Synthesis and Characterization of Alternating Polymers Incorporating Boron-Chelated Heterochrysene Units

The novel boron-chelated π-conjugated polymers named as BF2-poly and BPh2-poly were synthesized by a feasible condensation-chelation strategy. First, conjugated polymers bearing Boc group were prepared by using palladium-catalyzed Suzuki–Miyaura coupling reaction. Then, conjugated polymers (poly-1) were obtained with high efficiency by removing the Boc group from Boc-poly. Last, boron trifluoride diethyl etherate (BF3·Et2O) or triphenylboron (BPh3) chelated with poly-1 forming the target polymers. Furthermore, the boron-chelated polymers were characterized by UV−Vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry and thermogravimetric analysis. As expected, fluorescences peaks at 520 nm and 592 nm were observed in diluted CH2Cl2. In addition, BF2-poly and BPh2-poly showed strong fluorescence at 545 nm and 601 nm in homogeneous solid state. The results coming from thermogravimetric analysis and cyclic voltammetry also revealed that the conjugated polymers have favorable electrochemical and thermostable properties.