Synthesis and Characterization of Monodisperse Oligofluorenes

Jo, Jaemin; Chi, Chunyan; Höger, Sigurd; Wegner, Gerhard; Yoon, Do Y.

doi:10.1002/chem.200305659

Cited by 190 publications

(195 citation statements)

References 37 publications

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“…Inspired by the synthesis of well defined oligofluorenes [27] we next set out to develop a toolbox of phenothiazine derivatives suitable for a selective synthesis of well defined, monodisperse oligophenothiazines.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Electronic Properties of Monodisperse Oligophenothiazines

Sailer

Franz

Müller

2008

Chemistry A European J

120

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Starting from N-hexylphenothiazine, a versatile construction kit of brominated and borylated phenothiazines can be easily prepared by a sequence of bromination, bromo-lithium exchange/borylation, and Suzuki coupling. Subsequent Suzuki arylation of the building blocks gives soluble, monodisperse, and structurally well defined oligophenothiazines in good yields. The molecular weights at the peak maximum (Mp), obtained by GPC (gel permeation chromatography), and the actual molecular weights of the oligomer series, obtained by mass spectrometry, show excellent correlation. A QM/MM conformational analysis for the complete series reveals that the obvious butterfly-shaped phenothiazine structure multiplies and significantly reduces the hydrodynamic volume of the oligomers. The electronic properties (absorption and emission spectroscopy and cyclic voltammetry) give reasonable correlations with the chain length. With regard to the emission maxima, the effective conjugation length is already reached with the hexamer. Oligophenothiazines are highly fluorescent, with high fluorescence quantum yields, and are simultaneously highly electroactive, with low oxidation potentials.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Electronic Properties of Monodisperse Oligophenothiazines

Sailer

Franz

Müller

2008

Chemistry A European J

120

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“…These endcapping procedures also offer a way in which to control the molecular mass and thus chain length of the polymer and to synthesize rod-coil block copolymers. [75,76,78] Oligomers of fluorene up to hexadecamers are known, [79,80] but the nonlinearity of the fluorene monomer means that these are not rigidly linear species. The laddertype pentaphenylene (10) [71] is also readily available, This oligomer is already a 2-nm long linear rigid rod, and can be difunctionalized to permit attachment of other building units such as dyes.…”

Section: One-dimensional Polyphenylenes and Poly(phenyleneethynylene)smentioning

confidence: 99%

The Chemistry of Organic Nanomaterials

2005

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The development of nanotechnology using organic materials is one of the most intellectually and commercially exciting stories of our times. Advances in synthetic chemistry and in methods for the investigation and manipulation of individual molecules and small ensembles of molecules have produced major advances in the field of organic nanomaterials. The new insights into the optical and electronic properties of molecules obtained by means of single-molecule spectroscopy and scanning probe microscopy have spurred chemists to conceive and make novel molecular and supramolecular designs. Methods have also been sought to exploit the properties of these materials in optoelectronic devices, and prototypes and models for new nanoscale devices have been demonstrated. This Review aims to show how the interaction between synthetic chemistry and spectroscopy has driven the field of organic nanomaterials forward towards the ultimate goal of new technology.

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“…Unlike typical linear/branched oligo- [17,18] and poly-fluorenes, [9,10] where the spectral shapes of the photoluminescence (PL) differ significantly from solution to solid-state, the PL spectra of Tr1-Tr3 in thin-film format ( Fig. 2d) are little altered from those in dilute solution (Fig.…”

mentioning

confidence: 94%

Enhanced Solid‐State Luminescence and Low‐Threshold Lasing from Starburst Macromolecular Materials

et al. 2009

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Luminescence from organic materials is of long-standing and continuing interest, not only from a fundamental scientific perspective, but also for its promising technological relevance in applications such as organic light-emitting diodes (OLEDs) [1,2] and lasers. [3][4][5] So far, the most widely pursued materials have been either small molecules/oligomers or fully-fledged polymers, with fewer examples of efficient intermediate-molecular-weight luminescent materials. Here, we establish a novel series of nanosized monodisperse starburst macromolecules as valuable platforms for investigating the impact of molecular structure on condensed-phase optical and optoelectronic properties. Our results show that long fluorene chain lengths are not a necessary prerequisite for highly efficient solid-state luminescence. Indeed, for the investigated materials, arm lengths of just two or three fluorene units are found to be appropriate. Pure and stable deep-blue electroluminescence (EL) and ultralow-threshold lasing have been achieved, demonstrating that this class of materials is of substantial interest for a variety of luminescence applications.One of the key goals for the organic electronics industry is the development of manufacturable organic luminescent materials that can emit efficiently in the condensed state, since commercial applications in OLEDs and lasers are predicated on the ability to construct solid-state devices at low cost, in which the active materials are not subject to efficient nonradiative excited-state decay. Unfortunately, whilst many previously studied conjugated molecules with a planar and rigid structure emit strongly in dilute solution, they become only weakly luminescent in the solid-state, due to the formation of (physical) dimers and aggregates that quench singlet luminescence and/or facilitate the formation of excimer states, which often possess relatively low emission efficiencies. [6,7] These quenching effects can be the consequence of intrinsic molecular properties or may simply be the result of inadvertent degradation during synthesis, processing, device operation, or the presence of impurities. For example, the formation of C --O bonds via oxidative degradation is a common problem for conjugated polymers, [8] and has been identified as the cause of luminescence quenching for a number of materials. Extensive studies on linear polyfluorenes [9][10][11][12] have shown that they can suffer severely from the effects of oxidation (leading to the formation of fluorenone moieties within the polymer backbone). The result is a general quenching of emission efficiency, and the appearance of a green emission band that leads to a loss of the desirably saturated blue emission color (a particularly attractive attribute of polyfluorenes for display applications). There is still much debate on the origin of the green band, [11,12] but we strongly favor the fluorenone-fluorenone excimer explanation.

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Synthesis and Characterization of Monodisperse Oligofluorenes

Cited by 190 publications

References 37 publications

Synthesis and Electronic Properties of Monodisperse Oligophenothiazines

Synthesis and Electronic Properties of Monodisperse Oligophenothiazines

The Chemistry of Organic Nanomaterials

Enhanced Solid‐State Luminescence and Low‐Threshold Lasing from Starburst Macromolecular Materials

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