1. Contribution from the Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada, Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1, Canada, Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, and Department of Chemistry and Center for Nanoscale Science and Engineering, University of California, Riverside, California 92521-0403