1. Department
of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, United States
2. Instituto
de Química de São Carlos, Universidade de São Paulo, CP 780, São Carlos, São Paulo CEP 13560-970, Brazil
3. Department
of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
4. University of Colorado Cancer Center, Aurora, Colorado 80045, United States