Solvent Effect on the Photoinduced Electron Transfer Reaction Between Thioxanthen-9-one and Diphenylamine
- Received Date: 2015-03-30
- Electron transfer, Protonation, Reaction mechanism, Absorption spectra, Laser flash photolysis
Abstract: Photoinduced chemical reaction between thioxanthen-9-one (TX) and diphenylamine (DPA) were investigated by the nanosecond laser flash photolysis. With photolysis at 355 nm, the triplet TX (3TX*) is produced via a Franck-Condon excitation and intersystem crossing. In the transient absorption spectra of the reduction of 3TX* by DPA in pure and aqueous CH3CN, four bands are clearly observed and assigned to absorption of 3TX*, TXH·, TX·- and DPA·+, respectively. With the increase of solvent polarity, the blue-shift was observed for all absorption bands of the intermediates. With the aid of dynamic decay curves, an electron transfer followed by a protonation process is confirmed for the reduction of 3TX* by DPA. The quenching rate constants of 3TX* by DPA very slightly decrease from 9.7×109 L/(mol·s) in pure CH3CN, to 8.7×109 L/(mol·s) in CH3CN:H2O (9:1), 8.0×109 L/(mol·s) in CH3CN:H2O (4:1) and 7.5×109 L/(mol·s) in CH3CN:H2O (1:1). Therefore water plays a minor role in the title reaction, and moreover no obvious medium effect of solvent polarity is observed for the electron transfer between 3TX* and DPA, indicating that the 3nπ* and 3ππ* states of TX have the approximate ability to attract an electron from DPA.
|Citation:||Lin Chen, Qiao-hui Zhou, Xiang Liu, Xiao-guo Zhou, Shi-lin Liu. Solvent Effect on the Photoinduced Electron Transfer Reaction Between Thioxanthen-9-one and Diphenylamine[J]. Chinese Journal of Chemical Physics , 2015, 28(4): 493-500. doi: 10.1063/1674-0068/28/cjcp1503054|