Spiropyran to merocyanine conversion: explicit versus implicit solvent modeling.

A polarizable continnum model study and explicit solvation in water investigated through GPU-accelerated ab initio molecular dynamics followed by quantum-chemical calculations have been applied to the process of spiropyran to merocyanine isomerization of two spiropyran derivatives. It has been found that interaction with only one or two water molecules is sufficient to stabilize the merocyanine with respect to the spiropyran form. It has been shown that the agreement between energies obtained in implicit and explicit solvent models depends on the structure of the system and possible specific interactions (hydrogen bonds). Both solvent models predict similar effects in absorption spectra.