Measurement of radon and xenon binding to a cryptophane molecular host

Abstract

Xenon and radon have many similar properties, a difference being that all 35 isotopes of radon ( 195 Rn– 229 Rn) are radioactive. Radon is a pervasive indoor air pollutant believed to cause significant incidence of lung cancer in many geographic regions, yet radon affinity for a discrete molecular species has never been determined. By comparison, the chemistry of xenon has been widely studied and applied in science and technology. Here, both noble gases were found to bind with exceptional affinity to tris-(triazole ethylamine) cryptophane, a previously unsynthesized water-soluble organic host molecule. The cryptophane–xenon association constant, K a = 42,000 ± 2,000 M -1 at 293 K, was determined by isothermal titration calorimetry. This value represents the highest measured xenon affinity for a host molecule. The partitioning of radon between air and aqueous cryptophane solutions of varying concentration was determined radiometrically to give the cryptophane–radon association constant K a = 49,000 ± 12,000 M -1 at 293 K.

Sensitive on-chip methane detection with a cryptophane-A cladded Mach-Zehnder interferometer

“…Therefore, the cross-sensitivity of the sensor to other gases is scaled by the same factor, and can be eliminated by using a reference sensor cladded by a pure SAN film without the cryptophane component. Nevertheless, interference with the few species that also exhibit high affinity to cryptophane-A, such as xenon, radon and chloromethanes [8,25,26], is hard to avoid. This should be quantified and taken into consideration when targeting practical applications.…”

Design and Characterization of Two Bifunctional Cryptophane A‐Based Host Molecules for Xenon Magnetic Resonance Imaging Applications

“…The masses were confirmed with a MALDI-TOF AB SCIEX 5800 mass spectrometer (Applied Biosystems, Forster City, CA, USA). The calculated masses were m/z 1670 for C 92 H 94 N 4 O 26 (2) and m/z 1724 for C 96 H 104 N 6 O 24 (3), referred to as the lactone form, which is present to 70 % in aqueous environment. [45] Mass spectra relative to the two probes are presented in Figures S1 and S2 …”

Enantiopure cryptophane-129Xe nuclear magnetic resonance biosensors targeting carbonic anhydrase

“…Our laboratory (7, 13, 15, 19, 20) and others (6, 17, 18, 21-29) have explored biosensing and bioimaging applications with hyperpolarized 129 Xe magnetic resonance. A particular focus has been the development of hyperpolarized 129 Xe NMR biosensors for biomedically relevant protein targets, which has led to the attachment of protein-targeting moieties to high-xenon-affinity host molecules.…”