1. Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois61801, United States
2. Department of Process Research & Development, Merck & Co., Inc., MRL, Rahway, New Jersey07065, United States
3. Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey07065, United States