Some new Schiff base ligands giving a NNOS coordination sphere and their nickel(II) complexes: Synthesis,characterization and complex formation

Some new tetradentate ligands with a NNOS coordination sphere were prepared and their corresponding nickel(II) complexes were synthesized and characterized by elemental analysis, IR, ¹H NMR, UV–Vis and mass spectrophotometry. The thermodynamic formation constants of the complexes were measured spectrophotometrically, at a constant ionic strength of 0.1 M (NaClO₄) at 25 °C in DMF solvent. The trend of the complex formation for nickel is as follows:     

Design and performance simulation of a molecular Doppler wind lidar

A mobile molecular Doppler wind lidar at an eye-safe wavelength of 355 nm based on double-edge technique is being built in Hefei （China） for wind measurement from 10-to 40-km altitude. The structure of this lidar system is described. A triple Fabry-Perot etalon is employed as a frequency discriminator whose parameters are optimized. The receiver system is designed to achieve compactness and stability by putting in a standard 19-inch socket bench. Simulation results show that within the wind speed dynamic range of ±100 m/s, the horizontal wind errors due to noise are less than 1 m/s bdow 20-km altitude for 100-m vertical resolution, and less than 5.5 m/s from 20 km up to 40 km for 500-m vertical resolution with 400-mJ laser energy, 30-min temporal resolution, and a 45-cm aperture telescooe.     

Enhanced efficiency of polyfluorene derivatives: Organic–inorganic hybrid polymer light‐emitting diodes

Two novel organic–inorganic hybrid polyfluorene derivatives, poly{(9,9′‐dioctyl‐2,7‐fluorene)‐co‐(9,9′‐di‐POSS‐2,7‐fluorene)‐co‐[2,5‐bis(octyloxy)‐1,4‐phenylene]} (PFDOPPOSS) and poly{(9,9′‐dioctyl‐2,7‐fluorene)‐co‐(9,9′‐di‐POSS‐2,7‐fluorene)‐co‐bithiophene} (PFT2POSS), were synthesized by the Pd‐catalyzed Suzuki reaction of polyhedral oligomeric silsesquioxane (POSS) appended fluorene, dioctyl phenylene, and bithiophene moieties. The synthesized polymers were characterized with ¹H NMR spectroscopy and elemental analysis. Photoluminescence (PL) studies showed that the incorporation of the POSS pendant into the polyfluorene derivatives significantly enhanced the fluorescence quantum yields of the polymer films, likely via a reduction in the degree of interchain interaction as well as keto formation. Additionally, the blue‐light‐emitting polyfluorene derivative PFDOPPOSS showed high thermal color stability in PL. Moreover, single‐layer light‐emitting diode devices of an indium tin oxide/poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate)/polymer/Ca/Al configuration fabricated with PFDOPPOSS and PFT2POSS showed much improved brightness, maximum luminescence intensity, and quantum efficiency in comparison with devices fabricated with the corresponding pristine polymers PFDOP and PFT2. In particular, the maximum external quantum efficiency of PFT2POSS was 0.13%, which was twice that of PFT2 (0.06%), and the maximum current efficiency of PFT2POSS was 0.38 cd/A, which again was twice that of PFT2 (0.19 cd/A). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2943–2954, 2006     

Synthesis of metal/polymer colloidal composites by the tailored deposition of silver onto porous polymer microspheres

A new colloidal silver system is presented in which a fine colloidal silver is in situ deposited onto functionalized porous poly(ethylene glycol dimethacrylate) [poly(EGDMA)] microspheres. The effectiveness of the silver deposition has been investigated through an examination of the surface characteristics of poly(EGDMA) microspheres. The result reported in this study demonstrate that the control of the surface area and surface functionality (in this study, a hydroxyl group) of poly(EGDMA) microspheres is an important factor that practically determines the degree of deposition of colloidal silver. X‐ray analysis has shown that silver nanoparticles are dispersed evenly on inner and outer surfaces and have a face center cubic phase. Preservation testing has shown that silver‐containing poly(EGDMA) microspheres have powerful antibacterial properties and, therefore, have significant potential as new preservatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2551–2557, 2004     

Dendronized tricyanopyrroline‐based chromophores in nonlinear optical active host polymer

We synthesized new nonlinear optical (NLO) chromophores containing a 3,5‐bis(3,5‐bisbenzyloxy‐benzyloxy)‐benzoate dendron. Tricyanopyrroline (TCP)‐based chromophores were designed and prepared by virtue of its strong electron withdrawing property. A soluble polyimide containing 6‐({4‐[2‐(1‐allyl‐4‐cyano‐5‐dicyanomethylene‐2‐oxo‐2,5‐dihydro‐1H‐pyrrol‐3‐yl)‐vinyl]‐phenyl}‐butyl‐amino)‐hexanoyl group in the side chain was also prepared as an NLO active host polymer. A benzoate dendron was tethered at two different binding positions of the chromophore to yield two different guest molecules. Thin‐film composites of these dendronized chromophores dissolved in the NLO active polyimide host were employed to fabricate the electro‐optic (EO) samples. The EO properties of new NLO polyimides containing dendronized chromophores were compared with those of the sample with nondendronized plain chromophores. The effect of a bulky dendron on the EO properties was investigated using an in situ reflection technique. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5064–5076, 2008     

Carbazolevinylene‐based polymers and model compounds with oxadiazole and triphenylamine segments: Synthesis,photophysics, and electroluminescence

Two new soluble alternating carbazolevinylene‐based polymers POXD and PTPA as well as the corresponding model compounds MOXD and MTPA were synthesized by Heck coupling. POXD and MOXD contained 2,5‐diphenyloxadiazole segments, while PTPA and MTPA contained triphenylamine segments. All samples displayed high thermal stability. The polymers had higher glass transition temperature (T_g) than their corresponding model compounds. The samples showed absorption maximum at 364–403 nm with optical band gap of 2.62–2.82 eV. They emitted blue‐green light with photoluminescence (PL) emission maximum at 450–501 nm and PL quantum yields in THF solution of 0.15–0.36. The absorption and the PL emission maxima of PTPA and MTPA were blue‐shifted as compared to those of POXD and MOXD . The electroluminescence (EL) spectra of multilayered devices made using four materials exhibited bluish green emissions, which is well consistent with PL spectra. The EL devices made using poly(vinyl carbazole) doped with MOXD and MTPA as emitting materials showed luminances of 12.1 and 4.8 cd m^?2. POXD and PTPA exhibited 25.4, and 96.3 cd m^?2, respectively. The polymer containing the corresponding molecules in the repeating group showed much higher device performances. Additionally, POXD and MOXD exhibited better stability of external quantum efficiency (EQE) and luminous efficiency with current density resulting from enhancing the electron transporting properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5592–5603, 2008     

AGET ATRP in water and inverse miniemulsion: A facile route for preparation of high‐molecular‐weight biocompatible brush‐like polymers

Activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) of oligo(ethylene glycol) monomethyl ether methacrylate (OEOMA) was investigated in homogeneous aqueous solution targeting DP = 1000, and in inverse miniemulsion targeting DP = 600, at 30 °C. Several reaction parameters were examined in the preparation of biocompatible, brush‐like, high‐molecular‐weight, water‐soluble polymers. They include concentration of ascorbic acid (AscA), ratio of water to OEOMA, mode of addition of AscA, and ratio of initiator to Cu(II) complex. The results obtained in these studies indicate that AGET ATRP retains all of the benefits of normal ATRP and, additionally, provides a facile route for the preparation of well‐controlled high‐molecular‐weight polymers because of the use of oxidatively stable catalyst precursors. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1771–1781, 2009     

Synthesis and characterization of an ionic conjugated polymer: Poly[2‐ethynyl‐N‐(2‐thiophenecarbonyl) pyridinium chloride]

The activated polymerization of 2‐ethynylpyridine by using 2‐thiophenecarbonyl chloride yielded the corresponding conjugated ionic polymer, poly[2‐ethynyl‐N‐(2‐thiophenecarbonyl)pyridinium chloride] (PETCPC). The polymerization proceeded well to give high yield of polymer without any additional initiator or catalyst. The instrumental analysis data on polymer structure indicated that the present ionic polymer have a conjugated polymer backbone system having N‐(2‐thiophenecarbonyl)pyridinium chloride as substituents. The photoluminescence maximum peak of PETCPC was located at 573 nm, which corresponds to the photon energy of 2.16 eV. The aromatic functional substituents in the conjugated backbone system shift PL maximum values because it makes different molecule arrangement. The cyclovoltamograms of PETCPC exhibited the electrochemically stable window at ?1.24 to 1.80 V region. It was found that the kinetics of the redox process of polymer might be controlled by the reactant diffusion process from the experiment of the oxidation current density of polymer versus the scan rate. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6153–6162, 2009     

The stringy E‐function of the moduli space of Higgs bundles with trivial determinant

Let M be the moduli space of semistable rank 2 Higgs pairs (V, ϕ) with trivial determinant over a smooth projective curve X of genus g ≥ 2. We provide an explicit formula for the stringy E‐function of M . (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)