Thioether sulfur-bound [Cu₂] complexes showing catechol oxidase activity and DNA cleaving behaviour.

Area of Science:

• Coordination Chemistry
• Bioinorganic Chemistry
• Catalysis

Background:

• Rational ligand design is crucial for controlling the aggregation state of dinuclear copper complexes.
• Previous studies showed that ether analogues of the ligands lead to tetranuclear copper complexes via self-aggregation.
• Understanding the influence of ligand backbone on copper core formation is essential.

Purpose of the Study:

• To synthesize and characterize novel dinuclear copper complexes with thioether-containing ligands.
• To investigate the catalytic activity of these complexes in the oxidation of 3,5-di-tert-butylcatechol.
• To evaluate the DNA binding and cleavage properties of the synthesized copper complexes.

Main Methods:

• Synthesis of copper complexes using rational ligand design with N2O3S2 and N2OS2 donor sets.
• Structural characterization using single crystal X-ray diffraction, UV-vis spectroscopy, and HRMS analysis.
• Catalytic oxidation studies of 3,5-di-tert-butylcatechol and DNA binding/cleavage assays (pBR322).

Main Results:

• Successfully synthesized and structurally characterized three dinuclear copper complexes ([Cu2(μ-H2L1)(μ-OH)](ClO4)2·2H2O, [Cu2(μ-L2)(μ-OH)(OH2)](ClO4)2, and [Cu2(μ-L2)(μ-OCH3)(OH2)](ClO4)2).
• The complexes demonstrated catalytic activity in the oxidation of 3,5-di-tert-butylcatechol, with a mechanism dependent on the ligand backbone.
• All complexes exhibited significant DNA binding affinities (Kb values ranging from 4.2 × 10^4 to 5.6 × 10^4 M-1) and efficient DNA cleavage activity, particularly in the presence of reactive oxygen species.

Conclusions:

• The rational design of thioether-donor ligands effectively stabilizes dinuclear copper cores, preventing aggregation observed with ether analogues.
• The synthesized copper complexes serve as effective catalysts for catechol oxidation and possess promising DNA binding and cleavage capabilities.
• These findings highlight the potential of these copper complexes in both catalytic applications and as therapeutic agents targeting DNA.