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Chemistry


Elena Salvadeo

New polynuclear copper complexes active in oxidation reactions

Published on 27 November 2017


Thesis presented on November 27, 2017

Abstract:
This manuscript presents the development of new copper complexes for catalytic purposes. The design of the complexes takes inspiration from the active sites of multicopper oxidases. Three binuclear copper complexes have been synthesized and characterized, with a focus on their electrochemical behaviour and their potential use as catalysts for oxygen reduction. Spectroscopic and electrochemical studies revealed the importance of the coordination environment on the stability of the complexes. Cu(II) centers coordinated by not strong enough ligands are spontaneously reduced in solution, giving rise to mixtures of different complexes. At the same time more rigid structures capable of stabilising the two copper centers give rise to slow electron transfers, an undesirable characteristic in electrocatalysts. For these reasons more complex ligands have been synthesized, with the aim of obtaining trinuclear copper complexes with good properties as catalysts for dioxygen reduction. One of the binuclear complexes have been tested as oxidation catalyst in nitrene transfer reactions. The complex shows good performance in aziridination catalysis, both in its bis-Cu(II) and bis-Cu(I) forms. The catalytic activity have been analysed also from the mechanistic point of view. Preliminary results suggest different mechanisms of interaction of the reduced and oxidized forms of the complex with the nitrene donors.


Keywords:
Catalysis, biomimetic, oxygen reduction, copper