1. Department of Chemistry, University of Zululand, Private Bag X1001, KwaDlangezwa 3880, South Africa
2. Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw 01-224, Poland
3. Chemistry Department, University of Dar-es-salaam, P.O. Box 35091, Dar-es-salaam, Tanzania
4. Department of Chemistry, Pittsburg State University, Pittsburg, Kansas 66762, United States
5. School of Chemistry and Physics, University of KwaZuluNatal, Westville Campus, Chiltern Hills, Private Bag, X54001, Durban 4000, South Africa