Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• aromatic sextet in any neutral, closed-shell resonance form (Figure 2). Thus, compared to the corresponding acene, an isoacenofuran could possess a more highly delocalized π-system and an even smaller HOMO–LUMO gap. For example, consider pentacene and isotetracenofuran. Pentacene can be drawn in several

• . However, calculations indicate that the center ring of pentacene and other acenes is the most aromatic [2] and therefore resonance form P3 of Figure 1 is most significant. By contrast, isotetracenofuran and other isoacenofurans can only be drawn in one neutral, closed-shell resonance form in which only

• the corresponding isobenzofurans to 3.05 and 3.65 eV, respectively. These groups provide for expanded delocalization of π-electron density outside the isobenzofuran core. Phenylthio substituents have also been shown to impart considerable photooxidative resistance to pentacene [5]. The incorporation

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• introduced by Herwig and Müllen as early as in 1996 for pentacene, which was ultimately obtained in a thin-film by a thermally-activated retro-Diels–Alder reaction from a tailor-made tetrachlorobenzene-pentacene soluble adduct (Scheme 1, top left) [13][14]. Over the years, thermally-induced

• release of two CO molecules (Scheme 1, top right). After a proof of concept on pentacene with soluble precursors including a bicyclo[2.2.2]octane-2,3-dione framework [20][21], α-diketones were intensely exploited as soluble photoprecursors for the synthesis of acenes of increasing length up to undecacene

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

• Kan Tang,
• Megan R. Brown,
• Chad Risko,
• Melissa K. Gish,
• Garry Rumbles,
• Phuc H. Pham,
• Oana R. Luca,
• Stephen Barlow and
• Seth R. Marder

Beilstein J. Org. Chem. 2023, 19, 1912–1922, doi:10.3762/bjoc.19.142

• for the doping of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene, E1/20/− = −1.45 V, kET ≈ 0.15 M−1s−1) by (Cyc-DMBI)2 [18], consistent with the differences in the reduction potentials between BnBr and TIPS-pentacene. The observation of the “cleavage-first” mechanism for (N-DMBI)2 and not

• for (Cyc-DMBI)2 is consistent with DFT estimates of bond dissociation energies for these two dimers (ΔUdiss = 163 and 210 kJ mol−1, respectively [18][44]) and with their reactivity towards TIPS-pentacene [18][39]. Impact of photoexcitation The absorptivities, ε, of (N-DMBI)2 and (Cyc-DMBI)2 at 365 nm

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• 1g2 exhibit weaker bonds than 1e2 and 1h2 and thus react with 6,13-bis(triisopropylsilylethynyl)pentacene (VII) via a “cleavage-first” pathway, while 1e2 and 1h2 react only via “electron-transfer-first”. 1h2 exhibits the most cathodic E(12•+/12) value of the dimers considered here and, therefore

• PC61BM (VI, Figure 7) and that of the 12 derivatives with 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene, VII, Figure 7), since we have previously found that these dopant class/SC combinations often react on a timescale suitable for monitoring using UV–vis–NIR spectroscopy (1H derivatives do

• reactions of the dimers with TIPS-pentacene (VII) follow a more complex pattern: examples with Y = cyclohexyl react solely via an “electron-transfer-first” mechanism, consistent with a relatively strongly bonded dimer, whereas Y = 4-(dimethylamino)phenyl derivatives also react by a “cleavage-first

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• solubility decreases with the increased number of aromatic rings in a molecule [18]. Pentacene with five conjugated aromatic rings has been extensively investigated; however, it is quite challenging to investigate the spectral and electrical properties of acenes with a number of rings higher than 6 because

• might be achieved by a supramolecular interaction with a suitable host. Our initial plan was to enhance the solubility of higher acenes by the complexation with CDs. However, linear acenes with more aromatic rings (such as pentacene or heptacene) are, in addition to their poor solubility, also quite

• pentacene and other larger linear acenes if we would achieve some success with it. In this work, we report on the efficient synthesis of new cyclodextrin supramolecular hosts based on selectively methylated β-CD derivatives and their dimers; moreover, we compare their effectiveness in the solubilization of

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• significant effect on the molecular shape, is fluorination [5]. Suzuki et al. showed in 2004 the strong effect of perfluorination on the electronic properties [6]. While unsubstituted pentacene (1, PEN, Figure 1) is known to be a p-type semiconductor, the perfluorinated counterpart perfluoropentacene (2, PFP

• -positions resulted in a larger HOMO–LUMO gap compared to PEN, while PFP showed a smaller gap than PEN. Another example for a partially fluorinated pentacene is the F6PEN 4 [9]. Its unilateral substitution pattern leads to a disctinct electronic structure and a criss-cross packing motif, unlike the

• -difluoroanthracene. This strategy could be applicable for the synthesis of differently substituted 6,13-difluoropentacenes as well. Structures of pentacene and fluorinated pentacenes. UV–vis spectrum of F2PEN 5 in CH2Cl2. Retrosynthetic analysis of F2PEN 5. Synthesis of F2PEN 5. Decomposition of diol 13 in solution

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• pentacene, as it, along with numerous other acene derivatives, has been substituted with trialkylsilylethynyl groups of varying size to study the effect on the solid state packing in single crystals [17]. This was shown to have a large effect on the OFET performance as slight changes in the geometry can

Aryl substitution of pentacenes

• Andreas R. Waterloo,
• Anna-Chiara Sale,
• Dan Lehnherr,
• Frank Hampel and
• Rik R. Tykwinski

Beilstein J. Org. Chem. 2014, 10, 1692–1705, doi:10.3762/bjoc.10.178

• Alberta, Edmonton, AB T6G 2G2, Canada 10.3762/bjoc.10.178 Abstract A series of 11 new pentacene derivatives has been synthesized, with unsymmetrical substitution based on a trialkylsilylethynyl group at the 6-position and various aryl groups appended to the 13-position. The electronic and physical

• properties of the new pentacene chromophores have been analyzed by UV–vis spectroscopy (solution and thin films), thermoanalytical methods (DSC and TGA), cyclic voltammetry, as well as X-ray crystallography (for 8 derivatives). X-ray crystallography has been specifically used to study the influence of

• unsymmetrical substitution on the solid-state packing of the pentacene derivatives. The obtained results add to our ability to better predict substitution patterns that might be helpful for designing new semiconductors for use in solid-state devices. Keywords: carbon-nanomaterials; organic semiconductor

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• under a red laser line exposure at 635 nm. This result was very important as cationic polymerization in these irradiation conditions was not possible previously. Changing Vi or the anthracene derivative for a hydrocarbon (e.g. pyrene, naphthacene, pentacene) allows a tunable absorption of the system

• recently achieved in FRP for the first time [54][55]: they involve hydrocarbon derivatives (e.g., pyrene, naphtacene, pentacene), an amine (e.g., ethyl dimethylaminobenzoate) and an alkyl halide (e.g., phenacyl bromide); the mechanism is similar to that shown in Scheme 12. As above, a tunable absorption of

Crystal design using multipolar electrostatic interactions: A concept study for organic electronics

• Peer Kirsch,
• Qiong Tong and
• Harald Untenecker

Beilstein J. Org. Chem. 2013, 9, 2367–2373, doi:10.3762/bjoc.9.272

• as pentacene [5], which act as p-type semiconductors. However, acenes in the crystalline state tend to form slightly tilted molecular stacks (“herring bone” pattern), which is resulting in a strong directional anisotropy for the charge carrier mobility along the stacking direction. Charge carrier

• experimentally observed charge carrier mobilities, e.g., in pentacene based OFETs, remain far below the theoretically predicted limit of several tens of cm2·V−1s−1 [8]. In order to overcome this obstacle, it would be ideal to have acene-like organic semiconductors which pack in the crystal not in one-dimensional

• stacks but in a brickwork-like pattern with two-dimensional overlap. This has been very efficiently realized by Anthony et al. for pentacene derivatives by attaching sterically demanding trialkylsilylacetylene moieties to the central ring, forcing the crystal into a brick-like arrangement (Figure 1) [9

Functionalization of anthracene: A selective route to brominated 1,4-anthraquinones

• Kiymet Berkil Akar,
• Osman Cakmak,
• Orhan Büyükgüngör and
• Ertan Sahin

Beilstein J. Org. Chem. 2011, 7, 1036–1045, doi:10.3762/bjoc.7.118

• suitable for the preparation of poly-substituted anthracene-1,4-dione and pentacene derivatives, in which the bromo substituents enable further functionalization. As a consequence, the studies revealed that the reactivity of the anthracene derivatives displays interesting selectivity and appears to provide

The efficient synthesis of dibenzo[d,d′]benzo[1,2-b:4,3-b′]dithiophene and cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one

• Zhihua Wang,
• Sheng Zhu,
• Jianwu Shi and
• Hua Wang

Beilstein J. Org. Chem. 2009, 5, No. 55, doi:10.3762/bjoc.5.55

• ], have been developed and tested as active semiconducting channels in OFET devices due to their structural resemblance to pentacene [14] which possesses very high field-effect mobility (~3.0 cm2 V−1 s−1) for OFET devices. However, one of the possible analogs, dibenzo[d,d′]benzo[1,2-b:4,3-b′]dithiophene