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

• A new copper (II) complex with hetero N- and O-donor ligands has been prepared.
• The coordinated water molecules play a key role in the construction of crystal structures.
• The intermolecular interactions and solid state luminescent properties have been investigated.

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.

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