Abstract by JIEWEN SHEN
Chemistry and Biochemistry
Structures and Characteristics of Cucurbituril and Substituted Cucurbituril Complexes Containing Halide Anions
Cucurbiturils are noteworthy for their high binding affinities for certain species, which make them useful for molecular recognition. While selective cation binding by host molecules is well known, anion selectivity is relatively rare. Here, we report the result that both chlorine and bromine anions can be trapped inside CB5 by alkali metal cations, and these complexes are investigated using both computational simulations and gas-phase electrospray mass spectrometry collision-induced dissociation (CID) techniques.
CB5 complexes of the general formula CB5(M2X)+, where M = Na+ or K+ and X = Cl-, Br-, or I‑. High relative abundances are observed for complexes containing either the Cl- or Br‑ ion, but no I- ion. Results from CID experiments indicate that all of the CB5(M2X)+ complexes dissociate by loss of neutral MX. Complexes containing both a K+ and a Na+ ion cap have two distinct dissociation pathways: loss of neutral KX or NaX. Interestingly, collisional activation of the bromide-containing complexes capped by a Na+ ion results in two distinct dissociation energies, suggesting that this complex exists in at least two distinct isomeric sates.