The ability of several organic compounds [alcohols 1 and 2, the corresponding phosphate esters 3 and 4 and their sodium salts 5 and 6 as well as some commercial surfactants such as C14DMAO (7, zwitterionic), SDS (8, anionic) and CTABr (9, cationic)] to produce supramolecular complexes with β‐cyclodextrin has been investigated by four different techniques (ESI‐MS, surface tension measurements, UV/Vis and 1H NMR spectroscopy). The data collected have allowed information about the formation of complexes and the location of the guest in the host to be gained. Comparison of the results obtained for phosphate esters and their salts, for both saturated and unsaturated derivatives, has made it possible to evaluate the factors that affect the stability of the supramolecular complexes under the different experimental conditions used. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The effect of beta-cyclodextrin (beta-CD) on the mononuclear heterocyclic rearrangement of the (Z)-phenylhydrazone of 3-benzoyl-5-phenyl-1,2,4-oxadiazole (1) in aqueous borate buffer at pH = 9.6 has been analyzed at temperatures ranging from 293.15 to 313.15 K. The trend of the absorption spectra of 1 as a function of time has been accounted for with the formation of two different 1:1 complexes between beta-CD and 1, the first, "unreactive" complex being formed faster than the "reactive" one. The occurrence of negative activation enthalpy values for the studied interconversion evidences the kinetic relevance of inclusion processes. Computational models elaborated using the MM2 molecular mechanics force field give an idea of the relative importance of the different complexes, additionally helping us to formulate a suitable reaction scheme.