A hexa-peri-hexabenzocoronene cyclophane: an addition to the toolbox for molecular electronics.
Cyclophanes with the largest-to-date polycyclic aromatic hydrocarbon (hexa-peri-hexabenzocoronene, HBC) to be entrained in such a structural motif are reported. The two disks are covalently captured by intermolecular ring-closing olefin metathesis of dienes in good yield. DSC, optical microscopy, and WAXD show the new cyclophanes to self-assemble to thermotropic columnar liquid crystal mesophases similar to monomeric analogues. Solution spectroscopic studies reveal that the two disks within a single unit lie face-to-face, with a small average lateral offset. Self-assembly into two-dimensional crystals at a solid-liquid interface was visualized by STM, and the electrical properties of single molecules were assessed by scanning tunneling spectroscopy revealing a diode-like behavior which is similar to that previously reported for single HBC disks, laying the groundwork for future electrical interrogations of dynamic molecular complexes.
Watson
Mark D
MD
Max-Planck-Institute for Polymer Research, Postfach 3148, D-55021 Mainz, Germany.
Jäckel
Frank
F
Severin
Nikolai
N
Rabe
Jürgen P
JP
Müllen
Klaus
K