基于2-(2'-羟基苯基)苯并噻唑的激发态分子内质子转移化合物的光物理行为研究

Investigation of the Photophysical Behavior for the Excited State Intramolecular Proton Transfer Compound Based on 2-(2'-Hydroxyphenyl)Benzothiazole

运用量子化学理论计算方法结合现代光谱技术对激发态分子内质子转移(Excited state intramolecular proton transfer,ESIPT)化合物DHBIA{N,N'-di[3-hydroxy-4-(2'-benzothiazole)phenyl]5-tert-butyl-isophthalic amide}的激发态光物理行为进行了深入研究.研究表明:该化合物的醇式激发态很容易发生分子内C—N单键的快速扭转,使分子构型发生大幅扭曲,并显现出明显的扭曲的分子内电荷转移(Twisted intramolecular charge transfer,TICT)特征,激发态的这种构型弛豫导致的非辐射失活与质子转移过程相竞争,导致了激发态质子转移效率的降低以及相应酮式结构发光物种的大幅减少,从而致使化合物稀溶液的发光极为微弱.这种TICT特征也正是导致该化合物具有聚集发光增强性质的重要原因之一.

By spectrum analysis and theoretical calculation,the photophysics of the excited state for the excited state intramolecular proton transfer（ESIPT） compound,DHBIA {N,N＇-di[3-hydroxy-4-（2＇-benzothiazole）phenyl]5-tert-butyl-isophthalic amide},was thoroughly investigated.It was revealed that the vertical normal enol excited state favored an extremely fast twisted intramolecular charge transfer（TICT） deactivation via rotation of C—N bond,resulting in a greatly twisted configuration of the enol excited state.The nonradiative decay of this TICT geometry relaxation prevailed against the ESIPT deactivation to the keto excited state,leading to the weak luminescence of the dilute solution,which was essential to the enhanced emission of its aggregates.