1. Centre for Supramolecular and Macromolecular Chemistry, Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK, Fax: (internat.) + 44‐24‐7652‐4112
2. Discipline of Chemistry, School of Environmental and Life Sciences, The University of Newcastle, Callaghan, N.S.W. 2308, Australia