Preparation, QTAIM and Single-Crystal Exploration of the Pyrimethamine-Based Co-Crystal Salts with Substituted Benzoic Acids

Abstract

The effective preparation of pyrimethamine based co-crystal salts with substituted benzoic acids (4-nitrobenzoic acid 1 and 5-chlorosalicylic acid 2) in methanol has been reported. The crystal structure of salt 1 and 2 is acquired through the x-rays diffraction technique. Hirshfeld surface analysis elaborates the comparative study of the non-covalent interactions in salt 1 and 2. In order to theoretically evaluate the non-covalent interactions between molecular ions in salts 1 and 2, DFT and TD-DFT calculations of molecular salts were performed. FMO and GRD analyses were performed to evaluate the reactivity of molecular ions. While, NBO, AIM and NCI analyses were performed to explore the non-covalent interactions between cation and anions of molecular salts 1 and 2. The calculations demonstrated that salt 1 has H-bond slightly stronger than salt 2 due to the withdrawing effect of -NO2 substituent group. The molecular anions reactivity allows different patterns of non-covalent interactions that affect the salts arrangement in the crystal.