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Relevant bibliographies by topics / Isomeric Transition

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Academic literature on the topic 'Isomeric Transition'

Author: Grafiati

Published: 5 June 2025

Last updated: 15 July 2025

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Journal articles on the topic "Isomeric Transition"

1

Sasmal, Ashok, Eugenio Garribba, Carlos J. Gómez-García, Cédric Desplanches, and Samiran Mitra. "Switching and redox isomerism in first-row transition metal complexes containing redox active Schiff base ligands." Dalton Trans. 43, no. 42 (2014): 15958–67. http://dx.doi.org/10.1039/c4dt01699h.

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Switching and redox isomerism in first row transition metal complexes through the metal-to-ligand or ligand-to-ligand electron transfer stabilize redox isomeric forms in transition metal complexes with redox-active ligands.

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Rawat, Prerna Singh, S. Kumar, H. Chutani, and M. Goyal. "Systematic Compilation/Evaluation of Reduced B(E3) Transition Probabilities and Configurations of Octupole (∆I=3) Isomers in Mass A~200 Region." Journal of Nuclear Physics, Material Sciences, Radiation and Applications 9, no. 2 (2022): 177–85. http://dx.doi.org/10.15415/jnp.2022.92026.

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Background: Strong octupole correlations are observed in mass region giving rise to a number of isomeric states decaying via type of transition involving interacting orbitals. Theoretically, the and neutron orbitals or the and proton orbitals are predicted to be involved in these enhanced decays. Purpose: This work reports on the systematics of reduced transition probabilities and configurations of octupole isomers in order to compare them based on their structures such as even-even, even-odd, odd-even and odd-odd.  Methods: The data for a total of isomers is collected from the ENSDF/XUNDL Database of NNDC. The reduced transition probabilities are evaluated and compiled using the available data on half-life and branching ratios of the isomeric states having pure decay. In about cases, we have also evaluated the half-lives to get their adopted value to obtain the transition probability by RULER program. Results: A systematic variation in the reduced transition strength is discussed as a function of neutron and proton number to see the contribution/effect from the core particles. An enhancement is observed experimentally for the isomeric states involving the and neutron orbitals or the and proton orbitals Conclusions: The enhanced transitions rates are observed in nuclei having configurations with octupole effects.

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Perfiliev, Yu D., M. I. Afanasov, and A. M. Babeshkin. "Local doses associated with119mSn isomeric transition." Journal of Radioanalytical and Nuclear Chemistry Letters 93, no. 1 (1985): 29–35. http://dx.doi.org/10.1007/bf02168356.

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Chechev, V. P. "An exotic type of nuclear isomeric transition." Bulletin of the Russian Academy of Sciences: Physics 78, no. 7 (2014): 634–35. http://dx.doi.org/10.3103/s1062873814070077.

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MA, BAOLIANG, ZUOXIU TIE, DAWEI ZOU, JING LI, and WEI WANG. "UREA- AND THERMAL-INDUCED UNFOLDING OF BOVINE SERUM ALBUMIN." Modern Physics Letters B 20, no. 29 (2006): 1909–16. http://dx.doi.org/10.1142/s0217984906012171.

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In this work, the difference between pH-induced isomerization and urea-induced unfolding, and the urea- and thermal-induced unfolding processes in different isomeric forms of Bovine serum albumin (BSA) are studied experimentally. Our results show that urea-induced unfolding is a two-step, three-state transition in both the N-form and the B-form, but a single-step, two-state transition in both the E-form and the F-form. At the same time, thermal-induced unfolding shows a two-state transition in all isomeric forms, but the cooperativity of unfolding is different.

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Jóźwiak, Kinga, Aneta Jezierska, Jarosław J. Panek, Andrzej Kochel, and Aleksander Filarowski. "Inter- vs. Intra-Molecular Hydrogen Bond in Complexes of Nitrophthalic Acids with Pyridine." International Journal of Molecular Sciences 24, no. 6 (2023): 5248. http://dx.doi.org/10.3390/ijms24065248.

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This study covers the analysis of isomeric forms of nitrophthalic acids with pyridine. This work dwells on the complementary experimental (X-ray, IR and Raman) and theoretical (Car-Parrinello Molecular Dynamics (CPMD) and Density Functional Theory (DFT)) studies of the obtained complexes. The conducted studies showed that steric repulsion between the nitro group in ortho-position and the carboxyl group causes significant isomeric changes. Modeling of the nitrophthalic acid—pyridine complex yielded a short strong intramolecular hydrogen bond (SSHB). The transition energy from the isomeric form with an intermolecular hydrogen bond to the isomeric form with an intramolecular hydrogen bond was estimated.

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Lashko, A. P., and T. N. Lashko. "The internal conversion coefficient for the K-forbidden E1-transition with the energy of 55 keV in 177Hf." Nuclear Physics and Atomic Energy 13, no. 4 (2012): 356–60. https://doi.org/10.15407/jnpae2012.04.356.

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The precise γ-ray intensities of the transitions following the decay of 160-day isomeric state in 177Lu have been measured by using two different types of HPGe-detectors. The values of the internal conversion coefficient and penetration parameter λ for E1-transition with the energy of 55 keV were determined from intensity balance of 21/2- 1260 keV level in 177Hf.

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Melník, Milan, Peter Mikuš, and Clive Holloway. "Crystalographic and structural characterization of heterometallic platinum compounds. Part III: heterotrinuclear compounds." Open Chemistry 11, no. 6 (2013): 827–900. http://dx.doi.org/10.2478/s11532-013-0226-3.

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AbstractThis review article includes over three hundred and sixty heterotrinuclear platinum complexes of the composition Pt2M (205 examples), PtM2 (132 examples) and PtMM (24 examples). The heterometals include the non-transition and transition metals. Three metal atoms form a wide variability of frameworks: M3 triangular, dicapped M3 triangular, V shaped M3, M3 linear, five-, six- and seven- metallocycles and unique structures of which triangular and linear are the most common. This has led to a rich chemistry of platinum not only from variability of metals, but also from their framework and stereochemistry. The shortest Pt-M (non-transition) and Pt-M (transition) bonds are 2.315(1) Å for Pt-Ga and 2.4896(9) Å for Pt-Co. The shortest Pt-Pt bond distance is 2.581(1) Å. Two complexes exist in two isomeric forms and several others contain crystallographically independent molecules. All are typical examples of distortion isomerism. Correlations between structural parameters, heterometal and ligand donor atoms are developed and discussed.

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Singh, Narendra, Ramesh Singh, Swati Sharma, Khushboo Kesharwani, Khashti Ballabh Joshi, and Sandeep Verma. "Transition-metal ion-mediated morphological transformation of pyridine-based peptide nanostructures." New Journal of Chemistry 45, no. 1 (2021): 153–61. http://dx.doi.org/10.1039/d0nj04260a.

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Wu, Lianming, and R. Graham Cooks. "Chiral and Isomeric Analysis by Electrospray Ionization and Sonic Spray Ionization Using the Fixed-Ligand Kinetic Method." European Journal of Mass Spectrometry 11, no. 2 (2005): 231–42. http://dx.doi.org/10.1255/ejms.749.

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The fixed-ligand version of the kinetic method has been used for chiral and for isomeric analysis by studying the dissociation kinetics of transition metal-bound trimeric cluster ions ([(MII + Lfixed – H)(ref*)(An)]+, where MII is a transition metal, Lfixed is a fixed (non-dissociating) ligand, ref* is a reference ligand and An is the analyte. The trimeric cluster ions are readily generated by electrospray ionization (ESI) or sonic spray ionization (SSI). The size of the fixed ligand, L-Phe–Gly–L-Phe–Gly, is chosen based on previous results but with the inclusion of aromatic functionality to increase chiral recognition. Improved chiral/isomeric differentiation results from enhanced chiral/isomeric interactions (metal–ligand and ligand–ligand) due to the fixed ligand. As shown in the cases of chiral dipeptides (D-Ala–D-Ala/L-Ala–L-Ala), sugars (D/L-glucose, D/L-mannose) and isomeric tetrapeptides (L-Ala–Gly–Gly–Gly/Gly–Gly–Gly–L-Ala), improved chiral/isomeric discrimination by factors from three to six were obtained by the fixed ligand procedure. Chiral recognition is independent of the concentrations of the analyte, the reference ligand, the fixed ligand and the transition metal salt, a great advantage for practical applications. In addition to increased chiral distinction, the simplified dissociation kinetics also contribute to improved accuracy in chiral quantification, in comparison with data obtained by investigating the dissociation kinetics of simple trimeric cluster ions [MII(ref*)2(An) – H]+. Accurate determination of enantiomeric excess ( ee) is demonstrated by enantiomeric quantification of D-Ala–D-Ala/L-Ala–L-Ala down to 2% ee. Both ESI and SSI allow chiral quantification with similar accuracies. The performance of chiral analysis experiments is not limited to ion trapping devices such as quadrupole ion trap mass spectrometers; a hybrid quadrupole-time of flight (Q-ToF) mass spectrometer is shown to provide an alternative choice. The fixed-ligand kinetic method is not restricted to any particular kinds of isomers and, hence, represents a general procedure for improving molecular recognition and chiral analysis in the gas phase.

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Dissertations / Theses on the topic "Isomeric Transition"

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Bilous, Pavlo [Verfasser], and Adriana [Akademischer Betreuer] Palffy-Buss. "Towards a nuclear clock with the 229Th isomeric transition / Pavlo Bilous ; Betreuer: Adriana Palffy-Buss." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1177045389/34.

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Nickerson, Brenden Scott [Verfasser], and Adriana [Akademischer Betreuer] Pálffy-Buß. "Towards coherent control of the Th-229 isomeric transition in VUV-transparent crystals / Brenden Scott Nickerson ; Betreuer: Adriana Pálffy-Buß." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1201647304/34.

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Chandler, Catherine. "Spectroscopy of exotic f - p - g nuclei using projectile fragmentation and fusion evaporation reactions." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843034/.

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The structural properties of the very neutron deficient systems around N~Z~40 have been studied in two experiments performed at the GANIL and Legnaro laboratories. The fragmentation of a 60 MeV/u92 Mo beam on a natural nickel target at the GANIL Laboratory, France, produced exotic nuclei along the proton drip line in the mass 80 region. Isomeric decays have been observed for the first time in the N=Z+2 systems 74 36Kr, 80 39Y and 84 41Nb. The isomer in 74 Kr is interpreted as the hindered decay from an excited 0+ state, supporting the long-standing prediction of prolate/oblate shape coexistence in this nucleus. Transitions from states below an isomer in the N=Z nucleus 86 43Tc have also been tentatively identified, making this the heaviest N=Z system for which gamma-ray decays from excited states have been observed. Conclusive evidence for the existence of the Z=N+1 isotopes 77 39Y, 79 40Zr and 83 42Mo has also been obtained together with upper limits on the particle decay lifetimes of the odd-proton systems 81 41 Nb and 85 43Tc. The reported instability of the lighter odd-Z, Tz = -1/2 systems 69Br and 73Rb makes the observed existence for 77 39Y particularly interesting. A possible explanation for the relative particle stability of 77 39Y is given in terms of the shape polarising effect of the N=Z=38 prolate shell gap on the nuclear mean field and the increased centrifugal barrier associated with the occupation of a g9/2 proton orbital. The second experiment was performed to further investigate the oblate nature of the isomeric state in 74Kr. The reaction 40Ca(40Ca, alpha2p)74Kr was used at a beam energy of 135 MeV obtained from the Tandem XTU accelerator. The EUROBALL gamma-ray array was used in conjunction with the ISIS charged particle silicon ball to study the states above and below the isomer. The ISIS ball was used to highlight channel selection of non-yrast states by particle gating. No evidence for the 0+2 isomer in 74Kr was observed in this work.

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Poater, Teixidor Albert. "Isomerism and C-H, C-C, O-O, C-O bond activation studies by transition metals." Doctoral thesis, Universitat de Girona, 2006. http://hdl.handle.net/10803/7939.

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Aquesta tesi és el reflex que de la cooperació entre grups experimentals i grups teòrics s'aconsegueix l'assoliment d'objectius inassolibles de forma individual. A partir de la DFT s'expliquen processos inorgànics i organometàl·lics de gran valor biològic i/o industrial. La tesi està enfocada especialment a l'estudi de complexos mononuclears i binuclears de coure, on té lloc l'activació d'enllaços C-H, C-C, i O-O. L'estudi de complexos octaèdrics de ruteni ha permès dur a terme extensos estudis isomèrics i racionalitzar les propietats espectroscòpiques dels mateixos. A més a més, estudis més puntuals respecte clusters de coure, l'estudi de la reacció de Pawson-Khand, l'estudi d'enllaços Pt-Pt en complexos trimèrics de platí, a més a més de l'estudi de la isomeria de complexos de Ni i Pt.<br>This thesis shows that the cooperation between experimental and theoretical groups gives as a result the achievement of aims impossible working independently. From DFT calculations inorganic and organometallic problems related to great biological and industrial processes can be explained. This thesis is especially focused on the study of mononuclear and binuclear copper complexes, where a C-H, C-C, and O-O bond activation takes place. The study of octahedral ruthenium complexes has allowed carrying out isomeric studies and the rationalization of spectroscopic properties. Furthermore, other little studies related to copper clusters, the Pawson-Khand reaction, Pt-Pt bond interaction in trimer platinum complexes, and isomerism of Ni and Pt complexes.

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Nicol, Duncan Patterson. "The synthesis and reactions of an unprecedented isomer of the [16] membered Jager transition metal macrocyclic complex." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/587.

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Robinson, Oliver B. "A critical review of the phenomenon of bond-stretch and distortional isomerism in oxo and sulphido complexes of transition metals." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5758/.

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This thesis describes studies directed towards the preparation of oxo compounds of the early transition metals with a view to assessing their potentials for exhibiting distortional and bond-stretch isomerism. Analogous sulphido complexes in the case of the M(E)X(_3)(PMe(_3))(_3) system (M= Nb, Ta; X= CI; E= S) have also been investigated in detail to provide a contrast with another chalcogenide element and further aid an understanding of the phenomenon of bond-stretch isomerism. Chapter 1 reviews the body of evidence to date on the phenomena of distortional and bond-stretch isomerism, and considers possible theoretical origins for the phenomena. Chapter 2 describes the detailed study of distortional isomerism in the six coordinate series of complexes Mo(O)X(_2)(PMe(_2)Ph)(_3) (X= CI, Br, I) and confirms the existence of two pure blue forms for the chloro and bromo cases. Chapter 3 assesses the evidence for further examples of distortional isomerism in the complexes W(O)Cl(_2)(PMe(_2)Ph)(_3), Mo(O)(NCS)(_2)(PMe(_2)Ph)(_3) and Mo(O)Cl(_2)(Pet(_2)Ph)(_3). Structural characterisation by X-ray crystallography has indicated the existence of a link between the orientation of the aikyl and aryl substituents on the phosphine ligands and the general features observed in their infrared spectra. Chapters 4 and 5 describe the seven coordinate oxo and sulphido-halide derivatives of niobium and tantalum which exhibit the phenomenon of bond-stretch isomerism. Compounds studied include M(E)X(_3)(PMe(_3))(_3) (M= Nb, E= O, S, X=C1, Br; M= Ta, E= S, X=Cl). The structures of these compounds have been re-investigated by X-ray crystallography in order to assess the significance of the co-crystallised isostructural NbCl(_4)(PMe(_3))(_3) contaminant. Chapter 6 summaries the evidence for and against distortional and bond-stretch isomerism. Chapter 7 gives experimental details for chapters 2-5.

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El, Hamdi Lahfid Majid. "On the use of energy decomposition analyses to unravel the origin of the relative stabilities of isomers." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/124220.

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Structural isomers are molecules that have the same number and type of atoms but arranged in different manner. The isomerization energy is the energy difference between two isomers, i.e. the energy cost corresponding to the transformation of one isomer into another. In this thesis, the PhD student has focused on isomers that can be built from the same fragments, but simply connecting them differently, with a new methodology called "turn-upside-down." Basically one starts with the same two fragments and they are connected in different way to build the two isomers. Later, the energies involved in the bonding between the fragments are studied by an energy decomposition analysis in order to find the reason for the difference in stability between the two isomers. The computational results obtained have allowed us to justify the energy of isomerization of organic or inorganic or organometallic compounds<br>Isòmers estructurals són molècules que presenten el mateix nombre i tipus d’àtoms, però ordenats de diferent manera. L’energia d’isomerització és la diferència d’energia entre dos isòmers, o sigui, el cost energètic corresponent a la transformació d’un isòmer a l’altre. En aquesta tesi, el doctorand s’ha centrat en isòmers que es poden construir a partir dels mateixos fragments, però simplement unint-los de diferent manera, amb una nova metodologia anomenada “turn-upside-down”. Bàsicament es parteix dels mateixos dos fragments que unim de diferent manera per construir els dos isòmers. Posteriorment, les energies involucrades en la unió entre els fragments s’estudien amb una anàlisi de descomposició de l’energia per tal de saber la raó de la diferència d’estabilitat entre els dos isòmers. Els resultats computacionals obtinguts han permès justificar l’energia d’isomerització de compostos tant orgànics com inorgànics o organometàl·lics

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MAIDANA, NORA L. "Medidas de seccoes de choque para reacoes de captura de neutrons no sup(57)Co, sup(137)Cs e sup(241)Am considerando a formacao de estados isomericos." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10798.

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Made available in DSpace on 2014-10-09T12:44:06Z (GMT). No. of bitstreams: 0<br>Made available in DSpace on 2014-10-09T14:07:38Z (GMT). No. of bitstreams: 1 06881.pdf: 7889902 bytes, checksum: 7e22a20905b1e2b2ff4ed4439b25e2bb (MD5)<br>Tese (Doutoramento)<br>IPEN/T<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Clements, Joseph Shelby II. "Synthesis of Insecticidal Mono- and Diacylhydrazines for Disruption of K+ Voltage-Gated Channels, and Elucidation of Regiochemistry and Conformational Isomerism by NMR Spectroscopy and Computation." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/77918.

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Based on the success of diacyl-tert-butylhydrazines RH-5849 and RH-1266 in controlling agricultural crop pests, we endeavored to synthesize our own diacylbenzyl- and arylhydrazine derivatives for use against the malaria vector Anopheles gambiae. In the process of producing a library of compounds for assay against An. gambiae, it became clear that employing regioselective acylation techniques (in molecules that feature two nucleophilic, acyclic nitrogen atoms α to one another) would be imperative. Synthesis of the library derivatives proceeded rapidly and after topical assay, we found three compounds that were more toxic than the RH-series leads. One of the three displayed an LD50 value of half that of RH-1266, though patch clamp assay concluded that toxicity was not necessarily linked to inhibition of mosquito K+ channel Kv2.1. The acylation of monoarylhydrazines appears simple, but its regioselectivity is poorly understood when assumed as a function of basicity correlating to nucleophilic strength. We determined the ratio of the rate constants for distal to proximal N-acylation using 19F NMR spectroscopic analysis of reactions of 4-fluorophenylhydrazine with limiting (0.2 equiv) acylating agent in the presence of various bases. Acid anhydrides gave consistent preference for distal acylation. The selectivity of acylation by acyl chlorides when using pyridine gives strong distal preference, whereas use of triethylamine or aqueous base in conjunction with aroyl chlorides showed a moderate preference for proximal acylation. This observation yielded a convenient one-step method to synthesize proximal aroylarylhydrazines in yields comparable or superior to that provided by the standard three-step literature approach. Combined with NMR evidence of the distal nitrogen as the unambigiously stronger base of the two nitrogens, we propose a single electron transfer mechanism that predicts the regiochemistry of arylhydrazines toward acylating agents better than the nucleophilicity model based on pKa values. While synthesizing the acylhydrazine library for assay against An. gambiae, NMR spectroscopy revealed rotational isomerisms of two types: chiral helicity (M)/(P) and acyl (E)/(Z)-isomerism due to hindered rotation. Variable temperature NMR allowed the measurement of N-N bond rotational barriers, as well as estimate the barrier of (E)/(Z) interconversion. We obtained the X-ray crystal structures of four diacylhydrazines to test this hypothesis and revealed both the twist conformation around the N-N bond axis and (E)/(Z)-isomerism around the proximal acyl group. Computation (which agreed with the crystal structures) allowed us to estimate which (E)/(Z)-isomers were most likely being observed in solution at room temperature by NMR spectroscopy. In addition, we were able to calculate transition structures corresponding to N-N bond rotational barriers of (E,Z)- and (Z,Z)-isomers of model molecules and rationalize the difference in coalescence temperatures between (E,Z)- and (Z,Z)-isomers.<br>Ph. D.

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Ango, Jean-Paul. "Electrooxydation du D-Sorbitol sur électrodes métalliques (Pt, Au) : comparaison avec la photooxydation aux interfaces semi-conducteur (TiO(2) / électrolyte." Poitiers, 1989. http://www.theses.fr/1989POIT2261.

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Books on the topic "Isomeric Transition"

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Song, Jun. Bond-stretch isomers of transition metal complexes: Do they exist? Cornell Theory Center, Cornell University, 1991.

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Book chapters on the topic "Isomeric Transition"

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Liao, Wen-Te. "Coherence Enhanced Optical Determination of the $$^{229}$$ 229 Th Isomeric Transition." In Coherent Control of Nuclei and X-Rays. Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-02120-1_5.

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Keković, G., D. Raković, and David Davidović. "Relevance of Polaron/Soliton-Like Transport Mechanisms in Cascade Resonant Isomeric Transitions of Q1D-Molecular Chains." In Materials Science Forum. Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-441-3.119.

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Mudarra Navarro, A. M., C. E. Rodríguez Torres, and L. A. Errico. "Calibration of the isomer shift of the 14.4 keV transition of 57 Fe." In LACAME 2010. Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-4301-4_15.

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Aleksandrov, A. Yu, N. N. Belyagin, K. P. Mitrofanov, L. S. Polak, and V. S. Shpinel. "Quadrupole Interaction and Isomer Shifts of the 23.8 KeV Gamma Transition of the Sn119 Nucleus in Tin-Organic Compounds." In Proceedings of the Dubna Conference on the Mössbauer Effect 1963. Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-4848-9_20.

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Tanase, T. "Structure of Metal Complexes." In Coordination Chemistry. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781837673254-00013.

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The chemistry of transition metal complexes, which exhibit a wide variety of chemical and physical properties, is the result of combinations of the various electronic states of metal centres containing d- and f-electrons and the diversity of ligand systems and structures including inorganic, organic and bio-related compounds. In order to understand the structure of transition metal complexes, this chapter first introduces basic concepts of the electronic and physical properties of metal ions and shows representative mono-, bi- and multidentate ligands. The geometric structures of metal complexes are then systematically explained by following the coordination number of mononuclear complexes, and some di-, tri- and multinuclear metal complexes with and without metal–metal bonds are discussed. The isomerism observed in metal complexes and the resulting isomers, structural isomers and stereoisomers, is also explained focusing on the latter, which are divided into configurational and conformational isomers. Finally, the nomenclature of metal complexes is briefly discussed.

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Toyota, M., Y. Nishikawa, and K. Fukumoto,. "Formal Synthesis of (±)-Aphidicolin." In Exercises in Synthetic Organic Chemistry. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780198559443.003.0062.

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Abstract Discussion Points The condensation step a gave a 3 : 1 mixture of isomers 2. Assuming that the stereoselectivity of the reaction can be rationalised by a Zimmerman-Traxler transition state model, what should be the structure of the predominant isomer? What is the mechanism of step b? The tetracyclic product 9 was obtained in a 3 : 1 mixture with its epimer at C5. What is the mechanism of this reaction? Rationalise the stereochemical outcome. Further Reading For a recent review of the Heck reaction see: W. Cabri and I. Candiani, Acc. Chem. Res.,1995, 28,2.

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Soni, P. L., and Vandna Soni. "Isomerism and Stereochemistry." In The Chemistry of Coordination Complexes and Transition Metals. CRC Press, 2021. http://dx.doi.org/10.1201/9781003183426-6.

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Clugston, Michael, Malcolm Stewart, and Fabrice Birembaut. "Introduction to Organic Chemistry." In Making the Transition to University Chemistry. Oxford University Press, 2021. http://dx.doi.org/10.1093/hesc/9780198757153.003.0016.

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This chapter introduces organic chemistry. This type of chemistry involves the study of compounds formed by carbon. The chapter highlights how living organisms are mainly composed of carbon compounds. Structural formula shows exactly which atoms are bonded together. A homologous series is a collection of molecules with the same functional group differing only in the number of carbon atoms present. The chapter discusses the IUPAC nomenclature for the alkane molecules. It also examines the major classes of isomers: structural isomers and stereoisomers. Organic reactions are classified as either radicals, nucleophiles, or electrophiles. The functional group level of a particular carbon atom establishes the number of bonds to the atom that is more electronegative than carbon.

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Clugston, Michael, Malcolm Stewart, and Fabrice Birembaut. "Hydrocarbons: Alkenes." In Making the Transition to University Chemistry. Oxford University Press, 2021. http://dx.doi.org/10.1093/hesc/9780198757153.003.0018.

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This chapter focuses on alkenes, which are known to be unsaturated hydrocarbons with a carbon-carbon double bond. Ethene is known to be the simplest alkene, this is closely followed by propane. Alkenes undergo electrophilic addition reactions. This involves the addition of hydrogen halides, acidified water, and halogens. The chapter explains the Markovnikov's rule wherein the alkene and adduct are unsymmetrical. This is something which two isomers could form. Markovnikov's rule refers to the more stable carbocation forms carrying a positive charge with three bonds. The chapter also explicates the addition of a neutral molecule to ethene which is largely similar to the electrophilic addition of molecules under acidic conditions.

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Milhé, C. "Determination by 1H NMR of a Slow Conformational Transition and Hydration Change in the Consensus TATAAT Prsbnow Box." In Biological NMR Spectroscopy. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195094688.003.0027.

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The conformational dynamics and hydration of a DNA 14-mer containing the consensus Pribnow box sequence TATAAT have been measured using rotating frame T1 measurements and NOESY and ROESY in water. The H2 proton resonances of adenines show fast intermediate exchange behavior which can be attributed to a conformational transition that affects the distances between H2 protons of neighboring adenine residues, both sequential and cross-strand. The relaxation rate constant of the transition was measured at 4000s-1 at 25°C. Bound water close to the H2 proton of adenines was observed with residence times of >lns. At low temperature (5°C), the Pribnow box is in a closed state in which hydration water in the minor groove is tightly bound. At higher temperatures, the conformation opens up as judged by the increase in separation between sequential H2 protons of adenines and water exchanges freely from the minor groove. The conformational transition and the altered hydration pattern may be related to promoter function. The control of gene expression in procaryotes depends on the specific recognition by RNA polymerase of a six base-pair sequence (consensus: TTGACA) located at -35 from the transcription site, and a second one, named the Pribnow box (consensus: TATAAT) at about 10 base-pairs upstream the initiation site (Rosenberg and Court, 1979). It has been shown (Hawley and McClure, 1983) that strong promoters exhibit a high degree of homology with the consensus sequences, separated by an optimum consensus spacer length of 17 base pairs. The strength of a promoter depends on, among other thing, the rate of the initiation of transcription. This rate depends on the product between the thermodynamic and kinetic constants KB and k2 (McClure, 1980). The initial binding of RNA polymerase to the promoter results in the formation of a transcriptionally inactive ‘closed’ complex, characterized by the association constant KB. Isomerization to the active ‘open’ complex then occurs, and is characterized by the first order rate constant k2. Hence, the frequency of transcription initiation depends both on the strength of the polymerase-promoter interaction, and the ease with which this complex can isomerize to the productive state. Both of these events are likely to depend on the physical properties of the promoter.

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Conference papers on the topic "Isomeric Transition"

1

Bondarevskii, Svjatoslav I., Boris E. Dzevitskii, Vjacheslav V. Eremin, and German A. Skorobogatov. "Recent experiments on induced gamma emission under isomeric transition ^119m2Sn-^119m1Sn+hv(65.66 keV)." In Laser Optics '98, edited by Nikolay N. Rosanov. SPIE, 1999. http://dx.doi.org/10.1117/12.335834.

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2

Hendrickx, E., B. L. Volodin, D. D. Steele, et al. "Phase stability of guest/host photorefractive polymers studied by light scattering experiments." In Organic Thin Films for Photonic Applications. Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.fd.4.

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In recent years, we developed plasticized guest-host photorefractive polymers with a glass transition temperature below room temperature.1 However, in these guest/host polymers a gradual crystallization of the chromophores (50% wt.) limits the shelf lifetime of the samples. The lifetime of DMNPAA(2,5-dimethyl-4-(p-nitrophenylazo) anisole) : PVK(poly-vinylcarbazole) : ECZ(N-ethylcarbazole) : TNF(tri-nitrofluorenone) samples with 50% wt. of DMNPAA was found to vary between a few hours and a few months depending on the starting materials and the processing conditions. Here we present a new guest/host photorefractive composite based on isomeric mixtures of the chromophore NPADVBB (4-(4’-nitrophenylazo)l,3-di[(3”or 4”-vinyl)benzyloxy] benzene). These composites exhibit a performance level that is identical to that of DMNPAA-based samples but have an estimated shelf lifetime of several years at room temperature.

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3

Noid, D. W., F. X. Hartmann, and M. L. Koszykowski. "Classical and semiclassical calculation of nuclear-electron coupling." In International Laser Science Conference. Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.tud5.

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One aspect of making a gamma-ray laser concerns the rapid re lease of energy stored in a long-lived nuclear isomer. A proposed method for the release of this energy is to pump the isomerto a nearby, shorter-lived nuclear excited state. This excited state subsequently decays to a lasing transition. In this paper, we consider the dynamical coupling of the nucleon and electron motion using classical dynamics and calculate the perturbation on the spectra. In our model,1 a valence excited proton is bound as an independent particle to the nuclear core using a Woods-Saxon potential. The electron is bound to a core of protons and the valence proton by a Coulomb potential. Initial conditions for the classical trajectories were chosen to be semiclassical states of the separable Hamiltonian. A method2 to extract spectral information from classical trajectories is then used to calculate both transition intensities and frequencies. For some isomers, very strong coupling and chaotic motion were observed.

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4

Gibo, T. L., M. F. Rotella, A. J. Bastian, and A. M. Okamura. "Gradual anisometric-isometric transition for human-machine interfaces." In 2011 33rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2011. http://dx.doi.org/10.1109/iembs.2011.6091117.

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5

Kojima, Y., M. Shibata, A. Taniguchi, A. Murataka, K. Ota, and K. Shizuma. "Search for isomeric transitions in fission products around mass number 150." In International Conference on Nuclear Data for Science and Technology. EDP Sciences, 2007. http://dx.doi.org/10.1051/ndata:07185.

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6

Haase, W., S. Grossmann, S. Saal, T. Weyrauch, and L. M. Blinov. "Efficiency of photoassisted poling of azobenzene, stilbene and biphenyl dyes as studied by Stark spectroscopy." In Organic Thin Films for Photonic Applications. Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.pd5.

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Besides the usual thermal assisted poling procedure the photoassisted poling reported for polymers containing azobenzene chromophores is of current interest. Usually the enhanced orientational mobility under illumination with visible light in the absorption band of the chromophore is explained by the trans⇔cis isomerization cycle of the azo dye, with a photoisomerization trans⇒cis and a thermal relaxation cis⇒trans. Because of the more compact shape of the cis isomer the rotational mobility is much higher than that of the trans isomer, thus polar orientation under electric DC field is possible. Since the memory of the polar orientation is lost only partially during the cis⇒trans transition, the trans isomers will achieve also a polar ordering [1-4]. This theory cannot be applied to systems containing stilbene dyes, where no thermal cis⇒trans relaxation is present. Investigations on systems containing stilbene dyes have also shown enhanced polar order in a poling process under illumination with visible light in the absorption range of the chromophore [5,6]. Thus the influence of heating of the sample (both macroscopically and microscopically in the vicinity of the dye molecule) must be discussed. The aim of this work is to compare the photoassisted poling behaviour of azo and stilbene dyes as well as of a non isomerizable biphenyl dye.

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7

Bounds, J. A., P. Dyer, R. C. Haight, and S. A. Wender. "Nuclear transitions induced by atomic excitations." In International Laser Science Conference. Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.tud8.

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In the two-step pumping scheme for a gamma-ray laser, the most uncertain step is that of exciting the nucleus from a long-lived storage isomer to a nearby short-lived state that then decays to the upper lasing level. For a crystalline structure host, the radiation inducing this interlevel transfer step must be used efficiently so as not to destroy the crystal. High-intensity sources of photons are available only for relatively low quantum energy, but it is difficult to couple a long-wavelength photon directly to the very small nucleus. We propose experiments to induce this transfer by first exciting the atomic electrons. We expect nuclear excitation to take place through exchange of a virtual photon in the near field of the electrons. As a test case, the 75-eV123mU isomer might be excited by electronic motions induced by a bright source UV laser. We propose to detect conversion electrons from the decay of this isomer, measuring the 26-min decay curve.

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8

Bogdanović, M., та J. Simić. "Investigation of Gamma Transitions Populating the 1094 keV Isomeric State in the 167Er(n,γ) Reaction". У Capture gamma‐ray spectroscopy. American Institute of Physics, 1991. http://dx.doi.org/10.1063/1.41254.

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9

Kalmán, P. "Optical and x-ray lasers in nuclear spectroscopy." In OSA Annual Meeting. Optica Publishing Group, 1993. http://dx.doi.org/10.1364/oam.1993.fg.6.

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Recent results show that combined processes containing electron-nucleus interaction such as near-threshold internal conversion1, electronic-bridge2,3 and inverse electronic-bridge4 processes are expected to be modified by intense electromagnetic fields of optical and x-ray frequencies. Using the similarly recent result5 obtained for the leading term of the S-matrix element of the resonant, inverse electronic-bridge process the effect of optical and x-ray lasers on some nuclear isomeric transitions, which seem to be promising, are investigated. The possibility of the effect of synchrotron radiation on those processes, which contain bound-free electronic transitions is also discussed and the result obtained is compared to the effect made by the optical and x-ray lasers. This work was supported by the Hungarian National Research Fund (OTKA) through Grant. No. T4459.

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10

Trišović, Nemanja. "SELF-ASSEMBLY OF BENT-CORE MOLECULES AS A ROUTE TOWARDS FUNCTIONAL SOFT MATERIALS." In 17th International Conference on Fundamental and Applied Aspects of Physical Chemistry. Society of Physical Chemists of Serbia, 2024. https://doi.org/10.46793/phys.chem24i.283t.

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Bent-core liquid crystals (BCLCs) represent a promising field of research in both materials chemistry and supramolecular chemistry. Emergence of new polar mesophases, induction of supramolecular chirality using achiral molecules and their significant ferroelectric and antiferroelectric properties have attracted considerable interest in these compounds [1]. Some of important aspects that determine the application of BCLCs include their transition temperatures, the mesophase range and the ability to control their morphology. Although a progress has been made in lowering the transition temperatures of these compounds, new BCLCs that meet the commercial temperature range are still needed. An additional factor limiting their application is related to bulk phase alignment, as the conventional procedures used for LCs are not applicable to these systems. The ability to reversibly tune the material properties using an external stimulus is an important concept in materials science. Light is particularly interesting in this regard. It can be delivered remotely and momentarily, leading to dynamic supramolecular architectures that exist as long as the stimulus is applied. An attractive way to render BCLCs responsive to light involves incorporating a photoisomerisable chromophore such as the trans-azobenzene building blocks into their molecular structure. Exposure to UV light causes azobenzene to isomerize to the more polar cis-isomer, which induces metastable supramolecular arrangements that disintegrate in the dark within a few hours [2]. We present our contribution to the fundamental understanding of the structure–property relationship of the azo-containing BCLCs. Incorporating this photoisomerizable chromophore into BCLC design has provided access to new multifunctional materials where the polar response can be modulated by light. Azobenzenes with a strong push–pull configuration show very fast cis–trans isomerization kinetics even at room temperature [3]. Imparting control over structural features has led to novel photoswitchable materials with fast and efficient responses.

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