Poly(p-phenylene phosphaborene): A Modified Poly(p-phenylene vinylene) with π-Conjugated B═P Linkages

While the isoelectronic substitution of selected C═C by B═N units in π-conjugated organic compounds has evolved into a well-established concept to create novel hybrid materials with modified properties, the use of valence isoelectronic B═P units for such purposes has been hardly explored. Herein, we demonstrate substitutional doping of the famous optoelectronic organic polymer poly(p-phenylene vinylene) (PPV) with B═P linking groups for the first time. We report on the successful synthesis of a soluble polymer and a series of monodisperse oligomers of BP-PPV type. Our structural and photophysical investigations, supported by in-depth DFT calculations, evidence effective π-conjugation along their backbone, which is similary pronounced as in their previously reported BN congeners. In addition, the novel BCP compounds show distinct fluorescence emission in solution and emission enhancement upon aggregation (AIEE), occurring from a P-pyramidalized excited state.