Synthesis, structures and optical properties of 3,3′-disubstituted biphenyl compounds

Abstract The bromination of the electron-deficient 2,2′-dicyano-6,6′-difluorobiphenyl with elemental bromine in HNO 3 /H 2 SO 4 produces mainly 3,3′-dibromobiphenyl ( 1 ) and 3-nitro-3′-bromobiphenyl ( 2 ) in a total yield of 70 %. Compound 1 reacts with carbazole to yield the 3,3′-dibromo-6,6′-di(9 H -carbazol-9-yl)-[1,1′-biphenyl]-2,2′-dicarbonitrile ( 6 ). The structures of the products have been studied by spectroscopic methods and X-ray diffraction, as well as DFT calculations. The optical properties of some of the compounds have been investigated by UV/Vis or fluorescene spectrocopy, which show that compound 6 has Thermally Activated Delayed Fluorescence (TADF) and Aggregation-Induced Emission (AIE) properties (i.e. Aggregation-Induced Delayed Fluorescence, AIDF). These biphenyl products may find potential applications in the field of organic photofunctional materials.