1. 1P. A. College of Engineering, Department of Chemistry, Nadupadavu, Mangalore 574 199, India
2. 2Mangalore University, Department of Studies in Chemistry, Mangalagangotri 574 199, India
3. 3Nelson Mandela Metropolitan University, Summerstrand Campus, Department of Chemistry, University Way, Summerstrand, PO Box 77000, Port Elizabeth 6031, South Africa