Effect of substituents on the photochromism of a spiro[indoline-napthoxazine] under laser excitation

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

Two new spectrokinetic methods aimed at solving the identifiability problem and leading to the true solutions of AB(1k,2phi) and AB(2phi) 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 (alpha) 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.

Gas-Phase Dynamics of Spiropyran and Spirooxazine Molecules

The gas-phase dynamics of two classes of photochromic molecules, three spiropyrans and one spirooxazine, have been investigated here using both time-resolved mass spectrometry and photoelectron spectroscopy approaches. It is, to our knowledge, the first gas-phase experiment done of these kinds of molecules. The molecules are excited at 266 nm and probed at 800 nm. The comparison of the dynamics of these four molecules has been used to propose a sequential photoisomerization mechanism involving four steps occurring in the first 100 ps. Each of these steps is discussed and related to the observed condensed-phase dynamics and to theoretical calculations.

Photochromism of a spirooxazine in the single crystalline phase

The single crystals of a closed form spirooxazine spiro[azahomoadamantane-isoquinolinoxazine] were found for the first time to undergo photocoloration processes consistent with photochromism in the single crystalline phase.