Di-topic hybrid ligands with an isoxazole ring in the central unit: Synthesis, structural characterization and molecular modeling

Abstract Two novel di-topic hybrid ligands, useful for the generation of coordination polymers, have been synthesized. These ligands feature an isoxazole ring in their central unit, and have as coordinating moieties a carboxylate group at one end of the central unit, and either a tetrazole or an imidazole at the other end. The structure of the hydrochloride monohydrate of the imidazole–acid has been established by single crystal X-ray diffraction. Molecular structure of the imidazole–acid was also investigated theoretically. The optimized molecular geometry was found to be in good agreement with the structure determined by single-crystal X-ray diffraction (RMSD = 0.2046 A). The experimental maximum electronic absorption band observed at 294 nm in DMSO was reasonably close to the theoretical wavenumber of 296 nm computed by TD-DFT method. The energy gap (HOMO-LUMO), atomic charges distribution, mapped electrostatic potential; dipole moment, reactive descriptors, and calculated vibrational frequencies for the ligand were determined and discussed.