Salt and co-crystal formation from the reaction of fumaric acid with different N-heterocyclic compounds: Experimental and DFT study

Abstract

In this work, four fumaric acid adducts with different nitrogenous bases were synthesized and characterized with FT-IR, H-1 NMR, C-13 NMR and UV-Vis. spectroscopies. The solid-state structures of the compounds were determined by X-ray diffraction analysis. In addition, quantum chemical calculations employing density functional theory ( DFT/B3LYP) method with the 6 - 311++G(d, p) basis set were performed to study the structural and spectroscopic properties of the compounds, and the results were compared with the experimental findings. X-ray analysis suggests that the crystal structures is stabilized by O-H center dot center dot center dot O, N-H center dot center dot center dot O, O-H center dot center dot center dot N and C-H center dot center dot center dot O type hydrogen bonds and also pi center dot center dot center dot pi stacking interactions. The harmony between the experimental and theoretical structural and spectroscopic data is acceptable in general.