Infrared Photoisomerization of 1-Propanol CD3 and OD Trapped in Four Cryogenic Matrices: Ne, N-2, Ar, and Xe

The conformational equilibria and isomerization processes of 1-propanol -OD and -CD3 have been studied by vibrational spectroscopy at low temperatures in four cryogenic matrices to investigate the effect of deuteration on their photochemistry. These isotopic species were selectively irradiated in the nu(OH) and nu(OD) domains, resulting in the identification of several conformers that are able to interconvert upon selective IR irradiation. The experimental results were compared with theoretical geometries obtained at the B3LYP/6-311+G(d) level of theory. Alkyl chain isomerization can be induced in rare gas and nitrogen cryogenic matrices by suitable selective irradiation. Selective excitation of the OH and OD stretches of two Gauche isomers transfers the alkyl chain from the gauche to the trans form. The competition between intramolecular vibrational energy relaxation and the matrix-dopant interaction determines the torsional subspace dynamics of the vibrationally excited propanol molecules.