Solvent effects on the photochemistry of 4-aminoimidazole-5-carbonitrile, a prebiotically plausible precursor of purines

Szabla, R.; Šponer, J. E.; Šponer, J.; Sobolewski, A. L.; Góra, R. W. Phys. Chem. Chem. Phys. 2014, 16 (33), 17617–17626 DOI: 10.1039/C4CP02074J

Ab initio studies elucidate the molecular mechanisms underlying photostability of a prebiotically plausible precursor of purine nucleotides, indicating importance of charge-transfer-to-solvent processes. We have considered the photochemistry of AICN–water clusters, while including up to six explicit water molecules. Our calculations reveal charge transfer to solvent followed by formation of an H₃O⁺ cation, both of which occur on the ¹πσ^* hypersurface. Interestingly, a second proton transfer to an adjacent water molecule leads to a ¹πσ^*/S₀ conical intersection. We suggest that this electron-driven proton relay might be characteristic of low-lying ¹πσ^* states in chromophore–water clusters.

Source: Solvent effects on the photochemistry of 4-aminoimidazole-5-carbonitrile, a prebiotically plausible precursor of purines – Physical Chemistry Chemical Physics (RSC Publishing)