Author Archives: valerie

Chirality Related Properties in Helicene and Tetrathiafulvalene based Materials

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2023-12-22
News: Who ? Dr. Narcis AVARVARI du Laboratoire MOLTECH Anjou  (Université d'Angers).
Where ? salle de conférences de l'ISM (3e étage)
When ? 22 dec. 2023, 10h30-11h30
Keywords: CISS effect, eMChA effect, Helicene, Conductivity, TTF
Abstract and references on  : https://www.ism.u-bordeaux.fr/actualites/dr-narcis-avarvari
Laboratory : ISM

Deadline sur PEPR LUMA

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2023-09-15
News: Le PEPR LUMA invite les chercheurs travaillant dans les axes de recherche sur la chiralité listés sur : https://www.pepr-luma.fr/axes/chiralite/ de déposer des lettres d'intention (<3 pages) avant le 15 sept. 2023 afin de construire lors de workshops en visioconférence (dates prévisionnelles 27-28 sept. 2023) des consortia (typiquement 10 équipe de recherche travaillant ensemble) qui répondront aux AMI-appel à manifestation d'intérêts- auprès de l'ANR-PEPR-LUMA en automne 2023. Le template de la lettre d'intention et les dates clefs sont consultables sur : https://www.pepr-luma.fr/appels/appel-a-manifestations-dinteret-recherche-thematique/ NB : les AMI sont des financements sur 5 ans n'incluant pas de l'équipement >50 keuros.
Laboratory : chiralité

Design, preparation and chiroptical characterization of chiral molecules and monolayers for Chirality Induced Spin Selectivity studies

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Supervisor : mathieu.gonidec@icmcb.cnrs.fr
Laboratory/campus : ICMCB
Starting date : 2023-09-15
Duration/month : 36
Preferred Majors for applicants : chemistry
The main goal of this project is to provide systematic comparative studies to rationalize the occurrence and magnitude of the CISS effect in molecular nanodevices. In order to reach those objectives, we will synthesize series of coordination compounds designed to present a range of stable chiroptical activities, that will be deposited as thin films or grafted as monolayers on metallic substrates while preserving both their structure and their enantiopurity. We will then thoroughly study the chiroptical properties of these thin films by a range of surface sensitive spectroscopies. Ultimately, the CISS effect induced by these chiral surfaces will be studied (partly in house, partly with the help of external collaborators) by integrating them into vertical charge transport devices to probe their spin dependent properties and analyze their CISS activity.

A correlated view of chiral-induced spin selectivity

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Prof. Jonas Fransson (University of Uppsala)

Thursday May 4, 10 am

ICMCB amphitheatre – Conference de Quantum Matter

Lien vers les infos : QMBx seminar Jonas Fransson 2023 – Quantum Matter Bordeaux (cnrs.fr)

Chiral-induced spin selectivity is an intriguing phenomenon that, to our knowledge, rests on a foundation of structural chirality, spin-orbit interactions, and strongly non-equilibrium conditions. The effect is a measure of the response to changes in the magnetic environment coupled to the active region, and the phenomenology refers back to the experimental observations of substantial changes in the charge current amplitude through chiral molecules upon changes in the external magnetic conditions. Chiral-induced spin selectivity has been shown to not be limited to multistranded helical structures, such as double-stranded DNA molecules and bacteriorhodopsin, but has also been observed in, for example, various types of peptides and polyalanines and, recently, also in helicene.

In order to depart from the generic single electron, or, non-interacting models that have, quite unsuccessfully, been used in attempts to describe the chiral-induced spin selectivity effect, it is proposes to include many-body effects, arising from, e.g., electron-electron or electron-vibron interactions. In cooperation with spin-orbit interactions, the many-body interactions generate exchange splitting between the spin channels which is viable for the chiral-induced spin selectivity phenomenon. By constructing models comprising either electron-electron or electron-vibron interactions, it can be demonstrated that the chiral-induced spin selectivity effect increases by several orders of magnitude compared to the results from any non-interacting description. The phenomenology of the chiral-induced spin selectivity effect indicates that charge transfer within the chiral molecule is accompanied by the emergence of intra-molecular spin-polarization.

  1. Fransson, Chirality induced spin-selectivity: The role of electron correlation: J Phys Chem Lett, 10, 7126 (2019).
  2. Fransson, Vibrational origin of exchange splitting and chiral-induced spin selectivity: Phys Rev B, 102, 235416 (2020).
  3. Fransson, Charge Redistribution and Spin Polarization Driven by Correlation Induced Electron Exchange in Chiral Molecules: Nano Lett, 21, 3026 (2021).
  4. Fransson, Charge and Spin Dynamics and Enantioselectivity in Chiral Molecules: J Phys Chem Lett, 13, 808 (2022).

Contact: Elizabeth Hillard <elizabeth.hillard@icmcb.cnrs.fr>

Chirogenesis in Solid State and Spontaneous Resolution

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2023-04-18
News: Chirality is a property of asymmetry resulting, for an object, from the non-superposition of its image in a mirror. The notion of symmetry breaking, inherent in the organization of matter, the formation of new structural edifices, and, more fundamentally, weak interactions, is omnipresent. From the physics of elementary particles to molecules of the living world and functional organisms, to climatic phenomena inducing vortices of forces, chirality often plays a crucial role. It is also a conception of geometry exploited in design fields and man-made constructions for its functionality and uniqueness. In this chapter, we will focus on the chirality observed in solid state matter, that is, chirality based on the solid state organization of atoms or molecules. While there can be an important overlap with inorganic chiral nanostructures or nanoparticles for which there are a number of reviews, the solid state matters treated in this chapter can include crystals as well as amorphous solids of both organic and inorganic molecules. As we will discuss below, the study of the chirality of solid materials has mainly been focused on asymmetric ordered and periodic structures. When atoms are considered as a repeating unit, chiral crystals of achiral molecules can be classified as 3D asymmetric periodic structures. Chiral crystal faces of centric crystals and chiral 2D patterns of achiral molecules can be classified as 2D asymmetric periodic structures. Individual helical polymeric chains, chiral carbon nanotubes, and nanoparticles can be classified as 1D asymmetric periodic structures. We should also mention that chiral quasicrystals do not have mirror symmetry or translational symmetry, but have rotational symmetry, showing beautiful chiral ordered structures. We will also describe how chirality can be enhanced by the 2D or 3D organization of building components of solid materials. We will close with a discussion of spectroscopic methods to characterize chiral objects and assemblies. Reiko Oda, Peizhao Liu, Elizabeth Hillard, Patrick Rosa, Sylvain Nlate, Yutaka Okazaki, Emilie Pouget, Yann Battie and Thierry Buffeteau
https://doi.org/10.1142/9789811259227_0006
 
Laboratory : CBMN, ISM, ICMCB, Université de Lorraine, Kyoto University

Disentangling Excimer Emission from Chiral Induction in Nanoscale Helical Silica Scaffolds Bearing Achiral Chromophores

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2023-04-18
News: The synthesis and characterization of diketopyrrolopyrroles and perylenemonoimidodiesters linked to a substituted benzoic acid in the ortho, meta, and para positions, are reported. Grafting of these dyes on the surface of chiral silica nanohelices is used to probe how the morphology of the platform at the mesoscopic level affects the induction of chiroptical properties onto achiral molecular chromophores. The grafted structures are weakly (diketopyrrolopyrroles) or strongly (perylenemonoimidodiesters) emissive, exhibiting both locally-excited state emission and a broad, structureless emission assigned to excimers. The dissymmetry factors obtained using circular dichroism highlight optimized supramolecular organization between the chromophores for enhancing the chiroptical properties of the system. In the ortho- derivatives, poor organization due to steric hindrance is reflected in a low density of chromophores on walls of the silica-nanostructures (<0.1 vs. >0.3 and up to 0.6 molecules/nm2 for the ortho and meta or para derivatives, respectively) and lower gabs values than in the other derivatives (gabs<2×10−5 vs 6×10−5 for the ortho and para derivatives, respectively). The para derivatives presented a better organization and increased values of gabs. All grafted chromophores evidence varying degrees of excimer emission which was not found to directly correlate to their grafting density.
Maria João Álvaro-Martins, José Garcés-Garcés, Antoine Scalabre, Peizhao Liu, Fernando Fernández-Lázaro, Ángela Sastre-Santos, Dario M. Bassani, Reiko Oda ChemPhysChem 2023, 24, e202200573
Description unavailable
Laboratory : CBMN, ISM, Universidad Miguel Hernández

Chiral shaped perovskite nanocrystals growth inside hollow silica nanoribbons

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2023-04-18
News: Helical perovskite nanocrystals (H-PNCs) were prepared using nanometric silica helical ribbons as platforms for the in-situ growth of the crystals using supersaturated recrystallization method. The H-PNCs grow inside nanometric helical porous silica, their handedness are determined by the handedness of porous silica templates. They show strong induced circular dichroism (CD) and induced circularly polarized luminescence (CPL) signals, with very high dissymetric g-factors. Right-handed and left-handed PNCs show respectively positive and negative CD and CPL signals, with dissymmetric g-factor (abs and lum) of ~ +/- 2*10-2. Simulations based on the boundary element method demonstrate that the circular dichroism comes from the chiral shape of H-PNCs.
Peizhao Liu, Yann Battie, Takaki Kimura, Yutaka Okazaki, Piyanan Pranee, Hao Wang, Emilie Pouget, Sylvain Nlate, Takashi Sagawa, and Reiko Oda
https://doi.org/10.1021/acs.nanolett.2c04823 https://pubs.acs.org/cms/10.1021/acs.nanolett.2c04823/asset/images/large/nl2c04823_0006.jpeg
Laboratory : CBMN

The 2nd day meeting of kinoa

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2023-03-15
News: The Research Federation "Chirality in Nouvelle Aquitaine" (Ki-NOA) is organizing its 2nd day of scientific meetings and exchanges on the 25th of April at the IECB (2 rue Robert Escarpit, Pessac). This event will take place from 8h50-17h15, and the program is available at https://kinoa.cnrs.fr/2nd-kinoa-meeting/ Registration mandatory before the 7th of April on the framaform sent by email.
Laboratory : all labs

The kinoa tour

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2023-02-22
News: Nous avons eu 10 propositions de visite de labo sur le campus bordelais pour échanger autour de la chiralité. Ces visites se sont tenues entre décembre 2022 et février 2023, avec des échanges scientifiques très constructifs. Merci à tous ceux qui ont donné de leur temps et curiosité :)
Laboratory : all labs