The study of inter and intramolecular hydrogen bonds of NLO crystal melaminium hydrogen malonate using DFT simulation, AIM analysis and Hirshfeld surface analysis

Abstract

The analysis of inter and intramolecular interactions in a crystalline network, throws light on structure dependent crystalline properties. The DFT computation and crystal structural analysis of Melaminium hydrogen malonate (MHM) molecule has been conducted to explore the melaminium-malonate interaction and to exploit ‘charge assisted’ intramolecular hydrogen bonds with two equivalent resonant forms. Further, the hydrogen bonds are characterized using AIM theory which reveals that hydrogen bonds exhibit a certain amount of covalency which depends on the relative position and type of intervenient groups. In the present paper, DFT based vibrational spectral investigation of MHM has been contemplated in the stretching region (3500 cm−1–2800 cm−1) and by analyzing the half width of the OH and NH stretching profiles of the deconvoluted spectra, the extent of intermolecular interactions have been investigated. The correlation of vibrational spectra with Hirshfeld surface analysis and finger print plot has been analyzed, revealing that both these techniques form effective tool to investigate crystalline network. The hyperpolarizability tensor has been computed to assess the second order NLO activity, revealing that MHM possesses NLO activity 25.5 times that of urea. Molecular docking simulation study reveals the competitive inhibitory nature of malonate anion over succinate anion, in binding with the enzyme succinate dehydrogenase.