1. Contribution from the Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146, IFSC, Universidade de Sao Paulo, C.P. 369, Sao Carlos, Sao Paulo, Brazil, CMDMC, Department of Chemistry, UFSC, 13560-970 Sao Carlos, Sao Paulo, Brazil, and Biotechnology Team, Research and Technology Directorate, U.S. Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland 21010-5423