98928-28-0Relevant articles and documents
Structural Effect of Guest Molecules upon the Stability of Inclusion Complexes of 5-(4-Hydroxyphenylazo)naphthalene-1-sulphonic Acid and Some Substituted Analogues with Cyclodextrins
Yoshida, Noboru,Fujimoto, Masatoshi
, p. 2424 - 2460 (2007/10/02)
In order to examine the structural effects of substituted azo compounds upon the stability of inclusion complexes with cyclodextrins, the inclusion equilibria of various types of o-hydroxyphenylazo derivatives of naphthalenesulphonic acid with α- and β-cyclodextrins in aqueous solution have been studied by u.v.-visible spectroscopy.The stability of the inclusion complexes depends primarily on the size and the shape of the alkyl substituent of the azo compounds as guest molecule and the diameter of the cavity of the cyclodextrin as host molecule.It is found that the complementary geometry between the guest and the host molecule is an important factor in determining the stability of the inclusion complexes.The molecular disposition of the guest azo compounds in the cavity of the cyclodextrin is examined by the use of 1H-n.m.r. spectroscopy.The rate constants for the inclusion reaction are determined in some α- and β-cyclodextrin systems by stopped-flow and the temperature-jump spectroscopy.The activation parameters for the inclusion reactions are evaluated from the temperature dependence of the rate constants.Compensation effects are observed between the enthalpy of activation and the entropy of activation for the inclusion reactions.