1. Research Centre for Advanced Mineral and Materials Processing, University of Western Australia, 35 Stirling Highway, W. A. 6009, Australia
2. Current address: Department of Chemistry University of Aberdeen, AB24 3UE, Scotland
3. Current address: Institut de Science et de l’Ingénierie Supra‐moléculaires, 8 allée Gaspard Monge, 67083 Strasbourg, France, Fax: +33‐3‐90245140
4. Chemistry M313, University of Western Australia, Nedlands, W. A. 6907, Australia
5. Institut de Ciència de Materials de Barcelona, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Cerdanyola del Valles (Barcelona), Spain