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Attempts to functionalize polycyclic quinones using lithium diisopropylamide as a base led to the unexpected formation of acenes. This reaction proceeds by electron transfer from the base to the electron deficient quinone, whose radical anion can react with a variety of electrophiles. Siloxy derivatives synthesized by this method could be easily isolated but showed poor photostability. In situ reduced intermediate generation is a convenient approach to functionalization of oxidatively unstable hydroquinones.

A new class of nitrogen-containing arene organic semiconductors incorporating fused indolizine units is described. This system, though having a zigzag shape, mimics the electronic properties of its linear analogue pentacene as a result of nitrogen lone pair incorporation into the π-electron system. Solubilizing trialkylsilylethynyl groups were employed to target crystal packing motifs appropriate for field-effect transistor devices. The triethylsilylethynyl derivative yielded hole mobilities of 0.1 cm 2 V -1 s -1 and on/off current ratios of 10 5 .

The synthesis of dioxolane-functionalized hexacenes and heptacenes is reported. While heptacenes were too reactive to be successfully isolated, hexacenes showed higher stability and characteristic long-wavelength fluorescence both in solution and in the solid state as crystalline powders.

The synthesis of isomerically pure syn-anthradithiophene derivatives (syn-ADTs) is described. X-ray crystallography is used to compare the solid-state arrangement of syn-ADT derivatives 2a,b to the analogous mixture of syn- and anti-ADTs. Single-crystal OFETs based on isomerically pure syn-ADTs 2a,b display device performance comparable to those based on a mixture of ADT isomers syn/anti-2a,b with mobilities as high as 1 cm(2)/(V s).

The synthesis of three heptacyclic heteroacenes is described, namely anthra[2,3-b:7,6-b']bis[1]benzothiophenes (ABBTs). A stepwise sequence of aldol reactions provides regiochemical control, affording only the syn-isomer. The ABBTs are characterized by X-ray crystallography, UV-vis absorption, and emission spectroscopy, as well as cyclic voltammetry. Field effect transistors based on solution-cast thin films of ABBT derivatives exhibit charge-carrier mobilities of as high as 0.013 cm(2)/(V s)., (© 2011 American Chemical Society)

The synthesis of new silylethyne-substituted hexacene derivatives to investigate their solubility, stability, and pi-stacking is reported. It was found that "butterfly" dimerization, rather than photooxidation, is the dominant decomposition pathway for these molecules and that stability can be enhanced by functionalization to prevent close contact between specific regions of the aromatic core. Dimerization regioselectivity can be altered by suitable engineering of the solid-state arrangement of the chromophores.

[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.

[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.

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.

[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.

[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.

As part of an investigation into new synthetic routes to poly(peri-naphthalene), the synthesis and cycloaromatization of tetraethynylbiphenyls is described. The temperature-dependent cyclization of biphenyls containing unsubstituted alkynes provides the desired perylene in good yield.

[reaction: see text] Simple bis(bromoethynyl)arenediynes are easily prepared by the desilylative halogenation of the corresponding trimethylsilyl derivatives. Cycloaromatization of these halogenated enediynes leads to the otherwise difficult to prepare 2,3-dibromoarenes in good yield. Alkynylation of the resulting haloaromatic compound regenerates the soluble enediyne system, homologated by one aromatic ring. This iterative methodology can be terminated by the cycloaromatization of the unsubstituted enediyne, providing the simple acene hydrocarbon.