Synthesis, multiple interactions and spectroscopy analysis of ethyl-4-[(benzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate: Through experimental and quantum chemical approaches

The carboxaldehydes of pyrrole form important class of precursors for synthesis of acid hydrazide-hydrazones and their derivatives which show the various applications. A novel hydrazide-hydrazone of pyrrole: Ethyl-4-[(benzoyl)-hydrazonomethyl]-3,5-dimethyl-1H-pyrrole-2-carboxylate (3) has been synthesized by condensation of ethyl-4-formyl-3,5-dimetyl-1H-pyrrole-2-carboxylate and benzohydrazide. The product was characterized by spectroscopy methods (FT-IR, 1H NMR, UV–Vis and DART Mass) and quantum chemical calculations. The calculated thermodynamic parameters show that the formation of (3) is exothermic and spontaneous at room temperature. The local electronic descriptors analysis and molecular electrostatic potential surface were used to predict the sites and nature of interactions which indicate the dimer formation through multiple interaction through NH⋯O and C–H⋯O. The vibrational analysis shows red shifts in vNH and vCO as result of dimer formation. Topological and energetic parameters generated by AIM show the nature of interactions in dimer. The interaction energies of dimer formation using DFT and AIM calculations are found to be 14.19 and 15.19 kcal/mol respectively. Ellipticity analysis confirms the presence of resonance assisted heteronuclear H-bonding in dimer.