Experimental study and DFT calculation for the strength of intermolecular interactions in Schiff base with the phenylarsonic acid scaffold

Abstract

The crystal structure and supramolecular architectures of Schiff bases derived from the o-arsanilic acid, (E)-(2-(4-hydroxybenzylidene)aminophenyl)arsonic acid(I); (E)-(2-(4-methoxybenzylidene)aminophenyl)arsonic acid (II) and (E)-(2-(3-cyanobenzylidene)aminophenyl)arsonic acid (III) are reported. The intermolecular interactions, supramolecular architectures, and molecular conformations are compared with the (E)-(2-(2-hydroxybenzylidene)aminophenyl)arsonic acid(IV) to evaluate how different substituents influence the crystal packing. In the solid state, the O−H⋯O hydrogen bonding interaction predominantly stabilizes the crystal structures of I-IV. Further, the weak intermolecular C−H⋯O, C−H⋯N, C−H···π, π···π, and H⋯H contacts form a self-assembled motif. Various intermolecular interactions exist in I-IV and their energies are quantified using PIXEL, DFT and QTAIM analysis. The variant and invariant arsanilic acid dimers are observed in I-IV. The distribution of electrostatic potential on the molecular surface is found to be asymmetric nature in I-IV. The relative contributions of various intermolecular contacts in the I-III and the closely related analog (IV) are quantified by using Hirshfeld surface analysis and the decomposed 2D fingerprint plots. The total lattice energy of compound III is higher than the other compounds. It is due to the cyano substitution in III because the −CN group participates in the C−H⋯N interactions which favored very compact packing. Also, the contribution of intermolecular H⋯H, O⋯H/H⋯O, and C⋯H/H⋯C contacts are drastically reduced in III when compared with other compounds, this reduction is due to more contribution of H⋯N contacts in the crystal structure.