The unexpected salamo-type copper(II) complex: Synthesis, structure, theoretical calculations and fluorescence properties

An unexpected mono-nuclear Cu(II) complex [Cu(L-1)] was successfully prepared by a bis(salamo)-type ligand H3L and Cu(OAc)(2)center dot H2O in ethanol/acetone mixed solvent, and its structure and properties were analyzed. The crystal structure analysis showed that the Cu(II) complex is obtained by the reaction of copper(II) acetate with a new single salamo-type ligand H2L1, not obtained from the original ligand H3L. The molecular front orbitals HOMO and LUMO of the ligand H3L and the Cu(II) complex were analyzed by quantum chemical calculations, and the results showed that the energy gap of the Cu(II) complex is reduced due to the combination of orbitals compared to the ligand. The theoretical reaction sites of the ligand H3L with the Cu(II) were analyzed by ESP studies, and the results showed that the crystal structure of the Cu(II) complex is consistent with the theoretical predictions. Hirshfeld surfaces analyses confirmed the rich and diverse interactions present in the Cu(II) complex, which is essential for the stability of the molecules.

Automated summary

An unexpected mono-nuclear Cu(II) complex [Cu(L-1)] was synthesized using a new ligand H2L1 and Cu(II) acetate. The crystal structure analysis confirmed that the Cu(II) complex is obtained from the reaction with the ligand H2L1, not the original ligand H3L. Quantum chemical calculations revealed that the energy gap of the Cu(II) complex is reduced compared to the ligand due to orbital combination.