Theoretical study on the photocyclization reactivity mechanism in a diarylethene derivative with multicolour fluorescence modulation

For a photochromic spiro-diarylethene derivative (Spiro-DAE), its photocyclization reaction and multicolour fluorescence modulation performances were investigated based on a series of density functionals calculations in this work. Some elementary properties such as geometric and electronic structures at ground and the first excited state (S-1), absorption and emission spectra in respective open-ring and closed-ring structures were compared, which indicate the cyclization reaction may occur at S-1. It is further verified by the lower activation barrier (3.4 kcal/mol) of the transition state at S-1 potential energy surface. The photochromic reaction rates for both cyclization and cycloreversion processes were quantitatively estimated, which suggests the much smaller radiative and internal conversion rates contribute to the higher photocyclization rate and thus efficiency. Furthermore, we suspect that the dihydroacridine fragment may make important contribution to the cyclization reaction occurring at S-1 considering its contribution to electronic structure.

Automated summary

This study investigated the photocyclization reaction and multicolour fluorescence modulation performances of a photochromic spiro-diarylethene derivative using density functionals calculations. The findings suggest that the cyclization reaction may occur at the first excited state (S-1), with a higher photocyclization rate. The contribution of the dihydroacridine fragment to the cyclization reaction at S-1 was suspected to be significant based on electronic structure analysis.