1. Department of Chemistry School of Natural and Mathematical Sciences Faculty of Science Engineering and Agriculture University of Venda Private Bag X5050 Thohoyandou 0950 South Africa
2. Department of Chemistry Faculty of Natural and Agricultural Sciences North-West University South Africa.
3. Department of Chemistry Atma Ram Santa Dharma College University of Delhi New Delhi India
4. Department of Chemistry College of Science King Saud University P.O. Box 2455 Riyadh Kingdom of Saudi Arabia 11451
5. Department of Chemistry Southern University and A&M College Baton Rouge Louisiana 70813 USA