Axel RIQUET PhD defense
Möbius hexaphyrins: towards metallo-allosteric receptors with photoswitchable chirality
Mardi 9 décembre 2025, 13h30Passat
Organometallics: Materials & Catalysis (OMC) team
Abstract
Hexaphyrins are dynamic pyrrolic macrocycles which are able to adopt a Möbius ring conformation. This peculiar scaffold possesses an inherent topological helical chirality. This thesis focuses on the chirality induction and its modulation. To achieve this, several innovative strategies have been employed. Firstly, with the use of hexaphyrine bearing a chiral amine or carboxylic acid arm. The formation of zinc(II) complexes with exogeneous azo ligands allowed the obtention of impressive chirality inductions with d.e. up to >95%. The chiroptical activity of these systems has been modulated thanks to the trans->cis photoisomerization of the azo ligand giving rise to the formation of the very first Möbius ring with photoswitchable chiroptical activity. Also, new hexaphyrins with a second chiral recognition site composed of a squaramid unit, overhanging the ring, have been developped. Chirality inductions by remote control have been obtained thanks to different processes such as recognition or protonation. The modulation of the arrangement of the two recognition sites by conformational changes induced by complexation has also been observed. The promising results of these two strategies lay the foundation for the formation of allosteric receptors with photoswitchable chirality.
Jury
Céline Olivier, Directrice de recherche, Institut des Sciences Moléculaires de Bordeaux / Reviewer
Alexandre Martinez, Professeur des universités, Institut des Sciences Moléculaires de Marseille / Reviewer
Laure Guy, Ingénieure de recherche, École Normale Supérieure de Lyon / Examiner
Stéphane Le Gac, Directeur de recherche, Université de Rennes, Institut des Sciences Chimiques de Rennes / PhD Director
Contacts
Axel Riquet, axel.riquet@etudiant.univ-rennes.fr
Stéphane Le gac, stephane.legac@univ-rennes.fr
