An unexpected dinuclear Cu(II) complex with a bis(Salamo) chelating ligand: synthesis, crystal structure, and photophysical properties

Abstract

An unexpected dinuclear Cu(II) complex, [Cu2(L2)2], has been synthesized via complexation of Cu(II) acetate monohydrate with a bis(Salamo) ligand H2L1. Catalysis of Cu(II) ions results in unexpected cleavage of two N–O bonds in H2L1, giving a dialkoxo-bridged dinuclear Cu(II) complex. Each Cu(II) complex possesses a Cu–O–Cu–O four-membered ring instead of the usual bis(Salamo) [Cu2L1] complex with H2L1. The H2L1 molecule is stabilized by intramolecular O1–H1⋯N1 hydrogen bonds and π⋯π stacking interactions linking adjacent molecules into a 1-D infinite zigzag chain. In the structure of the Cu(II) complex, intermolecular hydrogen bonds have stabilized the Cu(II) complex to form a self-assembling infinite 1-D linear chain. Furthermore, the H2L1 ligand shows intense photoluminescence with two emissions at ca. 370 and 464 nm upon excitation at 310 nm. The Cu(II) complex shows photoluminescence with maximum emission at ca. 423 nm upon excitation at 370 nm.