Solvent-controlled formation of alkali and alkali-earth-secured cucurbituril/guest trimers.

ABSTRACT: Cucurbit[7]uril (CB[7]) encapsulates adamantyl and trimethylsilyl substituents of positively charged guests in dimethyl sulfoxide (DMSO). Unlike in water or deuterium oxide, addition of a selection of alkali and alkali-earth cations with van der Waals radii between 1.0 and 1.4 Å (Na⁺, K⁺, Ca²⁺, Sr²⁺, Ba²⁺ and Eu³⁺) to the CB[7]/guest complexes triggers their cation-mediated trimerization, a process that is very slow on the nuclear magnetic resonance (NMR) time scale. Smaller (Li⁺, Mg²⁺) or larger cations (Rb⁺, Cs⁺ or NH₄⁺) are inert. The trimers display extensive CH-O interactions between the equatorial and pseudo-equatorial hydrogens of CB[7] and the carbonyl

SUBMITTER: Loncaric D 

PROVIDER: S-EPMC10498720 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature