Synthesis, structural characterization, and Hirshfeld surface analysis of three cocrystals based on flexible bis(benzimidazole) derivatives with aromatic carboxylic acids

Based on 1,3-bis(2-methylbenzimidazole)propane (L1), 1,4-bis(2-methylbenzimidazole)butane (L2) and 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene (L3) with aromatic carboxylic acids, three cocrystals, [(H(2)L1)(2+)center dot 2(H(2)btrc)(1-)] (1), [(H(2)L2)(2+)center dot(H(2)btec)(2-)center dot 2H(2)O] (2) and [(H(2)L3)(2+)center dot(H(2)btec)(2-)] (3) (H(3)btrc = 1,2,4-benzenetricarboxylic acid, H(4)btec = 1,2,4,5-benzenetetracarboxylic acid) were synthesized in solution and obtained by slow evaporation. All solid products were characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. Components of the crystalline phase have also been investigated in terms of Hirshfeld surfaces. The bis(benzimidazole) derivatives interlinked with aromatic carboxylates through intermolecular H-bonding and pi-pi interactions generate diverse 3D supramolecular networks for 1, 2, and 3. The Hirshfeld surfaces and 2D fingerprint plots of three cocrystals show that 1-3 are stabilized by N-H center dot center dot center dot O, O-H center dot center dot center dot O, and pi-pi intermolecular interactions. The thermal stabilities and photoluminescence properties for cocrystals 1-3 were presented in the solid state.