1. Department
of Chemistry, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg, Gauteng 2006, South Africa
2. Department
of Chemistry and Chemical Technology, National University of Lesotho, Roma 180, Lesotho
3. Ferrier
Research Institute, Victoria University of Wellington, 69 Gracefield
Rd., Lower Hutt 5040, New Zealand