A New Family of Highly Emissive Soluble Poly(<i>p</i>-phenylene vinylene) Derivatives. A Step toward Fully Conjugated Blue-Emitting Poly(<i>p</i>-phenylene vinylenes)

Hsieh, B.J.; Yu, Yuan; Forsythe, Eric; Schaaf, Gregory M.; Feld, William A.

doi:10.1021/ja973553r

Cited by 186 publications

(135 citation statements)

References 17 publications

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“…Hsieh et al, for example, found out that the presence of monofunctional benzyl halogenides retards or even completely prevents gelation of the reaction mixtures and lowers the PPV's degrees of polymerization systematically. [123][124][125] He interpreted his results as support of anionic chain growth. Also Neef and Ferraris [126] and Yin and Zang [127] understood decreasing PPV molar masses and multimodal molar mass distributions obtained in the presence of 4-methoxyphenol and poly(ethylene glycol), respectively, as a consequence of anionic chain growth.…”

Section: The Gilch Routementioning

confidence: 99%

“…This protonation leads to very rapid and practically irreversible deactivation of the corresponding anions, and, through regenerating the base KO t Bu, effectively preventing the anionic mode of polymerization in the presence of protic species. Nevertheless, there is a further argument emphasized in the literature that might support anionic chain growth, i.e., the effect of monofunctional benzylhalogenides 19 when additionally present in Gilch reaction mixtures: [123][124][125] species such as 19a have been reported to lower the PPVs' molar masses systematically, and to suppress gel formation. Therefore, it was an issue to rationalize the reported effects in the light of the above conclusions.…”

Section: The Anionic Chain-growth Hypothesismentioning

confidence: 99%

“…It was a milestone when Hsieh and co-workers observed that monofunctional benzylhalogenides prevent gel formation during Gilch syntheses. [123][124][125] However, the rationalization of this effect offered by these authors, i.e., a lowering of the PPVs' molar masses, is obviously not valid (see Section 4.2.1, Figure 11), and there must be an alternative explanation instead. In the course of our studies, we have observed some evidence in favor of attractive (p-p, donor-acceptor, or dipolar) interactions between additive molecules and chain segments, which may lead to preferential solvation of the polymer chains by the additive molecules.…”

Section: Scheme 13mentioning

confidence: 99%

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The Gilch Synthesis of Poly(p‐phenylene vinylenes): Mechanistic Knowledge in the Service of Advanced Materials

Schwalm

Wiesecke

Immel

et al. 2009

Macromol. Rapid Commun.

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A consistent picture is presented of the mechanistic details and intermediates of the Gilch polymerization leading to poly(p-phenylene vinylenes) (PPVs). In-situ generated p-quinodimethanes are shown to be the real monomers, and spontaneous formation of the initiating radicals is effected by dimerization of some of these monomers to dimer diradicals, the latter also being the reason why significant amounts of [2.2]paracyclophanes are formed as side-products. Chain propagation predominantly proceeds by radical chain growth, occasionally interrupted by polyrecombination events between the growing α,ω-macro-diradicals. Based on this knowledge, oxygen is identified as a very efficient molar-mass regulating agent, and the temporary gelation of the reaction mixtures is interpreted to be the consequence of a very high entanglement of the polymers immediately after their formation. Last but not least, it is rationalized why the usually considered constitutional defects in Gilch PPVs might not be the only and most relevant ones with respect to the efficiency and durability of the organic light emitting devices produced thereof, and why cis-configurated halide-bearing vinylene moieties should be perceived as being among the most critical candidates. These considerations result in the recommendation of straightforward measures that should lead to clearly improved PPVs.

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Section: The Gilch Routementioning

confidence: 99%

Section: The Anionic Chain-growth Hypothesismentioning

confidence: 99%

Section: Scheme 13mentioning

confidence: 99%

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The Gilch Synthesis of Poly(p‐phenylene vinylenes): Mechanistic Knowledge in the Service of Advanced Materials

Schwalm

Wiesecke

Immel

et al. 2009

Macromol. Rapid Commun.

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“…Moreover, the absorption and emission spectra of PPV polymers 10 and 11 appear to be markedly blueshifted in comparison with those of PPDFV (λ max abs = 390 nm, λ max em = 580 nm) and DMOS-PPDFV (λ max abs = 385 nm, λ max em = 485 nm), which are the only other reported PPVs with fluorinated vinylene units. [6] To the best of our knowledge, polymer 11 shows the most blueshifted photoluminescence emission in the solid state reported to date for poly(p-phenylenevinylene)s. [20] Further photophysical and theoretical investigations are in progress in order to ascertain the role of the fluorine atoms in the emission properties of these materials and in the supramolecular organization in their solid state. [a] (sol.)…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Poly(arylenevinylene)s with Fluorinated Vinylene Units

et al. 2008

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Poly(arylenevinylene) polymers bearing fluorine atoms in the vinylene units were obtained by a Stille cross‐coupling reaction of (E)‐(1,2‐difluoro‐1,2‐ethenediyl)bis(tributylstannane) with diiodoaryl derivatives. The introduction of fluorine atoms on the double bond of the stannane leads to polymers with relatively high molecular weights. Furthermore, the presence of fluorinated vinylene units changes the optical properties of the polymers and shifts the emission towards the blue region of the visible spectrum. A fluorinated analogue of MEH‐PPV was obtained, and it shows photoluminescence that is considerably blueshifted, also in the solid state, relative to that found for nonfluorinated MEH‐PPV and to other PPVs with fluorinated double bonds.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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“…For instance, different alkyl side chains from pentyl to decyl groups were incorporated. 20 The resulting polymers show characteristic nematic texture under cross polarization at different temperature, depending on the varieties of the side group. A general route to the notable DP-PPV derivatives is depicted in Scheme 3.…”

Section: Lc Poly(p-phenylenevinylene)mentioning

confidence: 99%

Liquid crystalline conjugated polymers and their applications in organic electronics

Yang

Hsu

2009

J. Polym. Sci. A Polym. Chem.

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This article describes the syntheses and electrooptical applications of liquid crystalline (LC) conjugated polymers, for example, poly(p-phenylene vinylene), polyfluorene, polythiophene, and other conjugated polymers. The polymerization involves several mechanisms: the Gilch route, Heck coupling, or Knoevenagel condensation for poly(pphenylenevinylene)s, the Suzukior Yamamoto-coupling reaction for polyfluorenes, and miscellaneous coupling reactions for other conjugated polymers. These LC conjugated polymers are classified into two types: conjugated main chain polymers with long alkyl side chains, namely main-chain type LC polymers, and conjugated polymers grafting with mesogenic side groups, namely side-chain type LC conjugated polymers. In general, the former shows higher transition temperature and only nematic phase; the latter possesses lower transition temperature and more mesophases, for example, smectic and nematic phases, depending on the structure of mesogenic side chains. The fully conjugated main chain promises them as good candidates for polarized electroluminescent or fieldeffect devices. The polarized emission can be obtained by surface rubbing or thermal annealing in liquid crystalline phase, with maximum dichroic ratio more than 20. In addition, conjugated oligomers with LC properties are also included and discussed in this article. Several oligo-fluorene derivatives show outstanding polarized emission properties and potential use in LCD backlight application.

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A New Family of Highly Emissive Soluble Poly(p-phenylene vinylene) Derivatives. A Step toward Fully Conjugated Blue-Emitting Poly(p-phenylene vinylenes)

Cited by 186 publications

References 17 publications

The Gilch Synthesis of Poly(p‐phenylene vinylenes): Mechanistic Knowledge in the Service of Advanced Materials

The Gilch Synthesis of Poly(p‐phenylene vinylenes): Mechanistic Knowledge in the Service of Advanced Materials

Synthesis of Poly(arylenevinylene)s with Fluorinated Vinylene Units

Liquid crystalline conjugated polymers and their applications in organic electronics

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