Abstract

We have reported the effective production of the pyrimethamine based novel co-crystal salt with 4-methylbenzoic acid in methanol, namely 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium 4-methylbenzoate hydrate (1:1:1) (DEMH) compound. This co-crystal salt is stabilized by the presence of ionic interactions, via formation of the two-dimensional hydrogen bonding network and by weak interactions between rings known as cycle stacking interaction. The results of the detailed computational investigation support the existence of quite strong intracomplex hydrogen bonding. Both the HOMO/LUMO gap and time-dependent DFT (TDDFT) gap values suggest that the title complex should be quite stable and not significantly prone to chemical reactions. The natural bonding orbitals (NBO) analysis results support the formation of intracomplex hydrogen bonds. The global reactivity parameters (GRP) show that the title complex should be quite stable, both thermodynamically and kinetically.