Substituent effect on ionization potential, O–H bond dissociation energy and intra-molecular hydrogen bonding in salicylic acid derivatives

Abstract: The ionization potential (IP), O–H bond dissociation energy (BDE) and intra-molecular hydrogen bonding in selected para-substituted salicylic acids, 5-R-SA, with R as –NO2, –CHO, –COOH, -halogen, –OH, –OCH3, -alkyl, –NH2, –NH(CH3), –N(CH3)2 and their radicals have been investigated by density functional theory with B3LYP functional in conjunction with 6-31G(d) and 6-311++G(d,p) basis sets. All the calculations have also been performed using BHLYP functional in conjunction with 6-311++G(d,p) basis set. A common order of IPs and BDEs for the studied 5-R-SAs is found as –NO2 >–COOH (–CHO)>–H>–OCH3 >–NH2 >–NH(CH3)>–N(CH3)2. The effect of substituents on the structure, charge distribution and intra-molecular hydrogen bond has also been discussed. [Copyright &y& Elsevier]