Characterization of water-soluble cucurbit[7]uril in alcohol-water mixtures by high-pressure studies on the inclusion complexation with new methylene blue

Yoshimi Sueishi, Kazuyuki Asano, Masato Yamaoka, Shunzo Yamamoto

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The inclusion complexation of new methylene blue (NMB) with cucurbit[7]uril (CB[7]) was studied spectrophotometrically. It was found that CB[7] forms a 1:1 inclusion complex with NMB in alcohol-water mixtures and the structure of the inclusion complex has been established by 1H-NMR measurements. We have determined the association constants of CB[7] with NMB under high pressures. The association constants of CB[7] increase as the external pressure and solvent polarity increase. Pressure dependence experiments enabled us to calculate the reaction volume for inclusion of CB[7] to range from -15.8 to -10.8 cm3 mol-1. From analyses of the high-pressure results, the volume change caused by water and/or alcohol molecules repelled from the CB[7] cavity in the alcohol-water mixtures was evaluated, which is indicative of the presence of water and/or alcohol molecules in the CB[7] cavity in the alcohol-water mixtures. The volume of molecules repelled from the CB[7] cavity plays an important role in the volume change upon inclusion.

Original languageEnglish
Pages (from-to)153-161
Number of pages9
JournalZeitschrift fur Physikalische Chemie
Volume222
Issue number1
DOIs
Publication statusPublished - Feb 1 2008

Keywords

  • Cucurbit[7]uril
  • Inclusion complexation
  • Pressure effect
  • Solvent effect

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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