Polynorbornene-Based Double-Stranded Ladderphanes with Cubane, Cuneane, Tricyclooctadiene, and Cyclooctatetraene Linkers

Double-stranded ladderphanes 2, 3, and 5 having cubane, cuneane, and cyclooctatetraene linkers are synthesized by ring-opening metathesis polymerization (ROMP) of the corresponding bisnorbornene monomers 10, 11, and 13, respectively. Attempts to polymerize the corresponding tricyclooctadiene-linked bisnorbornene 12 are not successful, starting monomer being recovered. Polymer with this tricyclic diene linker 4 is obtained from the rhodium-catalyzed isomerization of 2. The scanning tunneling microscopic (STM) image of 2 shows an ordered pattern on the graphite surface by self-assembly.