Spectroscopic and Kinetic Studies of the Photochromism of N -Salicylideneanilines and Related Compounds

Abstract

Photochromism of N-salicylideneanilines and related compounds was studied by measuring the electronic and vibrational spectra of the transient species. The rise time of the transient electronic spectra of the photochromic colored species was measured by picosecond time-resolved spectroscopy and was found to be dependent upon solvent viscosity. FT IR spectra showed that the photochromic colored species took the keto amine form. Picosecond kinetic analysis demonstrated that an intermediate existed in the transfer process from cis-keto amine to the photochromic species. These facts led us to the conclusion that the photochromic phenomenon of N-salicylideneanilines occurred through enol imine\oversethν→enol imine*→cis-keto amine*→the intermediate→trans-keto amine (photochromic species).