The effect of substituents and polymer media on photochromism kinetics of indolinospironaphthoxazine

The effect of substituents in indoline moiety and polymer media on photochr omism and thermal decay processes of spirooxazine (ASP) was investigated. T he thermal decoloration rate was decreased with increasing steric hindrance of substituents in 1-position of indoline moiety. The stability of the col ored forms was improved when the hydrogen in the 5-position of indoline moi ety was replaced with electron-donating groups and was decreased when subst ituted by electron-withdrawing groups. In addition, the stability of the co lored forms was related to properties of polymer media. The thermal decay r ate decreased with an increase in the polarity and rigidity of polymer medi a. The thermal decay kinetics of the colored forms obeyed biexponential dec ay law.