Impact de la configuration relative Syn / Anti du Cryptophane-222 sur l'affinité du Césium et du Thallium

International audienceWe report in this article the synthesis, the X-ray crystal structure of compound syn-2 and its binding properties with cesium and thallium in aqueous solution under basic conditions. Compound syn-2 is the diastereomeric compound of anti-1 that shows very high affinity for cesium and thallium in aqueous solution in the same conditions. Despite the close structural similarities that exists between the syn-2 and anti-1 compounds, they show large discrepancy in their ability to bind cesium and thallium cations in the same conditions. Indeed, the syn-2 derivative has a lower affinity for these two cationic species and the binding constants are measured to be several orders of magnitude lower than those found for its congener. The large differences in affinity observed with these two compounds can be explained by the relative position of the six hydroxyl groups to each other.Nous rapportons dans cet article la synthèse, la structure cristalline aux rayons X du composé syn-2 et ses propriétés de complexation avec le césium et le thallium en solution aqueuse dans des conditions basiques. Le composé syn-2 est le composé diastéréomérique du composé anti-1 qui présente une très grande affinité pour le césium et le thallium en solution aqueuse dans les mêmes conditions. Malgré les similitudes structurelles qui existent entre les composés syn-2 et anti-1, ces deux composés présentent de grandes différences dans leur capacité à complexer les cations de césium et de thallium dans les mêmes conditions. En effet, le dérivé syn-2 a une affinité plus faible pour ces deux cations et les constantes de complexation mesurées sontinférieures de plusieurs ordres de grandeur à celles trouvées pour son congénère. Les grandes différences d'affinité observées avec ces deux composés peuvent s'expliquer par la position relative des six groupes hydroxyles l'un par rapport à l'autre

129^{129}Xe NMR-based biosensing on a benchtop spectrometer

International audienceThe nuclear polarization of noble gases, such as xenon, can be enhanced by several orders of magnitude through optical pumping, giving rise to very sensitive NMR probes. Moreover, due to its large and deformable electron cloud, xenon exhibits wide chemical shift range (more than 320 ppm for the monoatomic species) and is soluble in most biological fluids. It can be reversibly encapsulated in molecular host systems such as cage-molecules, decorated with ligands in order to target given receptors, and gives rise to sensitive detection of biological events. This two-step procedure, where the xenon host is first introduced and hyperpolarized xenon then delivered, benefits from the difference in resonance frequency between bound xenon and free xenon (in the gas phase or in the dissolved phase) [1]. This work has recently been published in Magnetic Resonance [2]

Xe Ultrafast Z-spectroscopy enables micromolar detection of biosensors on a 1T benchtop spectrometer

International audienceThe availability of a benchtop NMR spectrometer, of low cost and easily transportable, can allow detection of low quantities of biosensors, provided that hyperpolarized species are used. Here we show that the micromolar threshold can easily be reached, by employing laser-polarized xenon and cage-molecules reversibly hosting it. Indirect detection of caged xenon is made via chemical exchange, using ultrafast Z-spectroscopy based on spatio-temporal encoding. On this non-dedicated low-field spectrometer, several ideas are proposed to improve the signal

A 3D-printed device for in situ monitoring of an organic redox-flow battery via NMR/MRI

International audienceA mini organic redox-flow battery pluggable on the basis of a high-resolution NMR probehead has been conceived and built mainly by 3D printing. This device allows the realization of all modern spectroscopy experiments as well as imaging experiments. It has been tested for the real-time monitoring of redox cycling of 9,10-Anthraquinone-2,7-disulfonic acid disodium salt (2,7-AQDS) in acidic conditions, which has revealed the preponderant role of dimerization in the processes of oxidation and reduction. Determination of the thermodynamic properties of homo-and heterodimer formation through quantum chemical, multilevel modeling workflows confirm our hypotheses about the molecular processes occurring during charge and discharge

Integrated stopped-flow device for the study of porous materials using hyperpolarized 129^{129}Xe NMR

International audienceA simple, low-cost, and efficient device is proposed for the study of porous materials via NMR using small gas probes. Mainly built through additive manufacturing and being equipped with a radiofrequency solenoid microcoil, it only requires tiny quantities of sample and/or gas and is particularly suited for hyperpolarized xenon. The performances of this device have been accessed on a commercial sample of MCM-41 exhibiting multiporosity. Both the delivery mode of hyperpolarized xenon and the stopped-flow system are judged as efficient according to 2D $^{129}$Xe self-diffusion and EXSY experiments