1. Laboratory for Molecular Electronics of the Department of Chemistry, Department of Physics, and Department of Chemistry, Box 870336, The University of Alabama, Tuscaloosa, Alabama 35487-0336, Dipartimento di Scienze Farmaceutiche, Università di Trieste, Piazzale Europa 1, I-34127 Trieste, Italy, and Department of Chemistry and Biochemistry, University of California, Los Angeles, Box 951569, Los Angeles, California 90095-1569