Kinetics of the photochromic decay reaction of 2,2′,4,4′,5,5′-hexaphenyl-bi-imidazolyl

Abstract

Kinetic studies on this reaction show that the reaction order is three-halves in radical concentration falling to first order. A chain mechanism involving both ions and radicals is suggested. Studies on the order rate constant and equilibrium constant in mixed solvents of varying dielectric constant indicate that polar intermediates are involved. The rate constant is also weakly dependent on the concentration of photochromic dimer.