Green synthesis, crystal growth, and some physicochemical studies on an inter-molecular compound of anthranilic acid and m-nitro-benzoic acid system

Abstract

The phase diagram of anthranilic acid (AA)–m-nitro benzoic acid (NBA) system, determined by the thaw–melt method, shows the formation of a 2:1 (AA:NBA) inter-molecular compound (IMC) and two eutectics E1 and E2 containing 0.084 and 0.917 mol fractions of AA, respectively, with one eutectic on either side of the IMC. The heat of mixing, entropy of fusion, roughness parameter, interfacial energy, and the excess thermodynamic functions were calculated from the enthalpy of fusion data, obtained by the DSC method. While the spectroscopic investigations (IR and NMR) and optical studies suggest the presence of hydrogen bonding between the components, the powder X-ray diffraction spectra of eutectics and the IMC suggest that the eutectic E1 is a mechanical mixture of the IMC and NBA and the eutectic E2 is a mechanical mixture of the IMC and AA. A single crystal of cocrystal of AA and NBA was grown using slow evaporation technique at room temperature from its saturated solution in methanol solvent. Single-crystal analysis of the grown cocrystal shows the mode of the intermolecular hydrogen bonding in the molecule and the triclinic crystal structure with P − 1 space group.