Complexation of phenols with β- and γ-cyclodextrins: determination of the association constants by using the isomerization of spiropyran
作者:Yoshimi Sueishi、Tamami Miyakawa
DOI:10.1002/(sici)1099-1395(199907)12:7<541::aid-poc156>3.0.co;2-8
日期:1999.7
As a chemical indicator, the isomerization rate of so-called 6-SO3--spiropyran was used to estimate the equilibrium constants for the inclusion complex formation of beta- and gamma-cyclodextrins (beta and gamma-CDs). The association constants for inclusion complexes of beta- and gamma-CDs with various kinds of phenols were determined. It was found that beta- and gamma-CDs form 1:1 and 1:2 inclusion complexes with phenols, respectively. The substituent effects on the association constants for the 4-substituted phenols-beta-CD system can be interpreted in terms of the geometry of the inclusion complex. The magnitude of the association constants for the inclusion complex is related to molecular polarizability of the guest molecule. Based on the results, the dominant factor for CD complexation with phenols is discussed. Copyright (C) 1999 John Wiley & Sons, Ltd.