THEORETICAL STUDIES OF HYDROGEN BONDING INTERACTION BETWEEN TRIMETHYLAMINE AND SUBSTITUTED PHENOLS, INFLUENCE OF THE SUBSTITUENTS ON THE HYDROGEN BOND PROPERTIES AND THE VIBRATIONAL SPECTRUM

Hydrogen bonding interactions between trimethylamine (TMA) and a series of para substituted phenols (X-C6H4OH, X = H, CH3, NH2, Cl, CN, and NO2) are studied by using density functional theory with the hybrid B3LYP functional and the 6-31++G(d,p) basis set. Both electron donor and acceptor substituents (X) are chosen to study systematically the relation between the proton donor ability of the phenols and the strength of the OH center dot center dot center dot N hydrogen bond. The effect of hydrogen bonding on spectral and structural parameters and their inter relation are discussed. The natural bond orbital (NBO) analysis (occupation of sigma* orbitals, hyperconjugative energies and atomic charges) is also carried out to elucidate the reason behind the spectral and structural changes due to hydrogen bond formation. Several correlations between hydrogen bond strength and bond properties are discussed.