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Relevant bibliographies by topics / Electron-donating groups

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Academic literature on the topic 'Electron-donating groups'

Author: Grafiati

Published: 5 June 2025

Last updated: 24 June 2025

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Journal articles on the topic "Electron-donating groups"

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Xu, Jian, Bin Niu, Song Guo, et al. "Influence of Chromophoric Electron-Donating Groups on Photoinduced Solid-to-Liquid Transitions of Azopolymers." Polymers 12, no. 4 (2020): 901. http://dx.doi.org/10.3390/polym12040901.

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The photoinduced solid-to-liquid transitions property of azobenzene-containing polymers (azopolymers) enables azopolymers with various promising applications. However, a general lack of knowledge regarding the influence of structure of the azobenzene derivatives on the photoinduced liquefaction hinders the design of novel azopolymers. In the present study, a series of azopolymers with side chains containing azobenzene unit bearing alkyl electron-donating groups were synthesized. The photoisomerization and photoinduced liquefaction properties of newly synthesized azopolymers were investigated. Alkyl-based electron-donating group significantly facilitate the photoisomerization process of azopolymers in solution, as the electron-donating ability of substituents increased, the time required for photoisomerization of azopolymers continually deceased. Meanwhile, the electron-donating group can drastically accelerate photoinduced solid-to-liquid transitions of azopolymers, the liquefaction rate of obtained azopolymers gradually getting quicker as the electron-donating ability of substituents increased. This study clearly demonstrates that the electron-donating group that bearing in the azobenzene group of polymer side chain play an essential role on the photoinduced solid-to-liquid transitions of azopolymers, and hence, gives an insight into how to design novel azopolymers for practical applications.

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Ohwada, Tomohiko, and Koichi Shudo. "Ethylene dications substituted with electron-donating groups." Journal of Organic Chemistry 54, no. 22 (1989): 5227–37. http://dx.doi.org/10.1021/jo00283a012.

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Barbarella, Giovanna, Massimo Zambianchi, Rossanna Di Toro, Martino Colonna, Luciano Antolini, and Alessandro Bongini. "Functionalization of sexithiophene with electron-donating methylsulphanyl groups." Advanced Materials 8, no. 4 (1996): 327–31. http://dx.doi.org/10.1002/adma.19960080408.

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Du, Yang, Hui Zhang, Xia Du, et al. "A Theoretical Study on the Influence of the Functional Group Electronic Effect on the Electron Mobility of Cross-Linked Polyethylene." Applied Sciences 15, no. 2 (2025): 959. https://doi.org/10.3390/app15020959.

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The effect of electron-donating and electron-withdrawing groups grafted onto polyethylene on electron mobility was studied using density functional theory. In order to ensure the accuracy of the calculation results, 17 basis sets from six methods were screened. 3-methylpentane was selected as the cross-linked polyethylene model. Compared with the experimental values, the theoretical calculation results show that wB97XD/6-311G(d,p) is more suitable for studying the electron mobility system. The roles of electron-donating and electron-withdrawing functional groups were studied. The results show that the electron mobility of grafting nitrobenzene (Ebnb) to polyethylene is the smallest among the studied molecules. As the ability of electron-donating groups increases, the electron mobility gradually increases, while the addition of the electron-withdrawing group reduces the electron mobility and the electron mobility gradually increases with increasing temperature. This investigation is expected to provide reliable information for the development of insulation materials for cables.

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Bekki, Yosuke, and Atsuhiro Osuka. "meso‐ Free B III Subporphyrins with Electron‐donating Groups." Chemistry – An Asian Journal 15, no. 10 (2020): 1580–89. http://dx.doi.org/10.1002/asia.202000288.

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Gudimetla, Vittal B., Liqing Ma, Marlena P. Washington, John L. Payton, M. Cather Simpson, and John D. Protasiewicz. "meta-Terphenyl Phosphaalkenes Bearing Electron-Donating and -Accepting Groups." European Journal of Inorganic Chemistry 2010, no. 6 (2010): 854–65. http://dx.doi.org/10.1002/ejic.200900870.

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Cao, Wei, Kang Wang, Isabelle Ledoux-Rak, and Jianzhuang Jiang. "ABAB-type phthalocyanines simultaneously bearing electron donating and electron accepting groups. Synthesis, spectroscopy, and structure." Inorganic Chemistry Frontiers 3, no. 9 (2016): 1146–51. http://dx.doi.org/10.1039/c6qi00147e.

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Mg(trans-TPTCPc) was successfully prepared and structurally characterized, representing the first structurally characterized ABAB-type phthalocyanine compound simultaneously bearing electron-donating and electron-accepting groups.

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Durand, Raphaël J., Sébastien Gauthier, Sylvain Achelle, et al. "Incorporation of a platinum center in the pi-conjugated core of push–pull chromophores for nonlinear optics (NLO)." Dalton Transactions 46, no. 9 (2017): 3059–69. http://dx.doi.org/10.1039/c7dt00252a.

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Baek, Jong-Beom, and Frank W. Harris. "Synthesis of phenylquinoxaline oligomers containing pendant electron-donating and electron-withdrawing groups." Journal of Polymer Science Part A: Polymer Chemistry 43, no. 24 (2005): 6465–79. http://dx.doi.org/10.1002/pola.21119.

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Bahrami, Mozhgan, Xingwen Zhang, Morteza Ehsani, Yousef Jahani, and Richard M. Laine. "[PhSiO1.5]8,10,12as nanoreactors for non-enzymatic introduction of ortho, meta or para-hydroxyl groups to aromatic molecules." Dalton Transactions 46, no. 27 (2017): 8797–808. http://dx.doi.org/10.1039/c7dt00373k.

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Traditional electrophilic bromination follows long established “rules”: electron-withdrawing substituents cause bromination selective formetapositions, whereas electron-donating substituents favororthoandparabromination.

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Dissertations / Theses on the topic "Electron-donating groups"

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Sutradhar, Tanushree. "Theoretical investigation on optoelectronic properties of nanoclusters and conjugates." Thesis, University of North Bengal, 2021. http://ir.nbu.ac.in/handle/123456789/4750.

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Cheng, Hong-Yi, and 陳鴻儀. "The synthesis of porphyrins with electron-withdrawing and -donating groups." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/64541561928294591379.

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碩士<br>國立中興大學<br>化學系所<br>96<br>Abstract A series of zinc porphyrins with both electron donor and acceptor groups were synthesized for use as NLO chromophores in optoelectronic materials and devices.The porphyrin bridge connecting D and A groups should provide a pathway for strong electronic coupling between D and A. Organic molecules with strong electron donor and electron aceptor groups that are connected by a large conjugated π– electron system usually show high β values, so we utilized a ethynyl unit to extendπ– conjugation of the systems. The preparation of porphyrins with ethyne-linked functional groups can be achieved by the sonogashira cross-coupling method. Light - harvesting arrays that consist of porphyrin and perylene units were synthesized. These arrays show broad absorption in the visible region. The energy transfer between porphyrin and perylene pigments was investigated by fluorescence spectroscopy. We except that porphyrin – perylene systems have high energy conversion efficiency in solar cells.

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CHANG, HSIEH MING, and 謝明璋. "Mechanistic Studies on The Thermal [m+n] Cycloadditions of Electron-Withdrawing Group Heptafulvenes and Electron-Donating Group Fulvenes." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/66903829394433213991.

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碩士<br>中國文化大學<br>應用化學研究所<br>88<br>In order to determine the product selectivity，such as the diastereoselectivity，periselectivity，and regioselectivity，which is governed by steric effects and electronic effects of the exocyclic substituents on the fulvenes and heptafulvenes，the intermolcular cycloadditions of electron-rich disubstituted 2- (2，4-cyclopentien-1-ylidene)-1，3-dithiolanefulvene (3c)，with 8，8-dicyanoheptafulvene (9a) are investigated. The reaction of strong electron-deficient substituted heptafulvene 9a (LUMO) with the fulvene 3c (HOMO) afford [4+2] adducts 20a (syn) and 20b (anti) in a ratio of about 1.58：1 in 65％ yield.

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Book chapters on the topic "Electron-donating groups"

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Bachrach, Steven M. "More Hard Truths." In Thinking Like a Physical Organic Chemist. Oxford University Press, 2023. http://dx.doi.org/10.1093/oso/9780197640371.003.0013.

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Abstract Organic chemistry textbooks commonly discuss alkyl groups (groups composed of carbon and hydrogen atoms) as electron donating. This chapter presents the standard experiments that support that notion and delves into the gas-phase acidity experiments that upend this standard explanation.

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Hore, P. J. "Chemical shifts." In Nuclear Magnetic Resonance. Oxford University Press, 2015. http://dx.doi.org/10.1093/hesc/9780198703419.003.0002.

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This chapter discusses chemical shifts. These give information on molecular identity and structure. The nuclear magnetic resonance (NMR) frequency of a nucleus in a molecule is determined principally by its magnetogyric ratio and the strength of the magnetic field it experiences. Chemical shifts arise because the field actually experienced by a nucleus in an atom or molecule differs slightly from the external field produced by the magnet. A magnetic field can induce two kinds of electronic current in a molecule: diamagnetic and paramagnetic. Diamagnetic and paramagnetic currents flow in opposite directions and give rise to nuclear shielding and deshielding, respectively. Chemical shifts can often be understood by considering the effects of electron donating and withdrawing groups, induced currents in neighbouring groups, charged or polar groups, hydrogen bonds, and unpaired electrons.

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Vinduja, Puttanveedu, and Karuvanthodi Muraleedharan. "Theoretical Studies on Anti-Oxidant Activity of the Phytochemical, Coumestrol and Its Derivatives." In Functional Foods - Phytochemicals and Health Promoting Potential. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96967.

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Free radical-induced changes in cellular and organ levels have been studied as a possible underlying cause of various adverse health conditions. Important research efforts have, therefore, been made to discover more powerful and potent antioxidants/free radical scavengers for the treatment of these adverse conditions. The phytoestrogen coumestrol intensively attracted scientific interest due to their efficient pharmacological activities. In this scenario, DFT studies were carried out to test the antiradical activities of coumestrol and its derivatives. The results obtained from FEDAM plots demonstrated that the coumestrol derivatives pointed out were good radical scavengers relative to the parent molecule in the gas phase. The derivatives whose 16thposition substituted with electron-donating groups like -NH2, -OCH3 and -CH3 showed good antioxidant capacity. Three antioxidant mechanisms, including hydrogen atom transfer (HAT), electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET), were investigated by measuring thermodynamic parameters.

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Agrawal, Pratibha S., M. K. N. Yenkie, M. G. Bhotmange, B. D. Deshpande, and S. J. Dhoble. "Degradation of Substituted Benzoic Acids Related to Structural Reactivity." In Water Pollution Sources and Purification: Challenges and Scope. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050684122010006.

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The existence of organic acids in aqueous waste continues to be an important environmental concern because of the odor and toxicity they impart to water. The photochemical degradation of benzoic acids (BA) and some of the substituted benzoic acids (SBA), which act as environmental pollutants, are studied in the present investigation using the Advanced Oxidation Processes (AOPs) and combinations of different oxidants and UV irradiation (UV/H2O2 , UV/TiO2 , UV/ZnO, and Fe(III)- oxalate complex). The photo-oxidative degradation of these pollutants was followed by studying their concentration decay over the period of exposure to the UV-oxidant combination. The degradation kinetics of substituted benzoic acids (SBA) is observed to be dependent on the directory nature of the substituent groups, analyzed by the Hammett constant (σ), where electron-withdrawing groups (EWGs) show positive values and electron-donating groups (EDGs) account for its negative values. These observations figured out the processes that can be efficiently used for the system. Thus, this paper aims to examine parameters that affect the photocatalytic degradation of substituted benzoic acids.

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Keeler, James, and Peter Wothers. "Transition metals." In Chemical Structure and Reactivity. Oxford University Press, 2013. http://dx.doi.org/10.1093/hesc/9780199604135.003.0019.

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This chapter assesses the d-block elements, which form Groups 3–11 and are collectively often referred to as the transition metals. The common feature of these elements is the presence of a partially filled d sub-shell. It is the presence of this partly filled shell which is responsible for most of the special properties which set the transition metals apart from main-group metals. These special properties include: the existence of compounds in which a particular element shows a range of oxidation states; the presence of unpaired electrons associated with the metal; the formation of coloured compounds and solutions; the formation of a large number of complexes in which the metal is surrounded by typically between four and six electron-donating ligands; and the formation of organometallic complexes in which the ligands have π systems. The chapter focuses mainly on transition metal complexes.

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Roy, M. N., V. N. G. Lindsay, and A. B. Charette. "Using Metal Carbenes Bearing One Electron-Withdrawing Group and One Electron-Donating Group." In Stereoselective Synthesis 1 Stereoselective Reactions of Carbon—Carbon Double Bonds. Georg Thieme Verlag KG, 2011. http://dx.doi.org/10.1055/sos-sd-201-00407.

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Mingos, D. M. P. "Dative bond to dipole moment." In Essentials of Inorganic Chemistry 1. Oxford University Press, 1995. http://dx.doi.org/10.1093/hesc/9780198558484.003.0004.

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This chapter focuses on the dative bond and the dipole moment. A dative or co-ordinate bond is a covalent bond which originates from the donation of an electron-pair from one atom (or group of atoms) to an empty orbital on a second atom. Although the origin of the electron-pair in a co-ordinate bond is usually a lone pair on the donating atom, it can also be an electron-pair residing in a bonding σ- or π-orbital. Molecules act as electric dipoles if the charge distribution in them corresponds to a separation of regions of partial positive and negative charges. This occurs when the vector sum of the bond and lone pair dipole moments have a non-zero resultant.

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Mellor, Sarah L., and Donald A. Wellings. "Synthesis of modified peptides." In Fmoc Solid Phase Peptide Synthesis. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780199637256.003.0010.

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Several important hormones such as oxytocin, secretin, and LHRH are known to be peptidyl amides. In addition to these, other peptidyl amides such as indolicidin and the protegrins have been shown to exhibit potent antimicrobial activity. The in vivo production of such compounds is via endogenous enzymatic cleavage of propeptides, making their synthesis by genetic engineering notoriously difficult. Furthermore, to facilitate the survival of synthetic peptidyl amides in vivo, an obvious defence against the action of carboxypeptidases is the N-alkylation of the carboxylic amide terminus. Such secondary amides would be expected to exhibit vastly different solubility and transport properties to primary amides, thus their chemical synthesis is of immense importance. The solid phase synthesis of peptidyl amides and peptidyl N-alkyl amides is centred around two main strategies: 1. Ammonolysis/aminolysis of resin-bound esters. 2. Use of resin-bound primary amines, which may in turn be chemically modified to generate novel secondary amine functionalized linkers for the synthesis of peptidyl N-alkyl amides. Early examples of the use of resin-bound amines for the solid synthesis of peptidyl amides involve the use of linkers such as benzhydrylamine or benzylamine. Following peptide assembly, these linkers require highly acidic (e.g. HF) mediated cleavage, and hence simultaneous removal of acid-labile sidechain protection groups occurs and may cause problems. Systematic modifications of these linker-resins by substitution with electron-donating substituents have resulted in the generation of numerous linker-resins with increased acid sensitivity. Notably, the 4-(2',4'-dimethoxyphenylaminomethyl) phenoxy derivatized (Rink) resin 1, which is cleavable by 95% v/v TFA, and the 5-(2-fluorenylmethoxycarbonylaminornethyl-3,5-dimethoxy)- phenoxyvaleric acid (PAL) linker 2 acidolysed by 75% v/v TFA. Greater acid lability has been achieved using the xanthenyl derivatized resin, 9-(fluorenylmethoxycarbonylamino)xanthen-3-yloxymethyl polystyrene (Sieber amide) resin 3, which besides being cleavable by 1% v/v TFA, holds the added advantage of readily undergoing reductive N-alkylation to afford resin-bound secondary amines for the synthesis of peptidyl N-alkyl amides. In addition to the method detailed below, a number of alternative approaches have recently been reported.

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Clayden, Jonathan, Nick Greeves, and Stuart Warren. "Synthesis and reactions of carbenes." In Organic Chemistry. Oxford University Press, 2012. http://dx.doi.org/10.1093/hesc/9780199270293.003.0038.

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This chapter reviews the synthesis and reactions of carbenes. The best evidence for the existence of carbenes comes from a group of structures which contain a carbene but are stable compounds. The most important of these are known as the ‘N-heterocyclic carbenes’—the carbene is incorporated into a five-membered ring and stabilized by the presence of two adjacent electron-donating nitrogen atoms and the bulky N-substituents. These stable carbenes are very much the exception: most carbenes are too reactive to be isolated. Ultimately, carbenes can be formed from many other reactive intermediates, such as carbocations, carbanions, and diazoalkanes. The chapter then looks at how they can react to give yet further reactive intermediates such as ylids.

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Nawaz Shariff, Shakeel, Supriya Saravu, and Dileep Ramakrishna. "Schiff Base Complexes for Catalytic Application." In Schiff Base in Organic, Inorganic and Physical Chemistry [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107904.

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Primary amines are combined with an aldehyde group to generate Schiff base compounds, which are called condensation imine products. This class of compounds has a general structure, R-C=NR\', where R and R\' represent alkyl/aryl/cyclohexyl/heterocyclic group. These compounds contain an azomethine group that is basic in nature due to, (i) the presence of lone pair of electrons on the nitrogen and (ii) electron-donating nature of the double bond. Hence, these compounds, as ligands, participate in the formation of metal complexes. The presence of lone pair of electrons on the nitrogen atom and the hybridization involved explains the physical, chemical, and spectral properties of nitrogen-containing moieties. In the case of (sp2) hybridization (trigonal structure), the lone pair of electrons occupies either a symmetrical unhybridized 2p orbital that is perpendicular to the plane of trigonal hybrids or a symmetrical hybrid orbital, whose axis is in the plane, leaving behind only the π-electrons in the unhybridized 2p orbital. A very similar type of hybridization is experienced by the nitrogen atom in the azomethine group. Traditional phosphine complexes of nickel, palladium, and platinum, particularly those of palladium, have played an extremely important role in the development of homogeneous catalysis. Schiff base complexes as catalysts have been studied for various organic transformations such as oxidation, epoxidation, reduction, coupling reactions, polymerization reactions, hydroformylations, and many more.

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Conference papers on the topic "Electron-donating groups"

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Knorr, Erica S., Jordan C. Kelly, Daniel P. Harrison, and Thomas N. Rohrabaugh. "Effect of electron-donating and -withdrawing groups on the photophysical properties of iridium (iii) diphenyl quinoxaline complexes." In Organic Photonic Materials and Devices XXVII, edited by Ileana Rau, Okihiro Sugihara, and William M. Shensky. SPIE, 2025. https://doi.org/10.1117/12.3047905.

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Smith, David A. M., Scott Williams, P. Jenkner, Robert D. Miller, E. J. Ginsburg, and Robin M. Hochstrasser. "Localization of excitations in silicon chains by electron donating side groups." In Optics Quebec, edited by Roger A. Lessard. SPIE, 1994. http://dx.doi.org/10.1117/12.166345.

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Liu, Li, Jie-Ping Shi, Hong-Wen Hu, and Guo-Yuan Lu. "Photophysical properties of tribranched chromophores Based on 1,3,5-triazine core and 3,4-ethyllenedioxythiophene electron-donating end-groups." In 2011 IEEE 4th International Nanoelectronics Conference (INEC). IEEE, 2011. http://dx.doi.org/10.1109/inec.2011.5991650.

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Runser, Claude, Marguerite Barzoukas, Alain Fort, Mireille Blanchard-Desce, and Jean-Marie Lehn. "Push-pull polyenes with enhanced quadratic nonlinear susceptibilities." In The European Conference on Lasers and Electro-Optics. Optica Publishing Group, 1994. http://dx.doi.org/10.1364/cleo_europe.1994.cwf42.

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Organic molecules have been extensively studied in view of their potential applications for second-harmonic generation and electrooptic modulation in nonlinear optics.1 Molecules bearing a donor- acceptor (or push-pull) substituted π electron system can yield significant quadratic hyperpolarizabilities β. In addition, early experimental studies on para disubstituted polyenic systems have shown superlinear dependences of β with the length of the conjugation path linking the electron-donating and electron-accepting end groups.2−4 Also semiempirical calculations conducted on two series of push-pull polyene series predicted a rapid increase in β with the number n of double bonds, the effect per unit volume saturating beyond n = 20.5 Clearly longer push-pull polyenes are relevant candidates for the design of compounds with dramatically enhanced nonlinearities.

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MOTOYOSHIYA, J., T. TANAKA, M. KUROE, and Y. NISHII. "CHEMILUMINESCENCE OF 9-BENZYLIDENE-10-METHYLACRIDANS WITH ELECTRON-DONATING GROUPS BY CHEMICALLY GENERATED SINGLET OXYGEN – APPLICATION TO METAL ION SENSING USING AZACROWNED COMPOUND." In Proceedings of the 15th International Symposium. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812839589_0054.

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Chittibabu, K. G., L. Li, X. Wang, J. Kumar, and S. K. Tripathy. "Thiophene based Nonlinear Optical Chromophore functionalized Epoxy Polymers for Electro-Optic Applications." In Organic Thin Films for Photonic Applications. Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.thc.4.

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Polymeric materials present certain advantages over inorganic crystals for second-order nonlinear optical (NLO) applications because of their low dielectric constant, large optical nonlinearity, low cost, and ease of processability. Stable NLO polymeric materials are potential candidates for electro-optic (EO) devices such as high bandwidth electro-optic modulators [1], optical interconnects [2], and fiber optic gyros [3]. Second-order NLO properties in polymers are present when the chromophores are aligned in a non-centrosymmetric manner. Chromophores with enhanced NLO susceptibilities can be obtained by increasing electron-donating and/or accepting effects [4], by extending the conjugation length between the donor and acceptor groups [5] and by replacing the phenyl moieties in the chromophores with thiophene moieties [6]. Efforts were made by our group [7] and various other groups [6, 8] to synthesize and optimize the properties of the chromophore functionalized polymers with high optical nonlinearity. Jen and coworkers synthesized a variety of thiophene based chromophores with high optical nonlinearity, 'μβ' [6, 8]. Many of these chromophores, when doped in a polymer matrix exhibited an electro-optic value greater than 20 pm/V. Marder and coworkers studied the effect of strong acceptors in NLO chromophores and have found that an 'r33' value of 55 pm/V at 1.313 μm is realizable with some of these chromophore doped polycarbonate composites. However, most of these systems are of guest-host type, which limit the chromophore solubility as well as temporal stability of the poled order in the NLO chromophore-polymer composites.

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Yoshihara, K., A. Douhal, Y. Nagasawa, A. Yartzev, H. Kandori, and K. Kenmitz. "Femtosecond intermolecular electron transfer : dye in weakly polar electron-donating solvent." In International Conference on Ultrafast Phenomena. Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.md1.

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Ultrafast intermolecular electron transfer (0.1-0.2 ps) was observed for xantheme dyes in electron-donating solvents. Rates were limited by ultrafast nuclear relaxation not by solvent longitudinal relaxation, (470 mn) and AN (405 nm) and DMA (470 nm) cations in the subpicosecond timescale. From the recovery of ground-state depletion and decay of cation radicals, the reverse ET was also found to be fast, i.e., 4.0 ps in NB/DMA and 2.7 ps in NB/AN.

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Plaza, P., N. Dai Hung, M. M. Martin, Y. H. Meyer, and W. Rettig. "Investigation of Fast Relaxation Processes in Non-fluorescent Rhodamine Dyes." In International Conference on Ultrafast Phenomena. Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.fc21.

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Non radiative relaxation of various N-substituted ethyl-ester-Rhodamine dyes (scheme A) was explained by assuming an intramolecular rotational motion towards a low lying non emissive TICT-like state with charge localization [1]. Stationary and time-resolved fluorescence experiments evidenced that fluorescence quenching in those Rhodamines is linked with the rotation of the amino group. On the other hand, if the o-carboxyphenyl group is exchanged for a p-dimethylamino electron donor group (scheme B), the fluorescence quantum yield is very low in neutral ethanol but increases by more than two orders of magnitude in acidic ethanol solutions, where the electron donating property of the anilino group can be blocked by protonation [1, 2].

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Nagasawa, Yutaka, Arkadiy P. Yartsev, Keisuke Tominaga, and Keitaro Yoshihara. "Chemical Substitution and Deuterium Isotope Effects on Ultrafast Intermolecular Electron Transfer: Possible Role of Molecular Vibrations." In International Conference on Ultrafast Phenomena. Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.fa.3.

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We have observed ultrafast non-exponential fluorescence quenching of 7-aminocoumarin dyes in electron donating solvents by means of femtosecond fluorescence up-conversion technique [1]. We regarded this fluorescence quenching as an ultrafast intermolecular electron transfer (ET) from the solvent to the excited dye. When the carbon chain on the amino group becomes longer, the rate of ET becomes slower, and when the amino group is fixed by hexagonal carbon ring, it becomes the slowest. Some of the fast reactions occur much faster than the diffusive solvent relaxation process. The fastest reaction with a time constant of ~200 fs was observed for coumarin 151 (C151) in N,N-dimethylaniline (DMA). In such a case, some dynamics faster than diffusive orientational polarization of the solvent is required to induce the reaction.

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Andrade, Karine N. de, Amanda R. P. Costa, Rodolfo I. Teixeira, et al. "Photophysical characterization of 3-acyl-4-quinolones." In VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol202006.

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Abstract:

4-quinolones derivatives can present fluorescent properties, depending on their substituents and on the chemical environment (e.g., acidic medium), allowing their application as ion sensors. We theoretically evaluated the photophysical properties of previously synthesized 3-acyl-4-quinolones to verify how different substituents (R1=H, NH2 and R2 = OEt, OH, NHPh) affect their absorption profiles and the emission profile of a reference compound, PB3. All DFT and TD-DFT calculations were performed at B3LYP-D3/6-311++G(d,p) level and continuum polarization model for simulated acetonitrile as solvent. For PB2 (R1 = H, R2 = OEt), we observed hypsochromic shift compared to PB3 due to the increase of the gap between HOMO/LUMO (absence of electron-donating group), in accordance with experimental data. For R1=NH2 and R2=OH, NHPh (PB6 and PB10, respectively), the gap between HOMO/LUMO increases, resulting in a soft bathochromic shift for the simulated absorption spectra. In addition, we evaluated the effect of acid addition on the absorption and emission profile of PB3 and the results were compared with experimental data. Our thermodynamic results suggest that protonation occurs on the endocyclic carbonyl of the quinolone moiety, probably due to an increased aromatic character, as suggested by our NICS calculations. Finally, we associate the increase of the fluorescence in the acidic medium to the establishment of an intramolecular hydrogen bond and, thus, increased rigidity.

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