Linear and non-linear modelling techniques for the investigation of spectrum-structure relationships

The hydroxyl stretching vibration is very sensitive to the structural environment of the OH group. The effect of a number of structure descriptors on the absorption maximum is investigated systematically using advanced linear and non-linear regression techniques. The band maximum of saturated aliphatic mono-hydroxy alcohols and cyclohexanols is mainly affected by the number of α- and β-C atoms, whereas for hydrogen-bonded systems the aromaticity of donor and acceptor oxygen and the ringsize of the H-bonded system are of major importance. For prediction of full OH stretching profiles best results are obtained when using rotamer distributions as structure descriptors. The assumption of a statistical rotamer distribution seems to provide contradictory effects compared to experimental data for those rotamers where sterical repulsion is dominant.