The Investigation of the Effects of Counter-cations and Sterically Encumbered Ligands on the Structure and Catalytic Activity of Cu Complexes Supported by Bis(amidophenyl)amine Ligands Pubblico

Abstract

Bioinspired transition-metal complexes that catalyze oxidation reactions using O2 as the terminal oxidant are heavily studied in bioinorganic chemistry. Among the metalloproteins that effectively bind and activate O2, two kinds of type-3 copper proteins, tyrosinase and catechol oxidase, have been widely explored. In recent years, many synthetic models that both mimic the O2 binding mode of the proteins and display tyrosinase and catecholase activities towards external substrates have been developed. Yet, more investigations can be made on the ligand steric effect and the effect of counter-ions in such bioinspired models.

In chapter 2 of this thesis, the investigation of the effect of counter-cations on the structure and catalytic activity of a copper complex supported by a bis(amidophenyl)amine ligand is reported. This bioinspired bimetallic complex displays good catalytic activity towards the aerobic oxidation of catechol. The incorporation of K+ and (PPh4)+ as the counter-cations have been found to influence both the structure and the catalytic activity. The investigation of the difference in catalytic activity also reveals the formation of a catalytically irrelevant species in the reaction pathway.

Chapter 3 of this thesis focuses on the investigation of the ligand steric effect. Two bis(amidophenyl)amine ligands with sterically encumbered substituents are used, and two copper complexes with bridging-hydroxo ligand and one copper complex with phenolate coordination have been unexpectedly isolated. Questions about the assignment of the oxidation states of the copper centers in two of the complexes and the oxidative C-C bond cleavage of the ligand backbone in one of the complexes arise after the structural and spectroscopic characterizations. Both worth thorough investigations in future studies. 

Table of Contents

Chapter 1. Recent Developments of Copper Complexes with Phenolase and Catecholase Activities...........................................................................................................1

Chapter 2. The Effect of Counter-cations on the Reactivity of a Binuclear Cu Catalyst and the Characterization of an Off-pathway Species in Aerobic Catechol oxidation....18

Chapter 3. The Isolation and Characterization of Two Hydroxo-Bridged Cu Complexes and One Cu-Phenolate Complex...........................................................................37

About this Honors Thesis

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School	Emory College
Department	Chemistry
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Chemistry, Inorganic
Parola chiave	catecholase activity C-H oxidation copper redox-active ligands
Committee Chair / Thesis Advisor	Cora E. MacBeth, Emory University
Committee Members	Kurt Warncke, Emory University Craig L. Hill, Emory University

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