Hydrogen bond analysis of the p-coumaric acid-nicotinamide cocrystal using the DFT and AIM method

Background: The molecular geometric structure of p-coumaric acid-nicotinamide has been optimised using Density Functional Theory (DFT) and Atom In Molecule (AIM).     Objective: To analyse the hydrogen bond of the p-coumaric acid–nicotinamide cocrystal.     Method: Structural optimisation using DFT was carried out on the basis set B3LYP/6-311G++ (d, p). The electron density topology from the optimisation results obtained was then validated using the Non-Covalent Interaction (NCI) method.     Result: Optimisation results showed that there are intermolecular hydrogen bonds in the carbonyl group of p-coumaric acid and the amine group of nicotinamide, namely C1=O11∙∙∙O34 with length 1.804 Å. On the other hand, the results of the topology test with AIM showed a value of ∇2ρ = 0.1196 a.u; G = 0.0393 a.u; H = 0.0946 a.u; V = -0.0488 a.u which means there was an intermolecular Hydrogen bond with EH∙∙∙O = -64.05 a.u.     Conclusion: A hydrogen bond in the cocrystal of p-coumaric acid-nicotinamide is classified as an intermolecular hydrogen bond between the carbonyl group of p-coumaric acid and the amine group in the carboxyl group.