64568-31-6Relevant academic research and scientific papers
Transient Absorption and Two-Step Laser-Induced Fluorescence Studies of Excited States of Substituted Diphenylcarbenes
Fujiwara, Yoshihisa,Sasaki, Mamoru,Tanimoto, Yoshifumi,Itoh, Michiya
, p. 702 - 707 (1989)
Several para-substituted diphenylcarbenes were generated from the corresponding diphenyldiazomethanes at room temperature and 77 K.The transient absorption (Tn 1 and Tn 0) and fluorescence (T1 -> T0) spectra of the triplet states of a series of para-substituted diphenylcarbenes were obtained by laser flash photolysis and two-step laser-induced fluorescence (TS-LIF) spectroscopy at room temperature.A significant fluorescence spectral shift of these excited triplet states diphenylcarbenes between TS-LIF at room temperature and fluorescence at 77 K was observed.No spectral difference was detected in a structurally rigid carbene, 10,11-dihydrodibenzocycloheptenylidene.The facts are discussed in terms of a temperature dependence of the rotation of phenyl rings around a C-C bond and/or of a bending motion of a C-C-C bond in the fluorescent state of the diphenylcarbenes.Very small heavy-atom and deuterium isotope effects on the fluorescence (T1 -> T0) lifetimes of these diphenylcarbenes were observed.The data suggests that there is no Sn state of diphenylcarbene involved in the T1 relaxation process.
Photophysics of Some Substituted Diphenylmethylenes
Ono, Y.,Ware, W. R.
, p. 4426 - 4433 (2007/10/02)
Absorption, emission, and excitation spectra, fluorescence decay times, and quantum yields of a series of substituted diphenylmethylenes have been measured in various rigid organic matrices at low temperatures.Substitution on the phenyl ring led to a decrease in lifetime, the greatest effect being observed in the dibromo compound, the lifetime of which was 10percent that of the unsubstituted compound.In addition, there was a small but noticeable external heavy atom effect on the decay times.The fluorescence quantum yields of some of the substituted diphenylmethylenes were found to depend on the energy of excitation.Changes in the absorption spectra in the temperature range between 4 and 95 K may be the result of appreciable population of close-lying singlet and triplet levels in the ground state at 95 K.The spectral changes were irreversible, however, possibly implying geometrical configuration changes.
