Université de Strasbourg

Open Fellows seminar - When chemistry goes chiral

December 13, 2022
From 15:00 until 17:30
Salle de conférence, MISHA, Strasbourg

Chirality with hands - via Wikimedia Commons

Chirality is a geometric property of asymmetry. In chemistry, a molecule is called chiral if it cannot be superposed on its mirror image by any combination of rotations or translations. The word chirality is derived from the ancient Greek word for “hand” - like a person’s hands, chiral molecules are the same but different; they can exist in two forms (stereoisomers) that are mirror images of each other, called enantiomers. The two enantiomers have the same chemical and physical properties, except when reacting with other chiral compounds or with light. These differences can be very important (imagine trying to put a left-hand glove on your right hand).

The increasing understanding of the role of chirality in organic and inorganic molecules opens up possibilities to actively use these insights in chemical engineering (synthesis, catalysis, new materials, energy technology), and possibly to harness them for "green chemistry", which aims at making chemical processes more environment-friendly, and using chemistry to reduce pollution.

In this joint chemistry seminar, three USIAS projects will be presented in which chirality plays an important role. The USIAS fellows will talk about their findings, and reflect on the implications and applications of their research.


Programme and abstracts

15:00 Opening words
15:10 Chiral self-assembled cages - Pierre Mobian, 2020 Fellow, CMC, Strasbourg
15:45 Natural deep eutectic solvents: green media for the synthesis of chiral metal-organic frameworks - Stéphane Baudron & Benoît Louis, 2019 Fellows, CMC and ICPEES, Strasbourg
16:20 Coffee break with Christmas "bredele"
16:40 Chiral assemblies for next-generation energy technologies - Amparo Ruiz Carretero & Shu Seki, 2020 Fellows, ICS, Strasbourg, Kyoto University, Japan
17:15 Final discussion

Chiral self-assembled cages

Pierre Mobian, 2020 Fellow
Complex Matter Chemistry (CMC), University of Strasbourg & CNRS
Collaborator(s): Midhun Mohan (post-doc)

Chirality is a fundamental issue found in Nature that originates from the asymmetry of molecules. Numerous strategies have already been applied by chemists to control the handedness of organic compounds; much less is known, however, about the synthesis of enantiopure inorganic materials.

This talk will highlight the strategy that we have developed to access enantiopure metal oxides. This strategy involves the use of chiral organic cages acting as a templating agent. Consequently, we will report on the straightforward preparation and the characterization of enantiopure self-assembled cages created from readily accessible building blocks, such as enantiopure binapthol (BINOL) derivatives by applying reversible imine condensation chemistry. There will be a special focus on the structural description of these architectures, and the stability of these molecular objects will be discussed.

The reported cages, as schematically represented here, contain three hydroxy functions pointing inside the cage cavity. This indicates that these architectures are ideal candidates for chiral molecular recognition studies. It also offers a unique possibility to generate an oxocluster embedded into the cage to form a hybrid cage, which we could imagine using as a precursor to generate enantiopure oxides.

Natural deep eutectic solvents: green media for the synthesis of chiral metal-organic frameworks 

Stéphane Baudron & Benoît Louis, 2019 Fellows
Complex Matter Chemistry (CMC) and Institute of Chemistry and Processes for Energy, Environment and Health (ICPEES), University of Strasbourg & CNRS
Collaborator(s): Renata A. Maia (post-doc) & Michaël Teixeira (intern, Master 2 student)

In green chemistry, finding more sustainable solvents for chemical synthesis is an important quest, in order to arrive at more sustainable reaction methods.

Natural deep eutectic solvents (NaDES) represent an emerging class of green media that is of interest. They are formed by combining two or more solid compounds from natural sources such as cheap, abundant and available in enantiopure form derivatives like menthol, amino-acids or sugars for example. The resulting fluids show limited - if any - toxicity, an improved biocompatibility as well as low vapor pressure, relatively wide liquid range and non-flammability.

In this project, these media have been employed as solvents for the preparation of crystalline porous materials of the metal-organic framework type (MOF), with a particular focus on their chiral induction for applications as materials for enantioselective catalysis under heterogeneous conditions. In this context, the impact of NaDES on the synthesis and properties of prototypical and novel MOFs has been explored. In particular, the talk will describe aspects related to water sensitivity, porosity and chirality.

Chiral assemblies for next-generation energy technologies

Amparo Ruiz Carretero & Shu Seki, 2020 Fellows
Charles Sadron Institute (ICS), University of Strasbourg & CNRS and Kyoto University, Japan
Collaborator(s): Kyeong-Im Hong & Ana M. García Fernández (post-docs)

One of the main challenges of our generation is securing the global energy supply while fighting global warming. In this sense, solar energy is a great alternative since several materials can convert sun light into electricity. Despite the high efficiency of silicon panels, our unstoppable energy consumption demands additional alternative materials. Particularly, organic materials are the most versatile choice since it is possible to control the materials’ properties by molecular design.

Our goal is to contribute to these efforts by importing supramolecular chemistry strategies into the organic electronics field. More specifically, we explore the role of chiral supramolecular assemblies in charge transport processes, following the recently reported Chiral Induced Spin Selectivity (CISS) effect. It states that electrons of certain spin can go through chiral assemblies preferentially in one direction depending on their handedness. This strategy has great potential to reduce charge recombination, since charge carriers - which are spin-containing species - could have directionality through chiral assemblies.

For this purpose, we couple chiral substituents to electroactive segments, containing hydrogen-bonding motifs to form chiral supramolecular p-conjugated assemblies, and follow charge and spin transport using electrodeless techniques. We expect to screen the best chiral supramolecular structures and show the potential of chiral materials in organic photovoltaics.


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