Fluorenes polymer synthesis

In the effort to make pure blue-emitting materials Shim and coworkers [146] synthesized a series of PPV-based copolymers containing carbazole (polymers 95 and 96) and fluorene (polymers 97 and 98) units via Wittig polycondensation. The use of trimethylsilyl substituents, instead of alkoxy groups, eliminates the electron donor influence of the latter and leads to chain distortion that bathochromically shifts the emission (Amax = 480 nm for 95 and 495 nm for 97). In addition, a very high PLQY was found for these polymers in the solid state (64 and 81%, respectively). Single-layer PLEDs fabricated with 95 and 97 (ITO/polymer/Al) showed EL efficiencies of 13 and 32 times higher than MEH-PPV, respectively (see also Ref. [147] for synthesis and PLED studies of polymers 99 and 100) (Chart 2.20). 

From the above results it can be concluded that keto defect sites are preferably formed during polymer synthesis when non- or monoalkylated fluorene species are present in the reaction mixture. This points to the necessity of avoiding even small amounts of these components in order to provide polyfluorenes and polyfluorene-based materials without such centers of degradation and to realize high molecular weight polymers. This prerequisite for polyfluorenes with increased stability can also be transferred to other blue emitter materials as shown, e.g., by Romaner et al. [43] for ladder-type polyparaphenylenes. In this study, again, full alkylation was identified as an important parameter for highly stable materials as it was derived from com-... 

An aqueous Friedel-Crafts reaction has also been used in polymer synthesis. The acid-catalyzed polymerization of benzylic alcohol and fluoride functionality in monomeric and polymeric fluorenes was investigated in both organic and aqueous reaction media. Polymeric products are consistent with the generation of benzylic cations that participate in electrophilic aromatic substitution reactions. Similar reactions occurred in a water-insoluble Kraft pine lignin by treatment with aqueous acid. A Bisphenol A-type epoxy resin is readily emulsified in aqueous medium with an ethylene oxide adduct to a Friedel-Crafts reaction product of styrene and 4-(4-cumyl)phenol as emulsifier.Electrophilic substitution reaction of indoles with various aldehydes and ketones proceeded smoothly in water using the hexamethylenetetramine-bromine complex to afford the corresponding Z A(indolyl)methanes in excellent yields.InFs-catalyzed electrophilic substitution reactions of indoles with aldehydes and ketones are carried out in water.Enzymatic Friedel-Crafts-type electrophilic substitution reactions have been reported. ... 

The recent synthesis of silicon-containing fluorene polymers through the carbon-silicon couphng between fluorenyl Grignard reagents and dichlorosi-lanes may also be cited [31] (cf. Scheme 12). 

Recently, polyimines include the synthesis of long alkoxy (Cg-Cig) side chain derivatives [188,189], which are presumably soluble to some extent in organic solvents and derivatives containing fluorene cardo unit [190]. Trifluoromethyl groups [191] in the polymer backbone provide solubility in organic solvents. Studies of the electrical conductivity of doped conjugated aromatic polyimines and alkoxy derivatives have been reported [188], and the values are in the range of 10 to 10 S/ cm. 

N.C. Yang, Y.H. Park, and D.H. Suh, Synthesis and properties of new ultraviolet-blue-emissive fluorene-based aromatic polyoxadiazoles with confinement moieties, J. Polym. Sci., Part A Polym. Chem., 41 674-683, 2003. 

Another approach to CPL is the synthesis of conjugated polymers with intrinsic chiro-optical properties. A variety of polymers with CPPL have been synthesized so far. Most of them are based upon well-known conjugated polymers such as poly(thiophene)s [4,111], polyphenylene vinylene)s [123], poly(thienylene vinylene)s [124], ladder polymers [125], PPPs [126], polyphenylene ethynylene)s, [127] and poly(fluorenes) [128]. All of them have been modified with chiral side-chains, which induce the chiro-optical properties. 

Research Focus Synthesis of poly( fluorene-co-triphenylamine) derivatives as hole transport polymers. 

A fairly similar material has been obtained in an FTT synthesis extended over 6 months (Hayatsu et al., 1977). Upon pyrolysis, it gave a mass spectrum resembling that of the Murchison polymer (Fig. 9). The spectrum shows mainly benzene, naphthalene, and their alkyl derivatives, as well as alkyl-indanes, fluorene, anthra-cene/phenanthrene, alkenes, alkanes, and alkylphenols (Hayatsu et al., 1977). This material has not been studied by the more informative, gentle oxidation methods. 

Fluorene-based polymers have been used as the emissive element in commercially available polymer displays, announced in October 2000.1 The reported displays have a start emitting light below 2.5 V and an efficiency as high as 16 lm/W, and can emit 10 times the brightness of a CRT television screen at just 5 V. This achievement is all the more remarkable given that the synthesis of polyfluorene was first reported only in 1989.2 Ironically, polyfluorene was synthesized shortly before Burroughes et al. reported the discovery of the polymer LED in 1990.3 This pair of discoveries 1 year and half the world apart paved the way for the recent breakthrough. 

Altohyrtin C, which involved the synthesis of ylide (90) that contains the said side chain,and Xerulin, which inhibits the biosynthesis of cholesterol, which required the use of ylide (91). Wittig reactions are also useful reagents for the synthesis of polymeric materials, for example fluorene ylide (92) has been used to generate light emitting polymers. ... 

This ready accessability of dialkylfluorene monomers is one of the major reasons for the extensive investigation of poly(dialkylfluorene)s. Three main methods have been used for the synthesis of the polymers. PDAFs can be made by oxidative coupling of the monomer 6 with iron(III) chloride. Poly(9,9-dihexyl-2,7-fluorene) (12) with a molecular mass of 5000 (n = ca. 20) was made in this way by Yoshino and co-workers (Scheme 3) [16,17], and used to make low-efficiency blue-emitting (A.max = 470 nm) devices [18-20]. 

The first synthesis of a soluble and processible poly(2,7-fluorene) was reported by Yoshino and coworkers in 1989 [44,45]. Their approach involved coupling fluorene monomers with substituents at the C9 position by chemical oxidation with FeCls (see P3 in Scheme 1.2). However, the polymerization process was not regiospecific and the polymer backbone contained structural defects that influence the electronic delocalization. Thus, the synthesis of defect-free poly(fluorene)s became a major challenge and advances in carbon-carbon bond forming reactions promoted by organometallic catalysts provided the... 

The synthesis of the anionic P6 is shown in Scheme 1.7. Copolymerization of 2,7-dibromo-9,9-bis(4-sulfonylbutox rphenyl)fluorene (16) with 1,4-phenylenediboronic acid (3) using Pd(PPhg)4 produces a polymer that is... 

Hsu, J.C., Sugiyama, K., Chiu, Y.C., Hirao, A., Chen, W.C. Synthesis of new star-shaped polymers with styrene-fluorene conjugated moieties and their multicolor luminescent ordered microporous films. Macromolecules 43, 7151-7158 (2010)... 

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