1. Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, Division of Chemistry and Molecular Engineering, Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-747, Korea, Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, Pennsylvania 19104, and Department of Chemistry, French Family Science Center, 124 Science Drive, Duke University, Durham, North...