Three Modes of Proton Transfer in One Chromophore: Photoinduced Tautomerization in 2-(1H-Pyrazol-5-yl)Pyridines, Their Dimers and Alcohol Complexes
Three Modes of Proton Transfer in One Chromophore: Photoinduced Tautomerization in 2-(1H-Pyrazol-5-yl)Pyridines, Their Dimers and Alcohol Complexes
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DOI：
10.1002/cphc.201200602
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发表时间：
2012-11-12
期刊：
影响因子：
2.9
通讯作者：
Herbich, Jerzy
中科院分区：
文献类型：
--
作者：
Vetokhina, Volha;Dobek, Krzysztof;Herbich, Jerzy
研究2-（1H-吡唑-5-基）吡啶（PPP）及其衍生物2-（4-甲基-1H-吡唑-5-基）吡啶（MPP）和2-通过静态和时间分辨UV/维斯光谱方法和量子化学计算，对3-溴-1H-吡唑-5-基）吡啶（BPP）进行了研究，结果表明，这类化合物提供了一种罕见的表现出三种类型光反应的分子实例：1）顺式MPP中的激发态分子内质子转移（ESIPT），2）非极性介质中PPP二聚体中的激发态分子间双质子转移（ESDPT），以及3）PPP和MPP与醇类配体的氢键1：1复合物中的溶剂辅助双质子转移。激发态过程表现为双发光和双峰不可逆动力学耦合的两个荧光带的外观。基态synanti平衡检测和讨论。高能量反式的分数因不同的衍生物而异，并且强烈依赖于溶剂的极性和氢键供体或受体的能力。
Studies of 2-(1H-pyrazol-5-yl)pyridine (PPP) and its derivatives 2-(4-methyl-1H-pyrazol-5-yl)pyridine (MPP) and 2-(3-bromo-1H-pyrazol-5-yl)pyridine (BPP) by stationary and time-resolved UV/Vis spectroscopic methods, and quantum chemical computations show that this class of compounds provides a rare example of molecules that exhibit three types of photoreactions: 1) excited-state intramolecular proton transfer (ESIPT) in the syn form of MPP, 2) excited-state intermolecular double-proton transfer (ESDPT) in the dimers of PPP in nonpolar media, as well as 3) solvent-assisted double-proton transfer in hydrogen-bonded 1:1 complexes of PPP and MPP with alcoholic partners. The excited-state processes are manifested by the appearance of a dual luminescence and a bimodal irreversible kinetic coupling of the two fluorescence bands. Ground-state synanti equilibria are detected and discussed. The fraction of the higher-energy anti form varies for different derivatives and is strongly dependent on the solvent polarity and hydrogen-bond donor or acceptor abilities.