基于激发态分子内质子转移过程的HBT-OMe分子检测HClO的荧光增强机理  

Mechanism of fluorescence enhancement of HClO detected by excited-state intramolecular proton transfer based HBT-OMe molecule

作　　者：刘晓军[1] 杨雪[2] Liu Xiao-Jun;Yang Xue(College of Science,Qiqihar University,Qiqihar 161006,China;College of Science,Jilin Institute of Chemical Technology,Jilin 132022,China)

机构地区：[1]齐齐哈尔大学理学院,齐齐哈尔161006 [2]吉林化工学院理学院,吉林132022

出　　处：《物理学报》2023年第11期185-190,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11904126)资助的课题.

摘　　要：采用密度泛函理论(DFT)和含时密度泛函理论(TDDFT)方法,基于连续介质模型,对HBT-OMe分子及其与HClO反应的产物基态和激发态结构及电荷分布等性质进行研究,优化构型结果表明,HBT-OMe分子不能发生质子转移过程而其产物分子则能发生.红外振动光谱与分子共价作用分析进一步证实产物分子能发生质子转移过程.计算的前线分子轨道结果表明:HBT-OMe分子存在扭曲电荷转移(TICT)过程,最高已占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)电荷密度重叠小导致HBT-OMe分子荧光强度弱,结合产物分子势能曲线发现,产物分子质子转移过程能抑制分子的TICT过程,从而使其荧光强度增强.The molecule with excited-state intramolecular proton transfer(ESIPT)has wide applications in fluorescent probe,biology imaging,light-emitting materials,etc.Biologically active oxygen hypochlorite(HClO)exists widely in the biological and chemical environment,which can pose a great threat to human health.Design of HClO-sensitive molecules in solvents is very important.Recently,Wu et al.[Wu L L,Yang Q Y,Liu L Y,et al.2018 Chem.Commun.548522]designed an ESIPT-based HBT-OMe probe molecule,which can detect HClO due to its methoxy-hydroxy-benzothiazole.They found that the fluorescence intensity of the system gradually increases with HClO increasing.However,the microscopic mechanism of this highly efficient fluorescent probe is not well understood.Therefore,in this work,we theoretically investigate the ESIPT mechanism of the HBT-Ome and its product molecule by using density functional theory and time-dependent density functional theory.Based on polarizable continuum model(PCM)with the integral equation formalism variant(IEFPCM)and Becke’s three-parameter hybrid exchange function with the Lee-Yang-Parr gradientcorrected functional(B3LYP)as well as the TZVP basis,the optimized structures are obtained.The structures show that the HBT-Ome product molecules tend to undergo proton transfer in the excited state but HBT-OMe molecules cannot undergo the proton transfer process.The analysis of frontier molecular orbitals not only explains the reason why the fluorescence of the HBT-Ome product is enhanced,but also demonstrates that the HBT-Ome fluorescence intensity is diminished owing to twisted intramolecular charge transfer in the excited state.It is twisted intramolecular charge transfer that leads smaller charge density to be overlapped and the fluorescence intensity of HBT-OMe molecule to be further weakened.Infrared vibrational spectrum shows the enhancement of intramolecular hydrogen bond of O—H,which indicates the tendency of proton transfer.The molecular covalent interaction analysis shows that the intramolecular int

关 键 词：激发态质子转移 含时密度泛函 次氯酸 

分 类 号：O641.1[理学—物理化学]