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, 01-224, Warsaw, Poland
3. Department of Chemistry, Pittsburg State University, Pittsburg, KS 66762, USA
4. School of Chemistry and Physics, University of KwaZuluNatal, Westville Campus, Chiltern Hills, Private Bag X54001, Durban, 4000, South Africa