Spin exchange monitoring of the strong positive homotropic allosteric binding of a tetraradical by a synthetic receptor in water

David Bardelang, Gilles Casano, Florent Poulhès, Hakim Karoui, Jessica Filippini, A. Rockenbauer, Roselyne Rosas, Valérie Monnier, Didier Siri, Anouk Gaudel-Siri, Olivier Ouari, Paul Tordo

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

The flexible tetranitroxide 4T has been prepared and was shown to exhibit a nine line EPR spectrum in water, characteristic of significant through space spin exchange (Jij) between four electron spins interacting with four nitrogen nuclei (Jij 蠑 aN). Addition of CB[8] to 4T decreases dramatically all the Jij couplings, and the nine line spectrum is replaced by the characteristic three line spectrum of a mononitroxide. The supramolecular association between 4T and CB[8] involves a highly cooperative asymmetric complexation by two CB[8] (K1 = 4027 M-1; K2 = 202 800 M-1; α = 201) leading to a rigid complex with remote nitroxide moieties. The remarkable enhancement for the affinity of the second CB[8] corresponds to an allosteric interaction energy of ≈13 kJ mol-1, which is comparable to that of the binding of oxygen by hemoglobin. These results are confirmed by competition and reduction experiments, DFT and molecular dynamics calculations, mass spectrometry, and liquid state NMR of the corresponding reduced complex bearing hydroxylamine moieties. This study shows that suitably designed molecules can generate allosteric complexation with CB[8]. The molecule must (i) carry several recognizable groups for CB[8] and (ii) be folded so that the first binding event reorganizes the molecule (unfold) for a better subsequent recognition. The presence of accessible protonable amines and H-bond donors to fit with the second point are also further stabilizing groups of CB[8] complexation. In these conditions, the spin exchange coupling between four radicals has been efficiently and finely tuned and the resulting allosteric complexation induced a dramatic stabilization enhancement of the included paramagnetic moieties in highly reducing conditions through the formation of the supramolecular 4T@CB[8]2 complex.

Original languageEnglish
Pages (from-to)17570-17577
Number of pages8
JournalJournal of the American Chemical Society
Volume136
Issue number50
DOIs
Publication statusPublished - Dec 17 2014

Fingerprint

Artificial Receptors
Hydroxylamine
Molecular Dynamics Simulation
Complexation
Amines
Mass Spectrometry
Hemoglobins
Nitrogen
Electrons
Oxygen
Water
Monitoring
Molecules
Bearings (structural)
Exchange coupling
Hemoglobin
Discrete Fourier transforms
Mass spectrometry
Paramagnetic resonance
Molecular dynamics

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Spin exchange monitoring of the strong positive homotropic allosteric binding of a tetraradical by a synthetic receptor in water. / Bardelang, David; Casano, Gilles; Poulhès, Florent; Karoui, Hakim; Filippini, Jessica; Rockenbauer, A.; Rosas, Roselyne; Monnier, Valérie; Siri, Didier; Gaudel-Siri, Anouk; Ouari, Olivier; Tordo, Paul.

In: Journal of the American Chemical Society, Vol. 136, No. 50, 17.12.2014, p. 17570-17577.

Research output: Contribution to journalArticle

Bardelang, D, Casano, G, Poulhès, F, Karoui, H, Filippini, J, Rockenbauer, A, Rosas, R, Monnier, V, Siri, D, Gaudel-Siri, A, Ouari, O & Tordo, P 2014, 'Spin exchange monitoring of the strong positive homotropic allosteric binding of a tetraradical by a synthetic receptor in water', Journal of the American Chemical Society, vol. 136, no. 50, pp. 17570-17577. https://doi.org/10.1021/ja509586k
Bardelang, David ; Casano, Gilles ; Poulhès, Florent ; Karoui, Hakim ; Filippini, Jessica ; Rockenbauer, A. ; Rosas, Roselyne ; Monnier, Valérie ; Siri, Didier ; Gaudel-Siri, Anouk ; Ouari, Olivier ; Tordo, Paul. / Spin exchange monitoring of the strong positive homotropic allosteric binding of a tetraradical by a synthetic receptor in water. In: Journal of the American Chemical Society. 2014 ; Vol. 136, No. 50. pp. 17570-17577.
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