1. Department of ChemistryVidyasagar University Midnapore 721102 West Bengal India
2. Department of Human PhysiologyVidyasagar University Midnapore 721102 West Bengal India
3. Department of ChemistryDurham University Durham DH13LE U.K.
4. Department of Chemical and Pharmaceutical SciencesUniversity of Trieste 34127 Trieste Italy