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CB[7]-carborane_ChemRxiv_final.pdf (6.16 MB)
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Carborane Guests for Cucurbit[7]uril Facilitate Strong Binding and on Demand Removal

preprint
submitted on 21.08.2020 and posted on 24.08.2020 by Anna Kataki-Anastasakou, Jonathan C. Axtell, Selena Hernandez, RafalM. Dziedzic, Gary J. Balaich, Arnold L. Rheingold, Alexander Spokoyny, Ellen Sletten
High affinity guest have been reported for the macrocyclic host cucurbit[7]uril (CB[7]), enabling widespread applications, but preventing CB[7] materials from being returned to their guest-free state for reuse. Here we present polyhedral boron clusters (carboranes) as strongly-binding, yet easily removable, guests for CB[7]. Aided by a Pd-catalyzed coupling of an azide anion, we prepared boron-functionalized 9-amino and 9-ammonium modified ortho-carboranes that bind to CB[7] with a Ka=1010 M-1. Upon treatment with base, the ortho-carboranes readily undergo deboronation to yield anionic nido-carborane, a poor guest of CB[7], facilitating recovery of guest-free CB[7]. We showcase the utility of the modified ortho-carborane guest by recycling a CB[7]-functionalized resin. With this report, we introduce stimuli-responsive decomplexation as an additional consideration in the design of high affinity host-guest complexes.

Funding

NIGMS (1DP2GM13268)

Atomically Precise Nanoparticles with Multivalent Capabilities

National Institute of General Medical Sciences

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History

Email Address of Submitting Author

sletten@chem.ucla.edu

Institution

University of California-Los Angeles

Country

USA

ORCID For Submitting Author

0000-0002-0049-7278

Declaration of Conflict of Interest

The authors declare no conflict of interest.

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