Fine-tuning alkyl chain length in copper(II) complexes: effects on DNA binding and catalytic cleavage
摘要
Metal complexes are well known for their DNA cleavage activity. Copper is a metal that stands out for this purpose because it is able to perform cleavage through oxidative mechanisms using the Haber–Weiss cycle. We report two unprecedented copper(II) complexes (2 and 3) with long-chain ligands and compare the results with those of a previously reported complex (1), which we use as a reference in our studies. They were all properly characterized using a set of physicochemical methods, including elemental analysis, electron paramagnetic resonance, spectroscopic and electrochemical analysis. Density functional theory (DFT) modeling revealed a pseudo-octahedral environment where the ligands are trans to each other. The interaction of 1, 2, and 3 with salmon sperm DNA was monitored spectrophotometrically, and the binding constants (Kb) were 4.24 × 104 L mol−1, 1.92 × 104 L mol−1, and 1.15 × 104 L mol−1, respectively. The interactions were supported by docking studies conducted with the CCDC GOLD® docking suite. Finally, all complexes exhibited DNA binding and cleavage properties, but 2 stood out as the most active one (2, kobs = 0.88 ± 0.09 h−1 > 1, kobs = 0.54 ± 0.06 h−1 > 3, kobs = 0.50 ± 0.03 h−1). These results support the idea that fine-tuning the length of the alkyl chain can enhance DNA-targeting activity and contribute to the development of efficient strategies for catalytic cleavage of nucleic acids.