Designing stable open-shell organic materials through the modifications of the π-topology of molecular organic semiconductors have attracted recently considerable attention. However, their uses as an active layer in organic field-effect transistors (OFETs) are very limited and the obtained hole and electron charge mobilities are around 10 −3 cm 2 V −1 s −1. Herein, we disclosed the synthesis of two materials so-called tetracenotetracene (TT) and pentacenopentacene (PP) which have low band gap of 1.79 and 1.42 eV, respectively. Their ground state natures have been investigated by different experiments including steady state absorption, electron spin resonance, superconducting quantum interfering device (SQUID) and variable temperature NMR along with DFT calculations. TT and PP have closed-shell and singlet open-shell structures in their ground state, respectively, and possess high stability. Their biradical characteristics were found to be 0.50 and 0.64. The origin of the open-shell character of PP is related to the concomitant opening of two tetracenes with the recovering of two extra aromatic sextets and a small HOMO-LUMO energy gap (gap < 1.5 eV). Thanks to the high stability, thin film OFET devices could be fabricated. In TG-BC configuration PP shows remarkably high hole mobility of 1.4 cm 2 V −1 s −1 while TT exhibits a hole mobility of 0.77 cm 2 V −1 s −1. In configuration of BG-TC, ambipolar behaviors for both were obtained with hole and electron mobilities of 0.21 and 0.01 cm 2 V −1 s −1 for PP and 0.14 and 0.006 cm 2 V −1 s −1 for TT.
We report the synthesis and optoelectronic properties of TIPS‐peri‐pentacenopentacene (TIPS‐PPP), a vertical extension of TIPS‐pentacene (TIPS‐PEN) and a low‐band‐gap material with remarkable stability. We found the synthetic conditions to avoid the competition between 1,2‐ and 1,4‐addition of lithium acetylide on the large aromatic dione. The high stability of TIPS‐PPP is due to the peri‐fusion which increases the aromaticity by generating two localized aromatic sextets that are flanked with 2 diene fragments, similar to two fused‐anthracenes. Like TIPS‐PEN, TIPS‐PPP shows the archetypal 2D brickwall motif in crystals with a larger transfer integral and smaller reorganization energy. The high mobility of up to 1 cm2 V−1 s−1 was obtained in an organic field‐effect transistor fabricated by a wet process. Also, TIPS‐PPP was used as a near‐infrared (NIR) emitter for NIR organic‐light‐emitting‐diode devices resulting in a high external quantum efficiency at 800 nm.
We report the synthesis and optoelectronic properties of TIPS-peri-pentacenopentacene (TIPS-PPP), av ertical extension of TIPS-pentacene (TIPS-PEN)a nd al ow-band-gap material with remarkable stability.W ef ound the synthetic conditions to avoid the competition between 1,2-and 1,4addition of lithium acetylide on the large aromatic dione.The high stability of TIPS-PPP is due to the peri-fusion which increases the aromaticity by generating two localized aromatic sextets that are flanked with 2d iene fragments,s imilar to two fused-anthracenes.L ike TIPS-PEN, TIPS-PPP shows the archetypal 2D brickwall motif in crystals with alarger transfer integral and smaller reorganization energy.T he high mobility of up to 1cm 2 V À1 s À1 was obtained in an organic field-effect transistor fabricated by aw et process.A lso, TIPS-PPP was used as an ear-infrared (NIR) emitter for NIR organic-lightemitting-diode devices resulting in ah igh external quantum efficiency at 800 nm.
Biradicaloid compounds with an open-shell ground state have been the subject of intense research in the past decade. Although diindenoacenes are one of the most developed families, only few examples...
The benchmark of soluble organic semiconductors based on acenes is the 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN). However TIPS-PEN still suffers from photoinduced oxidation due to its low degree of aromaticity. Increasing the aromaticity while keeping similar optical and electrochemical properties as well as a shape suitable for good hole transport can be achieved with two-dimensional polycyclic aromatic hydrocarbons (2D-PAHs). Herein, we present an efficient synthesis and characterization of bistetracene derivatives that exhibit a band gap up to 1.71 eV and an increased stability up to 21 times compared to TIPS-PEN and mobility over 0.1 cm V s in solution-processed organic field-effect transistors. Based on simple structural consideration, the high stability is attributed to the aromaticity of the bistetracene which is comparable to an anthrancene along each tetracene. According to Clar's sextet rule, the bistetracene should be best regarded as two anthracenes fused at the face bridged by two ethylenic spacers. The synthesis path paves the way towards the preparation of ambipolar and/or longer 2D-PAHs such as bispentacenes and could give rise to organic semiconductors with interesting properties.
Two tetraceno[2,1,12,11-opqra]tetracene-extended tetrathia-fulvalenes were prepared and found to undergo reversible conversion into their planar polycyclic aromatic hydrocarbons (PAHs) upon electrochemical oxidation - at potentials probing the best valence bond representations.
DedicatedtoProf. FranÅoisDiederich on the occasion of his retirement Abstract: As et of fully-conjugated indenofluorenes has been synthesized and confirmed by solid-states tructure analysis. The indeno[2,1-c]fluorenes and their benzo-fused analogues all contain the antiaromatic as-indacene core. The molecules possess high electron affinities and show ab road absorption that reaches into the near-IR region of the electromagnetic spectrum.A ll of the featured compounds rever-sibly accept up to two electrons as revealed by cyclic voltammetry.A nalysis of molecule tropicity using NICS-XY scan calculations shows that, while the as-indacene core is less paratropict han s-indacene, benz[a]-annulation further reduces the antiaromaticity of the core. Antiaromatic strength of the as-indacene core can also be tuned by the position of fusion of additional arenes on the outer rings.
The extension of the pyrene ring from dimethyl 2,2'-(pyrene-1,6-diyl)dibenzoate derivatives by an intramolecular Friedel-Crafts acylation can be realized in an efficient and regioselective manner using triflic acid as proton source. Naphtho-tetracenone derivatives are obtained in high yields at room temperature while Bis-tetracene-diones are prepared upon heating. Both products display interesting fluorescence properties in the visible range with quantum yields varying from 50 to 60 %.
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