Synthesis, structure, and antioxidative properties of a copper(II) complex with 1,2‐bis(benzimidazol‐2‐yl)ethane ligand

• Published in: Journal of the Chinese Chemical Society (Taipei) 2020-04, Vol.67 (4), p.585-591
• Main Authors: Tang, Xia, Qu, Yao, Wang, Cong, Wu, Yancong, Zhao, Kun, Wu, Huilu
• Format: Article
• Language: English
• Subjects: 1,2‐bis(benzimidazol‐2‐yl)ethane; antioxidant activity; Antioxidants; Coordination compounds; Copper; Copper compounds; copper(II) complex; Crystal structure; Crystallography; Crystals; electrochemistry; Ethane; Fluorescence; Infrared analysis; Infrared spectra; Ligands; Photoluminescence; photophysical property; Single crystals; Structural analysis; Tetrahedra; Ultraviolet spectra
• ISSN: 0009-4536; 2192-6549
• DOI: 10.1002/jccs.201900189

1,2‐Bis(benzimidazol‐2‐yl)ethane (bbe) and its copper(II) complex, {[Cu(bbe)Br2]2}·2DMF (1), have been synthesized and characterized by elemental analysis, ultraviolet–visible, and infrared spectra. The single crystal structure analysis of 1 shows two crystallographically independent but chemically identical [Cu(bbe)Br2] molecules. The coordination geometry of the copper atoms may best be described as a distorted tetrahedron (τ4 = 0.740 for Cu1 and 0.696 for Cu2). The cyclic voltammogram of complex 1 represents quasi‐reversible Cu2+/Cu+ pairs. in vitro antioxidant tests showed that complex 1 has significant antioxidant activity against superoxide and hydroxy radicals. Photoluminescence investigations showed that the fluorescence intensity of complex 1 is significantly weaker than that of the ligand. This may be due to the paramagnetic effect of divalent copper to cause quenching of fluorescence. A new four‐coordinated copper(II) complex with 1,2‐bis(benzimidazol‐2‐yl)ethane has been synthesized and characterized. Cyclic voltammograms of the complex indicate a quasi‐reversible Cu2+/Cu+ couple. A solid fluorescence peak of complex 1 may be attributed to ligand‐centered luminescence. Complex 1 exhibited excellent antioxidant activities against OH. and O2−. radicals in vitro.