27/03/2019 Offres d'emploi

2 PhD positions in LPCNO - INSA/CNRS/Univ. Toulouse - 2019

1 - Supercrystal assembly by predictive approach 2 - Molecular oriented supraparticular chemistry

There are two PhD positions in the Laboratory of Physics and Chemistry of Nano-Objects (INSA, CNRS, University of Toulouse). Both topics are funded and described below. For each topic, applications must be sent by email (attach CV, transcripts and any recommendations). Full informations are provided in the pdf files:

1st Subject: Supercrystal assembly by predictive approach (pdf)

in collaboration with the "Laboratoire d'Informatique de Paris Nord" LIPN, (CNRS, University Paris 13).

Supervisors: Simon Tricard, tricard@insa-toulouse.fr & Thomas Fernique, fernique@lipn.fr

Context: Nanoparticles have been studied for years. A new challenge for the field is to assemble them to obtain superstructures with new properties, which result from concerted – or even cooperative – effects between building blocks, and which can depend on the nature of the packing (compact, porous, periodic, aperiodic, quasi-periodic, etc.). When nanoparticles are crystalline, crystals of crystals, also called supercrystals, are obtained. Various examples of supercrystals have been reported in the literature, but most of them have been obtained by serendipity, i.e. by happy chance.

The objective of this project is to develop a rational and predictive approach to synthesize nanostructured materials, by developing both theoretical techniques to determine the packings and experimental techniques to perform self-assembly. The work will be carried out in a cross approach between computer science and chemistry, combining algorithmic and combinatorial exploration on the one hand and chemical synthesis and physico-chemical characterization (IR spectroscopy, UV-Vis, NMR, XPS, electron microscopy, WAXS, etc.) on the other hand. The proposed PhD thesis is in chemistry, but the candidate is also asked to be open to theoretical considerations.

Superstructures offer a strategy of choice for assembling nano-objects of different natures and combining their functional properties (magnetic, semiconductor, luminescent, catalytic, etc.). A wide variety of applications can be considered combining the functions of the nanoparticles that make up the assembly. For example, the interposition of antennas (semiconductor nanoparticles, e.g. PbS, InP) will capture light and influence the electrical (metallic nanoparticles, e.g. Pt, Au) or catalytic (catalytic nanoparticles, e.g. Ru, Pd) properties of the materials. Charge transport studies and catalytic tests can be performed at LPCNO. The project will focus on the so-called compact packings, which are pavings, and on their synthesis by self-assembly of spherical nanoparticles. Initially, periodic binary assemblies will be carried out, before continuing towards ternary or quasi-periodic systems.

1 D.V. Talapin, et al. Quasicrystalline order in self-assembled binary nanoparticle superlattices. Nature, 461 : 964-967, 2009. Link
2 T. Fernique, et al. Compact packings of the plane with three sizes of discs. preprint, arxiv: 1810.02231, 2018. Link

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2nd subject: Molecular oriented supraparticular chemistry (pdf)

Supervisors: Simon Tricard, tricard@insa-toulouse.fr

Context: Nanoparticles have been studied for decades. A new challenge of the field is to combine them with molecules to form hybrid nanoparticle/molecule self-assemblies, which associate the structural and functional properties of each building block. As supramolecular chemistry brought new properties to molecular materials fifty years ago, the aim of the project is to take part in the development of supraparticular chemistry, i.e. the oriented self-assembly of nanoparticles, by controlling interactions between ligands that stabilize nanoparticles, and between ligands and the surface of nanoparticles.
At LPCNO, we develop self-assembly approaches where the driving forces are specific interactions between the molecular ligands that stabilize the nanoparticles. We use, as building blocks, ultra-small (1-2 nm) platinum nanoparticles, the size of which is of the same order of magnitude as that of the ligands used. Encouraging results have been obtained with simple organic molecules, coordination complexes, peptidic polymers, and coordination polymers. These hybrid self-assemblies are promised to show new functional properties in various fields: electron transport, catalysis, magnetism, optics, etc.

The aim of the project will first of all be to understand the formation of superstructures and to develop self-assembly models. The next objective will be to develop systems that respond to light by introducing "antenna" molecules, where a charge separation process occurs under irradiation. Finally, the effects of induced loading will be studied in transport and catalysis.

This is an experimental chemistry project, combining the synthesis of nanoparticles and their self-assembly in an inert atmosphere. The systems obtained will be characterized by conventional nanochemistry techniques (IR spectroscopy, UV-Vis, NMR, electron and near-field microscopy, XPS, etc.). A second part will consist in studying their physical and catalytic properties under light irradiation