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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Excited-State Intramolecular Proton Transfer in 2-(2'-Tosylaminophenyl)benzimidazole
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Excited-State Intramolecular Proton Transfer in 2-(2'-Tosylaminophenyl)benzimidazole

机译：2-（2'-甲苯磺酰基氨基苯基）苯并咪唑中的兴奋态分子内质子转移

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摘要

The spectroscopic properties of 2-(2'-tosylaminophenyl)benzimidazole (TPBI) have been studied in a series of different solvents. As revealed by absorbance, steady-state, and time-resolved emission spectroscopy, the molecule undergoes fast excited-state intramolecular proton transfer (ESIPT) to yield emission of the corresponding tautomeric species with a large quantum yield (0.5). The fluorescence emission shows monoexponential decay kinetics (τ = 4.5 ns) regardless of the nature of the solvent. The ground-state equilibrium is dominated by a single rotamer and small amounts of the deprotonated anion. The X-ray structure of TPBI shows a substantial out-of-plane twist along the aryl-benzimidazole bond axis, which is presumably due to π-stacking interactions between the tosylamide and benzimidazole rings. Ab initio calculations suggest a different structure in the gas phase without π-stacking interactions and a substantially reduced twist angel. A large energy barrier for interconversion of the cis- and trans-rotamers in the ground and excited state has been predicted on the basis of DFT calculations, which is in agreement with all experimental data. The ground-state equilibrium and ESIPT process of TPBI are essentially unaffected by the nature of the solvent, which is of particular interest to sensing applications in cell biology.
机译：在一系列不同的溶剂中研究了2-（2'-甲苯磺酰基氨基苯基）苯并咪唑（TPBI）的光谱性质。如吸光度，稳态和时间分辨发射光谱所揭示，该分子经历了快速激发态分子内质子转移（ESIPT），从而产生了具有大量子产率（0.5）的相应互变异构物质的发射。无论溶剂的性质如何，荧光发射均显示出单指数衰减动力学（τ= 4.5 ns）。基态平衡由单个旋转异构体和少量的去质子化阴离子控制。 TPBI的X射线结构显示出沿芳基-苯并咪唑键轴的大量平面外扭曲，这可能是由于甲苯磺酰胺和苯并咪唑环之间的π堆积相互作用。从头算计算表明，气相中的结构不同，没有π堆积相互作用，并且扭转角大大降低。在DFT计算的基础上，已经预测了基态和激发态的顺式和反式旋转异构体互变的巨大能量垒，这与所有实验数据都一致。 TPBI的基态平衡和ESIPT过程基本上不受溶剂性质的影响，这对于传感细胞生物学中的应用尤为重要。

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