项目一
Title:        Development of green oxidation processes using electrochemical O2 Reductive Activation and bioinspired Fe complexes
Advisor:        Dr. Elodie Anxolabéhère & Dr. Claire Fave
e-mail        elodie.anxolabehere@u-paris.fr
Institution:        Laboratoire d’Electrochimie Moléculaire (LEM) UMR 7591
Université de Paris, Bat. Lavoisier, 15 rue J.-A. de Baïf 75205 Paris Cedex 13, France

Subject:
Context Oxidation reactions are of main importance in the chemical industry for the production of large quantities of organic molecules. Current economic and ecological challenges require development of economically sound and ecologically viable chemical processes such as the use of molecular O2 to conduct oxidation reactions in mild conditions. In Nature, metalloenzymes, such as Fe containing oxygenases, are able to achieve highly efficient and selective oxidations under mild conditions throughout a process known as reductive O2 activation. This process results to the breaking of the O-O bond of O2 bound to the Fe catalytic center and leads to oxygen atom insertion into weakly reactive substrates. The observed reactivity in these processes at the Fe containing active site of the enzymes is a great source of inspiration for developing new earth abundant metal containing molecular catalysts for oxidation reactions.

Objectives: In an effort to reproduce the enzymes’ fascinating catalytic performance,we have developed at LEM an original complementary electrochemical and spectroscopic strategy using simple metal complexes as models of the active site, and carbon electrodes to provide the necessary electrons. Fe-peroxo, Fe- hydroperoxo and oxo species have been proposed as key reactive intermediates in the catalytic cycle of Fe containing
enzyme (eg. CytP450) capable of cleaving the O-O bond and of inserting oxygen atom in organic substrates. Using Fe porphyrins, we have shown that is possible to reproduce such a catalytic cycle.[4c] Our objectives is now to set up the optimal catalytic conditions (heterogeneous or homogeneous conditions) for electrocatalytic oxidation of organic substrates.

Strategy and methodology: In the first part of the project, we will design new complexes by modulating the nature of the chelating ligand. We will study the electrocatalytic activity for various organic substrates oxidation. To reach these objectives, mechanistic studies based on electrochemistry and spectroelectrohemistry will be the key to decipher the parameters that control the reactivity of the FeOOH and FeO reactive species. Rooted in these studies, optimization of the most active catalysts will be pursued, leading to robust and highly selective catalysts. The second part of the project aim at transferring the catalytic activity of Fe catalyst onto surface, since it is also a good way to prevent the use of a large amount of catalyst and to get an active electrode for performing catalysis in water. We will start our investigation with our most active complexes and we design catalytic materials along various strategies, ranging from non-covalent catalyst grafting on carbon nanotubes using weak interactions to covalent grafting of catalyst monolayer on carbon surface.

Requirement of the candidates: Expected skills of the PhD candidate: ligand and metal complexes synthesis, molecular electrochemistry, coordination chemistry, spectroscopy, analytical chemistry. The candidate should show a strong interest in experimental work.

项目二
Title: Electrocatalytic processes with molecular catalysts involving Halogen bond interactions.
Advisors: Dr Claire Fave and Dr. Audrey Guerlin
Mail: claire.fave@u-paris.fr
Lab: Laboratoire d’Electrochimie Moléculaire (LEM) UMR 7591
Université de Paris
Bat . Lavoisier
15 rue J.-A. de Baïf
75205 Paris Cedex 13
France

Description of the subject
The use of electrochemical methods for the investigation of Halogen Bonding (XB) in solution is a recent approach [Current Opinion in Electrochemistry 2019]. Most articles have been published during the past 5 years and many aspects are still to be explored. The fundamental concept of electrochemical XB switching for molecular recognition and detection has been well established by our group [Chem. Commun. 2014, PCCP 2016] and P. Beer [Chem. Commun 2015] at Oxford. Taking into account the reported results, electrochemistry can be considered as powerful tool for qualitative and quantitative study of XB as well as a method to control XB strength in supramolecular associations.
Also recently the community has started to consider XB in organic synthesis and more importantly in organocatalysis. We have identified a conceptionally new domain, ripe for exploration, that is XB promoted electron transfer reactions involving the activation of covalent bonds.
Based on the expertise of our team [Current Opinion in Electrochemistry 2019 and Chem Comm 2019], the present proposal is focused on the exploration of electrocatalytic systems in which XB could promote the formation of an intermediate complex between an electrochemically regenerated mediator and the substrate in solution or at the interface. The results will provide new insight into supramolecular reactivity involving XB, but also the development of electrochemically assisted catalytic redox reactions.
For this purpose, the synthesis of new redox active molecules will be performed and their electrochemical and catalytic properties will be systematically studied by spectroscopic, electrochemical and spectro-electrochemical methods.

Expected skills of the candidate: organic chemistry, molecular electrochemistry, catalysis. 返回小木虫查看更多