1. Department of Chemical Sciences, Faculty of Science and Technology, Midlands State University, Private Bag 9055 Senga Road, Gweru, Zimbabwe
2. Chalmers University of Technology, Department of Chemistry and Chemical Engineering, SE-412 96, Göteborg, Sweden
3. Research Centre for Synthesis and Catalysis, Department of Chemical Sciences, Faculty of Science, University of Johannesburg, Auckland Park 2006, South Africa