Assembly strategy for thieno[3,2-b]thiophenes via a disulfide intermediate derived from 3-nitrothiophene-2,5-dicarboxylate

• Roman A. Irgashev

Beilstein J. Org. Chem. 2025, 21, 2489–2497, doi:10.3762/bjoc.21.191

• ) derivatives are a valuable class of fused heteroaromatic compounds characterized by rigid planar π-conjugated backbones that provide narrow band gaps, high charge carrier mobility, and intermolecular π–π stacking interactions, making them particularly attractive for the design of organic materials. Indeed

• developed for photothermal and photodynamic therapy, where their π-conjugated frameworks contribute to both imaging and therapeutic functions [19]. Some other TT-based compounds have been reported to inhibit specific carbonic anhydrase isoforms [20], protein tyrosine phosphatase 1B [21], as well as to act

Solar thermal fuels: azobenzene as a cyclic photon–heat transduction platform

• Jie Yan,
• Shaodong Sun,
• Minghao Wang and
• Si Wu

Beilstein J. Org. Chem. 2025, 21, 2036–2047, doi:10.3762/bjoc.21.159

• polymer solar thermal fuels Conjugated azobenzene polymer solar thermal fuels [47][48] utilize π-conjugated systems as templates for azobenzene chromophore photoisomerization, as schematically illustrated in Figure 4. Han et al. developed azobenzene-functionalized polydiacetylene-based solar thermal fuels

• [47], where the azobenzene moieties undergo reversible photoisomerization and thermally induced reverse isomerization, enabling "energy charging–discharging" cycles (Figure 4a). Under ultraviolet (UV) irradiation (254 nm), the closely packed diacetylene polymers undergo polymerization to form π

• -conjugated polydiacetylene structures, with an energy storage density reaching 243 J/g (Figure 4b). These azobenzene-functionalized polydiacetylenes exhibit structural analogy to azobenzene-modified carbon nanotubes and graphene in terms of photoresponsive behavior. Sert et al. combined electroactive and

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• ][21][22][23]. In addition to benzene-based systems, pyridine-embedded aza[1n]metacyclophanes have been synthesized by Wang [24]. Despite these advances, N-doped chiral macrocycles incorporating extended π-conjugated moieties remain largely underexplored. To date, only a few examples, carbazole-based

Transition-state aromaticity and its relationship with reactivity in pericyclic reactions

• Israel Fernández

Beilstein J. Org. Chem. 2025, 21, 1613–1626, doi:10.3762/bjoc.21.125

• to the preparation of triazaphospholes and triazaarsoles, π-conjugated species with potential applications in materials science due to their luminescent properties [98]. However, these heavier alkyne analogues are typically kinetically unstable, which limits their use as dipolarophiles. Despite that

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• structures, such as one-handed helical and propeller-shaped structures, can be constructed by folding the π-conjugated system using [2.2]paracyclophane as the chiral crossing unit, leading to circularly polarized luminescence (CPL) properties. Chiral cyclic dimers and trimers were synthesized using planar

• chiral [2.2]paracyclophane-containing enantiopure ribbon-shaped compounds as the chiral monomers. Unicursal π-conjugated systems were folded at the [2.2]paracyclophane units, and exhibited good photoluminescence quantum efficiencies and CPL anisotropy factors. Opposite chiroptical properties were

• luminescence (CPL) [22][23][24][25] with high photoluminescence (PL) quantum efficiency (ΦPL) and anisotropy. Additionally, the π-stacked structure of [2.2]paracyclophane can be applied at a crossing point. By folding the π-conjugated system using [2.2]paracyclophane as the chiral crossing unit, optically

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• formation between carbonyl and alkene units. Keywords: bathtub; chirality; cyclobisbiphenylenecarbonyl; figure-eight; Wittig reaction; Introduction Figure-eight π-conjugated molecules represent chiral macrocycles with a twisted crossover structure [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• – particularly those incorporating additional heteroatoms within the helical π-conjugated framework – remains lacking. This review addresses this gap by systematically summarizing recent advances (from the past five years) in the synthesis, structural modification, and chiroptical properties of nitrogen-doped

• for NIR optoelectronic applications. Building on this work, in 2025 the same group reported the synthesis of a stable N-heterotriangulene dimer (compound 30) bridged by a rigid π-conjugated [5]helicene [44]. This chiral dimer undergoes reversible stepwise oxidation to 30•+ and 302+, accompanied by

• units, as well as extending π-conjugated frameworks, are widely employed strategies for achieving longer-wavelength emission in optoelectronic materials. Inspired by the electronic configuration of borazine, boron has emerged as a valuable electron-accepting counterpart to electron-donating nitrogen in

Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes

• Bartłomiej Pigulski

Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99

• design beyond all-hexagon polycyclic aromatic hydrocarbons (PAHs). Among these, π-conjugated scaffolds featuring embedded azulene units have gained considerable attention due to their unique optical and electronic properties. This review provides an overview of representative azulene-embedded

• ) can exhibit remarkably red-shifted absorption, even when incorporated into relatively small π-conjugated frameworks. Through careful molecular design – retaining the azulene-like electronic structure and promoting spatial separation of the HOMO and LUMO orbitals – it is possible to achieve

Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers

• Kenichi Kato,
• Tatsuki Hiroi,
• Seina Okada,
• Shunsuke Ohtani and
• Tomoki Ogoshi

Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95

• , Kanazawa, 920-1192, Japan 10.3762/bjoc.21.95 Abstract Development of three-dimensional (3D) building blocks is a key to change tight molecular assemblies of rigid π-conjugated planes into organic functional materials endowed with molecular-size cavities. To increase the diversity of available 3D building

• go beyond common organic functional materials composed of rigid π-conjugated planes and flexible peripheral substituents. Because larger π-conjugated planes mostly display low solubility and dense packing due to the π–π stacking and CH–π interactions, surrounding alkyl and other flexible moieties are

Recent advances in the electrochemical synthesis of organophosphorus compounds

• Babak Kaboudin,
• Milad Behroozi,
• Sepideh Sadighi and
• Fatemeh Asgharzadeh

Beilstein J. Org. Chem. 2025, 21, 770–797, doi:10.3762/bjoc.21.61

• process for synthesizing π-conjugated phosphonium salts at room temperature in catalyst/oxidant-free conditions. The reaction was carried out in an undivided cell using a platinum plate as the anode and platinum wire as the cathode at a constant current of 4 mA. The reaction proceeded via an anodic

Oxidation of [3]naphthylenes to cations and dications converts local paratropicity into global diatropicity

• Abel Cárdenas,
• Zexin Jin,
• Yong Ni,
• Jishan Wu,
• Yan Xia,
• Francisco Javier Ramírez and
• Juan Casado

Beilstein J. Org. Chem. 2025, 21, 277–285, doi:10.3762/bjoc.21.20

• ], including [3]naphthylenes 1 and 2 in Figure 1 [18]. They are endowed by three aromatic naphthalenoid (NAP) moieties, fused by two antiaromatic CBD ones in two different topologies. Structurally, these polycyclic π-conjugated hydrocarbons consist of eight fused rings and thirty π-electrons. In this work, we

• angular dication preserves the aromatic–antiaromatic confinement of the neutral and radical cation species. This is an unusual case scarcely described in 1D π-conjugated polycyclic molecules, where the stability of the linear dication is attributed to the formation of a global ring current. Experimental

• ] reported a stable heptacene dication in concentrated sulfuric acid, a stability attributed to the intermolecular Coulomb repulsion between the charged molecules, which prevents the dimerization of the acene. This exciting finding suggests possible modes of kinetic stabilization of oxidized species of π

Synthesis, characterization, and photophysical properties of novel 9‑phenyl-9-phosphafluorene oxide derivatives

• Shuxian Qiu,
• Duan Dong,
• Jiahui Li,
• Huiting Wen,
• Jinpeng Li,
• Yu Yang,
• Shengxian Zhai and
• Xingyuan Gao

Beilstein J. Org. Chem. 2024, 20, 3299–3305, doi:10.3762/bjoc.20.274

• studies, revealing that their photophysical behavior can be affected by the different substituents in the donor carbazole group. Keywords: carbazole; D−A−D type; noble-metal-free system; 9‑phenyl-9-phosphafluorene oxide; photophysical properties; Introduction π-Conjugated molecular materials containing

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

• Yang Chen,
• Jiao He,
• Hang Lin,
• Hai-Feng Wang,
• Ping Hu,
• Bi-Qin Wang,
• Ke-Qing Zhao and
• Bertrand Donnio

Beilstein J. Org. Chem. 2024, 20, 3263–3273, doi:10.3762/bjoc.20.270

• an effective tool for the design of liquid crystalline materials [3][4][5][6][7][8]. Rod-like liquid crystalline molecules with fluorine-substituted arenes are ubiquitous in the displays industry [12]. They are also gaining importance in the design of π-conjugated polycyclic aromatic discotic liquid

• increase their structural and functional diversity. In the modern organic synthetic tool-box, the fluoroarene nucleophilc substitution (SNFAr) reaction possesses many outstanding advantages in the synthesis of π-conjugated functional molecules: the electrophiles are plentiful and include cheaply available

• new, structurally-related series of π-conjugated aromatic compounds (Figure 1) based on a simple triphenylene core and evaluating the mesomorphic and optical properties. Specifically 1,2,4-trifluoro-6,7,10,11-tetraalkoxy-3-(perfluorophenyl)triphenylenes (Fn, Figure 1), bearing a terminal fluoroarene

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• these are porphyrins, chlorins, porphyrazines, bacteriochlorins, corroles, calix[4]pyrroles, and phthalocyanines. One of the major differences between these pyrrolic macrocycles is how the adjacent pyrrole rings are connected. The most widely studied tetrapyrrolic macrocycles are typically π‐conjugated

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• (pyridostilbenes, azastilbenes, styrylpyridines or azinylarylethenes) are an important class. Uniquely, stilbazole provides a universal framework (exclusive matrix) for the design of donor–π–acceptor (D–π–A) molecules [14][15]. It has a branched π-conjugated system, in which the aromatic ring acts as a donor and

• , full-color fluorescence of organic molecules is achieved by extending π-conjugated systems or by introducing combinations of donor and acceptor groups, which changes the electronic properties and consequently the emission spectra [35][36][37][38][39][40][41][42][43][44]. This approach is synthetically

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• systems to determine if this drawback can be overcome while maintaining the favourable properties of PDIs. Violanthrones are a class of materials featuring a large π-conjugated system composed of nine fused benzene rings with two carbonyl groups, in the 5 and 10 positions (Figure 1). The related

• structural features of violanthrones suggest that these materials may possess similar charge transport, optical and electrochemical properties to those of PDIs. However, the larger π-conjugated system of violanthrone, along with the two carbonyl groups, increases the possibility of stronger π–π

• that molecular tailoring of violanthrone is simple and feasible. We have synthesised three soluble violanthrone derivatives with different side chains and found that due to the introduction of the electron-deficient dicyanomethylene groups, along with the extended π-conjugated framework, all compounds

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

• Ruben Manuel Figueira de Abreu,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• , bathochromically shifted absorption and emission spectra with elevated extinction coefficients and quantum yields up to 71%. Further studies will be directed to the synthesis to polycyclic, π-conjugated uracil derivatives. Experimental General information Nuclear magnetic resonance spectra (1H/13C/19F NMR) were

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• diphenylacetylene structure as the π-conjugated core. As a part of our research projects, we have begun to explore diphenylacetylene-based luminescent molecules despite diphenylacetylene not exhibiting fluorescence at room temperature because it undergoes a πσ* excited state that rapidly forms a trans-bend

Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186

• functional materials for diverse uses [1][5][6][7]. Notably, to synthesize this vital heptacyclic star‐shaped π‐conjugated polyarene framework, only a single acid-mediated co-trimerization step is required from an inexpensive and commercially available starting material, namely 1-indanone [8]. It is to be

Hetero-polycyclic aromatic systems: A data-driven investigation of structure–property relationships

• Sabyasachi Chakraborty,
• Eduardo Mayo Yanes and
• Renana Gershoni-Poranne

Beilstein J. Org. Chem. 2024, 20, 1817–1830, doi:10.3762/bjoc.20.160

• on a range of electronic molecular properties of PASs. Keywords: computational chemistry; database; dataset; π-conjugated; polycyclic aromatic hydrocarbons; polycyclic aromatic systems; Introduction Polycyclic aromatic systems (PASs) – molecules made up of fused aromatic rings – are among the most

• composition The incorporation of different atoms is a well-known strategy for modulating the frontier molecular orbitals of π-conjugated systems. For example, it has been empirically observed, and can also be rationalized with molecular orbitals-based considerations, that lone-pair bearing heteroatoms such as

Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• . Instead, for o-anisidine and aniline, the lone pair electrons were delocalized into the antibonding NBO (i.e., BD*) with a smaller interaction energy of ≈26 kcal⋅mol−1. In other words, as shown in Scheme 8, the lone electron pair present at the nitrogen atom was delocalized into the π-conjugated system

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

• 73019, United States 10.3762/bjoc.20.92 Abstract Presented here is the design, synthesis, and study of a variety of novel hydrogen-bonding-capable π-conjugated N-heteroacenes, 1,4-dihydropyrazino[2,3-b]quinoxaline-2,3-diones (DPQDs). The DPQDs were accessed from the corresponding weakly hydrogen

• 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

• supramolecular approach in the solar cell arena. π-Conjugated linear and branched oligothiophenes appended to H-bonding capable phthalhydrazide (PH) were prepared [14][15]. These compounds demonstrated a power conversion efficiency (PCE) twice as high as that of non-hydrogen bonding controls upon photovoltaic

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• complex was also formed by mixing a 1:1 mixture of radical cations of [5]- and [10]CPP, [5]CPP•+ (SbCl6−) and [10]CPP•+ (SbCl6−), respectively (Figure 1c, path C). The observed results can be explained by two reasons; one is the oxidation potentials of [10]- and [5]CPPs. In sharp contrast to linear π

• -conjugated molecules, CPPs with shorter conjugations have lower oxidation potentials than larger CPPs, and the first and the second oxidation potentials of [5]CPP are by 0.69 and 0.51 V lower than those of [10]CPP, respectively [43]. The other is the stability of the CPP dications. Since the dications are

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

• , Nara 630-0192, Japan Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan 10.3762/bjoc.20.30 Abstract The “precursor approach” has proved particularly valuable for the preparation of insoluble and unstable π-conjugated polycyclic compounds (π-CPCs), which cannot be

• promising synthetic tool to access a wider variety of π-conjugated polycyclic structures and thus to expand the potentialities of the “precursor approach” for further improvements of molecular materials’ performances. This review gives an overview of synthetic strategies towards π-CPCs involving the

• ultimate elimination of chalcogen fragments upon thermal activation, photoirradiation and electron exchange. Keywords: arenes; chalcogens; extrusion; fused-ring systems; precursor approach; Introduction π-Conjugated polycyclic compounds (π-CPCs), including polycyclic aromatic hydrocarbons and their

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• triphenylamine as donor and dimesitylboron as acceptor linked through a thieno[3,2-b]thiophene (TT) π-conjugated linker bearing a 4-MeOPh group, was designed, synthesized, and fabricated as an emitter via a solution process for an organic light-emitting diode (OLED) application. DMB-TT-TPA (8) exhibited

• layers are composed of various aromatic π-conjugated small molecules/polymers including thiophene, anthracene, carbazole, and triphenylamine [9][10][11][12][13]. Thienothiophenes are two annulated thiophene rings having four isomers, among which the most widely used isomer is thieno[3,2-b]thiophene (TT

• (OFETs) [26][27][28], capacitors [29][30], hybrid films [31], and photosensitizers [32][33][34]. Another important π-conjugated unit is triphenylamine (TPA), having an ionization potential of 6.80 eV, which is lower compared to many other organic cores, thus providing a strong electron-donating ability