title: Solvent effects on 3-keto-1H-pyrido[3,2,1-kl]phenothiazine fluorescence in polar and protic solvents.
abstract: Solvent effects on 3-keto-1H-pyrido[3,2,1-kl]phenothiazine (PTZ-5) fluorescence in aprotic and protic solvents were investigated using the time-dependent density functional theory method. Enhancement of PTZ-5 fluorescence in the polar aprotic solvent is caused by the decoupling of the two proximity low-lying excited singlet states. In polar protic solvents, aside from the solvent polarity effects, hydrogen-bonding effects are significant to the enhancement of fluorescence. Hydrogen bonds confine C-H out-of-plane bending and severely decouple the two low-lying excited singlet states, greatly decreasing nonradiative decay. The excited state intermolecular proton transfer model is considered a quenching reaction for excited PTZ-5; however, it is uncompetitive in excited-state dynamics.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, PR China.
authors.forename: Songqiu
authors.initials: S
authors.lastname: Yang
authors.forename: Jianyong
authors.initials: J
authors.lastname: Liu
authors.forename: Panwang
authors.initials: P
authors.lastname: Zhou
authors.forename: Guozhong
authors.initials: G
authors.lastname: He