Plasmonic nanohelix arrays induced by chiral block copolymer self-assembly. Towards photocatalytic applications (M/F)

Job Description

Thesis Subject

Asymmetric (enantioselective) catalysis is the most relevant strategy leading to the formation of enantiopure chemicals, being of paramount importance for the development of modern pharmacology and new formulations in the agrochemical and food industries. Usually performed in homogeneous solutions with molecular catalysts, important efforts have been devoted to the development of asymmetric reactions in heterogeneous settings. Meanwhile, the field of visible light photocatalysis has experienced an important growth since the beginning of the 21st century, permitting the development of selective and more efficient chemical transformations through energy or electron transfer processes. In this respect, the use of plasmonic structures as heterogeneous photosensitizers and photocatalysts has proven to be particularly valuable. Solar radiation being an abundant, cheap and green source of energy, the development of photocatalytic approaches resonates today with the current need for more sustainable and affordable chemicals.
In the present project, we propose to combine the unique features of plasmonic photocatalysis with asymmetric reactivity, aiming at performing heterogeneous and asymmetric photocatalytic reactions driven by plasmons. As plasmonic systems, we will employ chiral nanostructures derived from supported helices obtained via block copolymer (BCP) self-assembly, specifically from the self-assembly of chiral BCP chains into the helical hexagonal phase (H*). Such structures are generated by chirality transfers at various length scales; i.e., from chiral monomers (molecular chirality), chiral BCP chains (conformational chirality), to hierarchical chiral superstructures (mesophase chirality). This homochiral evolution has only been barely explored in the literature for the generation of arrays of chiral features on surfaces with a controlled orientation based on the stabilization of the H* phase. In our approach, the vertically-aligned BCP helices of specific handedness will be further replicated into arrays of metal features (principally gold) by means of selective post-hybridization methods to generate the plasmonic-active structures. In a second step, the ability of such chiral plasmonic systems to interact asymmetrically with light and molecules will be assessed with model reactions. Finally, being heterogeneous, these systems will be a proof-of-concept of asymmetric plasmonic photocatalysts that can be easily recyclable.
Missions
Le/la candidat(e) aura plusieurs objectifs :
The candidate will be in charge of the synthesis and characterization of the plasmonic nanoobjets. Based on the BCP self-assemblies developed in LCPO by Guillaume Fleury, metallic salts impregnation strategies will be optimized to create metallic nanohelices array with specific orientation. After characterization, these objects will be used as photocatalysts for enantioselective synthesis based on model reactions.
Activités :
- Formation of the nanostructured films with an out-of-plane helical array.
- Hybridization of the BCP arrays towards the formation of pure gold nanohelices
-Electron microscopies and vibrational spectroscopies characterizations.
- Chiroptical characterization of the single helices and the aligned arrays.
- Enantioselective catalysis

In addition to its experimental missions, the PhD candidate will be in charge of a literature overview all along the 3 years.
She/he will also present the results in international conferences (for example, Bordeaux Polymer Conference, Chirality, Chirality@theNanoscale, META, etc…) and in national workshops like GDR OrNano.

Compétences / candidate profil:
– PhD in Chemistry, Physical chemistry or Nanoscience.
– Aptitude for working on multidisciplinary projects
– Ability to work independently in a highly organized fashion; ability to work safely, with good situational awareness, as the job requires significant manual tasks such as chemical synthesis and analysis
– Knowledge of written English and spoken fluency in English and/or French

Your Work Environment

This work will be performed in the CBMN institute (Institut CBMN – Recherche en Chimie, Biologie & Physique) in the team Chiral Molecular Assemblies which is specialized into chirality at the nanoscale, with a particular focus on plasmonic nanoobjects. The PhD candidate will have access to the laboratory of the team and all the characterization techniques of the IECB, Placamat and Elorpintec platforms.
The work will be performed in collaboration with the LCPO (LCPO - Organic Polymer Chemistry Laboratory) for the synthesis of the chiral BCP helical arrays.

Constraints and risks

The main risk is related to the use of nano-objects. All necessary protective measures are available in the laboratory to ensure a safe working environment.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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