Targeted water soluble copper-tetrazolate complexes: interactions with biomolecules and catecholase like activities

Area of Science:

• Inorganic Chemistry
• Bioinorganic Chemistry
• Materials Science

Background:

• Copper(II) complexes are investigated for their potential biological and catalytic applications.
• Metal-mediated cycloaddition reactions offer a pathway to synthesize novel coordination compounds.

Purpose of the Study:

• To synthesize and characterize two new water-soluble copper(II) tetrazolate complexes.
• To investigate the DNA binding affinity and DNA cleavage activity of these complexes.
• To explore the catecholase-like catalytic activity of the synthesized copper complexes.

Main Methods:

• Synthesis via metal-mediated [2 + 3] cycloaddition reaction.
• Structural characterization using X-ray crystallography and spectroscopic techniques (ESI-MS).
• DNA binding studies using fluorescence spectroscopy and gel electrophoresis.
• Density Functional Theory (DFT) calculations.
• Enzyme kinetic studies for catalytic activity.

Main Results:

• Two octahedral copper(II) complexes, [Cu{(5-pyrazinyl)tetrazolate}2(1,10-phenanthroline)] (1) and [Cu{(5-pyrazinyl)tetrazolate}(1,10-phenanthroline)2](NO3)0.5(N3)0.5 (2), were successfully synthesized.
• Complex 2 demonstrated a stronger binding affinity to calf thymus DNA (CT-DNA) compared to complex 1, attributed to a lower HOMO-LUMO energy gap.
• Both complexes exhibited moderate to strong DNA cleavage activity, with inhibition by sodium azide suggesting singlet molecular oxygen involvement.
• Complex 2 effectively mimicked catecholase activity, with ESI-MS suggesting dimeric copper species in the catalytic cycle.

Conclusions:

• The synthesized copper(II) complexes display significant DNA interaction and cleavage capabilities.
• Complex 2 shows promising potential as a biomimetic catalyst, particularly for catecholase-like reactions.
• These findings highlight the versatility of copper tetrazolate complexes in bioinorganic and catalytic applications.