3 years

PhD: Semi-crystalline mesostructured axides as supports for catalysis

position filled

Contact by mail to apply or for any information:

PhD supervisor: Pr. Jean-Luc Blin, Laboratoire Lorrain de Chimie Moléculaire, jean-luc.blin@univ-lorraine.fr

& co-supervisor: Dr. Bénédicte Lebeau, Institut de Science des Matériaux de Mulhouse, benedicte.lebeau@uha.fr

Context: Transition metal oxides play an important role in industry as catalyst, catalyst support or to take advantage of their optical and electronic properties, such as luminescence. However, the compounds existing on the market suffer from their low specific surface (25 m2 / g for example for TiO2). Thus, the preparation of structured mesoporous materials which have a large specific surface area is an advantageous solution for better exploiting the inherent properties of transition metals oxides. A collaboration between the Laboratoire Lorrain de Chimie Moléculaire (L2CM) and the Institut de Science des Matériaux de Mulhouse (IS2M), has led to the synthesis of mesostructured titania with 2D hexagonal porous network, having semi-crystalline framework and with high specific surface area (> 250 m²/g). Our synthesis strategy combined EISA with the Liquid Crystal templating pathway. Pluronic P123, an amphiphilic triblock copolymer, is used as pore templating agent and titanium isopropoxide as inorganic precursor. The mesostructure is stable until 500°C. The surfactant is removed by different methods: calcination, flash induction or water extraction. The obtained mesostructured titania have also been used as supports to design of “CoMoS” hydrotreatment catalysts (co-activated MoS2) which were tested for the conversion of 4,6-dimethyldibenzothiophene (46DMDBT). This study has been performed in collaboration with the Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP). Obtained results, stand out from what has been reported in the past. Firstly, mesostructured titania present a high concentration of Brønsted acid sites on the surface. This is very unusual for TiO2, which is reputed to be non-acidic. Secondly, a shift towards DDS selectivity in the conversion of 46DMDBT, which is unprecedented in literature, was observed. This change in selectivity allows to consume less hydrogen and thus making the process more eco-friendly. These results show that the amorphous phase involves modifications of the support leading to significant modifications of the catalytic properties (HYD / DDS selectivity ratio), which offers unexplored possibilities in terms of catalyst development.

Goal : Our objective during the thesis is to deepen the mechanisms of formation of mesostructured transition metal oxides by studying in particular the influence of the presence of additives (salt, complexing agent, etc.) produced or added during the synthesis on the phase behavior of the surfactant in solution. We also aim to describe in a rational way the existing relationships between the structural and textural characteristics of the support (in particular the presence of the amorphous phase) and the activity and selectivity of the final catalysts. The catalytic reactions envisaged concern the hydrotreatment and in particular HDS or oxidation reactions such as for example the oxidation of toluene We are mainly interested in alumina and zirconia. The synthesis methodology will also be extended to MgO which plays an important role in catalysis.

Pr. Jean-Luc Blin - Contacter
Université de Lorraine, Faculté des
Sciences et Technologies, UMR 7053 L2CM
54506 Vandoeuvre les Nancy

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6 months - January/July 2022

Internship - Master 2 - Syntheses of supramolecular photosensitizers with macro-bis-heterocyclic bis-imidazolium structure for phototherapy applications.

Background: This request is made in the context of the development of photoactive molecular systems for health, in particular for applications in phototherapy, opening the way to the treatment of many pathologies, including those of infectious and cancerous origin, using light.

Recent work carried out in the laboratory concerning the preparation of potential macro-bis-heterocyclic bis-imidazolium N-heterocyclic carbene (NHC) ligands, have shown interesting intrinsic photophysical and biological properties of these molecules, with a production of singlet oxygen (1O2), in yields of up to 84% for some of the macrocycles obtained. We wish to continue these syntheses in order to modify the structures and improve their photoactive properties with a shift towards higher wavelengths (> 800 nm) in particular for applications in phototherapy. We aim at preparing structures with a higher conjugation but also a larger size allowing a better coordination of transition metals (e.g. Zn (II), Ag (I), Au (III), Pt (II), Fe (II)).

Objectives: The Master 2 subject will concern the organic synthesis of original N-macro-bis-heterocyclic carbene ligands and the metal cation complexes of the isolated compounds (scheme above), as well as their characterization.

Methodology: The candidate will perform organic synthesis reactions and characterization of the isolated molecules by classical physicochemical methods (Infra Red (IR), Nuclear Magnetic Resonance (NMR), mass spectroscopy, microanalysis, etc.). The study of their coordination properties will then be carried out. Depending on the progress of the synthesis, the analysis of the photo-physical properties (fluorescence, 1O2, photoacoustics) and the application in biology (cytotoxicity, antimicrobial/antiviral properties, antiproliferative) will then be discussed in collaboration with Dr. Mihayl VARBANOV.

Desired profile: The candidate should have a strong knowledge in organic synthesis methodology and coordination chemistry. He/she should have the necessary knowledge of physico-chemical analysis (IR, NMR, mass spectroscopy, microanalysis). Good knowledge in biology is welcome. For international candidates, a good command of English is sufficient (a good knowledge of French would be appreciated).

Application: Applications should be sent to Florence Dumarçay (florence.dumarcay@univ-lorraine.fr)  and must include a CV and the transcript of records of BSc and MSc levels.

6 months - January/July 2022

Internship - Master 2 : Evaluation of the anti-infectious properties of supramolecular photosensitizers with a macro-bis-heterocyclic bis-imidazolium structure.

Background: The development of photoactive molecular systems, with application in phototherapy, opens the way to the treatment of many pathologies, including those of infectious and cancerous origin, using light. Recent work carried out in the laboratory concerning the preparation of potential macro-bisheterocycles bis-imidazolium ligands NHC (N-heterocyclic carbene) in coordination with transition metals (e.g. Zn (II), Ag (I), Au (III), Pt (II), Fe (II)), has shown interesting intrinsic photophysical and biological properties of these molecules. These observations concern particularly the production of singlet oxygen (1O2), the yield of which can reach 84% for some of the macrocycles obtained, as well as the antibacterial activities. We wish to continue the biological characterization of these structures in order to improve their photoactive properties, in particular for applications in phototherapy (PT).

Objectives: The objective of the traineeship will concern the biological characterization of the original N-macro-bis-heterocyclic carbene ligands and the metal cation complexes of isolated compounds (illustrated above). The focus will be on evaluating the anti-infectious properties of the molecules, in presence or absence of irradiation.

Methodology: The candidate will carry out the evaluation of the antibacterial (pathogenic strains, microbiota strains) and antiviral (coronavirus, herpesvirus) properties of the compounds, as well as the evaluation of their impact on the host cells (cytotoxicity, hematotoxicity). The link with photo-physical (fluorescence, 1O2, photoacoustic), physico-chemical and structure-activity relationships will then be discussed in collaboration with Dr. Florence Dumarçay.

Profile of the candidate: The candidate should have solid knowledge in bacteriology / virology and cell culture. He must have the necessary knowledge for analyzes in cell biology (light microscopy, immunofluorescence, FACS, Western blot), molecular biology (PCR, RT-PCR) and biochemistry. Good knowledge in chemistry / physical-chemistry will be welcome. For international applicants, fluency in English is sufficient (a good foundation in French will be appreciated).

Application: Applications should be sent to Mihayl Varbanov (mihayl.varbanov@univ-lorraine.fr) and must include a CV and the transcript of records of BSc and MSc levels.