1. Department of Chemistry, Jadavpur University, Kolkata 700 032, India, Department of Chemistry, Visva-Bharati, Santiniketan 731 235, West Bengal, India, School of Chemistry, The University of Manchester, Brunswick Street, Manchester, M13 9PL, U.K., Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands, and Department of Chemistry, Universitat de les Illes Balears, Crta. de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain