THE ROYAL SOCIETY OF CHEMISTRY Journal of Materials Chemistry Scientific Advisory Editor Editorial Manager Dr. Martin R. Bryce Dr. Robert J. Parker Department of Chemistry The Royal Society of Chemistry University of Durham Thomas Graham House South Road Science Park Durham DH1 3LE, UK Cambridge CB4 4WF, UK Staff Editor: Mrs. Janet M. Leader Senior Assistant Editor: Mrs. S. Shah Assistant Editor: Mrs. S. Youens Editorial Secretary: Miss D. J. Halls Graphics Designer: Ms. C. Taylor-Reid Materials Chemistry Editorial Board Allan E. Underhill (Bangor) (Chairman) Peter G. Bruce (St. Andrews) John W. Goodby (Hull) Martin R. Bryce (Durham) Klaus Praefcke (Berlin) David A. Dunmur (Sheffield) Brian J. Tighe (Aston) Jean Etourneau (Bordeaux) Anthony R.West (Aberdeen) Wendy R. Flavell (UMIST) John D. Wright (Canterbury) Robert J. Parker (Secretary) International Advisory Editorial Board K. Bechgaard (Risa, Denmark) J. S. Miller (Salt Lake City, UT, USA) J. Y. Becker (Beer-Sheva, Israel) K. Mullen (Mainz, Germany) J. D. Birchall (Runcorn, UK) M. Nygren (Stockholm, Sweden) A. J. Bruce (Murray Hill, USA) Y. W. Park (Seoul, Korea) A. K. Cheetham (Santa Barbara, USA) V. Percec (Cleveland, OH, USA) E. Chiellini (Pisa, Italy) N. Plate (Moscow, Russia) D. Coates (Poole, UK) M. Prato (Trieste, Italy) P. Day (London, UK) C. N. R. Rao (Bangalore, India) B. Dunn (Los Angeles, USA) J. Rouxel (Nantes, France) W. J. Feast (Durham, UK) R. Roy (University Park, PA, USA) A. Fukuda (Tokyo, Japan) J. L.Serrano (Zaragoza, Spain) D. Gatteschi (Florence, Italy) J. N. Sherwood (Glasgow, UK) J. B. Goodenough (Austin, TX, USA) J. Simon (Paris, France) A. C. Griffin (Hattiesburg, USA) J. F. Stoddart (Birmingham, UK) S-i. Hirano (Nagoya, Japan) S. Takahashi (Osaka, Japan) P. Hodge (Manchester, UK) J. 0.Thomas (Uppsala, Sweden) H. lnokuchi (Okazaki, Japan) G. J. T. Tiddy (Bebington and Salford, UK) W. Jeitschko (Munster, Germany) Yu. D. Tretyakov (Moscow, Russia) 0. Kahn (Orsay, France] J. W. White (Canberra, Austra4ia) R. McCullough (Pittsburgh, USA) R. Xu (Changchun, China) Y. Yamashita (Okazaki, Japan) Journal of Materials Chemistry (ISSN 0959-9428) is published monthly by The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB44WF, UK.All orders accompanied with payment should be sent directly to The Royal Society of Chemistry, Turpin Distribution Services Ltd., Blackhorse Road, Letchworth, Herts SG6 lHN, UK. NB Turpin Distribution Services Ltd., distributors, is wholly owned by The Royal Society of Chemistry. 1994 Annual subscription rate EC (inc. UK) f381.00, USA $718.00, Canada f431.00 (plus GST), Rest of World f410.00. Customers should make payments by cheque in sterling payable on a UK clearing bank or in US dollars payable on a US clearing bank. Air freight and mailing in the USA by Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003. USA POSTMASTER: send address changes to Journal of Materials Chemistry, Publications Expediting Inc., 200 Meacham Avenue, Elmont, NY 11003.Second Class postage paid at Jamaica, NY 11431. All other dispatches outside the UK by Bulk Airmail within Europe, Accelerated Surface Post outside Europe. PRINTED IN THE UK. 0 The Royal Society of Chemistry, 1994. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronic, mechanical, photographic, recording, or otherwise, without the prior permission of the publishers. Dr. R. J. Parker, Editorial Manager Tel.: Cambridge (01223) 420066 E-Mail (INTERNET): RSCl@RSC.ORG Fax: (01223) 426017, 420247 or 423623 Advertisement sales: Tel. +44 (0171-287 3091; Fax +44 (0171-494 1134 INFORMATION FOR AUTHORS The Royal Society of Chemistry welcomes submission of manuscripts intended for publication in two forms, Articles and Materials Chemistry Communications.These should describe original work of high quality dealing with the synthesis, structures, properties and applications of materials, particularly those associated with advanced technology. Articles Full papers contain original scientific work that has not been published previously. However, work that has appeared in print in a short form such as a Materials Chemistry Communication is normally acceptable. Four copies of Articles includ- ing a top copy with figures etc. should be sent to The Editor, Journal of Materials chemistry, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, UK.Materials Chemistry Communications Materials Chemistry Communications con- tain novel scientific work in short form and of such importance that rapid publication is warranted. The total length is normally restricted to two pages of the double-column A4 format. For a Communication consisting entirely of text and ten refer-ences, with no figures, equations or tables, this corresponds to approximately 1600 words plus an abstract of up to 40 words. However, special consideration will be given to communications with a large amount of essential diagramatic information. Submission of a Materials Chemistry Communication can be made either to The Editor, Journal of Materials Chemistry, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, UK, or via a member of the International Advisory Editorial Board. In the latter case, the top copy of the manuscript including any figures etc., together with the name of the person to whom the Communication is being submit- ted, should be sent simultaneously to the Editor at the Cambridge address.Authors may wish to contact the Board member to ensure that he is available to arrange review of the manuscript within reasonable time. In order to avoid delay in publication, proofs of Communications are not sent to authors unless this is specifically requested. Full details of the form of manuscripts for Articles and Materials Chemistry Communications, conditions for accept-ance etc. are given in issue number one of Journal of Materials Chemistry published in January of each year, or may be ob- tained from the Staff Editor. There is no page charge for papers pub- lished in Journal of Materials Chemistry. Fifty reprints are supplied free of charge. Any author who is publishing in Journal of Materials Chemistry is entitled to a free copy of the issue in which the paper appears.