Key-building block of all poly(para-phenylene)s is the simplest aromatic unit: benzene. The repetitive connection of benzene units can lead to various π-conjugated architectures of different size, shape and dimension. While linear poly(para-phenylene)s have a one-dimensional structure, fusion of benzene-hexagons into honeycomb-type carbon lattices leads to graphene and its smaller congeners, i.e. polycyclic aromatic hydrocarbons (PAHs). Different from those two dimensional sp2-carbon allotropes, three dimensional sp2-carbon-structures made of phenylene-crowded repeating units are of considerable interest for chemists and materials scientists. In 1946 the hypothetically “cubic graphite” received a lot of attention. In this infinite structure each phenylene unit is equal and therefore part of three intersecting poly(para-phenylene) chains. The hitherto elusive “cubic graphite” is expected to have a very high mechanical and thermal stability and ion uptake properties. Herein, we enter the 3D-world of benzene-crowded architectures with the challenging multistep synthesis of catenane-like paddle wheel (1). The beauty of this essentially strain free polyphenylene is that two orthogonal cyclo-m-hexaphenylene rings (highlighted in grey and orange) are rigidly interlocked by covalent phenyl-phenyl bonds ending up in a paddle wheel-shaped molecule.

Synthesis of catenane-like paddle wheel structures

253rd National Meeting (2017)

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