1. Inorganic Chemistry Research Laboratory, Department of Chemistry; Bharathiar University; Coimbatore 641 046 India
2. Department of Chemistry; Kongunadu Arts and Science College; Coimbatore 641049 India
3. Chemistry Research Centre, National Engineering College; K. R. Nagar, Kovilpatti 628503 Thoothukudi District Tamil Nadu India
4. Department of Chemistry; Texas A&M University; College Station TX 77843 USA