Synthesis and application of cryptophanol hosts:~(129)Xe NMR spectroscopy of a deuterium-labeled (Xe)_2@bis-cryptophane complex

摘要

The new bis-cryptophanes 7-9 were prepared from cryptophanols 1-3 and illustrate the synthetic possibilities offered by the latter for the design of new host systems featuring the preparation of large supramolecular receptors and new polycryptophane bio-sensors for NMR imaging.Hosts 1-3 were obtained from the monoprotected cryptophanes 4-6 following a multi-step strategy.The complexation of xenon by the dissymmetrical bis-cryptophane 8 was studied by ~(129)Xe NMR spectroscopy.At low temperature,a strong discrimination (DELTAdelta=1.16 ppm) of the encapsulated xenon guests inside the two cryptophane cavities was observed.The kinetic parameters for the complexation process were determined from 1D-EXSY ~(129)Xe NMR experiments.The activation energy E_a=39.0+-3 kJ mol~(-1) and associated parameters DELTAH~(not=)=37.0+-3 kJ mol~(-1) and DELTAS~(not=)=-46.0+-10 kJ mol~(-1) K~(-1) are in agreement with the values determined for cryptophane-A and [D_(27)]-cryptophane-A.