1. Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
2. Dipartimento di Chimica “U. Schiff” and UdR INSTM, Università di Firenze, 50019 Sesto Fiorentino (FI), Italy
3. Department of Physics, Faculty of Science and Art, Balikesir University, 10145 Balikesir, Turkey
4. Dipartimento di Scienze Chimiche e Farmaceutiche, University of Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy