1. Department of Chemistry and Polymer Science, Stellenbosch University, Stellenbosch 7600, South Africa
2. Department of Biology, New Mexico State University, Las Cruces ,New Mexico 88003, United States
3. Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
4. Department of Chemistry, Emory University, 1515 Dickey Drive ,Atlanta ,Georgia 30322, United States
5. Department of Chemistry and Biochemistry, Purdue University, 2101 East Coliseum Blvd. ,Fort Wayne ,Indiana 46805, United States
6. Department of Chemistry and Biochemistry, Texas State University, San Marcos ,Texas 78666, United States