1. Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata - 700 009, India
2. Department of Chemistry, Panchakot Mahavidyalya, Sarbari, Neturia, Purulia, 723121, India
3. Analytical Science Discipline, Central Salt and Marine Chemicals Research Institute, G.B. Marg, Bhavnagar 364 002, India
4. Dipartimento di Scienze Chimiche e Farmaceutiche, University of Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy