混合溶剂中粘度效应对TICT激发态生成的影响

Viscosity Effects on TICT Excited State in Mixed Solvents

利用时间相关单光子计数技术,研究了两种非刚性7-胺基香豆素在几种性质不同混合溶剂中的分子荧光衰减过程.结果发现,在非极性混合溶剂中,荧光寿命不受粘度的影响;而在极性的混合溶剂中,荧光寿命随粘度增大而增大.证明了非刚性7-胺基香豆素分子可以生成扭转型分子内电荷转移(即TICT)激发态.并研究了粘度等环境因素对TICT态生成的影响。

The fluorescence decay dynamics of two kinds of 7-aminocoumarin derivatives molecules with intramolecular ratable groups in different mixed solvents was investigated by time-correlated single photon counting methods. The results show that the fluorescence lifetime does not change with viscosity in nonpolar mixed solvents, while it increases with the viscosity in polar mixed solvents. These viscosity effects proved that the excited states of coumarin molecules with unrigid structure can change into a twisted intramolecular charge transfer state, and there exists a potential barrier between the planar state and the twisted state