Kinetic analysis and elucidation options for AB(1k,2ϕ) systems. new spectrokinetic methods for photochromes

Abstract

Two new spectrokinetic methods aimed at solving the identifiability problem and leading to the true solutions of AB(1k,2ϕ) and AB(2ϕ) kinetics are proposed in this paper. The methods consider the systems under two respective assumption conditions relating to the variability of the quantum yields with irradiation wavelengths. It is shown through a detailed mathematical analysis that a set of only two traces, obtained under isosbestic and non-isosbestic irradiations of the reactive system are sufficient to reach a solution. Evaluation tests of the validity of these assumptions, and hence the usefulness of the methods, are provided and discussed. Also, the analytical expression for a coefficient () is proposed, whose value can be calculated using available experimental data, and used for the determination of whether the forward quantum yield is wavelength dependent. The kinetics of a photochromic diarylethene derivative is used as an illustration for the application of the elucidation methods.