DFT and single crystal analysis of the pyrimethamine-based novel co-crystal salt: 2,4-diamino-5-(4-chloro-phenyl)-6-ethylpyrimidin-1-ium:4-hydroxybenzoate:methanol:hydrate (1:1:1:1) (DEHMH)

The present work is related to the synthesis, single crystal analysis, and computational investigation of pyrimethamine co-crystal salt with 4-hydroxybenzoic acid in methanol. The study shows that hydrogen bonding interactions are responsible for the stabilized 3-dimensional network. In the title compound, protonation of the pyrimethamine molecule results in the more basic nitrogen atom present in the 1,3-diazine ring to form a cation which interacts with the carboxylate (the conjugate base) of 4-hydroxybenzoic acid. Moreover, the computational study including analyses of charge distribution, frontier molecular orbitals, reactivity parameters, and molecular electrostatic potential has been also performed for this compound. Both the experimental and computational results showed the formation of intermolecular hydrogen bonding and electrostatic interactions that suggest the increased reactivity and potential biological activity of the compound. The current compound can have potential future applications in pharmacology for the production of new antimalarial drugs. (C) 2019 Elsevier B.V. All rights reserved.