Infrared Induced Conformer Interconversion Processes in Low‐Temperature Matrices

Molecules embedded in low-temperature matrices experience conformer interconversionprocesses due to IR- (or UV-)irradiation. This paper summarizes the knownIR-induced conformational changes, of which the majority has been studied by usingbroad-band sources provided with filters. We focus at the thermal and IR-photochemicalmethods in obtaining information of conformational energetics of matrix isolatedmolecules, at the usefulness of ab initio calculations in assigning the spectra ofconformers involved and in finding the reaction path on the ground state surface. Thedata obtained from a number of molecules is used to discuss possible mechanisms in bothintramolecularly hydrogen-bonded and non-bonded molecules. Also possible indicationsof mode-selective phenomena in these processes are dealt with. In addition,common trends found for photorotamerization in different hosts are discussed.