1. Department of Chemistry, University
College of Science, University of Calcutta, 92, APC Road, Kolkata-700 009, India
2. School of Chemistry, The University of Reading, P.O. Box 224, Whiteknights,
Reading RG6 6AD, U.K.
3. Departament
de Química, Universitat de les Illes Balears, Crta. de Valldemossa
km 7.5, 07122 Palma de Mallorca, Baleares, Spain