极性敏感的BDP分子溶剂化效应的光谱性质  

Spectroscopic Characterization of Solvation Effect for a Polarity-Sensitive BDP

作　　者：赵宇辉 李明乐 龙飒然 樊江莉[1] 彭孝军[1] ZHAO Yuhui;LI Mingle;LONG Saran;FAN Jiangli;PENG Xiaojun(State Key Laboratory of Fine Chemicals,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学精细化工国家重点实验室,大连116024

出　　处：《高等学校化学学报》2020年第9期2018-2024,共7页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21703025,21925802,21421005)资助.

摘　　要：合成了具有分子内电荷转移(ICT)性质的三重态光敏剂分子BDP,研究了其稳态吸收光谱、荧光光谱、荧光寿命、飞秒/纳秒瞬态吸收光谱及诱导产生单线态氧的能力等性质,发现强极性溶剂对BDP分子的溶剂化效应降低了其ICT态和第一激发三重态(T1态)的能量,从而降低了BDP分子单线态氧的产量.Polarity is an important physical and chemical property of solvent systems.Hence it is of a great significance to study the dynamics mechanism of excited photosensitizers influenced by the solvent polarity.A push-pull molecule BDP,which contains dipyrrometheneboron difluoride(BDPIPY)and carbazole groups,was synthesized.Measurements such as steady-state spectra,fluorescence lifetime and femtosecond/nanosecond transient absorption were performed on BDP in different polar solvents in order to research spectroscopic characters of its excited states.The red-shifted fluorescence spectra with increasing solvent polarity show that it is possible to form an intramolecular charge transfer(ICT)state in excited BDP.Furthermore,fluores⁃cence lifetimes measured by means of time-correlated single photon counting(TCSPC)also prove the existence of ICT state since the fluorescence lifetime of BDP in high-polar solvent is shorter than that in low-polar sol⁃vent.Femtosecond transient absorption experiments reveal that a solvation-stabilized relaxed ICT state(ICT′)is formed only in high-polar solvent because of its solvation effect.The time constant of solvation-stabilized pro⁃cess is 3.14 ps obtained by global analysis of the transient absorption spectra based on the sequential model.In addition,nanosecond transient absorption measurements show different lifetimes of the first excited triplet state(T1 state)for BDP in high/low-polar solvent under air or N2 condition.The lifetime of T1 state in low-polar sol⁃vent with oxygen is much shorter than that without oxygen,indicating the generation of singlet oxygen by ener⁃gy transfer.However,there is only a small difference between the lifetimes of T1 state in high-polar solvent with or without oxygen,which indicates that it is difficult to generate singlet oxygen by energy transfer.This re⁃sult proves that the energy of T1 state in high-polar solvent becomes lower accordingly,which will cause a lower singlet oxygen yield because of the disadvantage in energy transfer.The fol

关 键 词：极性 溶剂化 瞬态吸收 光敏剂 单线态氧 

分 类 号：O644.1[理学—物理化学]