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

• 7 in Figure 5), which consisted of the twisted A–π–D–π–A structure with N-(4-aminophenyl)carbazole (CzPA) as electron donor unit, pyridine as electron acceptor unit, and 9,9-dioctylfluorene (F) as π-conjugated linker [32]. Compound 7 showed remarkable dual-fluorescence properties when mixed with a

• pyridine electron acceptor with high electron affinity. Later in 2020, Wang’s group employed this host material, respectively mixed with two Lewis acids, namely BCF and B(C6H5)3, to construct highly luminescent exciplexes [29]. The PL spectra of the new emission system showed an obvious red-shift through

• the addition of suitable Lewis acids can lead to a dramatic red-shift in the absorption and emission of the mixtures. The electrophilic Lewis acid as electron acceptor frequently reacts with the nitrogen-containing heterocyclic conjugated molecules, ascribed to the charge redistributions of the

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• zero or even negative [12][13], while the SOC is as large as possible. One of the promising molecular design strategies to meet the above-mentioned criteria involves a highly twisted (D)n–(A)m (D: electron donor; A: electron acceptor) system, in which efficient intramolecular charge transfer (ICT

Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions

• Robin Schulte and
• Heiko Ihmels

Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41

• based on Diels–Alder reactions of cyclopentadiene with alkynes [13][14][15][16][17][18][19][20][21][22][23]. However, since this synthetic route requires strongly electrophilic alkynes, its scope is limited to products that contain at least one electron-acceptor group, such as an ester, a nitrile or

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• here as it is polar resonance stabilized and protonation leads to a drift in its electron density from the seven-membered ring to the five-membered ring generating a stable tropylium cation making it a strong electron acceptor during the intramolecular charge transfer (ICT) process. These protonated

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• PCE of the octyl analogue 25b increases to 6.4% [38]. A slight change in the substituent at the nitrogen atom and the introduction of electron-donor methyl or electron-acceptor cyano groups in the thiophene fragment can lead to a sharp deterioration of all characteristics (structure 26: efficiency

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• ) reduced in this way was reoxidized to Pd(II) by adding oxygen to the reaction mixture. Excellent enantiomeric excesses were observed (80–96% ee), but the conversions were low (13–83%), especially for boronic acids with electron-acceptor substituents (Table 31). The authors also proposed a plausible

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• , Chengdu 610100, China 10.3762/bjoc.17.67 Abstract The reversible, weak ground-state aggregate formed by dipole–dipole interactions between an electron donor and an electron acceptor is referred to as an electron-donor–acceptor (EDA) complex. Generally, upon light irradiation, the EDA complex turns into

• in line with the theme of green chemistry. This review discusses the synthetic reactions concerned with EDA complexes as well as the mechanisms that have been shown over the past five years. Keywords: EDA complex; electron acceptor; electron donor; radical; visible light; Review Introduction

• electron donor (D) and electron acceptor (A). The two components A and D may not absorb visible light, but the resulting EDA complex does [5]. If the EDA complex is irradiated with a particular wavelength (or heated to a corresponding temperature), the complex could be excited to the state [D, A]*, causing

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

• Information File 1. Parent compound 2 and borane complex 6 showed reversible reduction peaks (Ered = −1.25 and −1.26 V, respectively). Due to the increased electron–acceptor character of the phosphorus center, P-modification compounds 4 and 5 show a more positive oxidation potential than parent 2 [26

Exploring the possibility of using fluorine-involved non-conjugated electron-withdrawing groups for thermally activated delayed fluorescence emitters by TD-DFT calculation

• Dongyang Chen and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 210–223, doi:10.3762/bjoc.17.21

• to the greatest stabilization of the HOMO level at −5.89 eV. 2CzTRZ, and 2CzBP possess destabilized HOMO levels of −5.69 and −5.60 eV, respectively. The LUMOs of 2CzBN, 2CzTRZ and 2CzBP are each located on the bridging benzene ring and the electron-acceptor groups. The LUMO levels for 2CzBN, 2CzTRZ

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• + and crown ether, leading to the formation of cyclobutane in a high yield. D’Souza et al. constructed a photosynthetic triad 4 to mimic the photosynthetic reaction center [19]. A BODIPY, an ammonium-functionalized fullerene, and a zinc porphyrin functioned as the energy donor, electron acceptor, and

Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores

• Asitanga Ghosh

Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190

• carried out the photoreactions of 5,6-dibenzoyl-4-phenylbicyclo[2.2.2]oct-5-en-2-one (7a) and 5,6-dibenzoyl-4-isopropenylbicyclo-[2.2.2]oct-5-en-2-one (7b) in detail (Figure 2). Both of the molecules contain electron-acceptor groups like phenyl and isopropenyl at its bridgehead position (C-4) and these

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• photocatalysts interact with organic molecules via three main pathways: electron transfer (ET), EnT, and atom transfer (AT). In the first case (Scheme 1, box 1), the excited photocatalyst (PC*) undergoes a single-electron transfer (SET) with a suitable electron acceptor A or electron donor D. In an oxidative

• photocatalyst PC•− and the oxidized donor D•+. Following this initial SET, a second electron transfer must occur to ensure the catalyst turnover and restore the ground state photocatalyst: PC•+ needs to be reduced by an electron donor D, whereas PC•− needs to undergo an oxidation by an electron acceptor A. In

• , such as a trialkylamine. The ensuing radical anion (PC•−), associated to an extended π-system, is persistent enough to absorb a second photon. The resulting excited state of the radical anion (PC•−*) is a strong reductant (E(PC/PC•−*) < −1.5 V), which can reduce the electron acceptor (A), resulting in

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

• were selected in the build-up of the new electroactive compounds. The commonly used carbazole, phenothiazine, and dimethyldihydroacridine donor units and the scarcely used quinazoline unit as the electron acceptor were chosen for the design of the compounds (Scheme 1). A facile and reliable one-pot

• an electron acceptor in donor–acceptor systems [14]. The target compounds were obtained by nucleophilic substitution reaction of the intermediate quinazoline derivative Q1 with the corresponding donor compounds. The chemical structures were characterized by 1H NMR, 13C NMR, ATRIR spectroscopy and

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

• splitting (∆EST) between the lowest singlet and triplet excited states [5]. Various TADF derivatives have been developed with the aim to obtain highly efficient OLEDs by combining diverse donor and electron-acceptor moieties [6][7]. To successfully exploit TADF emitters in OLED structures, appropriate hosts

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• electron acceptor than its ground state (E1/2(TPP/TPP−•) = −1.03 V vs SCE). Thus, depending on the reaction system in which this photocatalyst is being used, reductive or oxidative processes can be accomplished. In this review, we intend to highlight applications of porphyrins and their analogs in both

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

• -step electron transfer from the merocyanine to the metal cations, which acted as electron acceptors. Similarly, Malatesta et al. found that the thermal dark reaction of spironaphthoxazines in the presence of a suitable electron acceptor, such as 7,7,8,8-tetracyanoquinodimethane, gave the corresponding

• conditions, indicating an electron transfer from a reaction intermediate to the copper ions. In addition, we tested whether 4a may also be formed upon the addition of the previously not employed Fe3+ ion as this also acts as a strong electron acceptor (Figure 6B). Indeed, the addition of Fe3+ to 3a resulted

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• often no reaction between a cationic sensitizer and an electron acceptor; i.e. an iodonium salt [5]. However, the use of stronger emitting LEDs resulted sometimes in successful PET [67]. Particularly, light sources with low emission intensity arose these issues. This supports the idea that the system

• formation of reactive intermediates such as initiating radicals follows the Equations 1–7 vide supra. The system comprises as sensitizer an absorber derived from structure IV or V, and an electron acceptor such as 88 or 89. The main challenge can be seen to drive the system somehow that Equation 5 relating

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• bands of the electron acceptor-substituted derivative 3d were shifted to even shorter wavelengths. DNA-binding properties The DNA-binding properties of the 2-styrylquinolizinium derivatives 3a–d were investigated by spectrometric titrations of calf thymus DNA (ct DNA) to 3a–d in a phosphate buffered

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

• arylhydrazines 5b–d containing electron–acceptor substituents or electron–donor ones. There was no obvious change in the yields of compounds 6l–o (78–84%, Scheme 3), which may indicate that the starting ketones had a rather high reactivity. To confirm the structure of TTI derivatives 6, we attempted to grow

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• situated in between. These trends support that for the herein investigated dyes intramolecular charge-transfer (ICT) phenomena might play a role in the observation of the LW emission features. According to our previous observations the electron-acceptor moiety is likely constituted by the isoquinolinyl

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• number of drugs and [1,2,4]triazolo[4,3-a]pyridines were shown to have herbicidal [5][6], antifungal [7], neuroprotective [8][9] and antibacterial activity [10]. In addition, [1,2,4]triazolopyridine has been used as electron-acceptor unit in the synthesis of organic light emitting diodes (OLED) [11]. 2

Conformational signature of Ishikawa´s reagent using NMR information from diastereotopic fluorines

• Laize A. F. Andrade,
• Lucas A. Zeoly,
• Rodrigo A. Cormanich and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2019, 15, 506–512, doi:10.3762/bjoc.15.44

• conformer in a nonpolar medium. In part, the hyperconjugative interaction above (which is possible in 1B and 1C conformers) is somewhat counterbalanced by an σC–H → σ*C–N interaction in 1A, since σ*C–N is also a good electron acceptor orbital (see NBO energies in Table 3). In addition, this conformation

Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning

• Hiroaki Yoshida,
• Ken Kikuta and
• Toshiyuki Kida

Beilstein J. Org. Chem. 2019, 15, 89–95, doi:10.3762/bjoc.15.10

• promising as an approach for fiber functionalization, the scope is limited to cases with 1:1 inclusion complexes and chemically modified CD. Fullerenes have been widely studied in the fields of chemistry and materials science because they have attractive chemical structures and good electron acceptor

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• created as illustrated in Figure 1 to regenerate the PC. As illustrated, for an oxidative cycle, the excited photocatalyst (PC*) reacts first with an electron acceptor (also named oxidation agent, OA1 in Figure 1) which leads to PC●+ and OA1●− . Then, PC can be regenerated with an electron donor (also

• mechanisms. From a single or triplet state of the photoredox catalyst, an electron is transferred. According to Rehm–Weller, an electron can be transferred from the electron donor to the electron acceptor in the excited state if the free energy change ∆Get is negative. ∆Get can be calculated from the

• equation: where Eox is the oxidation potential of the electron donor, Ered the reduction potential of the electron acceptor, E* the excited state energy level and C the coulombic term for the initially formed ion pair (if there are ions in solution). For polar solvent, C is neglected. (TMS)3SiH is not

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• the anaerobic bacteria, Sulfurospiririllum multivorans, uses 1,1,2,2-tetrarchloroethene as a terminal electron acceptor to be reduced to trichloroethene (Scheme 8a) [87]. In electron transport chains, reductases reduce the Co(II) species of the B12 cofactor to the Co(I) species in the active site of