1. Departamento de Química Orgánica; Universidade de Vigo; Lagoas-Marcosende s/n Vigo 36310 Spain
2. College of Chemistry and Chemical Engineering; Central South University; 932 Lushan S Rd, Yuelu, Changsha Hunan P. R. China
3. Instituto de Física; Universidad Nacional Autónoma de México; Apartado Postal 20-364 01000 México, D. F. México
4. Department of Life Sciences; New York Institute of Technology; 1855 Broadway New York NY 10023 USA