1. a Department of Chemistry, Karnatak University, Dharwad 580 003, India
2. b Department of Chemistry, Karnatak University, Dharwad 580 003, India
3. c Department of Chemistry, Karnatak University, Dharwad 580 003, India
4. d Department of Chemistry, Karnatak University, Dharwad 580 003, India
5. e K.L.E.S's. Pharmacy College, J.N.M.C. Campus, Belgaum 590 010, India
6. f Polymer Division, National Chemical Laboratory, Pune 411 008, India