Synthesis, structural characterization and Hirshfeld surface analysis of C-H•••O hydrogen-bonded supramolecular complexes of 18-crown-6 with imidazolinium derivatives

Two supramolecular complexes of 18-crown-6 (18C6) with 1,3-dimethylimidazol-3-ium iodide and 1H-benzimidazol-3-ium iodide were synthesized successfully from methanolic solution by slow evaporation solution growth technique. Crystal structure of bis(1,3-dimethylimidazol-3-ium iodide)-18C6 (I) and bis(1H-benzimidazol-3-ium iodide)-18C6 (II) are elucidated by single-crystal X-ray diffraction analysis. It reveals that both belong to the monoclinic system with centrosymmetric space group P2(1)/n. Hydrogen bonding interactions and weak Van der Waals forces construct the supramolecular assembly in the crystal packing. The characteristic functional groups present in the cocrystals are identified by FT-IR spectral analysis. Direct band gap energies estimated by diffuse reflectance spectra are 4.34 (I) and 3.94 eV (II). The scanning electron microscopy (SEM) images reveal the surface morphology of the complexes. Molecular interactions are analyzed by Hirshfeld surfaces, derived from single-crystal XRD data. Fingerprint plots of Hirshfeld surfaces were used to locate and analyze the percentage of hydrogen bonding interactions. (C) 2022 Elsevier B.V. All rights reserved.