The effects of the rigidity of molecular recognition sites in fluorene-based conjugated polymers P1 and P2 on metal ion sensing have been investigated. The structures of polymers P1 and P2 have twisted 2,2

A type of soluble and thermally stable ladder-type poly(p-phenylene) (LPF) with fluorene units in polymer backbone has been synthesized by Suzuki coupling and Friedel-Crafts ring-closing reaction. The full characterization of structures and properties as well as the performances of electroluminescence devices of the new ladder polymers are presented. LPFs show the well-defined structures, high molecular weights, excellent thermal stability, and good solubility in common organic solvents. The high-efficiency emission and absence of low-energy emission band in photoluminescence spectra are observed from LPFs both in the solution and in the solid film. Furthermore, the single layer light-emitting device using LPFs as the active layer shows very stable blue-green emission with maximum luminescence of 5400 cd/m2 and maximum luminance efficiency of 0.66 cd/A. The extraordinary low concentration of keto defects in LPFs may be corresponding to the improvement in optical and device properties. The attractive properties exhibited by new ladder-type poly(p-phenylene)s establish them as good candidates for active layers in light-emitting devices.

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The novel biphenyl derivative 1, which has planar conformation in crystal at room temperature, is synthesized and investigated by X-ray diffraction. A hydrogen-bonding network, which may be the driving force for the formation of planar conformation, is observed in the crystal of 1. 1 exhibits a strong UV-fluorescent emission in the solid state at room temperature.

Red electrophosphorescence from light-emitting devices based on a ruthenium(II) complex [Ru(4,7-Ph2-phen)3]2+-doped wide-band-gap semiconductive polymers, e.g., poly(vinylcarbazole) (PVK), polydihexylfluorene (PF), and ladder-like polyphenylene (LPPP), as the emitting layer are reported. These polymers show the short-wavelength electroluminescence emission peaking ranged from 410 to 490 nm, which overlaps well with the absorption band of [Ru(4,7-Ph2-phen)3]2+; however, very efficient energy transfer was investigated in the PVK system, likely due to relative long excited-state lifetimes of PVK than that of PF and LPPP and good chemical compatibility of [Ru(4,7-Ph2-phen)3]2+ with PVK. The EL spectra show the characteristic spectrum of [Ru(4,7-Ph2-phen)3]2+, with a peak at 612nm and CIE of (0.62, 0.37) which is comparable with standard red color. The optimized device ITO/PVK 5wt % [Ru(4,7-Ph2-phen)3]2+/PBD/Alq3/LiF/Al shows the maximum luminance efficiency and power efficiency of 8.6 cd/A and 2.1lm/W, respectively.