Probing the balance of attraction and repulsion in binary mixtures of dimethyl sulfoxide and n-alcoholsElectronic supplementary information (ESI) available: Additional experimental Raman and IR data as well as discussion of intermolecular interactions. See DOI: 10.1039/c2cp42902k

Published volumetric mixing data for DMSO- n -alcohol systems show a transition from attractive to repulsive interaction dominance for increasing alkyl chain length. A spectroscopic marker for the relative dominance of these interactions is investigated by FTIR measurements. While most vibrational modes show very similar behavior for the alcohols (C3-C5) studied, the CO torsion mode reveals a strong correlation between maximum red-shift and the balance of attraction and repulsion. The CO torsion provides a suitable spectroscopic probe for the balance of attractive and repulsive forces in DMSO-alcohol mixtures.