Structural characterization and theoretical calculations of the monohydrate of the 1:2 cocrystal salt formed from acriflavine and 3,5-dinitrobenzoic acid

Abstract

The synthesis and structural characterization of the monohydrated 1:2 cocrystal salt of acriflavine with 3,5-dinitrobenzoic acid [systematic name: 3,6-diamino-10-methylacridin-10-ium 3,5-dinitrobenzoate–3,5-dinitrobenzoic acid–water (1/1/1), C14H14N3 +·C7H3N2O6 −·C7H4N2O6·H2O] are reported. Single-crystal X-ray diffraction measurements show that the title solvated monohydrate salt crystalizes in the monoclinic space group P21 with one acriflavine cation, a 3,5-dinitrobenzoate anion, a 3,5-dinitrobenzoic acid molecule and a water molecule in the asymmetric unit. The neutral and anionic forms of 3,5-dinitrobenzoic acid are linked via O—H...O hydrogen bonds to form a monoanionic dimer. Neighbouring monoanionic dimers of 3,5-dinitrobenzoic acid are linked by nitro–nitro N—O...N and nitro–acid N—O...π intermolecular interactions to produce a porous organic framework. The acriflavine cations are linked with carboxylic acid molecules directly via amine–carboxy N—H...O, amine–nitro N—H...O and acriflavine–carboxy C—H...O hydrogen bonds, and carboxy–acriflavine C—O...π, nitro–acriflavine N—O...π and acriflavine–nitro π–π interactions, or through the water molecule by amino–water N—H...O and water–carboxy O—H...O hydrogen bonds, and are located in the voids of the porous organic framework. The intermolecular interactions were studied using the CrystalExplorer program to provide information about the interaction energies and the dispersion, electrostatic, polarization and repulsion contributions to the lattice energy.