title: Significant effects of substituents on substituted naphthalenes in the higher triplet excited state.
abstract: Substituent effect on the lifetimes of a series of substituted naphthalenes (Np) in the higher triplet excited state (Tn) was studied with transient absorption measurements using the two-color two-laser flash photolysis technique. Lifetimes of Np(Tn) in cyclohexane solution were determined from the triplet energy transfer quenching by carbon tetrachloride to be 0.98-63 ps. The different lifetimes of Np(Tn) were explained by the energy gap law for the internal conversion from Np(Tn) to Np(T1), indicating that Np(Tn) quenched by carbon tetrachloride is assigned to Np(T2) with the longest lifetime among Np(Tn). The lifetime of Np(Tn) was correlative with the Hammett sigmap constant. Electronic characters of substituents showed a more significant influence on the energy of the T2 state than that of the T1 state.
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Xichen
authors.initials: X
authors.lastname: Cai
authors.forename: Michihiro
authors.initials: M
authors.lastname: Hara
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fujitsuka
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima
mesh_terms: D003116:Color; D007700:Kinetics; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D010782:Photolysis; D013057:Spectrum Analysis
chemical_list: D009281:Naphthalenes