1. L. A. Bumm, J. J. Arnold, M. T. Cygan, T. D. Dunbar, P. S. Weiss, Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA.
2. T. P. Burgin, L. Jones II, J. M. Tour, Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
3. D. L. Allara, Departments of Chemistry and Materials Science, Pennsylvania State University, University Park, PA 16802, USA.