1. Department of Chemistry, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
2. School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209, South Africa
3. The Biomedical Biotechnology Research Unit (BioBRU), Department of Biochemistry and Microbiology, Rhodes University, Makhanda, 6139, South Africa
4. Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, PO WITS, 2050, Johannesburg, South Africa