We studied the (PA) 1 (w) 0-5 , (LA) 1 (w) 0-5 , (ProA) 1 (w) 0-5 , (diol) 1 (w) 0-5 , (PA) 1 (Na + ) 0-1 (Cl -) 0-1 (w) 0-5 , (PA -) 1 (w) 0-5 and the (PA -) 1 (Na + ) 1 (Cl -) 0-1 (w) 0-5 cluster systems. Figure below presents the four different conformers of PA. The PA conformers are conventionally assigned conformational abbreviations according to the cis-trans nomenclature, with the first letter denoting the geometric relationship between the two carbonyl groups and the second letter denoting the geometric relationship between the α-carbonyl group and the carboxylic acid proton. Blair et al. calculated the relative zero-point vibrational corrected electronic energies of the four PA conformers to be 0.00 kcal/mol for the Tc conformer, 2.68 kcal/mol for the Tt conformer, 4.36 kcal/mol for the Ct conformer, and 10.31 kcal/mol for the Cc conformer at 298 K and at the ωB97X-D/aug-cc-pVTZ level of theory. In addition to the conformers of PA, Figure and Figure Note that there are two conformers of ProA corresponding to an eclipsed and a staggered conformer, which are not represented here. Note also that there are four conformers of the diol but as these are equivalent to the conformers of PA, they are omitted for clarity.