Diffusion coefficient of cucurbit[n]urils (n = 6 or 7) at various concentrations, temperatures, and pH

Maxine P. Grant, Nial J. Wheate, Janice R. Aldrich-Wright

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

The diffusion coefficient of cucurbit[6]uril (CB[6]) and cucurbit[7]uril (CB[7]) was determined using pulsed gradient spin - echo nuclear magnetic resonance spectroscopy. Both CB[6] and CB[7] diffuse faster through H 20 than D20 with increasing temperature, consistent with the Stokes - Einstein equation where diffusion is proportional to temperature divided by viscosity. The activation energy (EA) was also determined and is larger for CB[n] in 90 % H2O/10 % D20 v/v than in D20. Both compounds aggregate with increasing concentration between (0.25 and 2)· 10-3 mol·L-1. The pH of the solution does not significantly affect the diffusion coefficient of CB[6] and CB[7], except at very low pH where protonation of the carbonyl groups induces aggregation, which slows their rate of diffusion.

Original languageEnglish
Pages (from-to)323-326
Number of pages4
JournalJournal of Chemical and Engineering Data
Volume54
Issue number2
DOIs
Publication statusPublished - 12 Feb 2009
Externally publishedYes

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