Poly(BODIPY)s: A New Class of Tunable Polymeric Dyes

We present a new class of polymeric dyes bearing the difluoroboraindacene (BODIPY) chromophore within the main chain. Starting from a diiodinated BODIPY monomer, homo- and copolymers with a fully conjugated backbone were efficiently synthesized by transition-metal-catalyzed polycondensation reactions. The photophysical properties of the resulting polymeric materials were investigated in bulk and at the single molecule level. It was found that the BODIPY homopolymer resembles the absorption and emission properties of the individual BODIPY chromophore. In contrast, the copolymer products of 1,4-diethynylbenzene and benzene exhibit absorption and emission spectra that are shifted hypsochromically and bathochromically in regard to the homopolymer, respectively, allowing for easy color tuning by the choice of comonomers. The fluorescence quantum yield of the BODIPY homopolymer is remarkably high (57%). The exceptional brightness of the materials was confirmed in the single molecule investigations; the BODIPY homopolymer emitted several times more photons than the well-established fluorescent probe Rhodamine 6G with a quantum yield close to unity.