Journal of Molecular Liquids 94 (2001) 193–201 0167-7322/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII S0167-7322(01) 00268-9 © 2001 Elsevier Science B.V. All rights reserved. Received 30 November 2000; accepted 15 May 2001