Hydrogen-bonding and self association investigated in the binary mixture (C6H5C
N + CH3OH)
via concentration dependent Raman study of the C
N stretching mode of benzonitrile (C6H5C
N) and ab-initio calculations
Abstract
The Raman study of (C6H5CN + CH3OH) binary mixture has been presented. The isotropic part of the Raman spectra, Iiso are analyzed in the C
N stretching region. For neat C6H5C
N, the Iiso shows a double peak structure, which has been explained in terms of self association. A quantum chemical calculation on the optimized structures and wavenumbers of different modes of neat C6H5C
N, self associated C6H5C
N and the hydrogen-bonded C6H5C
N⋯HOCH3 complex reveals that the wavenumber position of the C
N stretching mode is blue shifted due to both the self association and the hydrogen-bonding with CH3OH. The
N), C = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, as well as neat liquid have been explained in terms of self association and hydrogen-bonding. A variation of intensity ratio of the peak assigned to the hydrogen-bonded complex to the main band with concentration exhibits a regular trend. The dephasing of the C
N stretching mode in the free C6H5C
N molecules seems to be governed predominantly by the concentration fluctuation model, but other effects like diffusion and motional narrowing may also have some small influence.