Clusters of acrylonitrile in methanol/ethanol: A structure-spectra correlation by quantum chemical and polarized Raman study

Ab initio and DFT calculations were performed to obtain the ground state geometry of neat acrylonitrile (C2H3C N, Acr), self-associated dimer, trimer and their hydrogen bonded complexes with methanol (M) and ethanol (E) in gas phase. Polarized Raman study was made for neat Acr and its binary mixtures with M/E. The nu(C N) line profile of neat Acr was analyzed to two component bands at 2228.7 and 2226.9 cm(-1) and attributed to free and self-associated Acr, respectively. The calculated nu(C N) mode of self-associated dimer/trimer complex and hydrogen bonded complex were compared with the experimentally observed Raman spectra. The dephasing of the nu(C N) mode as a function of concentration was explained in terms of two contributions, one arising from micro viscosity dependence and the other from concentration fluctuation. The viscosity dependent contribution, however, dominates over the concentration fluctuation in the present case. Overall in this study we present very nice structure-spectra correlation. (C) 2011 Published by Elsevier B.V.