1. Department of Chemistry, Vanderbilt University, Nashville, TN 37240, USA
2. Department of Biological, Physical and Human Sciences, Freed Hardeman University, Henderson, TN 38340, USA
3. Department of Chemistry, Tennessee Tech University, Cookeville, TN 38505, USA
4. Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37240, USA