Organic electron transport materials

• Joseph Cameron and
• Peter J. Skabara

Beilstein J. Org. Chem. 2024, 20, 672–674, doi:10.3762/bjoc.20.60

• react with acceptors to produce reducing radical species, capable of reducing organic electron transport materials with a low electron affinity [4][5]. It is not only in modifying the molecular structure to improve the electron accepting ability that there is innovation in new organic electron transport

Enhanced reactivity of Li⁺@C₆₀ toward thermal [2 + 2] cycloaddition by encapsulated Li⁺ Lewis acid

• Hiroshi Ueno,
• Yu Yamazaki,
• Hiroshi Okada,
• Fuminori Misaizu,
• Ken Kokubo and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2024, 20, 653–660, doi:10.3762/bjoc.20.58

• yield of multiadducts compared to previously reported functionalizations of Li+@C60. The reason can be explained by the difference in electron-accepting ability between the monoadduct and pristine Li+@C60 investigated by cyclic voltammetry (Figure 5). Both products exhibited reversible first and second

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• absorption band and increases its intensity, while the presence of the EA (electron-accepting) substituents in these positions leads to a hypsochromic shift (Figure 5). On the contrary, the introduction of the ED substituents at the para (6,6')- or ortho (4,4')-positions to the electron-withdrawing C=O group

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• chromophores, wherein both electron-donating and electron-accepting substituents are incorporated into a π-electron-conjugated system, exhibit exceptional optical and electronic properties. They hold significant promise for applications in diverse fields, particularly materials science (specifically in

• cyclopentadiene moieties. TCBD 4, obtained through the [2 + 2] CA–RE reaction, continues to function as an electron-accepting alkene, as shown in Scheme 4. Subsequent [2 + 2] CA–RE reactions involving electron-rich alkynes yield tetracyano-1,3,5-hexatrienes (TCHTs). These reactions occur seamlessly in a one-pot

• , exhibiting enhanced electron-accepting capabilities, reacts with 1, it displays a more intricate reaction profile compared with that of 4 (Scheme 5). In addition to pentacyano-1,3-5-hexatriene (PCHT) compound 7, compounds 8 and 9 are generated [102]. This reaction is notably influenced by the different

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• other end of the IF core with electron-accepting moieties. An overview of general motifs targeted in this work is shown in Figure 1. Results and Discussion Synthesis The synthetic building blocks 1–8 used in this work are shown in Figure 2. The dione 1 and the ketones 4 and 6 were synthesized according

• ) expanding to ca. 680 nm. UV–vis absorption spectra of compounds 22, 23, 26, and 27 are depicted in Figure 5. By comparing donor–acceptor chromophores 22 and 23, it is observed that the RA moiety of DTF-IF-RA scaffold 23 induces a significant redshift, presumably due to the stronger electron-accepting

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions

• Karolis Leitonas,
• Brigita Vigante,
• Dmytro Volyniuk,
• Audrius Bucinskas,
• Pavels Dimitrijevs,
• Sindija Lapcinska,
• Pavel Arsenyan and
• Juozas Vidas Grazulevicius

Beilstein J. Org. Chem. 2023, 19, 1867–1880, doi:10.3762/bjoc.19.139

• values of Ered,onset are comparable with those of recently published compounds containing a dicyanopyridyl moiety as a central electron-accepting core [7]. In case of oxidation potentials (0.96 to 1.04 V) there is only a slight effect of the extended conjugation between the dicyanopyridyl moieties. The

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• . Photovoltaic performance of some of the reported materials is tabulated in Table 2. Quinoxalines as auxiliary acceptors and π-bridges Qx derivatives are highly attractive auxiliary acceptor and bridging materials for DSSCs. Their strong electron-accepting ability enables efficient electron injection and charge

• (PTFTs) with Qx54 copolymer showed ambipolar characteristics, while the PTFTs with Qx55 copolymer exhibited only n-type charge transport [57]. Kamble et al. designed and synthesized a series of eight new indolo[2,3-b]naphtho[2,3-f]quinoxaline derivatives (Qx56) by incorporating an electron-accepting

• in emission properties through mechanical stimulation offers exciting possibilities for optomechanical applications [68]. Another notable strategy, performed by Gupta and co-workers, involves fine-tuning of the electron accepting tendency of quinoxaline by incorporating various groups with different

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• device. Conclusion In summary, a new D–A–D-type fluorophore as a deep-red emitter has been designed and synthesized by exploiting a strong electron-accepting naphtho[2,3-c][1,2,5]thiadiazole (Nz) as A unit and N-(4-(1,2,2-triphenylvinyl)phenyl)carbazole as D unit. The integration of 4-(1,2,2

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• the energy ordering of the transient species involved in the TADF photophysical process, the electron-donating strength of the PTZ moiety is lowered by oxidation of the sulfur atom to the corresponding sulfoxide. Conversely, the electron-accepting capability of the NI unit is varied by introducing

• ability of the PTZ unit are unchanged, but the electron-accepting ability of the NI part is changed by introducing different aryl substituents at the nitrogen of the NI unit. We found the magnitude of the long-lived components of the TADF emitters is changed (Figure 4a–d). Interestingly, the dyads with

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• -space charge transfer (CT) in the rod-like donor–acceptor molecules showed that adding a stronger electron-donating group does not systematically induce an enhancement of the CT if a strong electron-accepting moiety is used, the latter tending to extract the electron from the conjugated chains rather

A novel spirocyclic scaffold accessed via tandem Claisen rearrangement/intramolecular oxa-Michael addition

• Anastasia Vepreva,
• Alexander Yanovich,
• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1649–1655, doi:10.3762/bjoc.18.177

• crystallography. In all other cases, only the pure syn diastereomer was isolated and characterized. The yields of spirocyclic products were generally modest to good over two steps. An electron-accepting group in the benzylidene portion (5j) or an N-benzyl substitution in the starting material (5g) lowered the

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• to poor solubility as a consequence of strong π–π interactions between the planar molecules [4]. Thus, attaching solubilising alkyl chains is necessary [5]. A common way to further decrease the HOMO–LUMO gap is attaching electron-donating and electron-accepting groups. Electron-rich units raise the

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• fluorescent materials containing Lewis basic nitrogen heterocycles are more likely to provide the feasible band gap modulation. The essence of such phenomenon originates from Lewis acid–base coordination and adducts, which highly depends on the electron-accepting property of the Lewis acids. This

• spectral red-shift of protonated conjugated polymers depended greatly on the strength of the Lewis acid (Figure 3a) [26]. Wang et al. modulated the electron-accepting strength of intramolecular charge transfer molecules by using different acids and obtained four distinctly different solid-state emission

Mechanochemical halogenation of unsymmetrically substituted azobenzenes

• Dajana Barišić,
• Mario Pajić,
• Ivan Halasz,
• Darko Babić and
• Manda Ćurić

Beilstein J. Org. Chem. 2022, 18, 680–687, doi:10.3762/bjoc.18.69

• Information File 1), in the case of NBS in the order: L3 > L4 > L5 >> L2 (Figures S3–S6 in Supporting Information File 1), and in the case of NIS in the order: L4 >> L5 for the succinimide products (Figure S7 in Supporting Information File 1). The presence of an electron-accepting substituent (NO2) at the

• azobenzenes with electron-donating substituents by electrophilic activation with NXS. Halogenation of azobenzenes with electron-accepting substituents Using the optimal parameters for the mechanochemical bromination and iodination of L1 [51], we investigated the halogenation of azobenzene substrates with

• electron-accepting substituents at the para position relative to the azo group: 4-chloroazobenzene (L6), 4-bromoazobenzene (L7), and 4-iodoazobenzene (L8) (Scheme 2 and Table 2). The synthetic protocols included milling the mixture of Ln/NXS/TsOH 1:1.2:0.5 equiv, 5 mol % Pd(OAc)2 precatalyst, and 15 µL

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• modified with various substituents in position 2 of the pyrimidine ring (Figure 1). For comparison, analysis of the TADF properties of a similar pyrimidine–carbazole emitter tCbz-mPYR is also included in this paper [29]. To enhance the electron-accepting character of the pyrimidine moiety some electron

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• the synthesis of the simple phenanthridine natural product trisphaeridine (3). Results and Discussion To investigate the scope and limitations of the reaction we initially opted to prepare a number of biaryl substrates possessing one aromatic electron accepting ring possessing a variety of methoxy

Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

• Viola Kolaříková,
• Markéta Rybáčková,
• Martin Svoboda and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

• rings, as described in reference [23], was not observed in our cases. The absence of ethene resulted in a significant decrease of the yield, which gradually decreased from R = H (2a) to R = Pr (2d). Further, the reaction was not sensitive to the presence of electron-accepting groups (R = COOMe, 2e) at

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• electron-accepting group coupled with various donors connected via a π-conjugation bridge [31][32][33]. Such dyes offer good NLO characteristics when compared to Disperse Red 1 as well as remarkable thermal stabilities with dissociation temperatures up to 300 °C [31][32]. Schiff bases containing an

• dyes containing a morpholinyl substituent (6 and 11) showed the least one. In addition, dyes 7 and 12 bear a proton-sensitive and electron-accepting pyridin-2-yl group and therefore, the absorption maxima for dyes 7 and 12 were lower than the maximum absorption wavelengths of the other dyes. The

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• corresponding trimethylsumanene 28 by means of nucleophilic oxidation using NaHMDS in the presence of molecular oxygen in DMF as the solvent (Scheme 8). It has been noticed from the literature that the directly linked π-conjugated systems act as promising electron-accepting materials because of their high LUMO

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• groups, such as electron-donating groups (4-Me: 2b, 4-OMe: 2e, and 3,4,5-trimethoxy: 2g), an electron-accepting group (4-NO2: 2l), and halogen atoms (4-F: 2m, 4-Cl: 2n, and 3-Br: 2s), respectively, at different positions on the aromatic ring displayed a good reactivity with malononitrile (8) and

• ), 3,4-dimethoxy (2f), 3-OH (2r), and 2-OH (2h), respectively, at different positions on the ring reacted well with ethyl acetoacetate (4) and urea (5) to produce the products, 7b–f in good isolated yields that ranged from 92–96% (Table 6, entries 2–6). A benzaldehyde derivative with an electron

• -accepting nitro group (2l) at the para position on the ring showed a good reactivity with ethyl acetoacetate (4) and urea (5) to afford the product 7g in an excellent isolated yield (94%, Table 6, entry 7). Halogen atoms at different positions on the ring of benzaldehyde derivatives (4-F: 2m, 4-Cl; 2n, and

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• . As shown in Figure 2, the LUMOs were located on the central electron-accepting quinazoline core and the phenyl unit, whereas the HOMOs were mainly localized on the electron-donating peripheral substituents. The HOMO energy values (Table 1) showed dependence on the donating characteristics of the

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• homoleptic or heteroleptic iridium(III) complexes were also reported in the construction of different OLEDs [10][11][12][13]. In OPVs, carbazole derivatives are frequently used as small molecule p-type (electron-donating) materials or electron-accepting (n-type) materials with a variety of donor–acceptor

Aryl-substituted acridanes as hosts for TADF-based OLEDs

• Naveen Masimukku,
• Dalius Gudeika,
• Oleksandr Bezvikonnyi,
• Ihor Syvorotka,
• Rasa Keruckiene,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

• the incorporation of electron-accepting and electron-donating moieties into the same molecule [18][19]. Conventional hosts such as 1,3-bis(N-carbazolyl)benzene (mCP) and bis[2-(diphenylphosphino)phenyl] ether oxide (DPEPO), are generally used as hosts in blue phosphorescent OLEDs, are also widely

• , Figure 4b, and Table 2). The IPPES values were further used for constructing OLED structures. The highest IPPES of 5.62 eV was obtained for compound 6 which contains electron-accepting fluorine atoms. The other compounds (3–5) demonstrated similar IPPES values mainly attributed to removing an electron

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• have shown that depending on the nature of the metal ion, the adopted position relative to the nitrogen and oxygen atoms may vary [82]. In 3a and 3b, the electron density of the phenolate oxygen atom was significantly reduced due to the direct conjugation with the strong electron-accepting

• Knoevenagel reaction from the readily available 5-formyl-substituted spirooxazine 1b. Due to the introduction of the electron-accepting quinolizinium(ethenyl) substituent, the spirooxazines 3a and 3b were photoinert towards the electrocyclic ring opening, thus constituting one of the rare cases of

• Phil M. Pithan Soren Steup Heiko Ihmels Department of Chemistry and Biology, University of Siegen and Center of Micro- and Nanochemistry and Engineering (Cμ), Adolf-Reichwein-Str. 2, 57068 Siegen, Germany 10.3762/bjoc.16.82 Abstract Two new spiroindolinonaphthoxazine derivatives with an electron

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

• Afef Mabrouki,
• Malek Fouzai,
• Armand Soldera,
• Abdelkader Kriaa and
• Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

• standard. The oxadiazole moieties are thought to be responsible for the majority of the dipole moment in the prepared compounds. Due to the electron-donating effect of alkyl groups in combination with the electron-accepting oxadiazole [35], the prepared hydrocarbon compounds are expected to perform dipole