Theoretical Studies of Hydrogen Bond Interactions in 4-Substituted Benzoic Acids Dimers

ABSTRACT. Two conformations of benzoic acid derivatives (NH2, OH, H, F, Cl, CN, NO, NO2) have been investigated at MP2, DFT and HF level using the 6-311++G(d,p) basis set. It was found that the cis isomers are more stable. Hydrogen bond-ing formation of benzoic acids has been estimated from stabilization energies. The calculated hydrogen-bonding energies of dimers showed a cooperative interaction in the cyclic ones. It was found that an electron-releasing group (ERG) into the phe-nyl rings resulted in the formation of more stable hydrogen bonding. Red shift of O–H bond was found from-565.3 to-589.3 for dimers. The natural bond orbital (NBO) analysis was applied to characterize nature of the interaction