Host-guest geometry in paramagnetic cavitands elucidated by F electron-nuclear double resonance.

Elucidating structural information of supramolecular host-guest systems is pivotal for understanding molecular recognition and designing functional materials. This study explores the binding modes of fluorinated benzylamine guests in cyclodextrin-based paramagnetic cavitands, employing Gd(III)-capped cyclodextrins (Gd-α-CD and Gd-β-CD, comprising six and seven glucopyranoside units, respectively) and high-field F electron-nuclear double resonance (ENDOR). The F ENDOR spectra revealed distinct behaviors based on the fluorine position and cyclodextrin cavity size.

A Reactive and Specific Sensor for Activity-Based F-MRI Sensing of Zn.

The rapid fluctuations of metal ion levels in biological systems are faster than the time needed to map fluorinated sensors designed for the F-MRI of cations. An attractive modular solution might come from the activity-based sensing approach. Here, we propose a highly reactive but still ultimately specific synthetic fluorinated sensor for F-MRI mapping of labile Zn.

NMR exchange dynamics studies of metal-capped cyclodextrins reveal multiple populations of host-guest complexes in solution.

Metal-capped molecular hosts are unique in supramolecular chemistry, benefitting from the inner cavity's hydrophobic nature and the metal center's electrochemical properties. It is shown here that the paramagnetic properties of the metals in lanthanide-capped cyclodextrins (Ln-α-CDs and Ln-β-CDs) are a convenient NMR indicator for different populations of host-guest complexes in a given solution. The paramagnetic guest exchange saturation transfer (paraGEST) method was used to study the exchange dynamics in systems composed of Ln-α-CDs or Ln-β-CDs with fluorinated guests, revealing multiple co-existing populations of host-guest complexes exclusively in solutions containing Ln-β-CDs.

Versatile non-luminescent color palette based on guest exchange dynamics in paramagnetic cavitands.

Multicolor luminescent portrayal of complexed arrays is indispensable for many aspects of science and technology. Nevertheless, challenges such as inaccessible readouts from opaque objects, a limited visible-light spectrum and restricted spectral resolution call for alternative approaches for multicolor representation. Here, we present a strategy for spatial COlor Display by Exploiting Host-guest Dynamics (CODE-HD), comprising a paramagnetic cavitand library and various guests.