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Development and Physicochemical Studies of Supramolecular Systems for Recognition and Catalysis in Water

par Carpentier, Romain
Président du jury Bruylants, Gilles
Promoteur Bartik, Kristin
Co-Promoteur Jabin, Ivan
Publication Non publié, 2025-01-14

Thèse de doctorat

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Résumé :

Supramolecular chemistry in water presents unique challenges due to the high dielectric constant of the solvent and its hydrogen-bonding abilities, which often make interactions more complex. At the same time, the hydrophobic effect can facilitate the formation of supramolecular assemblies. Nature offers many examples of successful binding in aqueous media, most often achieved by ensuring that the binding sites are protected from the bulk environment. In this thesis, we focused on the development and physicochemical characterization of supramolecular macrocyclic receptors for the efficient binding of organic and metal cations in aqueous media. In this context we also explored a micellar incorporation strategy. This strategy was also used to transfer into water a reaction catalyzed by an organometallic complex.In the first part of this thesis, the binding properties of hexahomotrioxacalix[3]arene and calix[5]arene receptors, both bearing carboxyl groups, toward primary ammonium cations are investigated. The studies were conducted, primarily using 1H NMR spectroscopy, in organic solvents, and also in aqueous solutions following the deprotonation of their carboxyl groups. The two receptors exhibit, in organic solvents, a similar binding with the ammonium head (R-NH3+) buried in the receptors’ polyaromatic cavities. H-bonds and cation-π interactions contribute to the stabilization of the complexes. While the more flexible hexahomotrioxacalix[3]arene does not bind primary ammonium cations in water, the calix[5]arene does so very efficiently, including ones of biological relevance such as dopamine and lysine derivatives. When incorporated into DPC micelles, both receptors are however able to bind primary ammonium cations, with the calix[5]arene receptor still outperforming the hexahomotrioxacalix[3]arene. The hydrophobic effect plays a key role in the recognition process in water, including with the micellar incorporation strategy. These results have been reported in two publications: (i) “Specific Binding of Primary Ammoniums in Aqueous Media by Homooxacalixarenes Incorporated into Micelles”, R. Carpentier, S. Lambert, E. Brunetti, I. Jabin and K. Bartik. J. Org. Chem. 2022, 87, 19, 12749–12758. DOI: 10.1021/acs.joc.2c01318 and (ii) “Binding of Bioactive Ammonium Ions in Water with a Cavity-based Selectivity: Water Solubilization versus Micellar Incorporation”, R. Carpentier, C. Testa, A. Pappalardo, I. Jabin and K. Bartik J. Org. Chem. 2025, 90, 1, 682–690. DOI: 10.1021/acs.joc.4c02610.In the second part of this thesis, the focus lies on the development of macrocyclic ligands that exhibit high affinity and stability for metal cations in water. A calix[6]arene macrocycle was functionalized with three imidazole ligands on its small rim and three primary amine ligands on its large rim. This macrocycle was shown, through 1H NMR, to coordinate Zn2+ both in organic solvents and in water (at pH around 7), forming an ouroboros-like complex with one of the primary amine ligands occupying the coordination site located inside the polyaromatic cavity. The coordination of Zn2+ by the self-included amine ligand benefits from a favourable entropic effect, imparting greater thermodynamic stability to the resulting complex compared to a similar system that requires the binding of an exogenous amine. Additionally, intramolecular coordination provides supramolecular protection, enabling the iteroselective functionalization of two out of the three amine groups. This work has been reported in the manuscript “Development of a Water-Soluble Ouroboros-like Calix[6]arene-trisimidazole-based Ligand for Enhanced Binding of Zinc”, R. Carpentier, R. Lavendomme, B. Colasson, K. Bartik and I. Jabin. Dalton Trans. 2025, Advance Article. DOI: 10.1039/D4DT03158J.In the last part of this thesis, the focus lies on the physicochemical monitoring of the catalytic oxidative cleavage of vicinal diols in DPC micelles. A hydrophobic vanadium aminotriphenolate (V-TPA) complex was incorporated into micelles to overcome its solubility issues in water. The catalyst was characterized for its robustness through UV-Vis spectroscopy and substrate reactivity was monitored via HPLC and 1H NMR. Extensive DOSY NMR experiments were performed to understand the effect of local concentration and partitioning between micelles and bulk water on reactivity. Decreased reactivity was observed with the more hydrophilic substrates suggesting that the local concentration in the micellar core indeed plays a role, though further investigation is required to fully explain the observed reactivity. This work, alongside previously obtained results, is reported in the publication: “Vanadium Catalyst in Micelles: Toward a Greener Aerobic Oxidative Cleavage of Vicinal Diols in Water”, R. Carpentier, W. Denis, F. Sanz Azcona, D. Carraro, G. Grauwels, M. Orlandi, C. Zonta, G. Licini and K. Bartik. ACS Sustainable Chem. Eng. 2023, 11, 23, 8633–8641. DOI: 10.1021/acssuschemeng.3c01820.