Photochemical Synthesis of Pentacene and its Derivatives

Yamada, Hiroko; Yamashita, Yūko; Kikuchi, Makoto; Watanabe, Hidenobu; Okujima, Tetsuo; Uno, Hidemitsu; Ogawa, Takuji; Ohara, Kouzou; Ono, Noboru

doi:10.1002/chem.200500564

Cited by 150 publications

(105 citation statements)

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“…However, the environmental instability of acene-based organic semiconductors critically limits their applicability in electronic circuitry. [ 8 ] For this reason, many research groups have sought to realize new molecular building blocks that are environmentally stable, and, at the same time, exhibit efficient charge transport. Fused thiophene have been scrutinized, such assumptions have been proven to sometimes be inaccurate, and it is now known that molecular packing in thin fi lms may differ signifi cantly from that in the bulk crystal structures, especially near the dielectric interface.…”

Section: Introductionmentioning

confidence: 99%

Fused Thiophene Semiconductors: Crystal Structure–Film Microstructure Transistor Performance Correlations

Youn

Kewalramani

Emery

et al. 2013

Adv Funct Materials

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The molecular packing motifs within crystalline domains should be a key determinant of charge transport in thin-fi lm transistors (TFTs) based on small organic molecules. Despite this implied importance, detailed information about molecular organization in polycrystalline thin fi lms is not available for the vast majority of molecular organic semiconductors. Considering the potential of fused thiophenes as environmentally stable, highperformance semiconductors, it is therefore of interest to investigate their thin fi lm microstructures in relation to the single crystal molecular packing and OTFT performance. have been scrutinized, such assumptions have been proven to sometimes be inaccurate, and it is now known that molecular packing in thin fi lms may differ signifi cantly from that in the bulk crystal structures, especially near the dielectric interface. For example, in thin fi lm form, both tetraceno[2,3-b]thiophene [ 17 ] and pentacene [ 16 ] exhibit a local molecular packing distinctly different from that in the bulk crystal. These observations highlight the necessity of obtaining microstructural details for thin organic fi lms.In this contribution, the molecular packing motifs of fi ve newly synthesized BTDT [ 9 ] derivatives ( Scheme 2 ), are studied both in bulk single crystals and in thin fi lms by single crystal diffraction and grazing incidence wide angle X-ray scattering (GIWAXS). We fi rst introduce the new BTDT molecules and describe their thermal, optical, and electrochemical properties. We then compare the bulk and thin fi lm structures by analyzing single-crystal X-ray diffraction and GIWAXS data. Lastly, the effect of thin fi lm microstructure on TFT performance is discussed. The results indicate that these BTDT derivatives have different molecular packing in thin fi lms versus the bulk crystals. In the case of P-BTDT , Bp-BTDT , Np-BTDT , and BBTDT , it will be seen that two types of lattices coexist, and that these are slightly strained compared to their bulk crystal forms. In contrast, for PF-BTDT fi lms, a single lattice is observed, however, this lattice has no apparent correspondence to the bulk crystal form. For P-BTDT , which yields the best performing TFTs of the series, the dominance of the more strained lattice relative to the bulk-like lattice may explain the excellent charge transport properties. On the other hand, poor crystallinity and poor surface coverage at the substrate interface explains the poor device performance of PF-BTDT fi lms. Results SynthesisDetails of the various BTDT syntheses can be found in the Supporting Information or previous literature. [ 9 ] Briefl y, the derivatives [ 2 , 9-14 ] offer a potential solution to this challenge, owing to their combination of suffi ciently high-lying excited states and high ionization potentials to suppress photo-oxidation, [ 11 ] and bulk single crystal packing motifs which are very similar to that of pentacene. Among organic semiconductor materials for p-channel devices, several fused thiophene derivatives with increased numb...

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Section: Introductionmentioning

confidence: 99%

Fused Thiophene Semiconductors: Crystal Structure–Film Microstructure Transistor Performance Correlations

Youn

Kewalramani

Emery

et al. 2013

Adv Funct Materials

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“…19 Fluorescence maxima at 612 (for 8a under excitation at 540 nm) and 609 nm (for 8b under excitation at 540 nm) were observed in CHCl 3 (Figure 1). The electron-withdrawing ester connections of the dendritic substituents of 8a and 8b cause bathochromic shifts in the absorption and fluorescence spectra compared with pristine pentacene, for which absorption bands appear at 495, 530, and 578 nm 15 and an emission band is observed at 580 and 631 nm. 16 It is notable that the fluorescence intensity ( ex = 580 nm) of 8a was stronger than that of 8b.…”

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confidence: 99%

“…The 13 C NMR results showed two bridgehead carbons at 67.5 ppm. 15,18 The MALDI-TOF MS of 9a showed a molecular ion peak at m/z 2174.01 (9a, C 126 H 118 O 34 requires m/z 2174.75) using negativeion mode. On the other hand, photolysis of 8b gave the endoperoxide 9b (89%) together with the pentacene quinone 10 (11%) as judged by the 1 H NMR spectra.…”

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“…In marked contrast to the chemoselective photolysis of dendrimer 8a, other end-substituted pentacenes transformed to many products such as photodimers, endoperoxides, and their decomposition products. 15 Hence, the dendritic wedges of 8a and 8b might prevent Figure 1. Excitation and emission spectra of 8a (black line: 1.14 © 10 ¹5 M in CHCl 3 , Em = 640 nm, Ex = 580 nm) and 8b (dotted line: 1.14 © 10 ¹5 M in CHCl 3 , Em = 640 nm, Ex = 580 nm).…”

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Synthesis and Characterization of 2,3,9,10-Tetradendronized Pentacene

et al. 2012

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A new pentacene dendrimer was synthesized in 81% yield through the aromatization of a dihydropentacene derivative having benzyl ether dendrons at the C2, C3, C9, and C10 positions. The dendrimer is very soluble in various organic solvents such as toluene, benzene, chloroform, dichloromethane, acetone, and ethyl acetate. The half-life of the dendrimer reaches 22.4 min upon photoirradiation in air. Interestingly, regiospecific [4 + 2] cycloaddition reactions proceeded at the central ring of the pentacene.Dendrimers having polyacene at the core are of great interest in the fields of material science and supramolecular chemistry, because intermolecular interactions between ³-systems are controlled effectively owing to the site isolation effect of the dendritic architecture. Recently, we reported the intermolecular photodimerization of anthryl dendrons, which proceeded in a regiospecific or regioselective manner owing to the self-assembled suprastructures. 1 The Diels Alder reaction of the anthryl dendron with fullerene produced various fullerodendrons with unique properties. 2 7 The surface modification of single-walled carbon nanotubes (SWCNTs) by the use of the anthryl dendron provided SWCNT/anthryl dendron supramolecular nanocomposites, which showed stable charge-separated states in aqueous media. 8 On the other hand, the incorporation of pentacene into the dendritic system has scarcely been reported, 9 although various pentacene derivatives have been synthesized to improve the poor solubility and stability for the development of solution-based processing of organic electronic devices. 10 Furthermore, most pentacene derivatives have substituents at the C6 and C13 positions, 11 because the central ring of pentacene is very reactive and is a cause of diverse decomposition pathways. Therefore, there are few clear-cut reaction examples employing pentacene derivatives of which the C6 and C13 positions are unsubstituted. 12 This background prompted us to investigate the reactivity of dendrimers having pentacene cores. This paper describes the synthesis and properties of 2,3,9,10-tetradendronized pentacene 8. To the best of our knowledge, 8 is the first example of a dendrimer having a pentacene moiety at the core.The core moiety of the pentacene dendrimer 8 was synthesized as shown in Scheme 1. Tetrabromination of dimethyl 4,5-dimethylphthalate (1) with N-bromosuccinimide (NBS) afforded dimethyl 4,5-bis(dibromomethyl)phthalate (2) in 87% yield. Compound 2 was allowed to react with pbenzoquinone in the presence of potassium iodide to obtain 2,3,9,10-tetramethoxycarbonylpentacene-6,13-quinone (3) in 34% yield via the Diels Alder cyclization of the o-quinodimethane intermediate and an aromatization reaction. Upon treatment of 3 with hydroiodic acid in acetic acid solution, reductive deoxygenation of the benzoquinone moiety and hydrolysis of the ester groups proceeded to afford 6,13-dihydropentacene-2,3,9,10-tetracarboxylic acid (4) in 76% yield.The pentacene dendrimer 8a was synthesized as shown in Scheme 2. The dendritic...

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“…Another approach to circumvent acene instability is the use of protecting groups that reduce their reactivity,allowing for long-term storage as well as imparting additional solubility,b efore deprotection reveals the acene. [3,5] In this regard, partially saturated acenes, which have been extensively employed as direct precursors of the corresponding fully conjugated acenes, [3c, 6] can be considered to be "hydrogen-protected", [7] exhibiting improved solubilities and excellent stabilities.T he synthesis of partially hydrogenated acene derivatives has been achieved by direct reduction of the corresponding acenes or quinones. [7,8] However,t hese methods often require harsh conditions and are prone to produce regioisomeric mixtures.T herefore,g eneral methods to selectively obtain partially saturated acenes still remain elusive.…”

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confidence: 99%