Synthesis of "molecular landers"

PAHs (molecular landers), 17.7 to 30 Angstrom long, devised for the study o f electron transport along a single molecular wire in an STM tip-molecule-e lectrode experiment, have been obtained by Diels-Alder cycloadditions of be nzadiyne to two cyclopentadienone precursors. They comprise a polyaromatic molecular board with a terminal fluoranthene group for chemisorption (and e lectrical contact) on a metallic diatomic terrace, and 4 to 8 3,5-di-tert-b utylphenyl spacers. As a result of steric crowding, these spacers are held in such a conformation that the phenyl rings are nearly perpendicular to th e main board plane and maintain the molecular wire 6.8 Angstrom above the m etallic surface.