1. Department
of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
2. Department
of Chemistry and Biochemistry, Magnetic Resonance Research Center, Arizona State University, Tempe, Arizona 85287-1604, United States
3. Department
of Chemistry and Biochemistry, San Diego State University, 5500
Campanile Drive, San Diego, California 92182-1030, United States