- Interaction between a pyridyl and a naphthyl/pyrenyl moiety in covalently linked systems
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Photophysical properties of two bichromophoric systems comprising a pyridyl moiety and a naphthyl/pyrenyl moiety covalently linked through a dimethylene bridge have been investigated. The spectral behavior of the systems suggests the formation of an intramolecular complex between the two terminal moieties of the molecules in the ground state. Interestingly, no intermolecular complexation could be observed with a 1:1 mixture of the constituting components. This contrasting behavior has been interpreted taking into consideration the difference in the entropy change associated with the complexation process. Based on the effect of solvent polarity on the absorption and emission behavior of the complex and taking into consideration the molecular geometry, it is concluded that the interaction between the aromatic hydrocarbon and pyridyl moieties is primarily driven through an overlap of the π-clouds.
- Sankaran,Das, Amitava,Samanta, Anunay
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- Photochemical Structural Transformation of a Linear 1D Coordination Polymer Impacts the Electrical Conductivity
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A pair of 4-(1-naphthylvinyl)pyridine (4-nvp) ligands has been successfully aligned in head-to-tail fashion in a one-dimensional (1D) double chain ladder polymer [Cd(adc)(4-nvp)2(H2O)]n (1; H2adc = acetylenedicarboxylic acid) that undergoes a photochemical [2 + 2] cycloaddition reaction accompanied by single-crystal to single-crystal (SCSC) structural transformation from a 1D chain to a 2D layer structure. These structural changes have a significant impact on the conductivity and Schottky nature of the compound.
- Dutta, Basudeb,Dey, Arka,Sinha, Chittaranjan,Ray, Partha Pratim,Mir, Mohammad Hedayetullah
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- In Situ Assembly of Choline Acetyltransferase Ligands by a Hydrothiolation Reaction Reveals Key Determinants for Inhibitor Design
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The potential drug target choline acetyltransferase (ChAT) catalyses the production of the neurotransmitter acetylcholine in cholinergic neurons, T-cells, and B-cells. Herein, we show that arylvinylpyridiniums (AVPs), the most widely studied class of ChAT inhibitors, act as substrate in an unusual coenzyme A-dependent hydrothiolation reaction. This in situ synthesis yields an adduct that is the actual enzyme inhibitor. The adduct is deeply buried in the active site tunnel of ChAT and interactions with a hydrophobic pocket near the choline binding site have major implications for the molecular recognition of inhibitors. Our findings clarify the inhibition mechanism of AVPs, establish a drug modality that exploits a target-catalysed reaction between exogenous and endogenous precursors, and provide new directions for the development of ChAT inhibitors with improved potency and bioactivity.
- Wiktelius, Daniel,Allgardsson, Anders,Bergstr?m, Tomas,Hoster, Norman,Akfur, Christine,Forsgren, Nina,Lejon, Christian,Hedenstr?m, Mattias,Linusson, Anna,Ekstr?m, Fredrik
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supporting information
p. 813 - 819
(2020/12/09)
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- [2+2] Photodimerization of Stilbazoles Promoted by Oxalic Acid in Suspension
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In this study, a very simple technique to perform efficiently photodimerization of some vinylpyridines is reported. By irradiating a stirred mixture of several stilbazoles with solid oxalic acid dihydrate dispersed in a nonpolar (i.e., cyclohexane) or moderately polar (benzene, dichloromethane, dioxane) solvent, the corresponding dimeric cyclobutane adducts were obtained in high yields and excellent regio- and stereoselectivities. The strategy could also be applied successfully to oily, waxy, or even insoluble stilbazoles. Moreover, the oxalic acid loading could be lowered to substoichiometric amounts. When further optimizations were needed, our strategy was found to be highly flexible to identify other oligocarboxylic acids as alternative additives to improve, or even overturn, the regioselectivity. Oxalic acid and other oligocarboxylic acids were found to be capable of orienting more than 50 stilbazoles toward photodimerization under these conditions.
- Nguyen, Thanh Binh,Nguyen, Tuan Minh,Retailleau, Pascal
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supporting information
p. 4682 - 4689
(2020/04/15)
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- Triplet and Radical Ion Properties of Styrylnaphthalenes and their Aza-derivatives: A Laser Flash Photolytic Study
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Laser flash photolysis was used to produce and investigate the lowest excited triplet state (T1) and radical ions (DAE+ radical and DAE- radical) of some diarylethylenes (DAE).In particular, the two trans-styrylnaphthalene isomers (n-StN, where n = 1 or 2 on the naphthalene) and four trans-1-(n-naphthyl)-2-(n'-pyridyl)ethylenes (n,n'-NPE, with n,n' = 1,4'; 2,2'; 2,3' and 2,4') were studied.The transients were characterized in terms of their absorption spectra, decay kinetics, molar absorption coefficients (for DAE+ radical and DAE- radical) and formation quantum yields (for T1 and DAE+ radical).Except for 1-StN, under direct excitation in the absence of quenchers (λexc = 308 and 347 nm), T1 -> Tn absorption was undetectable and DAE+ radical was the only transient observed, even though it was produced in low yield (ΦPI 1 of the DAEs was characterized in n-hexane, in the presence of 4-bromo-N, N-dimethylaniline (BrDMA) which enhances the intersystem-crossing quantum yields, while DAE- radical was produced and studied in acetonitrile, by laser excitation at 347 nm, in the presence of diethylaniline (DEA) and BrDMA.
- Aloisi, Gian Gaetano,Elisei, Fausto,Latterini, Loredana
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p. 2139 - 2146
(2007/10/02)
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