1. Contribution from the Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada, Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, Department of Chemistry and Center for Nanoscale Science and Engineering, University of California, Riverside, California 92521-0403, and Department of Chemistry, University of Toledo, Toledo, Ohio 43606-3390