Ab initio calculations elucidate the influence of water solution on the photostability of AICN

What is it about?

4-aminoimidazole-5-carbonitrile (AICN) was suggested to be a prebiotically plausible precursor of purine nucleobases and nucleotides. AICN can be formed in a series of photoreactions. Thus, it's UV-resistance is a very important issue in tracking the origins of RNA and DNA. In this work, we discuss the mechanisms of the photostability of this molecule based on state-of-the-art quantum chemical calculations. In particular, we show how water solution could affect its photostability.

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Why is it important?

We present a reaction channel that could explain the photochemistry of πσ* states (present in other molecules too) in water solution. This mechanism is initiated by excited-state electron transfer from the chromophore to solvent. After that, several subsequent proton transfers from photo-excited AICN towards the hydrated electron enable the relaxation to the the ground state. Nearby water molecules may act as bridges for proton relay. Most importantly - the reaction is practically barrierless!