Polyfluorene synthesis

Polyfluorenes synthesized by Fukuda et al. have relatively local molecular weights and some degree of branching and nonconjugated linkages via conjugation at carbon atoms at positions other than 2 and 7.11 Inbasekaran and co-workers chose to minimize such effects by using transition-metal-catalyzed reactions of 

FIGURE 10.2. Absorption and fluorescence spectra of PDHF (a) absorption and (b) fluorescence spectra in chloroform solution (c) absorption spectrum of a film. (From Ref. 11.) 

TABLE 10.1. Molecular Weights of Dialkyl-Substituted Polyfluorenes. 

Note The typical number of repeat units was calculated from the number-weight average (Mn). The boldfaced values are for polymers synthesized via the improved Suzuki coupling reaction Ref. 13 and 25. 

FIGURE 10.3. Absorption (dashed line) and fluorescence (solid line) spectra of a spin-cast PFO film. (From Ref. 10.) Inset Chemical structure of PFO. 

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C. Chi, C. Im, V. Enkehnann, A. Ziegler, G. Lieser and G. Wegner, Monodisperse ohgofluorenes with keto defect as models to investigate the origin of green emission from polyfluorenes synthesis, self-assembly and photophysical properties. Chem. Eur. J., 11, 6833-6845 (2005). 

Kulkami AP, Zhu Y, Jenekhe SA (2005) (Juinoxaline-eontaining polyfluorenes synthesis, photophysics, and stable blue electroluminescenex . Maeromoleeules 38(5) 1553—1563. doi 10. 

One of the first examples was that reported by Yoshino et al. [12] concerning the synthesis of polyfluorenes via oxidative coupling of fluorene derivatives as decribed above. 

The 2,5-dicyanophenylene unit has also been used by Jen and coworkers [164] in the synthesis of a series of polyfluorene (PF) PPV copolymers 129-131 through Suzuki-coupling... 

J. Rault-Berthelot, Polyfluorenes, a family of versatile conjugated polymers. Anodic synthesis, physicochemical properties, electrochemical behaviour and application fields, Recent Res. Dev. Macromol. Res., 3 425-437, 1998. 

M. Fukuda, K. Sawada, and K. Yoshino, Synthesis of fusible and soluble conducting polyfluorene derivatives and their characteristics, J. Polym. Set, Part A Polym. Chem., 31 2465-2471, 1993. 

H.-J. Cho, B.-J. Jung, N.S. Cho, J. Lee, and H.-K. Shim, Synthesis and characterization of thermally stable blue light-emitting polyfluorenes containing siloxane bridges, Macromolecules, 36 6704—6710, 2003. 

Q. Peng, Z.-Y. Lu, Y. Huang, M.-G. Xie, S.-H. Han, J.-B. Peng, and Y. Cao, Synthesis and characterization of new red-emitting polyfluorene derivatives containing electron-deficient 2-pyran-4-ylidene-malononitrile moieties, Macromolecules, 37 260-266, 2004. 

S. Setayesh, D. Marsitzky, and K. Mullen, Bridging the gap between polyfluorene and ladder-poly-p-phenylene synthesis and characterization of poly-2,8-indenofluorene, Macromolecules, 33 2016-2020, 2000. 

Zhang Y, Liu B, Cao Y (2008) Synthesis and characterization of a water-soluble carboxy-lated polyfluorene and its fluorescence quenching by cationic quenchers and proteins. Chem Asian J 3 739-745... 

Originality The synthesis of polyfluorenes having lateral high electron field-effect... 

The synthesis of a series of polyfluorene 18 incorporated with chloro-tricarbonyl rhenium(I) 2,2-bipyridine complexes was reported (Scheme 10).78 Suzuki cross-coupling reactions were used to construct the main chain, and the... 

From the late 1970s onwards, efforts to synthesise conjugated polymers rapidly expanded and numerous new materials were prepared. Many of these still proved to be intractable substances that were difficult if not impossible to purify and characterise. The maximum levels of conductivity achieved on doping often fell well short of the metallic range. Such properties meant that the majority of these materials attracted little attention beyond the initial reports, and certainly no commercial interest. An example of the few polymers produced at this time that have been extensively studied subsequently is polythiophene (PTh), Fig. 9.2(h). Although this polymer was also reported in the nineteenth century (Meyer, 1883), the first reliable synthesis appeared in 1980, see McCullough (1998). Another example is polyfluorene, Fig. 9.2(i), which was prepared chemically and electrochemically in 1985, see Rault-Berthelot and Simonet (1986). Much subsequent synthesis has been directed to the inclusion of pendent groups to either enhance solubility,... 

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. 

Scheme 4 Synthesis of a polyfluorene network by oxidative coupling...

Scheme 6 Synthesis of end-capped polyfluorene by AB-type Suzuki polycoupling...

Poly(dibenzosilole)s are a relatively new class of compounds for the area of organic electronic materials. Poly(dibenzosilole)s are not easily oxidised and have advantages of solubility and processibility over other polyfluorene analogues, such as carbazoles, dibenzophosphole oxides and dibenzothiophene dioxides. Several groups have already incorporated poly(dibenzosilole)s in the latest organic electronic devices such as OLEDs, OFETs and OSCs and have found improved performance over similar polyfluorene-based devices. With continual advancement in their synthesis, dibenzosilole-based polymers are set to match the popularity of polyfluorenes in organic electronic materials. 

Scheme 9 Synthesis routes of polyfluorenes with on-chain Pt(II) complexes by postpolymerization metalation (route 1) and copolymerization from Pt(II) metal complexes (route 2)... 

Scheme 14 Synthesis of end-capped polyfluorenes with on-chain Re(I) complexes...

In this review, the synthesis, properties, and applications in optoelectronic fields of polyfluorenes with on-chain metal centers have been briefly summarized. Metal complexes involving iridium(III), platinum(II), europium(III), rhenium(I), and ruthenium(II) complex coupled with polyfluorene are surveyed. Efficient energy transfer from polymer main-chain to metal-centers can occur in these host-guest systems. These kinds of novel polymers are usually applied in the fields of phosphorescent OLEDs, memory devices, and sensors. In particular, the realization of efficient energy transfer and phosphorescence offers a huge potential for future optoelectronic devices based on these kinds of materials. 

There is a wide range of so-called bottom-up methods for achieving complex structural hierarchies within polyfluorene nanostructures. Synthesis of block... 

Because polyfluorenes have undoubtedly emerged as a very attractive class of blue-emitting polymers, not surprisingly, a number of synthesis methods have been applied for the preparation of polyfluorenes and polyarylenes [20],... 

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