A Shape-Persistent Polyphenylene Spoked Wheel.

A shape-persistent polyphenylene with a "spoked wheel" structure was synthesized as a subunit of an unprecedented two-dimensional polyphenylene that we name graphenylene. The synthesis was carried out through a sixfold intramolecular Yamamoto coupling of a dodecabromo-substituted dendritic polyphenylene precursor, which had a central hexaphenylbenzene unit as a template. Characterizations by NMR spectroscopy and matrix-assisted laser ionization time-of-flight mass spectrometry provided an unambiguous structural proof for the wheel-like molecule with a molar mass of 3815.4 g/mol. Remarkably, scanning tunneling microscopy visualization clearly revealed the defined spoked wheel structure of the molecule with six internal pores.