Computational study of noncovalent interactions within the various complexes of para aminosalicylic acid and Cr2+, Mn+, Fe2+, Co+, Ni2+, Cu+, Zn2+ cations: exploration of the enhancing effect of the cation–π interaction on the intramolecular hydrogen bond

Abstract

The quantum chemical calculations are performed to investigate the effect of cation–π interactions on structural and electronic characterization of the various complexes of para aminosalicylic acid with mono- (Mn+, Co+, Cu+) and divalent (Cr2+, Fe2+, Ni2+, Zn2+) metal cations. Topological analysis of the atoms in molecules is applied to evaluate the nature of the considered interactions. Electron populations obtained from the natural bond orbital analysis also give insight into the electron nature of the studied systems. The achieved outcomes from calculations show that the strongest/weakest interactions belong to the divalent/monovalent complexes. Besides, one O–H···O intramolecular hydrogen bond (H-bond) is observed in the analyzed complexes. Our findings indicate that the H-bond of complexes is placed in the medium H-bonds category. In addition, it can be stated that the O–H···O H-bond is strengthened/weakened by cation–π interactions in the presence of divalent/monovalent complexes. The energy gap, electronic chemical potential, chemical hardness, softness, and electrophilicity index are also calculated by using frontier molecular orbitals.