Synthesis, Characterization, Crystal Structure, and Biological Activities of Transition Metal Complexes with 1-Phenyl-3-methyl-5-hydroxypyrazole-4-methylene-8′-quinolineimine

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) 2013-04, Vol.639 (5), p.832-841
• Main Authors: Cheng, Xiao-Ying, Wang, Ming-Fang, Yang, Zheng-Yin, Li, Yong, Liu, Zeng-Chen, Zhou, Qiao-Xia
• Format: Article
• Language: eng ; ger
• Subjects: Antioxidants; Crystal structure; Cytotoxicity; Deoxyribonucleic acid; DNA; DNA binding; Ligands; Metal complexes; Metals; Schiff bases; Spectrum analysis
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.201200475

The Schiff base ligand, 1‐phenyl‐3‐methyl‐5‐hydroxypyrazole‐4‐methylene‐8′‐quinolineimine, and its CuII, ZnII, and NiII complexes were synthesized and characterized. The crystal structure of the ZnII complex was determined by single‐crystal X‐ray diffraction, indicating that the metal ions and Schiff base ligand can form mononuclear six‐coordination complexes with 1:1 metal‐to‐ligand stoichiometry at the metal ions as centers. The binding mechanism and affinity of the ligand and its metal complexes to calf thymus DNA (CT DNA) were investigated by UV/Vis spectroscopy, fluorescence titration spectroscopy, EB displacement experiments, and viscosity measurements, indicating that the free ligand and its metal complexes can bind to DNA via an intercalation mode with the binding constants at the order of magnitude of 105–106 M–1, and the metal complexes can bind to DNA more strongly than the free ligand alone. In addition, antioxidant activities of the ligand and its metal complexes were investigated through scavenging effects for hydroxyl radical in vitro, indicating that the compounds show stronger antioxidant activities than some standard antioxidants, such as mannitol. The ligand and its metal complexes were subjected to cytotoxic tests, and experimental results indicated that the metal complexes show significant cytotoxic activity against lung cancer A 549 cells.