternative anion binding motifs into interlocked architectures are reported. The exploitation of anion templated synthesis to allow for the construction of higher order structures (including [3]catenanes, a “handcuff” catenane and a Janus [2]rotaxane), as well as a [2]catenane system with anion controlled molecular motion is also described. Chapter Five presents the experimental procedures and characterization data relating to the compounds prepared in Chapters Two, Three and Four. Chapter Six summarizes the main conclusions of the work contained within this thesis. Supplementary experimental information relating to titration protocols, investigations into self-assembled monolayers (SAMs) and crystallographic data are provided in Appendices I, II and III.

This thesis describes the synthesis and investigation of novel anion templated interlocked structures which incorporate the positively charged imidazolium and triazolium binding motifs for applications in anion recognition and sensing. Chapter One introduces the fields of anion supramolecular chemistry and mechanically interlocked structures, focusing on topics of particular relevance to this thesis, including anion recognition, anion sensing and the templated synthesis of interlocked architectures. Chapter Two details the incorporation of the imidazolium motif into the axle components of anion templated rotaxane hosts to achieve selective anion recognition by virtue of their interlocked binding cavities. The effects of exploiting imidazolium motifs with contrasting hydrogen bond donor arrangements and reducing the macrocycle size on the anion recognition properties of such systems were investigated using 1H NMR spectroscopy. Chapter Three reports the work undertaken to utilise fluorescent reporter groups as stoppers in the synthesis of anion sensing rotaxanes. Imidazolium- and triazolium based systems containing either luminescent ruthenium(II) bipyridyl complexes or the organic fluorophore anthracene were prepared and their anion sensing behaviours explored using fluorescence spectroscopy. Synthetic efforts to construct suitable photo-active rotaxanes are detailed. Chapter Four describes investigations of the novel naphthalimide triazolium motif both for use in interlocked molecular motion systems, and for fluorescence sensing applications. The preparation of a naphthalimide triazolium rotaxane, capable of selective, anion-induced, uni-directional shuttling which was investigated extensively using 1H NMR spectroscopy and optically signalled by perturbations in the UV/Vis spectrum, is detailed. Preliminary research studies into the potential to exploit this motif for surface based fluorescence sensing devices are also included. Chapter Five presents research into the utilisation of acyclic receptors displaying considerable binding induced conformational changes for fluorescence anion sensing. The recognition properties of a series of imidazolium-based receptors were studied, whilst the ability of a pyrene appended analogue to signal anion complexation via changes in excimer emission is reported. The control of interpenetrated assembly formation using anion-induced conformational changes within the threading component of a pseudorotaxane is also discussed. Chapter Six provides the experimental procedures and characterisation details for the compounds synthesised in this thesis. Chapter Seven is a summary of conclusions from Chapters Two, Three, Four and Five. Supplementary information relating to titration protocols, crystallographic data and surface studies is provided in the Appendices.

This thesis describes the synthesis of acyclic, macrocyclic and, in particular, interlocked anion and ion-pair receptors and sensors. Chapter One will introduce the field of supramolecular chemistry with particular emphasis on areas which are pertinent to this thesis, including anion receptor design and templated synthesis of interlocked structures. Chapter Two focuses on the synthesis of new heteroditopic macrocycles functionalised with both cation and anion recognition sites and their incorporation into interlocked architectures. The affinity for a range of anions and ion-pairs is explored via ¹H NMR and UV-visible spectroscopy as well as by X-ray crystallography. Chapter Three details the incorporation of d- and f-metal luminescent reporter groups into an isophthalamide motif in order to construct acyclic, macrocyclic and [2]rotaxane receptors. Chapter Four investigates the synthesis of complex higher-order interlocked structures through post-synthetic modification of lower-order interlocked structures. Chapter Five explores the potential for fluorescent gold nanoparticle conjugates to act as luminescent and colourimetric sensors for chemical warfare agents (CWAs) by employing a fluorescent displacement assay technique.

Aqueous anions play an important role in our world, and the ability to continuously measure them provides both environmental and health benefits. Chemically-sensitive field effect transistors (ChemFETs) are becoming increasingly popular in the field of aqueous measurement due to their relatively low-cost capability for real-time, continuous sensing. Receptor molecules or mixtures displaying affinity for a particular ion can also be utilized in a ChemFET gate membrane. Receptors can be incorporated into the gate oxide membrane and the entire ChemFET can utilized in an aqueous environment, thus utilizing hydrophobic receptors in an aqueous anion-sensing application. Demonstrating the ability to reuse the sensors validates an important characteristic for ChemFET-based research. Additionally, numerous other receptor molecules are evaluated against an array of common anions. Selectivity coefficients are compared to the Hofmeister Series. Additional membranes are evaluated for suitability for incorporation of receptors on the ChemFET gate oxide surface. This thesis includes previously unpublished co-authored material.
2021-04-30

Surface-active luminescent transition metal complexes are synthesised, characterised and successfully attached to gold surfaces for the purposes of micropatterning and biomolecular recognition. Monolayers of ruthenium(II) and iridium(III) complexes bearing disulfide moieties display enchanced lifetimes on gold surfaces compared with aerated solution, and are micropatterned through the use of microcontact printing (µCP). The monolayers also display recognition of serum protein bovine serum albumin through surface plasmon resonance spectroscopy and time-resolved and steady state luminescence spectroscopy. Mixed monolayers of these respective complexes with commercially available surfactants are studied to provide understanding of nanoparticle systems and their involvement in protein interactions. Cyclodextrin containing transition metal complexes are synthesised and characterised for the purposes of supramolecular micropatterning. Mixed monolayers of ruthenium(II) and iridium(III) complexes bearing cyclodextrin moieties can be attached through directed assembly afforded by the µCP technique. Surface-active cyclodextrin containing transition metal complexes are synthesised and characterised for use in selective biomolecular recognition and stepwise assembly. Monolayers of ruthenium(II) and iridium(III) complexes bearing cyclodextrin and disulfide moieties are shown to be luminescent on gold surfaces, and through stepwise assembly afford a selective recognition motif for the protein streptavidin through luminescence and surface plasmon resonance studies. The results indicate the potential of these systems in reusable functional sensing systems.

The work presented develops three different branches of the supramolecular chemistry. Across the chapters that compose this thesis, results are discussed about different forms of self-assembled structures. The first chapter focus on obtaining nanostructured gels that are assembled due to the amphiphilic character of the gelator molecule. These gels are formed when compound 1•2Br is solubilised in a mixture of ethanol and water with adequate proportions. Due to the ability of the compound to complexate anions, we pursued the possibility of the formed gel to incorporate anions of therapeutic interest, namely anonic drugs. Ibuprofenate, indomethacin (anti-inflammatory drugs) and methotrexate (antitumor) could be incorporated within the gel fibbers (as confirmed by NMR) and could be released. Methotrexate showed differences comparing with the other two drugs: it render the gel more resistant and also presented a different release profile. The same molecule 1•2Br was also studied in the synthesis of gold nanoparticles. Following a biphasic method based on the Brust-Schiffrin method, 1•2Br could be used to obtain gold nanoparticles, filling the role of transfer agent and stabilizer. Due to the ability of 1•2Br to incorporate the drug, the same application was tested with the synthesized nanoparticles. Ibuprofenate was used as model, and could be successfully incorporated and released. Because the obtained nanoparticles were soluble in organic media, an alternative synthetic method was used in order to make them water soluble. These nanoparticles could also incorporate an anionic drug, piroxicam, which is poorly soluble in water. Besides the compound 1•2Br, an analogue with cyclic head was also used to obtain nanoparticles and could also incorporate ibuprofenate, but because this analogue has more affinity for anions, it retains more the ibuprofenate and releases less amounts. Nanoparticles were also obtained using 1•2Br in the form of gel, as template, and it was found that these had lower monodispersity and more uniform shapes than the ones obtained with 1•2Br in solution. It was also aimed the immobilization of peptides in gold nanoparticles, but because the nanoparticles with 1•2Br were not viable, they were synthesized through the citrate reduction method or synthesized in methanol. Different strategies were pursued for the immobilization using different thiols, the best results being obtained with the peptide bearing a chain with a thiol group on its end. In the same manner as the molecules assemble in the surface of the nanoparticles, they can also assemble in surfaces. Two different works regarding the self-assembly of monolayers on surfaces are discussed, one for obtaining layers with immobilized lanthanides that can be used as molecular thermometers, and other for the functionalization of surfaces and STM probe tips for the study of the interaction between biotin and streptavidin, serving as model to confirm that the studied tips can be used for the detection of intermolecular interactions. The affinity between antibodies anti-EGFR and their antigen were also assessed.
Aquesta tesi s’enfoca a trobar aplicacions de la química supramolecular en el camp de la Nanomedicina. Els processos supramoleculars permeten obtenir estructures amb una aproximació coneguda com “bottom-up”, que consisteix en la interacció d'unitats petites com àtoms, ions, molècules, formant unitats funcionals més grans. El nostre treball s’ha centrat en nanomaterials les estructures dels quals es poden formar mitjançant processos de autoassemblatge: hidrogels, nanopartícules d’or, o monocapes de biomolècules en superfícies. Els hidrogels es van obtenir amb un compost amb una estructura de tipus gemini basada en imidazoli que pertany a una família estructural que pot formar micel•les i té la capacitat de reconèixer i incorporar anions. Es va estudiar la possibilitat d'incorporar fàrmacs en el gel i alliberar aquests fàrmacs. Les corbes d’alliberament del fàrmac es van determinar in vitro. El mateix compost també es va utilitzar per sintetitzar partícules d’or en un sistema bifàsic. La seva natura anfifílica, pot exercir el doble rol d'agent de transferència de fase i estabilitzador. També es va provar amb ibuprofè la incorporació i alliberament de fàrmacs in vitro. També vam sintetitzar nanopartícules en aigua, que també van incorporar i alliberar in vitro un fàrmac model. També hem utilitzat anàlegs cíclics amb estructura de bis-imidazoli per sintetitzar nanopartícules en sistema bifàsic. Les nanopartícules poden incorporar l'ibuprofèn, però la quantitat que s’allibera és més baixa. Els gels obtinguts es van utilitzar com plantilla per la síntesi de les nanopartícules d’or, que van resultat amb dispersió de mida millorada. Addicionalment vam conjugar pèptids cíclics amb nanopartícules, sintetitzades amb dos mètodes alternatius: el mètode de citrat i en metanol. La síntesi es fa amb un tiol que conté un grup funcional que es va utilitzar per reaccionar amb els pèptids. Finalment una part de la tesi s’ha dedicat a la biofuncionalització de superfícies. Així, vam formar monocapes en superfícies amb polímers que es coordinen amb lantànids per construir termòmetres moleculars, i monocapes en superfícies i en puntes de sondes de microscopi de rastreig, seguida de conjugació amb biomolècules (biotina i avidina) amb l'objectiu de estudiar interaccions entre lligand i receptor.

This thesis describes the synthesis of interlocked anion host systems which exploit hydrogen bonding, halogen bonding, and lanthanide-coordination for anion recognition and sensing in aqueous solution. Chapter 1 introduces the field of anion supramolecular chemistry, with particular focus on areas of particular relevance to this thesis, namely anion recognition and sensing, anion templation and the synthesis of interlocked structures. Chapter 2 describes the synthesis of hydrogen bonding rotaxane and catenane hosts for recognising and sensing oxoanions in aqueous solvent media. The novel use of nitrate anion templation for the synthesis of interlocked molecules is reported, and the unprecedented selective recognition of nitrate in aqueous solvent media is demonstrated. Chapter 3 details the preparation of water soluble permethylated β-cyclodextrin-stoppered rotaxane hosts that utilise halogen bonding and hydrogen bonding interactions to bind anions in pure water. The first thermodynamic investigation into halogen bonding in water is reported, and the relative capabilities of halogen and hydrogen bonding for anion recognition in water are compared. Chapter 4 investigates the incorporation of lanthanide cations into rotaxane hosts for optical anion sensing. The seminal use of lanthanide cation templation for interlocked molecule synthesis is described, before anion templation approaches towards the synthesis of lanthanide-based rotaxanes are discussed. The luminescence anion sensing capabilities of these interlocked hosts are investigated. Chapter 5 describes the experimental procedures used in this work, and details the characterisation of compounds presented in Chapters 2–4. Chapter 6 summarises the conclusions of this thesis.

This thesis describes the synthesis of macrocyclic and interlocked receptors which exploit halogen- and hydrogen-bonding intermolecular interactions for anion recognition. Chapter One introduces the field of supramolecular chemistry, with particular focus on applications of host–guest chemistry to anion coordination and anion templation in the construction of mechanically interlocked molecules. Chapter Two details the synthesis of a series of cyclic and cage-like porphyrin-based receptors which bind anions through halogen- and hydrogen-bonding interactions. The ability of these receptor systems to bind and sense anionic guest species is investigated and comparisons between hydrogen- and halogen-bonding are discussed. Chapter Three reports anion-templated pseudorotaxane assemblies stabilised by both halogen- and hydrogen-bonding. The related catenanes are also prepared and their affinity for anions is investigated. The first examples of interpenetrated and interlocked architectures constructed by a single charge-assisted halogen bond are also reported. Chapter Four describes the synthesis of a 1,3-dialkyl-1,2,3-triazolium-containing threading component, whose anion binding properties are studied and compared with other threading molecules. The ability of this novel thread to form pseudorotaxanes is investigated and the preparation of the related rotaxane species is outlined. Chapter Five discusses attempts to prepare rotaxanes with improved anion binding affinities through increasing the lipophilicity of the anion binding clefts. Several novel rotaxanes are described and their anion binding properties are probed. Chapter Six describes the experimental procedures used in this work and the characterisation of compounds presented in chapters two to five. Chapter Seven summarises the conclusions of this thesis.

The synthesis, characterisation and anion binding properties of a series of mono- and bifunctional Lewis acidic borylferrocene compounds are described within this thesis. The original parent compound FcBMes₂ (3.1), revealed a versatile route for the synthesis of such borylferrocenes and subsequently the analogous compound Fc*BMes₂ (3.2) was synthesised. The anion binding properties of (3.1) and (3.2) were investigated and both were shown to bind one equivalent of cyanide. The binding event was signalled by an electrochemical shift (ca. -560 mV) and a quenching of bands at 510 or 542 nm respectively in the UV/Vis spectrum, while the mode of anion binding in the solid state was established by X-ray crystallography for [ⁿBu₄N]⁺[(3.1)·CN]⁻. Incorporation of a suitable redox active dye (i.e. tetrazolium violet for 3.2) allowed conversion of the electrochemical response to a colorimetric change on cyanide binding. However, a competing response for fluoride is also seen for (3.1) and (3.2). Thus a two component system is reported involving (3.2) and the boronic ester FcB(OR)₂ (3.4), [where (OR)₂ = OCH(Ph)CH(Ph)O], which from previous research is known to selectively bind fluoride, and allows for selective colorimetric cyanide sensing by simple Boolean AND/NOT logic. 1,4-C₆H₄(BMes₂)[B(OR)₂] (3.5), 4,4-C₁₂H₈(BMes₂)[B(OR)₂] (3.6) and 1,1′-fc(BMes2)(B(OR)2) (3.7) were synthesised as possible single molecules for discrimination between cyanide and fluoride. (3.5) and (3.6) proved only capable of binding one equivalent of either anion, (3.7) showed some ability to bind two equivalents of fluoride however based on ESI-MS studies although only in the presence of a large excess of anion. Systematic variation of the para-boryl substituent was investigated by synthesis of compounds FcB(Xyl^F)₂ (4.1), FcB(Xyl)₂ (4.2) and FcB(Xyl^OMe)₂ (4.3). Anion binding studies reveal a linear increase in fluoride binding affinity consistent with that expected based on the para,/em>-Hammett parameters, however with only minor differences, while no pattern is observed with respect to their cyanide binding capabilities. The addition of neutral and cationic peripheral substituents has been investigated through synthesis of [1,2-fc(CH₂NMe₂)BMes₂] (4.6) and [1,2-fc(CH₂NMe₃)BMes₂]⁺ (4.7). Subsequent binding studies revealed (4.6) to be moisture sensitive, however reaction of (4.7) with fluoride and cyanide led to formation of the adducts [(4.7)·F]⁻ and [(4.7)·CN]⁻. The anion affinity of (4.7) exhibits a substantial increase when compared to the parent compound (3.1). Even when compared to the isomeric 1,1′ system an increase of approximately three orders of magnitude is seen attributed to the closer nature of the cationic charge and in the fluoride adduct the presence of a cooperative intramolecular hydrogen bond. The 1,1′-bifunctional analogues of the mono-substituted systems were synthesised [e.g. 1,2-fc(BMes₂)₂ (5.1)] and shown to complex two equivalents of fluoride or cyanide in acetonitrile. The 1:1 cyanide adduct of (5.1) was isolated in chloroform however, no evidence for chelation was observed. The analogous systems 1,2-fc(BMes₂)₂ (5.5), 1,2-fc(BXyl₂)2 (5.7), and 1,2-fc(BMes₂)(BXyl₂) (5.8) were also investigated. Reaction of (5.5) with fluoride and cyanide revealed it to bind only one equivalent of either anion, neither however was bound in a chelating fashion although X-ray crystallography revealed cyanide binds exo whilst fluoride binds endo to the B···B cavity. Finally the kinetics of fluoride binding were studied by UV/Vis spectroscopy and showed a systematic increase in rate constant upon reduction of steric bulk.

The utility of fluorophores for sensing applications in the current state of the art of biological imaging hardly needs to be stated. The use of fluorophores in exploring and determining the internal structure and active dynamics of cellular processes has been pivotal, allowing us to explore areas of study inaccessible through other means. A simple search of fluorophores in Scifinder© demonstrates their popularity, as the number of hits increases year after year, until the year of 2015 when there were 1400+ journal articles published with the phrase. Fluorophore applications range far and wide, from sensing applications related to environmental concerns, to public health, to clinical usage. Fluorophores have been developed to detect explosive residues, to monitor environmental pollutants, and even to detect illicit substances. In cellular applications, a fluorophore needs to be well suited to examining the relevant processes, including participating in the cellular milieu and actively signifying the phenomena that are desired. Chapter I examines the usage of alkynes in fluorescent sensing scaffolds and gives a survey of their applicability in the field. Chapter II demonstrates the utility of disulfide-based macrocyclic scaffolds in the design of supramolecular hosts for chloride anions and their use as solid-state sensors for these anions. Chapter III explores the synthesis and application of an alkyne-based scaffold in the reversible detection of dithiol/disulfide redox flux and a new mode of quantification of dithiol-disulfide redox couples, a classically difficult area of study. Chapter IV focuses on methods utilized to improve the disulfide-based redox sensing capabilities. Chapters V and VI explore the properties of a new fluorophore scaffold discovered during research into another sensing scaffold, demonstrating a new reaction which yields a heretofore underexplored heterocycle with novel photophysical and supramolecular behaviors. This dissertation contains both previously published and unpublished co-authored material.

This thesis describes the synthesis and anion recognition properties of a variety of interlocked host receptors and the application of metal nanoparticles in the areas of catalysis and sensing. Chapter One introduces the field of anion supramolecular chemistry, with particular emphasis on areas relevant to the research discussed in later chapters. Following this, the synthesis and applications of metal nanoparticles are outlined. Chapter Two details the synthesis of a range of halo-triazolium based rotaxanes and explores the effects of altering both the halogen bond donor atom and degree of preorganisation on the anion recognition properties of the interlocked host system. A halogen bond containing catenane is also prepared and its anion binding properties investigated. Chapter Three initially reports the anion-templated synthesis of a series of neutral pyridine N-oxide axle containing rotaxanes before their ability to recognise anions in aqueous solvent mixtures is studied. Attempts to enhance anion binding through the incorporation of a positive charge into the macrocyclic component of the rotaxane structure are also explored. Chapter Four outlines the preparation of β-cyclodextrin functionalised metal nanoparticles and investigations of their catalytic and sensing properties. Chapter Five describes in detail the synthetic and analytical procedures discussed in chapters two to four. Chapter Six summarises the conclusions of this thesis.

This thesis describes the synthesis of halogen bonding receptors for integration within interlocked anion host systems. Chapter 1 introduces the field of supramolecular chemistry, with a particular focus on anion recognition and sensing, halogen bonding, and the synthesis of mechanically interlocked structures. Chapter 2 describes the preparation and anion binding properties of carbazole-based receptor molecules. A systematic anion binding study on a series of halogen- and hydrogen-bonding 3,6-bis-triazolium carbazole acyclic receptors is described initially, followed by the development of a halogen bonding rotaxane. The anion and metal complexation properties of acyclic and macrocyclic systems incorporating the 1,8-bis-triazole carbazole motif are also presented. Chapter 3 details the synthesis and anion complexation investigations of halogen and hydrogen bonding naphthalene-based acyclic and interlocked rotaxane host molecules. Chapter 4 presents receptors based on the 4,4'-bis-triazole-2,2'-bipyridyl motif. A halogen bonding rhenium(I) bipyridyl complex is exploited in the development of a rotaxane host system which optically senses anions via luminescence purely through halogen bonding interactions. The anion recognition and sensing properties of diquat-based receptors are also investigated, and shown to exhibit optical and electrochemical responses to anions. Chapter 5 summarises the major conclusions from Chapters 2-4. Chapter 6 describes the experimental procedures used in the work, and includes characterisation data for the synthesised compounds. Supplementary information relating to crystallographic data, and absorption, luminescence and electrochemical studies, is provided in the Appendices.

We have designed and synthesized boradiazaindacene (BODIPY) derivatives, appropriately functionalized for metal ion mediated supramolecular polymerization. Thus, ligands for 2- and 2,6-terpyridyl and bipyridyl functionalized BODIPY dyes were synthesized through Sonogashira couplings. These new fluorescent building blocks are responsive to metal ions in a stoichiometry dependent manner. Octahedral coordinating metal ions such as Zn(II), result in polymerization at a stoichiometry which corresponds to two terpyridyl ligands to one Zn(II) ion. However, at increased metal ion concentrations, the dynamic equilibria are re-established in such a way that, monomeric metal complex dominates. The position of equilibria can easily be monitored by 1H NMR and fluorescence spectroscopy. As expected, open shell Fe(II) ions while forming similar complex structures, quench the fluorescence emission of all four functionalized BODIPY ligands.

Supramolecular chemistry is an emerging field of chemistry which has attracted much attention in recent years as a result of its broad applicability in many areas. Thus, the design of functional supramolecular systems is strongly in demand in this field. For this purpose, we have developed near-IR emitting ratiometric fluorescent chemosensors for transition metal ions. Judicious placement of dithiodioxaazamacrocycles on the BODIPY chromophore generates this chemosensor which is selective for Hg(II) ions and both absorption and emission spectra display large changes that would allow ratiometric sensing.

Los complejos “metalosalen” [salen = N,N’-bis(salicilideno)etilendiamina] han sido objeto de estudio en la catálisis homogénea y últimamente también en la ciencia de materiales y catálisis multimetálica. En cuanto a esto, hemos explorado el potencial de los complejos “salfen” [N,N’-bis(salicilideno) fenilendiamina] centrados en Zn(II) como componente en el desarrollo de nuevos materiales y sistemas multimetálicos. Los primeros capítulos de esta tesis proporcionan una mejor comprensión sobre las propiedades de estos complejos y esto es seguido por aplicación como detector quiral y estudios de comportamiento de autoensamblaje. Los últimos capítulos se centran en sistemas metalosalen multimetálicos mediante enfoques supramolecular y covalente para su aplicación en la catálisis cooperativa. Este tesis demuestra el potencial de los compuestos salen para su aplicación en ciencia de materiales y catálisis cooperativa.
Metallosalen complexes [salen = N,N’-bis(salicylidene)ethylenediamine] have been well-studied in homogeneous catalysis and lately reveive inceasing interest in materials science and multimetallic catalysis. In view of this, we have explored the potential of Zn(II)-centered salphen [N,N’-bis(salicylidene)phenylenediamine] complexes as a building block in the development of new materials and multimetallic systems. The first chapters of this thesis provide a better understanding of the properties of these complexes and this is followed by application as a chiral sensor and studies of their self-assembly behavior. The last chapters focus on multimetallic metallosalen systems for application in cooperative catalysis using supramolecular and covalent approaches. This thesis illustrates the potential of metallosalen complexes for application in materials science and cooperative catalysis

La presente tesis doctoral titulada “Materiales de sílice funcionales para la liberación controlada, detección y eliminación de moléculas de interés” se centra en el diseño y desarrollo de materiales híbridos orgánico-inorgánicos mediante la aplicación de los conceptos de Química Supramolecular. Durante el desarrollo de la presente tesis doctoral se han preparado y caracterizado diferentes materiales de base silícea para distintas aplicaciones. La primera parte de la tesis se centra en el desarrollo de materiales de base silícea capaces de variar su comportamiento fluorescente en función de la presencia o ausencia de un cierto analito en el medio. Estos materiales emplean como soporte nanopartículas de sílice que se funcionalizan superficialmente con dos unidades diferentes, una coordinante y una indicadora (un fluoróforo). La interacción del analito de interés (en nuestro caso aniones) con la unidad coordinante modificará las propiedades emisivas del fluoróforo. Así, se han preparado dos materiales en los cuales el grupo fluorescente es rodamina mientras que el grupo coordinante es un imidazolato o una sal de guanidinio respectivamente. Una vez caracterizados ambos materiales se estudió su comportamiento frente a diferentes especies aniónicas a diferentes concentraciones resultando selectivos a la presencia de benzoato (el material funcionalizado con imidazolatos), dihidrógeno fosfato e hidrógeno sulfato (el material funcionalizado con sales de guanidinio). El tercer capítulo de la tesis se centra en la aplicación de materiales híbridos orgánico-inorgánicos para la detección y eliminación de especies altamente tóxicas como son los agentes neurotóxicos. Estos son compuestos organofosforados capaces de causar graves lesiones en el sistema nervioso central. En una primera aproximación se emplea el concepto de puerta molecular para la detección de agentes neurotóxicos. Para ello, se utiliza como soporte inorgánico un material mesoporoso de sílice (MCM-41) cuyos poros se cargan con un colorante que actúa de indicador mientras que la superficie externa del mismo se funcionaliza con una molécula capaz de reaccionar con dichos agentes neurotóxicos. Dicha molécula es capaz de interaccionar entre sí (mediante enlaces de hidrógeno) formando una red que mantiene bloqueada la salida de los poros. En presencia de DCP (dietilclorofosfato, un simulante de agente neurotóxico), y después de que este reaccione con dicha molécula, se produce una reorganización espacial que permite la liberación del colorante. De este modo, la presencia de los agentes neurotóxicos está señalizada mediante un cambio de color. En una segunda aproximación se aborda el uso de soportes inorgánicos de tipo MCM-41 como materiales para la eliminación de agentes neurotóxicos. Para ello se modificaron químicamente las superficies de estos materiales silíceos mediante tratamiento con distintas bases. Como consecuencia de este tratamiento básico los silanoles de la superficie se desprotonan dando lugar a los correspondientes silanolatos (nucleófilos fuertes). Estos silanolatos son capaces de reaccionar con los agentes neurotóxicos descomponiéndolos y favoreciendo su eliminación de un medio contaminado. Por último, se estudia la aplicación de materiales híbridos orgánico-inorgánicos funcionalizados con puertas moleculares en aplicaciones de liberación controlada, concretamente, en liberación controlada intracelular de fármacos de interés. El material híbrido consta de un soporte de sílice mesoporosa cuyos poros se cargan con un compuesto citotóxico (camptotecina) y su superficie externa se funcionaliza con una gluconamida. La presencia de una monocapa densa de gluconamidas por el exterior del material inhibe la liberación del compuesto citotóxico. Al añadir enzimas con capacidad para hidrolizar enlaces amida (amidasa y pronasa) se produce la liberación de la camptotecina. El correcto funcionamiento del material se comprobó in vitro e in vivo (en células HeLa).
Candel Busquets, I. (2014). Functional silica materials for controlled release, sensing and elimination of target molecules [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/39101
TESIS

[EN] Abstract The present PhD thesis entitled "Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules" is based on the application of supramolecular chemistry and material science principles for the development of optical chemosensors for anions and neutral molecules detection. The second chapter of this PhD thesis is devoted to the preparation of chemodosimeters for the chromo-fluorogenic detection of fluoride, diisopropyl fluorophosphates (DFP) and hydrogen sulfide. The optical detection of fluoride anion was achieved by using a pyridine derivative containing a t-butyldimethylsilyl ether group. Aqueous solutions of the chemodosimeter were colorless but turned yellow upon addition of fluoride anion. Also a remarkable enhancement in emission was observed only upon the addition of fluoride. The optical changes were ascribed to a fluoride-induced hydrolysis of the silyl ether moiety. Also a chemodosimeter for the optical recognition of DFP, a nerve agent simulant, was prepared. In this case, the chemodosimeter was based on a stilbene pyridinium derivative functionalized with hydroxyl and silyl ether moieties. Aqueous solutions of the chemodosimeter were colorless changing to yellow upon DFP addition. The optical changes were ascribed to a hydroxyl phosphorylation followed by a fluoride-induced hydrolysis of the silyl ether group. Besides, that probe was implemented in test strips and DFP detection in gas phase was accomplished. Finally, the fluorogenic recognition of hydrogen sulfide anion was explored. For this purpose different fluorophores were selected and fucntionalized with 2,4-dinitrophenyl ether groups. The prepared probes were neraly non-emissive but remarkable emission enhancements upon addition of hydrogen sulfide were observed. The emission enhancements observed were due to a selective sulfide-induced hydrolysis of the 2,4-dinitrophenyl ether moiety that yielded the free fluorophores. Another set of chemodosimeters equipped with azide and sulfonylazide moieties were prepared. Again these probes were non-fluorescent but upon addition of hydrogen sulfide an important enhancement in emission was found. The selective response was ascribed to a reduction of the azide and sulfonylazide moieties to amine and sulfonylamide induced by hydrogen sulfide anion. Besides, the viability assays showed that these dosimeters were essentially non-toxic and real-time fluorescence imaging measurements confirmed their ability to detect intracellular hydrogen sulfide at micromolar concentrations. The third chapter of this PhD thesis was devoted to the preparation of nanoscopic gated materials and their use in sensing protocols. In a first step a gated material for the optical detection of glutathione (GSH) was prepared. For this purpose MCM-41 mesoporous silca nanoparticles were selected as inorganic scaffold. The pores were loaded with safranine O and the external surface was functionalized with disulfide-containing oligo(ethylene glycol) moieties. Dye delivery from aqueous suspensions of the sensory material was only observed in the presence of GSH. The signalling paradigm was ascribed to the selective reduction of the disulfide bond by GSH which induced pore opening and dye release. Also capped organic-inorganic hybrid materials for the selective detection of hydrogen sulfide were prepared and characterized. In this case the same MCM-41 support was used and charged with [Ru(bipy)3]2+ dye. Then, the external surface was functionalized with Cu(II)-macorcyclic complexes and finally, the pores were capped by the addition of the bulky anion hexametaphosphate. Aqueous suspensions of this material showed negligible dye release whereas in the presence of hydrogen sulfide anion a remarkable colour change was observed. This optical response was ascribed to a demetallation process of the Cu(II) complex induced by hydrogen sulfide.
[ES] Resumen La presente tesis doctoral titulada "Química supramolecular: Nuevos dosímetros químicos y materiales híbridos para la detección cromo-fluorogénica de aniones y moléculas neutras." está basada en la aplicación de principios básicos de la química supramolecular y de la ciencia de materiales en el desarrollo de sensores ópticos para aniones y moléculas neutras. El segundo capítulo de esta tesis doctoral está dedicado a la preparación de dosímetros químicos para la detección cromo-fluorogénica de fluoruro, diisopropil fluorofosfato (DFP) y sulfuro de hidrógeno. Para la detección óptica del anión fluoruro se sintetizó un derivado de piridina funcionalizado con un t-butildimetilsilil éter. En este capítulo también se describe la preparación de un dosímetro químico para la detección de DFP, que es un simulante de agentes nerviosos. Este dosímetro está basado en un estilbeno funcionalizado con una sal de piridinio que contiene grupos hidroxilo y silil éter en su estructura. Finalmente se prepararon dos familias de sensores para la detección óptica de hidrógeno sulfuro. La primera familia de sensores consiste en fluoróforos comunes funcionalizados con 2,4-dinitrofenil éteres. Los sensores preparados no presentaron una emisión de fluorescencia importante mientras que, en presencia del anión hidrógeno sulfuro, se observó un aumento significativo. La segunda familia de dosímetros también estaba compuesta por ciertos fluorofóros pero, en este caso, funcionalizados con grupos azida y sulfonilazida. Los dosimétros preparados, siguiendo esta segunda aproximación, tampoco dieron una fluorescencia significativa observándose un aumento de la misma al añadir el anión hidrógeno sulfuro. El tercer capítulo de esta tesis doctoral está dedicado a la preparación de materiales híbridos nanoscópicos funcionalizados con puertas moleculares y su aplicación en protocolos de reconocimiento. En primer lugar se preparó un material para la detección óptica de glutatión (GSH). Para ello se emplearon nanopartículas de MCM-41 mesoporosas como soporte inorgánico. Los poros del soporte fueron cargados con el colorante safranina O y la superficie externa funcionalizada con oligo(etilenglicol) conteniendo enlaces disulfuro. También se prepararon y caracterizaron varios materiales híbridos para la detección selectiva del anión hidrógeno sulfuro. En este caso también se empleó, como soporte inorgánico, sílice mesoporosa MCM-41. Los poros del soporte inorgánico fueron cargados con [Ru(bipy)3]2+ y la superficie externa funcionalizada con varios complejos macrocíclicos de Cu(II). El material sensor final fue obtenido al añadir el anion hexametafosfato, que compleja con los complejos de Cu(II), produciendo un bloqueo de los poros.
[CAT] Resum La present tesi doctoral titulada "Química supramolecular: Nous dosímetres químics i materials híbrids per a la detecció cromo-fluorogènica d'anions i molècules neutres." està basada en l'aplicació dels principis bàsics de la química supramolecular i de la ciència dels materials en el desenvolupament de sensors òptics per a anions i molècules neutres. El segon capítol d'aquesta tesi doctoral està dedicat a la preparació de dosímetres químics per a la detecció cromo-fluorogènica de fluorur, diisopropil fluorofosfat (DFP) i sulfur d'hidrogen. Per a la detecció òptica de l'anió fluorur es va sintetitzar un derivat de piridina funcionalitzat amb un t-dibutildimetilsilil èter. En aquest capítol també es descriu la preparació d'un dosímetre químic per a la detecció de DFP, que és un simulant d'agents nerviosos. Aquest dosímetre està basat en un estilbè funcionalitzat amb una sal de piridina que conté grups hidroxil i silis èter en la seua estructura. Finalment varen ser preparades dues famílies de sensors per a la detecció òptica de sulfur d'hidrogen. La primera família consisteix en fluoròfors comuns funcionalitzats amb 2,4-dinitrofenil èters. Els sensors preparats no presentaren una emissió de fluorescència significativa mentre que, en presencia de l'anió hidrogen sulfur, es va observar un augment significatiu. La segona família de dosímetres també estava composada per certs fluròfors però, en aquest cas, funcionalitzats amb grups azida i sulfonilazida. Els dosímetres preparats, seguint aquesta segona aproximació, tampoc donaren una fluorescència significativa observant-se un augment de la mateixa al afegir l'anió hidrogen sulfur. El tercer capítol d'aquesta tesi doctoral està dedicat a la preparació de materials híbrids nanoscòpics funcionalitzats amb portes moleculars i la seua aplicació en protocols de reconeixement. En primer lloc es va preparar un material per a la detecció òptica de glutatió (GSH). Per a aquest propòsit es varen emprar nanopartícules MCM-41 mesoporoses com a suport inorgànic. Els porus del suport varen ser carregats amb el colorant safranina O i la superfície externa funcionalitzada amb oligo(etilenglicol) que contenia enllaços disulfurs. També varen ser preparats i caracteritzats diversos materials híbrids per a la detecció selectiva de l'anió hidrogen sulfur. En aquest cas també es va emprar, com a suport inorgànic, sílice mesoporosa MCM-41. Els porus del suport inorgànic varen ser carregats amb [Ru(bipy)3]2+ i la superfície externa funcionalitzada amb diversos complexos macrocíclics de Cu(II). El material sensor final es va obtindre al afegir l'anió hexametafosfat, que es complexa amb macrocicles de Cu(II), produint un bloqueig dels porus.
El Sayed Shehata Nasr, S. (2015). Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52598
TESIS

Rational design of fluorescent chemosensors is an active area of supramolecular chemistry, photochemistry and photophysics. Ratiometric chemosensors are even more important, as they have an internal system for selfcalibration. In order to develop a new methodology for a ratiometric chemosensor design, we proposed coupling of energy transfer phenomenon to ion sensing. In this study, we targeted energy transfer cassette type chemosensors, where the efficiency of transfer is modulated on the donor side, by metal ion binding which changes the spectral overlap. This work involves the synthesis of a number of EET systems with varying degrees of EET efficiency. The results suggest that this strategy for ratiometric ion sensing is a promising one, enabling a modular approach in chemosensor design.

El presente proyecto de investigación está enfocado al desarrollo de sensores químicos fluoro-cromogénicos, para la detección y determinación de especies químicas de interés biológico, industrial y medioambiental de forma selectiva y con alta sensibilidad. En forma general, se busca el diseñar nuevos sistemas sensores basados en compuestos (receptores) formados por dos unidades: una unidad coordinante que interacciona con el anión a determinar y una unidad generadora de señal que alerta del reconocimiento molecular efectuado. Durante este estudio se están preparando diversas moléculas receptoras funcionalizandas con grupos modificadores de estructura para evaluar su influencia sobre las capacidades de detección y selectividad como receptores de especies específicas en diferentes condiciones y medios. Las diferentes aproximaciones en prueba implican a su vez el diseño y síntesis molecular, así como el análisis de las diferentes señales ópticas producidas en el reconocimiento, con el fin de diseñar sistemas de alta eficacia y eficiencia, y con posibilidades reales de aplicación.
Santos Figueroa, LE. (2014). New approaches for the development of chromo-fluorogenic sensors for chemical species of biological, industrial and environmental interest [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/43216
TESIS
Premiado

In chapter 1 the principles behind circular dichroism spectroscopy and exciton coupled circular dichroism spectroscopy are outlined, and examples are cited that illustrate the utility of these methods in the determination of absolute configuration and ee of chiral amines. This provides background and context for this thesis, which mostly pertains to the sensing of chirality in amines. An exciton coupled circular dichroism method based on the induction of helical chirality in an organometallic host for sensing chiral amines is presented in chapter 2. The method can be used to determine absolute configuration by relating the sign of the first Cotton effect of the host-amine complex to the handedness of the amine. Analysis of the primary circular dichroism optical data is by principal component analysis allows for differentiation of the analytes based on their idendity and handedness. A novel circular dichroism method for detecting chiral amines is discussed in chapter 3. The method uses a highly efficient derivatization method to convert the primary amine into a bidentate imine. Three equivalents of the imine are then assembled together by coordination to Fe(II). The proximity and chiral orientation of the imines leads to exciton coupled circular dichroism, which is of utility in the determination of absolute configuration. Additionally, there is a metal-to-ligand charge transfer band in the visible region that can be used to develop calibration curves, which allow for the determination of the enantiomeric excess of unknown samples with an absolute error of ±5%. Chapter 4 details another imine based circular dichroism method for chiral amines. The method uses a commercially available aldehyde, Fe(II), and circular dichroism spectrometry to sense chirality in amines. It is shown that the circular dichroism signals in the ultraviolet spectrum vary predictably with the handedness of the chiral amine, which has potential applications in the determination of absolute configuration. By developing calibraton curves, signals in the visible spectrum can be used to determine enantiomeric excess with an absolute error of ±6%. Analyzing the primary circular dichroism optical data with linear discriminant analysis allows for differentiation between amines based on their identity and handedness. Finally, chapter 5 illustrates the potential of using the thermodynamic parameters of partitioning between water and octanol as a predictive tool for estimating the contributions of hydrophobicity to host-guest binding events. This is done by showing a relationship between the thermodynamics of partitioning and thermodynamics of hydrophobic binding events for a series of guests and cyclodextrin. A plot of the thermodynamic parameters of binding of a variety of guests to cyclodextrin as a function of the thermodynamic parameters of partitioning between water and octanol shows a linear relationship for a series of alcohols.
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This dissertation consists of four chapters. The first chapter provides an in-depth background of synthetic receptors for recognitions of phosphorylated molecules. This chapter covers synthetic receptors developed within the last two decades, and it focuses on the diverse functionalities and detection techniques involved in the receptor design. Chapter 2 discusses the synthesis and employment of a metalated receptor for the selective recognition of organic phosphates and phospho-amino acids, and describes a receptor with a pseudo tetrahedral cavity, which was found to be selective to phosphate, was synthesized utilizing a new and efficient synthetic route. UV-Vis titrations were used to determine binding constants for various organic phosphates and phospho-amino acids. The receptor:Cu(II) complex was found to differentiate the degree and size of phosphate substitutions. Chapter 3 describes the synthesis and application of a type of differential receptors for the recognition of phosphorylated tri-peptides from regular tri-peptides. The tri-peptide couples described in this chapter were part of sequences in protein Filamentous R-synuclein, which was discovered to have a close relation to Parkinson's disease. Extensive Ser129 phosphorylation was observed in diseased brains. Both solid phase and solution phase differential receptors were obtained in the investigations of peptide differentiation. A series of screening methods were applied to narrow down the system combinations. Linear discrimant analysis (LDA) statistical analysis generated a large spatial separation among six tripeptides. Chapter 4 describes the synthesis of a boronic acid based receptor for carboxy and phospho sugars recognition. Due to the large affinity to gluconic acid, which is the only product of enzyme catalyzed glucose oxidation, this receptor was successfully applied in determination of glucose concentration in human serum.

The focus of the research presented in this thesis is the design, synthesis, and anion recognition properties of a structurally novel class of poly(amides) that incorporates the diaminocyclobutenedione (squaramide) group into the polymer backbone. In Chapter 1, a brief overview of different anion-responsive synthetic macromolecules is presented. Emphasis is placed on the wide structural diversity of the polymers, the mechanisms of their anion-induced responses, and features such as signal amplification, multivalency, and cooperative behavior that can be exploited productively in the context of anion recognition and sensing. Chapter 2 describes a new method for the regioselective preparation of squaramides, using Lewis acid-catalyzed condensations of diethyl squarate and different anilines. Zinc trifluoromethanesulfonate promotes efficient condensations of anilines with squarate esters, providing access to symmetrical and unsymmetrical squaramides in high yields from readily available starting materials. Colorimetric anion-sensing behavior and computational studies illustrating the enhanced hydrogen bond donor ability and acidity of squaramides in comparison to ureas are presented. In Chapter 3, the application of the synthetic method described above to the selective preparation of polysquaramides composed of 1,2-isomeric repeat units is described. The optical, thermal and aggregation properties of these materials are also discussed. Finally, Chapter 4 describes self-assembly properties as well as applications of these materials in the area of anion recognition and sensing. Incorporating an anion-binding squaramide group into a polymeric architecture results in drastic alterations in the selectivity and magnitude of its anion-induced response, resulting in a sensitive and discriminating turn-on fluorescence sensor for dihydrogenphosphate ions. This unusual behavior is the result of a cooperative, anion-triggered aggregation process that was further probed by dynamic light scattering (DLS), transmission electron microscopy (TEM) and laser confocal microscopy.

The thesis entitled “New Supramolecular Ion Sensing Probes and their Application in the Detection of Environmentally Relevant Ions” deals with the design and synthesis of several small molecular probes which can specifically sense environmentally relevant ions of (anion or cation) particularly in aqueous or biological medium. The probes have been designed using four different molecular entities which include anthraquinone, oxidized bis-indolyl system, pyrene and rhodamine. The probes afford naked eye detection of a particular ion in the aqueous medium. This work has been divided into six chapters. Chapter 1. Introduction The first chapter gives a brief idea of ion sensor. It provides the description of various approaches used for designing molecular sensors. The chapter further presents an overview of the four different dyes (anthraquinone, oxidized-bis-indole, pyrene and rhodamine) used for designing probes in this work. The properties of these probes, their advantages and disadvantages to use as a signaling subunit have been discussed. This chapter also describes the use of micellar medium for solubilizing different organic dyes in water. Chapter 2. Colorimetric Probes based on Anthraimidazolediones for Selective Sensing of Fluoride and Cyanide ion via Intramolecular Charge Transfer. The second chapter describes the design and synthesis of four different probes based on anthra [1, 2-d] imidazole-6, 11-dione. The anthraquinone part of each molecule has an acceptor moiety whereas substituted nitrogen linked aromatic unit forms the donor site. Each probe acted as strong colorimetric sensor for fluoride and cyanide ion detection and exhibited intramolecular charge transfer (ICT) band which showed significant red-shifts after addition of either the F¯ or CN¯ ion. One of the probes 2 showed selective colorimetric sensing for both cyanide and fluoride ions. In organic medium 2 showed selective color change with fluoride and cyanide, whereas in aqueous organic medium it showed a selective ratiometric response towards cyanide ion. The effect of anionic charge (on the donor moiety) on ICT has been discussed. Among the various donor moieties, the donor site having negative charges on them was found to disperse greater electron density on them. Figure 1. Molecular structures of the sensors Chapter 3 deals with chemodosimetric detection of cyanide ion in water using various oxidized bis-indole based compounds. Chapter 3A. A Chemodosimetric Probe based on a Conjugated and oxidized Bis¬ indolyl System for Selective Naked Eye Sensing of Cyanide ion in Water. The chapter 3A describes the design and synthesis of a new water-soluble bis-indolyl based probe, 5 which possesses two –COOH groups. This probe specifically reacted with the CN¯ ion in pure water at ambient temperature and produced a remarkable change in color from red to colorless. The mechanism of this process was investigated by NMR (1H, 13C and DEPT-135) spectroscopy, mass spectrometry and kinetic studies. The mechanism investigation showed that the cyanide ion reacts with the probe and removes the conjugation of the bis-indolyl moiety of the probe with that of the 4-substituted aromatic ring which renders the probe colorless. Taken together a plausible mechanism of the reaction was presented which showed to operate via a Michael type adduct formation under ambient conditions of pH and temperature in water. The probe gave a detection limit of 0.38 ppm for detection of cyanide ion in water. Figure 2. Molecular structure of the probe 5. Chapter 3B. Micelle Assisted ppb level Detection of Cyanide ion in Water by Chemodosimetry and Visual detection of the Endogenous Cyanide. The chapter 3B deals with the synthesis of a bis-indole based colorimetric probe 6. The probe showed selective detection of the cyanide ion in water at ppb level and a visible detection of endogenous cyanide from cassava (a major staple food in the developing world) by chemodosimetry. The cyanide ion binds with the probe 6 in a chemodosimetric fashion and follows pseudo first-order kinetics in water under appropriate conditions. It showed a highly sensitive detection of the cyanide ion in water with a detection limit of 0.33 ppm. The use of the micellar medium improved the detection limit drastically and a ppb level detection limit was achieved. The probe also showed the detection of the endogenously bound cyanide in cassava both visually and by spectrophotometer. Figure 3. Molecular structure of the probe 6. Chapter 3C. Ratiometric Cyanide ion probe in Water and for the detection of the Endogenously bound cyanide. Chapter 3C presents the synthesis of two new bis-indolyl (7 and 8) based probes for colorimetric detection of cyanide ion in pure water. Compound 8 showed a ratiometric response with cyanide in water and a visual detection of the endogenously bound cyanide ion in cassava. Using compound 8 the selective detection of the cyanide ion in water was achieved with a detection limit of ~ 17 ppb which is almost 13 times lower than the permitted limit as specified by EPA, United States. 7; R = H 8; R = -(OCH2CH2)3CH3 Figure 4. Molecular structures of the probes 1 and 2. Chapter 4 deals with the colorimetric and ratiometric detection of the Cu2+and Hg2+ions using different small synthetic molecular probes. Chapter 4A. Colorimetric Sensors for Ratiometric Detection of Copper and Mercury ions in Biological media and below ppm level in Water. The chapter 4A deals with the synthesis of two novel colorimetric probes (9, 10) using bispicolyl unit as the binding moiety and anthraimidazolediones and bis-indolyl system as a signaling sub-unit. Using the two sensors, Cu2+ion can be detected below the permitted limit (1.3 ppm) in both drinking water and at physiological pH 7.4. Sensor 9 can detect both Cu2+and Hg2+ in water with very low detection limit. It showed specific binding with Cu2+ at physiological pH 7.4 and in presence of serum albumins. Chemosensor 10 can be used for the specific detection of both Cu2+and Hg2in water as well as for the contamination in microorganisms. Figure 5. Molecular structure of the sensors 9 and 10. Chapter 4B. A New Molecular Probe for the Selective Sensing of Cu2+ and Hg2+ ions in Micellar Media and in Live ells.This chapter describes a synthesis of a novel bispicolyl based sensor 11 which can detect Cu2+ ion specifically in water medium and both Cu2+ and Hg2+ ions selectivelyin Brij-58 micellar medium. In micellar medium both the ions can be detected in the ppb level. Using fluorescence spectroscopy these two metal ions can be discriminated.The probe is also be useful for checking metal ion contamination in cellular samples. Figure 6. Molecular structure of the sensor 11. Chapter 4C. Rhodamine based Sensors for Cu2+ and Hg2+ ions in Water and in Biological media. The chapter 4C presents the synthesis and the sensing properties of the three positional isomers of the pyridine end of the rhodamine-pyridine compounds (12-14). The three isomers only differ in the position of nitrogen of the pyridine moiety. Sensor 12, which contains the pyridine nitrogen at the ortho-position showed selective sensing toward Cu2+ ion in both pure water and in buffered physiological media of pH 7.4. It gave a detection limit of ~13 ppb which is 100 times lesser than the EPA permitted limit. The other two sensors 13 and 14, which possessed the pyridine ends with the nitrogen atom at the meta- and the para- positions respectively showed the selective sensing of Hg2+ ion in water and did not show any interaction with the Cu2+ ion. Probes 2 and 3 showed ‘turn-on’ detection of Hg2+ ion both in the UV-vis and the fluorescence emission spectroscopy. Compound 2 and 3 showed a detection limit of ~ 9 and 4 ppb respectively. The NMR titration showed the change in color was due to the opening of the spirolactam ring of the rhodamine. The sensors can also be used for the detection of Cu2+ and Hg2+ ion in real life water samples and in the live cells. Figure 7. Molecular structure of the sensors 12, 13 and 14. Chapter 5. Ratiometric and ppb level Detection of Toxic Transition Metal ions using a Single Probe in Micellar media. This chapter describes the selective sensing of multiple ions using a single probe 15. The probe incorporates pyrene and pyridine as signaling and interacting moiety respectively. The sensor showed different responses towards different metal ions just by varying the medium of detection. In organic solvent (acetonitrile), the probe showed selective detection of Hg2+ ion. In water the fluorescence quenching was observed with three metal ions, Cu2+, Hg2+ and Ni2+. Further just by varying the surface charge of different micellar media, the probe showed selective interaction with Hg2+ ion in neutral micelles (Brij-58). However, in anionic micellar medium (SDS), the probe showed selective changes with both Cu2+ and Ni2+ in the UV-vis spectroscopy. The discrimination between these two ions was achieved by emission spectroscopy, where it showed selective quenching only with Cu2+. Thus using a single probe all the three metal ions Cu2+, Hg2+ and Ni2+ can be detected and discriminated just by varying the surface charge of the micellar medium. Figure 8. Molecular structure of the sensors 15. Chapter 6. Highly sensitive Rhodamine Based Dual Probes for the Visual detection of F¯ and Hg2+ ions in Water. This chapter deals with the design and synthesis of two new rhodamine based probes (16-17) which act as dual probes for the ppb level selective detection of Hg2+ and F¯ ions in water and at physiological pH 7.4. The two probes were synthesized by coupling tert-butyldiphenylsilyl (TBDPS) protected forms of 4-hydroxybenzaldehyde and 2, 4- dihydroxy benzaldehyde with rhodamine hydrazone. The F¯ ion detection is based on the desilylation of the probe, whereas the spirolactam ring opening leads to the detection of Hg2+ ion. The two probes gave turn-on detection of both Hg2+ and F¯ ion selectively in aqueous medium with the detection limit well below the EPA permitted limits. The probes showed detection of both the ions by dual mode with visibly different color and fluorescence under UV-lamp. The F¯ ion interacts with the silyl bond of probe and the cleavage results into yellow color whereas; the addition of Hg2+ ion to the probe solution opened the spirolactam ring and resulted into appearance of pink color. Figure 9. Molecular structure of the probes 16 and 17. (For structural formula pl see the abstract file)

Chapter 1: Luminescence property of lanthanide and its applications Lanthanides are well-known for their unique luminescence property and have found widespread applications in sensing, bioimaging, lasers, optoelectronic devices, etc. Due to Laporte forbidden f-f transitions, lanthanides have very low intrinsic emission. The problem can be overcome by use of an ‘antenna’, which is an organic chromophore with excited state energy higher than the lanthanides’ emitting levels. Thereby it is possible to get highly emitting lanthanide complexes through energy transfer from the ‘antenna’. Due to long lifetime of lanthanides’ excited states, it's possible to perform time delayed measurement which is useful in bioassays and bioimaging since the short-lived background emission is effectively filtered. Research in supramolecular metallogels has grown rapidly in recent years, and already proven to have potential for designing advanced materials for a variety of applications, such as sensing, optoelectronics, catalysis, nanoparticle synthesis, biomedicine etc. A supramolecular gel where a lanthanide is an integrated part of it can combine the advantages of the supramolecular gel along with the unique property of lanthanide luminescence and thus such materials can be explored for potential applications. This chapter discusses the background information on the unique luminescence of lanthanides, and some examples of the applications of lanthanide complexes and lanthanide based gels. Chapter 2: Lanthanide luminescence based enzyme sensing in hydrogels This chapter describes the use of Tb/Eu luminescence in the sensing of biologically important enzymes. We discovered the sensitization of Eu(III) in Eu-cholate gel by 1-hydroxypyrene, and of Tb(III) in Tb-cholate gel by 2,3-dihydroxynaphthalene. These two sensitizers were covalently modified and sensitizer-appended hybrid (artificial) enzyme substrates were prepared for a few biologically important hydrolases. The covalently modified sensitizer termed as “pro-sensitizers”, didn't sensitize Tb(III)/Eu(III) in the hydrogel and no photoluminescence was observed. In the presence of the appropriate enzyme in the hydrogel, the pro-sensitizer was cleaved to liberate the sensitizer, which led to an enhancement of luminescence with time. Alkaline phosphatase and β-lactamase were assayed using pyrene phosphate and pyrene-oxo-cephalosporanic acid derivatives, respectively, in Eu-cholate hydrogel (Figure 1). β-Galactosidase was assayed using Tb(III) luminescence in Tb-cholate gel. The enzyme detection was based on red/green luminescence response from the gel. To understand the behaviour of the enzymes in the hydrogel, kinetic parameters were determined. The detection of different enzymes was also demonstrated in natural/biological samples like blood serum, milk and almond extract. Figure 1. Three different pro-sensitizers used for alkaline phosphatase, β-lactamase and β-galactosidase assays Chapter 3: Enzyme sensing on paper discs using lanthanide luminescence Developing a user-friendly biosensor is of considerable importance in clinical and analytical chemistry. Paper based biosensor design is an emerging field of research and paper based point of care (PoC) testing devices have already found applications in clinical, veterinary, environmental, food safety, security etc. Paper is made out of natural cellulose fibres, and has advantages of low cost, biodegradability, biocompatibility, and user friendliness. Paper based sensors have been used for the detection of ions, glucose, proteins, nucleic acids, antigens etc., with mostly colorimetric, fluorescent, electrochemical, chemiluminescence and Electrochemiluminescence readouts. In this work, the non luminescent Tb(III) and Eu(III) were embedded on paper as their cholate hydrogels and were used for detecting different hydrolases. Pro-sensitizers, as reported in Chapter 2, were immobilized on paper for the detection of a specific enzyme. The “pro-sensitizer” released the sensitizer upon enzyme action and led to luminescence enhancement from the gel coated paper disc. By this way, four different hydrolase enzymes detection were carried out using Tb(III)/Eu(III) luminescence as the readout (Figure 2) and the practical utility was demonstrated by the detection of specific enzymes in natural/biological samples. This paper disc based enzyme sensing provides a simpler and user friendly approach over the contemporary approach of enzyme sensing typically carried out in solution. Figure 2. Paper based biosensors for hydrolase enzymes Chapter 4: Luminescence resonance energy transfer in self-assembled supramolecular hydrogels Luminescence resonance energy transfer is a phenomenon of energy transfer between a FRET (Förster resonance energy transfer) pair, where a lanthanide is the donor. Lanthanides have attracted attention for the last several decades for their unique luminescence properties. LRET is a FRET process along with added advantages of Lanthanides, i.e. long lifetime of the lanthanides and characteristics emission spectra. LRET has been used for studying interaction of biomacromolecues, immunoassay, bioassays, etc. LRET in either a supramolecular organogel or a hydrogel is still an unexplored field. In this work we showed the energy transfer from Tb(III) to two different red emitting dyes in Tb-cholate hydrogel (Figure 3). The self assembly processes during hydrogelation assisted the energy transfer process without any need for laborious synthesis. The energy transfer was confirmed by time delayed emission, excitation spectra and lifetime measurement in the hydrogels. Energy transfer was observed both in the gel and the xerogel states. These luminescent materials may find applications in optoelectronics. Figure 3. Energy transfer from DHN to Tb3+ and then to red emitting dyes (Rhodamine B & Sulforhodamine 101) in the Tb-Cholate hydrogel Chapter 5: Room temperature synthesis of Lanthanide phosphate nanoparticle using a gel as a soft template Lanthanide orthophosphates are an important class of rare earth compounds, and have widespread applications in laser materials, optical sensors, heat resistance materials, solar cell etc. There are several methods in the literature for the synthesis of rare earth phosphate nanoparticles. Most of these are based on hydrothermal, microwave assisted, micro emulsion, arrested precipitation etc., which invariably dependent on stringent conditions such as (i) high temperatures and pressures, (ii) inert atmosphere and (iii) the use of external capping agents as stabilizers. Synthesis of such nanoparticles under milder conditions would always be preferable. In this context, the preparation of nanoparticles using hydrogel as template can be a possible alternative approach. The LnPO4 nanoparticle synthesis was done by diffusion of Na3PO4 in Ln-cholate hydrogels. The particles were characterized by transmission electron microscopy (TEM) and powder XRD analysis. TEM showed the formation of 3-4 nm size particles with an ordered arrangement on the gel fibre. This work demonstrated that the lanthanide cholate gels have high potential for the synthesis, and immobilization of lanthanide phosphate nanoparticles at room temperature to produce new types of composite materials. (For structural formula pl see the abstract pdf file)

Noble metal nanostructures display collective oscillation of the surface conduction electrons upon light irradiation as a form of localized surface plasmon resonance (LSPR) properties. Size, shape and the refractive index of surrounding environment are the key features that controls the LSPR properties. Surface passivating ligands have the ability to modify the charge density of nanostructures to allow resonant wavelength to match that of the incident light, a phenomenon called “plasmoelectric effect,”. According to the drude model Red and blue shifts of LSPR peak of nanostructures are observed in the event of reducing and increasing charge density, respectively. However, herein we report unusual LSPR properties of gold triangular nanoprisms (Au TNPs) upon functionalization with para-substituted thiophenols (X-Ph-SH, X = -NH₂, -OCH₃, -CH₃, -H, -Cl, -CF₃, and -NO₂). Accordingly, we hypothesized that an appropriate energy level alignment between the Au Fermi energy and the HOMO or LUMO of ligands allows delocalization of surface plasmon excitation at the hybrid inorganic-organic interface, and thus provides a thermodynamically driven plasmoelectric effect. We further validated our hypothesis by calculating the HOMO and LUMO levels and also work function changes of Au TNPs upon functionalization with para substituted thiol. We further utilized our unique finding to design ultrasensitive plasmonic substrate for biosensing of cancer microRNA in bladder cancer and owe to unpresidential sensitivity of the developed Au TNPs based LSPR sensor, for the first time we have been utilized to analysis the tumor suppressor microRNA for more accurate diagnosis of BC. Additionally, we have been advancing our sensing platform to mitigate the false positive and negative responses of the sensing platform using surface enhanced fluorescence technique. This noninvasive, highly sensitive, highly specific, also does not have false positives technique provide strong key to detect cancer at very early stage, hence increase the cancer survival rate. Moreover, the electromagnetic field enhancement of Surface-Enhanced Raman Scattering (SERS) and other related surface-enhanced spectroscopic processes resulted from the LSPR property. This dissertation describes the design and development of entirely new SERS nanosensors using flexible SERS substrate based on unique LSPR property of Au TNPs and developed sensors shows excellent SERS activity (enhancement factor = ~6.0 x 106) and limit of detection (as low as 56 parts-per-quadrillions) with high selectivity by chemometric analyses among three commonly used explosives (TNT, RDX, and PETN). Further we achieved the programable self-assembly of Au TNPs using molecular tailoring to form a 3D supper lattice array based on the substrate effect. Here we achieved the highest reported sensitivity for potent drug analysis, including opioids and synthetic cannabinoids from human plasma obtained from the emergency room. This exquisite sensitivity is mainly due to the two reasons, including molecular resonance of the adsorbate molecules and the plasmonic coupling among the nanoparticles. Altogether we are highly optimistic that our research will not only increase the patient survival rate through early detection of cancer but also help to battle the “war against drugs” that together is expected to enhance the quality of human life.