Suzuki polycondensation polymers

Scherf and Mullen prepared (Scheme 47) the ladder-type polyphenylene (LPPP, 5) with methine bridges [126-129], via a poly(diacylphenylene-co-phenylene) precursor copolymer 103 obtained by an AA-BB type Suzuki polycondensation. The key step is the polymer analogous Friedel-Crafts ringclosing reaction on the polyalcohol 104, obtained by the reduction of 103. This was found to proceed quickly and smoothly upon addition of boron-trifluoride to a solution of 104 in dichloromethane. The reaction appeared to be complete by both NMR and MALDI-TOF analysis, indicating the presence of less than 1% of defects due to incomplete ring closure. LPPPs with num-... 

Another way to introduce Ir(III) complexes into the main-chain of polyfluorenes was realized by Suzuki polycondensation of fluorene segments and /3-diketone ligand chelated with Ir(III) chloride-bridged dimmer (polymer 26 and 27) [34,35]. A saturated red-emitting polymer light-emitting diode was achieved from the device ITO/PEDOT/polymer 27 + PBD (40%)/Ba/Al with the maximum external quantum efficiency of 0.6% at the current density (J) of 38.5 mA/cm2 and the maximum luminance of 541 cd/m2 at 15.8 V. 

Polyfluorene with on-chain ruthenium complex (polymer 49) has been synthesized by Suzuki polycondensation [77]. The photoluminescence of the copolymer was slightly blue-shifted as the concentration of dipyridy-lamine increased. The introduction of dipyridylamine and the ruthenium complex into the polymer significantly improved the photoluminescence efficiency. 

Hereby, poly(p-phenylene) polymers containing ether and carbonyl linkages in the polymer backbone are accessible. By polymerization of the AB2 monomer 3,5-dibromobenzene boronic acid in a biphasic aqueous/organic medium, Kim and Webster obtained hyperbranched polyphenylenes [233]. Suzuki polycondensation in aqueous systems has proven to be a versatile method, which has been applied to the synthesis of various polymer types ]234]. 

An excellent example of the use of Suzuki polycondensation is the synthesis of ladder-type PPPs (67) (see Scheme 6.16) [84]. A precursor polymer 79 is prepared by AA-BB coupling and then converted to the ladder polymers by polymer analogous reactions. Reduction followed by ring closure with boron trifluoride produces a polymer (67a) with bridgehead hydrogens, while addition of methyl lithium instead of reduction leads to Me-LPPP (67b) with methyls at the bridgeheads. 

P 25 and 125 [according to gel-permeation chromatography (GPC) on a gram scale]. Although the actual molar mass of this polymer is still unclear, these data clearly show that Suzuki polycondensation can function even for sterically enormously loaded G4 monomers. 

Suzuki polycondensation of a dendronized maaomonomer with a comonomer has been used to generate cylindrical dendronized brushes. One objective of research on dendronized polymers is to use the decoration with dendrons as a means to stiffen the backbone to the point that it is fully stretched. This goal should be reached when the individual... 

Figure 10 Synthesis of dendronized polymer brush (with fourth-generation dendrons) from a dendronized macromonomer and a comonomer via Suzuki polycondensation. ...

The only example of rod-rod copolymers with polyphenylene-based rods are the polymers 230 and 231, in which two polyfluorene blocks are separated by a short arylene vinylene unit (Scheme 105). These were prepared by Suzuki polycondensation of a fluorene monoboronic acid 232 in the presence of the bromo-substituted oUgo(arylene vinylene) units 233 and 234 [321], From the molecular masses of the polymers, the total number of fluorene units in both 230 and 231 is about 18. 

M. Jayakannan, X. Lou, J. L. J. Van Dongen and R. A. J. Janssen. Synthesis of regioregular poly(3-octylthiophene)s via Suzuki polycondensation and end-group analysis by matrix-assisted laser desorption/ ionization time-of-fiight mass spectrometry. J. Polym. Sci., Part A Polym. Chem. 43(7), 1454-1462 (2005). 

The Suzuki reaction shares many common similarities and features with aforementioned Stille reaction, such as similar catalytic cycles and Pd-based catalysts, and wide tolerance of functionalities. Highlighted below are a few notable factors one needs to consider when choosing Suzuki polymerization to prepare D A polymers. Interested readers are referred to a more general review for details on Suzuki polycondensation." ... 

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