1. a Department of Mathematics , Dr. B. N. Dutta Smriti Mahavidyalaya , Hatgobindapur, Burdwan , 713407 , India
2. b Department of Chemistry , University College of Science, Calcutta University , Kolkata , 700 009 , India
3. c Department of Chemistry , The University of Burdwan , Burdwan , 713104 , India