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, [(H2L1)2+·2(H2btrc)1−] (1), [(H2L2)2+·(H2btec)2−·2H2O] (2) and [(H2L3)2+·(H2btec)2−] (3) (H3btrc = 1,2,4-benzenetricarboxylic acid, H4btec = 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 π–π 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···O, O–H···O, and π–π intermolecular interactions. The thermal stabilities and photoluminescence properties for cocrystals 1–3 were presented in the solid state.