A thermally labile copper (II) complex with hetero N- and O-donor ligands: crystal structure, Hirshfeld surfaces, thermal and luminescent properties

Abstract

A new complex ([Cu(L1)2(H2O]2]⋅2H2O, 1) derived from a hetero N- and O-donor ligand 5-methyl-imidazole-3-carboxylic acid (L1H) has been synthesized and characterized. Comparisons between [Cu(L1)2(H2O]2]⋅2H2O, [Co(L2)(H2O]2⋅H2O (2), and [Cu(L2)2H2O]⋅H2O (L2H=5-methyl-isoxazole-3-carboxylic acid) revealed that the coordinated water molecules play a key role in the construction of crystal structures: two coordinated water molecules in the axial positions lead to single-deck 1D chain and 3D motif while one coordinated water molecule resulted to double-deck 1D chain and 2D stacking motif. Molecular Hirshfeld surfaces revealed that complexes 1 and 2 were supported mainly by H-H, C-H⋯π, and O-H⋯O intermolecular interactions. The room temperature solid state luminescent properties of complexes 1 and 2 were all shown as two distinct bands, which attribute to ligand-metal charge transfer and metal purterbed ligand centered emission.

Keywords: Hetero ligands; Hirshfeld surfaces; Luminescent properties; Thermal behaviour.