Piperidine aminoxyl radicals as EPR probes for exploring the cavity of a water-soluble cryptophane
Abstract
Piperidine aminoxyl radicals are reversibly bound in the cavity of a water-soluble cryptophane with an affinity of the order of 103 dm3 mol–1; the complexation equilibrium is slow on the EPR timescale and the magnitude of the nitrogen hyperfine splittings of the bound substrates indicates that the cavity of this cryptophane has a polarity comparable to that of halogenated solvents.