1. Department of Chemistry; Inorganic Chemistry Section, Jadavpur University; Kolkata 700 032 India.
2. Division of Microbiology; Department of Pharmaceutical Technology, Jadavpur University; Kolkata 700 032 India.
3. Institute of Molecular Science; Key Laboratory of Chemical Biology and Molecular Engineering of the Education Ministry, Shanxi University; 92 Wucheng Road Taiyuan, Shanxi 030006 People's Republic of China.