Xenon binding by a tight yet adaptive chiral soft capsule

Abstract

Xenon binding has attracted interest due to the potential for xenon separation and emerging applications in magnetic resonance imaging. Compared to their covalent counterparts, assembled hosts that are able to effectively bind xenon are rare. Here, we report a tight yet soft chiral macrocycle dimeric capsule for efficient and adaptive xenon binding in both crystal form and solution. The chiral bisurea-bisthiourea macrocycle can be easily synthesized in multi-gram scale. Through assembly, the flexible macrocycles are locked in a bowl-shaped conformation and buckled to each other, wrapping up a tight, completely sealed yet adjustable cavity suitable for xenon, with a very high affinity for an assembled host. A slow-exchange process and drastic spectral changes are observed in both 1H and 129Xe NMR. With the easy synthesis, modification and reversible characteristics, we believe the robust yet adaptive assembly system may find applications in xenon sequestration and magnetic resonance imaging-based biosensing.

A tetraphenylethene-based hexacationic molecular cage with an open cavity

“…S18, ESI†). 20 Diffusion-ordered spectroscopy (DOSY) of 1 in D 2 O gave a diffusion coefficient [ D H = (1.617 ± 0.177) × 10 −10 m 2 s −1 ] with a hydrodynamic radius of ∼1.2 nm (the whole size is ∼2.4 nm; Fig. S19, ESI†), which is consistent with the size (1.9–2.8 nm) of the dimer (Fig.…”

Creating Optimal Pockets in a Clathrochelate-Based Metal–Organic Framework for Gas Adsorption and Separation: Experimental and Computational Studies

“…Based upon our previous high-throughput computational prediction that an optimal adsorbent for gas capture should have a pore diameter similar to the specific probe gas, we synthesized a highly porous and robust Cu-MOF of NU-200 based on a cyclohexane-functionalized iron­(II) clathrochelate building block. The unique ultramicroporous pocket-like cavities generated by the bulky cyclohexyl moieties were found to be optimal for Xe and SO 2 capture as well as Xe/Kr and SO 2 /CO 2 separation due to the pore confinement effect . Exceptionally high gravimetric and volumetric uptake of Xe and SO 2 and high IAST selectivity of Xe/Kr and SO 2 /CO 2 were achieved, making NU-200 a novel benchmark material for the purification and storage of Xe and trace SO 2 removal.…”

“…The unique ultramicroporous pocket-like cavities generated by the bulky cyclohexyl moieties were found to be optimal for Xe and SO 2 capture as well as Xe/Kr and SO 2 /CO 2 separation due to the pore confinement effect. 61 Exceptionally high gravimetric and volumetric uptake of Xe and SO 2 and high IAST selectivity of Xe/Kr and SO 2 /CO 2 were…”

Chiral Water-Soluble Molecular Capsules With Amphiphilic Interiors

“…A functional chiral cavity is indispensable for the effective separation of enantiomers or catalytic purposes. While a set of chiral capsules that are soluble in organic solvents is quite large ( Tokunaga and Rebek, 1998 ; Rivera et al, 1998 ; Rivera et al, 2001 ; Mateos-Timoneda et al, 2004 ; Sansone et al, 2004 ; Seeber et al, 2006 ; Katagiri et al, 2007 ; Castilla et al, 2014 ; Brown et al, 2015 ; Liu et al, 2015 ; Beaudoin et al, 2016 ; Chen et al, 2017 ; Gropp et al, 2018 ; Kohlhaas et al, 2019 ; Guo et al, 2020 ; Nie et al, 2020 ; Ning et al, 2020 ), there is only a limited number of examples of capsules that are water-soluble and chiral. The examples include cages based on covalent bonds and coordination bonds ( Bolliger et al, 2013 ; He et al, 2018 ) or cages obtained by internal functionalization with a chiral appendage ( Watfa et al, 2019 ).…”