Eco-Friendly Solid-State Synthesis of Antibacterial Binary Organic Material: Crystal Growth, Physicochemical Properties, Thermal Study, Antibacterial Activity, and Hirshfield Surface Analysis

The organic compounds, 2-aminopyrimidine (AP) and 4-aminobenzoic acid (PABA), are selected for the synthesis of a compound by establishing the phase diagram adopting the solid-state synthesis method. Phase diagram study infers the formation of a novel intermolecular compound (IMC) at 1:1 stoichiometric ratio of AP and PABA along with two eutectics at 0.25 and 0.90 mole fractions of AP. The FTIR and NMR spectroscopy are studied for structure elucidation of intermolecular compound. Powder X-ray diffraction study reveals the novel nature of IMC (APPABA) and the mechanical mixture nature of eutectics. Sharp and single peak of the DSC curve suggests the melting and pure nature of the synthesised IMC. Various thermodynamic parameters of IMC and eutectics have been studied. The single crystal of IMC has grown from solution and its single crystal X-ray diffraction analysis reveals that IMC has crystallised in a monoclinic having P21/n space group. Hirshfeld surface analysis further validated the weak non-covalent interactions summarized through single crystal X-ray study. Studies on IMC thoroughly have been done for its antibacterial activity and it has shown significant positive responses against various pathogenic microbial isolates (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella aeruginosa, Shigella boydii) and non-pathogenic microbial isolates (Enterobacter cloacae, Pseudomonas azotoformans). It was also found effective against methicillin-resistant bacterial strains viz. Staphylococcus aureus MRSA. The biodegradable IMC is an effective functional material with its future applicability as an antibacterial agent extending up to drug-resistant bacterial strains.