Co(II) and Ni(II) bis(salamo)-based tetraoxime complexes: Syntheses, structural characterizations, fluorescence properties, and Hirshfeld analyses

Abstract

Two new asymmetric complexes with the chemical structural formulas [{Co₂(L)(μ₂-OH)}{Co₂(L)(OAc)(CH₃OH)}{Co₂(L)(μ₂-OCH₃)}{Co₂(L)(μ₂-OAc)}]⋅4CH₃OH and [Ni₂(L)(μ₂-OAc)(CH₃OH)]⋅CH₂Cl₂⋅3CH₃OH have been synthesized from cobalt(II) acetate, nickel(II) acetate, and a bis(salamo)-based tetraoxime ligand derived from 3-bromo-5-chlorosalicylicaldehyde and 4-tert-butyl-2,6-diformylphenol, respectively, and characterized by elemental analyses, IR, UV–vis, fluorescence spectra, and single-crystal X-ray diffraction analyses. The Co(II) complex unit cell contained four crystallographically independent and chemically different heterotrinuclear complexes (molecules A, B, C, and D). The crystal structure included eight Co(II) ions, four completely deprotonated ligand (L)³⁻ moieties, one bridging hydroxide, one monodentate acetate, one bridging methoxy, one bidentate chelating acetate, one coordinated methanol, and four crystallization methanol molecules. The Ni(II) complex had a dinuclear structure. The crystal structure of the Ni(II) complex included two Ni(II) ions, one completely deprotonated ligand (L)³⁻, one bidentate bridging acetate, one coordinated methanol, one crystallized dichloromethane, and three crystallized methanol molecules. Hirshfeld surface analyses showed that the complexes are stable. Furthermore, the fluorescence quenching of the Co(II) and Ni(II) complexes with H₃L further confirmed the above experimental results.

Graphical Abstract

Keywords:

• Bis(salamo)-based ligand
• synthesis
• crystal structure
• Hirshfeld surface analysis
• fluorescence property

Supplementary data

CCDC-2033414 and 2033413 contains the supplementary crystallographic data for the Co(II) and Ni(II) complexes. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK (Telephone: [phone]; Fax: [phone]; or E-mail: deposit @ccdc.cam.ac.uk).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [21761018] and the Program for Excellent Team of Scientific Research in Lanzhou Jiaotong University [201706], which is gratefully acknowledged.