1. Department of Chemistry, University College of Science, University of Calcutta, 92, A.P.C. Road, Kolkata-700 009, India
2. Bankura Sammilani College, Bankura-722102, West Bengal, India
3. Bolpur College, Bolpur-731204, West Bengal, India
4. School of Chemistry, The University of Reading, P.O. Box 224, Whiteknights, Reading RG6 6AD, U.K.
5. Department of Chemistry, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma de Mallorca, Spain