Biomedical subjects

Sean R Parkin

Publications and source records attributed to Sean R Parkin.

8 recordsLinked to original sources

PubMed2005

Synthesis and characterization of electron-deficient pentacenes.

[structure: see text]. Halogen functional groups on pentacene can be used both as synthetic handles for further functionalization as well as to tune the pi-stacking in these systems. The halogenated pentacene derivatives described here (X = Br, X' = H, and X = X' = F) are all stable and soluble, with reduction potentials significantly lower than that of the parent functionalized pentacene (X = X' = H). The bromopentacenes could be further elucidated to pentacene nitriles, further decreasing the acene's reduction potential, while the charge-carrier mobility in the fluorinated systems was shown to scale with the degree of fluorine substitution.

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PubMed2005

Functionalized higher acenes: hexacene and heptacene.

We have extended our functionalization strategy for pentacene to the higher acenes hexacene and heptacene. Provided a large enough alkyne substituent is used, these large aromatic rods are both stable and soluble and can be characterized spectroscopically as well as by single-crystal X-ray diffraction.

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PubMed2005

Organic field-effect transistors from solution-deposited functionalized acenes with mobilities as high as 1 cm2/V x s.

We present the device parameters for organic field-effect transistors fabricated from solution-deposited films of functionalized pentacene and anthradithiophenes. These materials are easily prepared in one or two steps from commercially available starting materials and are purified by simple recrystallization. For a solution-deposited film of functionalized pentacene, hole mobility of 0.17 cm2/V.s was measured. The functionalized anthradithiophenes showed behavior strongly dependent on the substituents, with hole mobilities as high as 1.0 cm2/V.s.

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PubMed2005

Partial fluorination overcomes herringbone crystal packing in small polycyclic aromatics.

[structure: see text] We report the synthesis and characterization of partially fluorinated condensed tetracyclic aromatic compounds. Typical edge-to-face/herringbone packing of nonfluorinated analogues is replaced here by columnar stacks with disk planes orthogonal to the columnar axes. Enhanced pi-overlap results with overlaid electron-poor and -rich regions.

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PubMed2004

Stable, crystalline acenedithiophenes with up to seven linearly fused rings.

[structure: see text] We report the synthesis of a series of crystalline acenedithiophenes with up to seven linearly fused rings and silylethynyl substituents. These functional groups are designed to both improve solubility and enhance cofacial interactions in the solid. We discuss the crystal packing of these materials, as well as their physical properties such as oxidation potential, UV-vis absorption, fluorescence emission, and decomposition pathways.

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PubMed2004

Robust, soluble pentacene ethers.

We report the synthesis and characterization of a series of alkoxy-substituted silylethynylated pentacene derivatives (R = CH(2)CH(2), CHCH, CH(2)). All three compounds are easily prepared, soluble in common organic solvents, and stable both as solids and in solution. Two of the derivatives possess significant pi-face interactions in the crystal. Values for lambda(max) for these new pentacene derivatives range from 621 to 674 nm, and oxidation potentials lie between 109 and 301 mV versus ferrocene.

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PubMed2003

Tetracene derivatives as potential red emitters for organic LEDs.

[structure: see text] As part of our program investigating the use of ethynylated acenes in organic electronics, we have prepared a series of functionalized tetracene derivatives in search of a material with red emission suitable for use in display technologies. A number of such compounds with functionalization on the alkyne and/or the acene ring were easily prepared in one or two steps from commercially available materials. Solution fluorescence quantum efficiencies were generally good for these derivatives, which possessed emission maxima spanning the range 540-637 nm. Simple light-emitting diodes fabricated from these compounds showed that one of the derivatives did exhibit red electroluminescence.

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PubMed2002

A road map to stable, soluble, easily crystallized pentacene derivatives.

[structure: see text] A series of 6,13-disubstituted pentacenes, in which the substituents are functionalized ethyne units, were synthesized and analyzed by X-ray crystallography. The resulting pentacene derivatives were highly soluble and oxidatively stable and exhibited a significant amount of pi-stacking in the crystal.

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