Unveiling the conformational diversity of succinic acid: Insights from IR spectroscopy and quantum chemical calculations

Small α-dicarbonyl compounds like succinic acid are found abundantly in the atmosphere, thereby contributing to the formation of secondary organic aerosols through solid or liquid particles and gas-phase molecular clusters. The vibrational spectrum of succinic acid was measured in two different environments to evidence the role of the medium on the geometry adopted by the acid. Different structures were observed. The planar and extended structures of succinic acid were favored in the solid state whereas the non-planar gauche conformer was the predominant form in an argon matrix at 20 K, similar to the gas phase. Aided by quantum chemistry calculations and the non-covalent interactions analysis, we investigated the conformational diversity of succinic acid to understand the factors that govern the stability of the acid.