1. Department
of Chemistry, P.O. Box 9000, University of Puerto Rico—Mayagüez Campus, Mayaguez 00680-9000, Puerto Rico
2. Department
of Chemistry, P.O. Box 372230, University of Puerto Rico—Cayey Campus, Cayey 00737-2230, Puerto Rico
3. Department
of Chemistry, P.O. Box 23346, University of Puerto Rico—Río Piedras Campus, San Juan 00931-3346, Puerto Rico