The scientific part of the project was separated in 3 work packages that have been run over the 2 years.
Work Package 1: Synthetic copper complexes for oxidation catalysis
During the first period of the project, the focus was on the design of a synthetic copper complex that would allow oxidation reactions to perform under mild and environment friendly conditions. Two lines of research were conducted in parallele in order to maximize the impact.
On one hand, our attention was focused on the comprehension of N-heterocyclic carbenes (NHCs) based copper complexes. Indeed, very few investigations on the influence of NHC ligand on copper(II) had been performed so far. While many information can be found on precious metals, low valence metals and low oxidation states, it was of interest to get insights into the influence of NHC ligands on high oxidation metals such as copper(II). Synthetic NHC-copper(II) complexes were succesfully synthesized and allowed a better understanding of NHC-Cu bonds via a full spectroscopic study. The results were presented at different international conferences (ICBIC, SCF, ISOC) and reported in a peer-reviwed paper (Inorg. Chem. 2019).
On the other hand, another class of ligands was used (PYA) to generate new copper(II) complexes. Through a thorough study, different types of PYA ligands were discriminated as best targets for the preparation of copper(II) complexes for oxidation catalysis. This methodology allowed the establishment of a new procedure for the oxidation of a type of organic compounds, benzylic alcohols, in a more gentle and environment friendly manner than reported so far. Those results will be published in the coming weeks.
Work Package 2: Copper peptide design
First, a peptide mimick of a well known protein was prepared and copper(II) binding was investigated. The results showed that a too flexible peptide couldn't stabilize a metal into the coordination site, such as copper(II). Based on this result, two lines of research were conducted.
We moved to the use of the full protein to study how to modify an active enzyme known to oxidize organic compounds to accelerate its activity. Indeed, many enzymes have been discovered but are rarely used in the industry world due to their sensitivity. We thus studied the modification of selected enzymes with NHC ligands. The pilar of this line of research was the results found in Work Package 1: using the information we previously discovered, NHC ligands were succesfully incorporated into a modified protein which incresead its activity as electron transfer. Those results were communicated through a peer-reviewed paper (Angewandte, 2019) and international conferences (ICBIC, SCF, SOC, SCS).
Since it is anyway easier to synthesize and use peptides instead of proteins, espacially for industrial application, peptides were designed and synthesized where an NHC ligand was incorporated. Different metals could be coordinated to those artificial peptides and the host group is now focusing on the binding of copper.
Work package 3: Synthetic complex into a peptide
Thanks to the results obtained from the 2 first packages, members of the hostgroup are now investigating the incorportion of copper complexes into a peptide scaffold. Application for oxidation catalysis will be considered.
