A One-Step Synthesis of a Poly(iptycene) through an Unusual Diels-Alder Cyclization/Dechlorination of Tetrachloropentacene

There is a continuous interest in polycyclic aromatic compounds mostly as materials for optoelectronic applications (LED, FET, photovoltaics, etc.), but also as building blocks in construction of supermolecular systems such as fullerenes, nanotubes, and trip-tycenes (tribenzo[2.2.2]bicyclohexadiene, Tr).1 In the latter, the intramolecular cavities allows for strong, noncovalent binding to suitably sized species, which can be used in sensing of, e.g., nitric oxide.2 Even more specific cavities have been synthesized with dendritic molecules, “superiptycenes”, containing up to nine Tr units connected by rigid benzene rings.3 Recently, the special geometry of Tr was recognized as a way to control the supramolecular architecture in liquid crystals and polymer matrices.4 Several polymers incorporating iptycene moieties, connected by (phenylene ethynylene) or (phenylene vinylene) units, have been synthesized and shown to possess improved order and electronic properties.