Substituent-controlled aggregate luminescence:Computational unraveling of S_(1)/S_(0)surface crossing  

作　　者：Ping-An Yin Qi Ou Qian Peng Zhigang Shuai 

机构地区：[1]MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering,Department of Chemistry,Tsinghua University,Beijing,China [2]AI for Science Institute,Beijing,China [3]School of Chemical Science,University of Chinese Academy of Sciences,Beijing,China [4]School of Science and Engineering,The Chinese University of Hong Kong,Shenzhen,Guangdong,China

出　　处：《Aggregate》2023年第3期110-119,共10页聚集体（英文）

基　　金：National Natural Science Foundation of China,Grant/Award Numbers:21788102,2017YFA0204501。

摘　　要：We computationally investigated the molecular aggregation effects on the excited state deactivation processes by considering both the direct vibrational relaxation and the S0/S1 surface crossing,that is,the minimum energy conical intersection(MECI).Taking classical AIEgens bis(piperidyl)anthracenes(BPAs)isomers and the substituted silole derivatives as examples,we show that the deformation ofMECI always occurs at the atom with greater hole/electron overlap.Besides,the energetic and structural changes of MECI caused by substituent has been investigated.We find that effective substituent such as the addition of the electron-donating groups,which can polarize the distribution of hole/electron density of molecules,will lead to the pyramidalization deformation of MECI occurring at the substituent position and simultaneously reduce the required energy to reach MECI.And MECI is sterically restricted by the surrounding molecules in solid phase,which remarkably hinders the non-radiative decay through surface crossing.Through quantitative computational assessments of the fluorescence quantum efficiency for both solution and solid phases,we elucidate the role of MECI and its dependence on the substitutions through pyramidalization deformation,which give rise to the aggregation-induced emission(AIE)phenomenon for 9,10-BPA,to aggregation-enhance emission(AEE)behavior for 1,4-BPA,and to conventional aggregation-caused quenching(ACQ)for 1,5-BPA.We further verify such mechanism for siloles,for which we found that the substitutions do not change the AIE behavior.Our findings render a general molecular design approach to manipulating the aggregation effect for optical emission.

关 键 词：aggregation-caused quenching aggregation-induced emission minimum energy conical intersection substituent effect 

分 类 号：O62[理学—有机化学]