A Water-Soluble Xe@cryptophane-111 Complex Exhibits Very High Thermodynamic Stability and a Peculiar 129Xe NMR Chemical Shift

Abstract
International audienceThe known xenon-binding (±)-cryptophane-111 (1) has been functionalized with six [(η5-C5Me5)RuII]+ ([Cp*Ru]+) moieties to give, in 89% yield, the first water-soluble cryptophane-111 derivative, namely [(Cp*Ru)61]Cl6 ([2]Cl6). [2]Cl6 exhibits a very high affinity for xenon in water, with a binding constant of 2.9(2) × 104 M−1 as measured by hyperpolarized 129Xe NMR spectroscopy. The 129Xe NMR chemical shift of the aqueous Xe@[2]6+ species (308 ppm) resonates over 275 ppm downfield of the parent Xe@1 species in (CDCl2)2 and greatly broadens the practical 129Xe NMR chemical shift range made available by xenon-binding molecular hosts. Single crystal structures of [2][CF3SO3]6·xsolvent and 0.75H2O@1·2CHCl3 reveal the ability of the cryptophane-111 core to adapt its conformation to guests

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