1. Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, New Jersey 07974, Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California 90095, Department of Chemistry & Biochemistry, Ohio University, Athens, Ohio 45701-2979, Rutgers University, Department of Chemistry and Chemical Biology, Piscataway, New Jersey 08854, and Agere Systems, 600 Mountain Avenue, Murray Hill, New Jersey 07974