Synthesis and Characterization of Dicopper(II) Complexes with Biological Relevance

Abstract

The research discussed in this study focused on the design, synthesis, and characterization of new model complexes that mimic the type-3 enzyme, catechol oxidase, which oxidizes catechols to their corresponding quinones. Our approach focused on the design and synthesis new model complexes that contain a dicopper(II) center that can be fine-tuned in a variety of ways, such as sterics and exogeneous bridging molecules. This method allows a multitude of complexes to be created and compared to determine how the overall structure affects the catecholase activity of the complexes.

Two ligands were synthesized; they contain a phenolate body, two amide groups, and two bis(pyrazolyl)methane ligand side-arms. They were named LNH4Pz and LCO4Pz, depending upon which end of the amide was bound to the phenol ring. These ligands were characterized using 1H-NMR and IR spectroscopy. Using these ligands, copper(II) ions were coordinated to the ligands, along with specific exogenous bridges to produce a total of four complexes, two LNH4Pz-copper complexes and two LCO4Pz-copper complexes. These complexes were characterized by 1H-NMR, IR spectroscopy, X-ray crystallography, and UV-Vis spectroscopy.

The catechol oxidase-like behavior of these compounds was also analyzed, and we found that the LNH4Pz-based copper compounds have small activity; in contrast, the LCO4PzCu2(OH) complex has a high catecholase activity, with a substrate to product conversion of over 90%. Furthermore, UV-Vis spectroscopy revealed that the reaction is first order in catalyst and that there is a substrate saturation at high substrate concentrations. 1H-NMR confirmed that the quinone was the only product produced during this reaction.

Date of Award	2016
Original language	American English
Awarding Institution	Eastern Illinois University
Supervisor	Radu Semeniuc (Supervisor)