Stereoisomers of hydroxymethanes: Probing structural and spectroscopic features upon substitution

Ab initio studies on CH_x(OH)_4-x (x = 0-3) polyols are carried out to derive their structural and spectroscopic features. Several stereoisomers (both equilibrium structures and transition states) are found. Some are predicted here for the first time. We determined hence their geometrical parameters, vibrational frequencies, electronic excitation energies for the singlet manifold, and IR spectra. While the IR spectra for all polyols present similar shapes, their UV spectra exhibit however distinct band origin that are specific to each polyol and more interestingly to each diasteroisomer. Stereoelectronic effects are also noticed and discussed. It is suggested that UV spectroscopy is an efficient probe to experimentally identify polyols in mixtures involving polyols.