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.

Keywords:

• Bis(Salamo) ligand
• Cu(II) complex
• synthesis
• crystal structure
• photophysical property

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work was supported by the National Natural Science Foundation of China [grant number 21361015]; the Fundamental Research Funds for the Gansu Province Universities [grant number 212086]; and the science and technology support funds of Lanzhou Jiaotong University [grant number ZC2012003], which are gratefully acknowledged.