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

• Acenes are composed of linearly annellated benzene rings. Compared to their non-linearly annellated isomers, acenes possess smaller HOMO–LUMO gaps. This is attributed to their novel electronic structures which manifest that no more than one benzene ring can be drawn with a full aromatic sextet in any

• smaller HOMO–LUMO gaps. Isoacenofurans are composed of linearly annellated benzene rings that terminate with a furan ring. Isoacenofurans and acenes possess isoelectronic π-systems when the total number of rings is the same. Unlike acenes, none of the 6-membered rings in an isoacenofuran possess an

• . 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

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• and charge injection/extraction processes [7]. The additional merits of H-bonding designs in organic optoelectronic materials include higher thermal stability, synergistic stabilizing effects with π-stacking interactions, etc. [8]. Acenes and N-heteroacenes are two prominent π-conjugated scaffolds for

• . reported the synthesis, electronic characteristics, and liquid-crystalline properties of several electron-accepting acenes, including 1,4-dihydropyrazinoquinoxalinediones (Figure 1b). The incorporation of strong hydrogen-bonding interactions facilitated the formation of a highly ordered liquid-crystalline

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

• compounds, thus limiting their final purity, and restricts the processing techniques to physical vapor deposition. In addition, some π-CPCs appear to be sensitive to oxidative and/or photolytic degradation, which hinders their use in devices under ambient conditions. The case of acenes is representative of

• this situation. Acenes are a class of aromatic compounds composed of linearly fused benzene rings, which can be regarded as the narrowest graphene nanoribbons. They are highly promising p-type organic semiconductors, but suffer from insolubility and instability leading to dimerization and/or

• retrocycloadditions were further exploited from bridged bicyclo[2.2.2]octadiene solubilizing fragments to generate (hetero)acenes and larger bidimensional π-CPCs such as extended porphyrin derivatives with the concomitant release of ethylene (Scheme 1, bottom left) [9][11][15]. It is important to note here that in

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• for use in cutting-edge technologies. In particular, acenes, a subgroup of polycyclic aromatic compounds, are sought-after synthetic targets due to their remarkable optoelectronic properties which stem from their π-conjugation and planar structure. Despite all these promising characteristics, acenes

• antiaromatic four-membered ring. This review gives a brief overview of the methods used in the synthesis of biphenylenes and summarizes the recent studies on biphenylene-containing polycyclic conjugated compounds, elucidating their synthesis, and distinct optoelectronic properties. Keywords: acenes

• ; biphenylene; [N]phenylenes; polycyclic aromatic compounds; Introduction Acenes represent an important category of carbon-rich polycyclic aromatic hydrocarbons (PAHs) characterized by the presence of linearly fused benzene rings [1][2]. Investigating the electronic properties of acenes is essential for

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

• could be expected that the extension of the hydrophobic cavity by the combined methylation and “dimerization” may improve the binding potential towards such substrates even more. Linear polycyclic aromatic hydrocarbons (acenes) and their derivatives are good organic semiconductors and show interesting

• 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

• of poor solubility and mainly because of their low stability [18][19][20]. Moreover, a general method for the preparation of long acenes have been recently published [21]. According to the literature [22], the only reasonable solution to overcome the solubility and stability problems is

Electrochemical and spectroscopic properties of twisted dibenzo[g,p]chrysene derivatives

• Tomoya Imai,
• Ryuhei Akasaka,
• Naruhiro Yoshida,
• Toru Amaya and
• Tetsuo Iwasawa

Beilstein J. Org. Chem. 2022, 18, 963–971, doi:10.3762/bjoc.18.96

• , a strong photoluminescence was observed for DBC-H and DBC-Si. Keywords: DFT calculation; dibenzo[g,p]chrysenes; fluorescent compounds; oxidation; polycyclic aromatic hydrocarbon (PAH); twisted acenes; Introduction Polycyclic aromatic hydrocarbons (PAHs) have attracted interest as potential

• acenes are an interesting class of compounds due to their characteristic structures and conjugation systems [23][24][25]. Dibenzo[g,p]chrysene (DBC), which consists of a twisted naphthalene core with four fused benzene rings (Figure 1a) [26], is a promising framework for serving as organic semiconductors

• . Conversely, the LUMO level of the highly twisted DBC-H(56°)-2 was 0.05 eV lower than the less twisted DBC-H. As a result, the HOMO–LUMO gap of DBC-H(56°)-2 becomes smaller than that of DBC-H. This is consistent with the trend reported for twisted acenes [57]. The conformational effect of the MeO group was

Synthesis, structural characterization, and optical properties of benzo[f]naphtho[2,3-b]phosphoindoles

• Mio Matsumura,
• Takahiro Teramoto,
• Masato Kawakubo,
• Masatoshi Kawahata,
• Yuki Murata,
• Kentaro Yamaguchi,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2021, 17, 671–677, doi:10.3762/bjoc.17.56

• Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Research Initiative for Supra-Materials (RISM), Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan 10.3762/bjoc.17.56 Abstract Phosphole-fused π-conjugated acenes have been

Helicene synthesis by Brønsted acid-catalyzed cycloaromatization in HFIP [(CF₃)₂CHOH]

• Takeshi Fujita,
• Noriaki Shoji,
• Nao Yoshikawa and
• Junji Ichikawa

Beilstein J. Org. Chem. 2021, 17, 396–403, doi:10.3762/bjoc.17.35

• ], which are rarely found in planar aromatic hydrocarbons (e.g., acenes and phenacenes). Therefore, the wide breadth of applications of helicenes as organic optical materials make them interesting synthetic targets. Although several methods for the synthesis of helicenes have been reported, there are still

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

• HOMO–LUMO gap of 6,13-difluoropentacene was determined via UV–vis spectroscopy and compared to other fluorinated pentacenes. Keywords: fluorinated acenes; Friedel–Crafts reaction; ortho-lithiation; synthesis; Introduction Pentacenes are a prototype in the field of organic semiconductors due to their

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• multiarylated anthraquinone derivatives [16][17][18][19][20]. Using this method, we have synthesized various π-extended aromatic compounds such as multiarylated acenes [16][18][20], dibenzo[h,rst]pentaphenes and dibenzo[fg,qr]pentacenes [19]. In the course of our reaction development, it was found that an

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• condensed (hetero)acenes from rather simple polyarenes, in which several aromatic units are connected with each other through appropriate linker units [2][3][4][5][6][7][8][9][10][11]. Recently, we reported the synthesis and optical properties of a series of furan-fused aromatics via the formal

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• used to architect various ring-fused S-heteroacenes, which have been studied extensively [8][9][10] due to their better characteristics compared to heteroatom-free acenes. For instance, S-heteroacenes have a better oxidation stability due to lower-lying HOMO levels, as well as more efficient charge

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• ; heteroacene; selenophene; Introduction In recent years, great interest has been devoted to the development of new π-conjugated polycyclic molecules, in particular to polycyclic aromatic hydrocarbons (PAH) such as acenes [1], phenacenes [2], or nanographenes [3]. Corresponding heteroacenes incorporating

Molecular recognition using tetralactam macrocycles with parallel aromatic sidewalls

• Dong-Hao Li and
• Bradley D. Smith

Beilstein J. Org. Chem. 2019, 15, 1086–1095, doi:10.3762/bjoc.15.105

• enables them to be effective hosts for a wide range of guest molecules including organic biscarbonyl derivatives, near-infrared dyes, acenes, precious metal halide complexes, trimethylammonium ion-pairs, and saccharides. Keywords: fluorescent dye; host–guest chemistry; hydrogen bonding; hydrophobic

• flexibility of the macrocyclic tetralactams enables them to be effective hosts for a wide range of guest molecules including organic biscarbonyl derivatives, near-infrared dyes, acenes, precious metal halide complexes, trimethylammonium ion pairs, and saccharides. Because of this versatility, macrocyclic

Adhesion, forces and the stability of interfaces

• Robin Guttmann,
• Johannes Hoja,
• Christoph Lechner,
• Reinhard J. Maurer and
• Alexander F. Sax

Beilstein J. Org. Chem. 2019, 15, 106–129, doi:10.3762/bjoc.15.12

Steric “attraction”: not by dispersion alone

• Ganna Gryn’ova and
• Clémence Corminboeuf

Beilstein J. Org. Chem. 2018, 14, 1482–1490, doi:10.3762/bjoc.14.125

• cages [10]. Intermolecular interactions in hydrocarbons are also subject to significant dispersion contribution. In the unsaturated systems, from benzene dimer to higher acenes and, ultimately, graphenes, dispersion is increasingly the key force behind the π–π stacking interactions [11]. Large and flat

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• elaborated protocol is the only one up to date that enables synthesis of ortho-formyl-protected diarylmethane derivatives under reductive conditions. The latter may be used as key substrates both for the synthesis of biologically active diarylmethanes or for the synthesis of (hetero)acenes via the Bradsher

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• . Hetero aromatic aldehydes also worked efficiently to give the products in 96–98% yield [158]. Acenes and hetero-acenes have important applications in material development such as semiconductors, photovoltaic cells, field effect transistors, organic light emitting diodes, etc. [159][160][161][162][163

• ][164][165]. Moreover, the literature known methods adopted mainly harsh reaction condition and they are generally found to be low yielding [166][167][168]. Recently, Mal and co-workers reported mechanochemical synthesis of hetero-acenes from 1,2-dicarbonyl compounds and 1,2-diaminoarenes using 10 mol

Anionic sigmatropic-electrocyclic-Chugaev cascades: accessing 12-aryl-5-(methylthiocarbonylthio)tetracenes and a related anthra[2,3-b]thiophene

• Laurence Burroughs,
• John Ritchie,
• Mkhethwa Ngwenya,
• Dilfaraz Khan,
• William Lewis and
• Simon Woodward

Beilstein J. Org. Chem. 2015, 11, 273–279, doi:10.3762/bjoc.11.31

• in the vanguard of new field effect and other organic electronic based devices [1][2]. Although the simple parent acenes have useful device characteristics in their own right, it is often desirable to be able to tune this performance by use of suitable substituted variants [3][4]. Unfortunately

• rapid access to mono sulfur-containing acenes, and is applicable to small scale library synthesis. Only low cost reagents are required and otherwise difficult to synthesise hindered 1,3,4,12-tetrasubstituted species can be made straightforwardly. Use of bis-allene intermediates 2 for rapid access to

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

• to chemically assemble small organic molecules for such applications, clever design and synthesis have rapidly offered new materials for the nascent era of molecular electronic [4][5][6][7][8][9][10][11]. Prominent p-type organic semiconductors include substituted acenes in general [12][13][14][15

• (Figure 1b). To determine the influence of aryl substitution, the obtained pentacenes have been studied by a variety of spectroscopic characterization methods as well as X-ray crystallography of eight derivatives. The studies reported herein offer an opportunity to interpret various properties of acenes

• , drastically alters the solid-state arrangements of the acenes [30]. In certain cases, this leads to a 2D face-to-face “bricklayer” arrangement, which can potentially facilitate charge transport in an electric device by several orders of magnitude [49]. With the understanding that the solid-state packing 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

• distribution of partial charges are readily available. In contrast to most other acenes, these compounds crystallize with a slipped-stack, brickwork-like packing which is mainly controlled by electrostatic interactions. This type of packing offers an advantage for organic semiconductors, because it allows more

• isotropic charge transport compared to the “herring bone” stacking observed for other acenes. Keywords: aromatic stacking; charge carrier transport; crystal design; electrostatic control; organic semiconductor; organo-fluorine; Introduction Within a very few years the first organic semiconductors have

• techniques [3]. High charge carrier mobilities are a particularly critical prerequisite for application in backplanes for OLED displays. The highest charge carrier mobilities in organic compounds have so far been reported for single crystals of small molecules [4], the “classics” among them being acenes such

Self-assembly and semiconductivity of an oligothiophene supergelator

• Pampa Pratihar,
• Suhrit Ghosh,
• Vladimir Stepanenko,
• Sameer Patwardhan,
• Ferdinand C. Grozema,
• Laurens D. A. Siebbeles and
• Frank Würthner

Beilstein J. Org. Chem. 2010, 6, 1070–1078, doi:10.3762/bjoc.6.122

• bisimides [10][11][12], acenes [13][14] and merocyanines [15][16] have been studied in recent years. Self-assembly of various oligothiophene derivatives have been extensively investigated on account of their semiconducting and optoelectronic properties [17]. Feringa and co-workers reported organogels based