The X−···benzohydrazide complexes: the interplay between anion-π and H-bond interactions

Abstract

The compounds containing the benzohydrazide (BH) nucleus have a variety of biological activities because of various noncovalent intermolecular interactions. The interplay between anion-π and H-bond interactions, which can affect the activity of compounds, has been investigated in ten substituted BH exposed to the chloride ion using the quantum mechanical calculations. The total interaction energy is separated into the anion-π (ΔE Aπ) and H-bond (ΔE HB) contributions where both interactions are presented in the complexes. The electron-withdrawing substituents (EWSs) increase |ΔE Aπ| and decrease |ΔE HB|, while reversed changes are observed with the electron-donating substituents (EDSs). In addition, the total binding energy (ΔE) becomes more/less negative in the presence of EWSs/EDSs. The synergetic effects of mentioned interactions and substituent effects have also been investigated using the atoms in molecules (AIM), natural bond orbital (NBO) and molecular electrostatic potential (MEP) analyses. A good correlation is found between the energy data and the Hammett constants, the minimum of electrostatic potential (V min) and the results of population analyses.