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Search for "π-conjugation" in Full Text gives 71 result(s) in Beilstein Journal of Organic Chemistry.

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

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  • azahelicenes represent a particularly significant subclass due to their extended π-conjugation and potential for enhanced chiroptical properties. Over the past few years, multiple research groups have investigated their synthesis, structural characteristics, and optoelectronic behavior. Notably, in 2021, Jux
  • = 2.1 × 10−2, and BCPL values up to 76 M−1 cm−1. Collectively, these investigations underscore the efficacy of heteroatom doping, extended π-conjugation, and radical design in advancing azahelicene-based systems. These approaches significantly enhance optical and chiroptical performance, paving the way
  • ), with compound 53a setting a new record for BN-containing helicene CPL brightness [68]. These collective findings underscore the critical role of rational BN doping, π-conjugation engineering, and structural rigidity in precisely tuning the photophysical and chiroptical properties of helicene-based
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Published 11 Jul 2025

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

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  • –base reaction. Cyclization of alkynes: The extension of π-conjugation in polycyclic aromatic hydrocarbons (PAHs) through alkyne-benzannulation reactions has become an increasingly popular method in recent years [91]. Such benzannulations can be mediated by Brønsted acids, Lewis acids or transition
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Published 26 Jun 2025

Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts

  • Katy Medrano-Uribe,
  • Jorge Humbrías-Martín and
  • Luca Dell’Amico

Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76

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  • 5a (3.9 eV) as a consequence of the extended π conjugation compared with 4a and 6a (4.4 and 4.4 eV, respectively). Interestingly, compound 6a, which possesses the weakest sulfur-based acceptor, showed an inversion in the LUMO distribution, localizing it in the TBA core – this behavior of the named
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Published 14 May 2025

Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

  • Yuuki Ishii,
  • Minoru Yamaji,
  • Fumito Tani,
  • Kenta Goto,
  • Yoshihiro Kubozono and
  • Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

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  • -extension (ΔλABS = ca. 6 nm per increment of one benzene ring) and the spectral profiles resemble each other irrespective of the length of the phenacene π conjugation and the fluorine substitution. The results suggest that these factors could provide insignificant effects on the apparent electronic spectral
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Published 24 Mar 2025

Effect of substitution position of aryl groups on the thermal back reactivity of aza-diarylethene photoswitches and prediction by density functional theory

  • Misato Suganuma,
  • Daichi Kitagawa,
  • Shota Hamatani and
  • Seiya Kobatake

Beilstein J. Org. Chem. 2025, 21, 242–252, doi:10.3762/bjoc.21.16

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  • to N1(c)–N4(c), which is due to the localization of the π conjugation in the central part of the molecular skeleton as reported in inverse-type diarylethenes [64]. Figure 1c and the video (Supporting Information File 2) show the photochromic behavior of N4 at room temperature in n-hexane. It was
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Published 31 Jan 2025

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

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  • spectra. Their LUMO electron density maps distribute across to the side arm for F1 (−1.88 eV; −1.78 eV for PH1) and to the other triphenylene core for the dimer G11 (−1.78 eV). The π-conjugation of excited states results in a difference of their HOMO and LUMO energy levels: the fluorine dimer G11
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Published 16 Dec 2024

Efficient modification of peroxydisulfate oxidation reactions of nitrogen-containing heterocycles 6-methyluracil and pyridine

  • Alfiya R. Gimadieva,
  • Yuliya Z. Khazimullina,
  • Aigiza A. Gilimkhanova and
  • Akhat G. Mustafin

Beilstein J. Org. Chem. 2024, 20, 2599–2607, doi:10.3762/bjoc.20.219

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  • ][19][20]. The catalytic activity of metallophthalocyanines originates from their planar, cyclic structure with a developed π-conjugation system. This makes the fifth and sixth coordination sites of the central metal ion available for coordination with the reactant molecules of the catalytic reaction
  • . Additionally, the π-conjugation system facilitates the redistribution of electron density within the reaction complex, thereby lowering the activation barrier of the reaction [21]. The study employed the following oxidation catalysts for phthalocyanines – PcCo, PcFe(II), PcFe(III), PcMn, PcNi, and PcZn. The
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Published 16 Oct 2024

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

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  • -planar having πconjugation [2][3][4]. Remarkably, these unique characteristics of the truxene scaffold, results in strong π–π stacking ability in addition to the strong electron‐donating capability – hinting for the truxene’s capability as a worthy building block in the advancement of cutting-edge
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Published 29 Aug 2024

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

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  • analyze the structure–property relationships of the cc-hPASs. Results and Discussion At first glance, the chemical space of PASs may appear to be quite homogenous. After all, the molecules share certain structural features, such as their multi-ring structures, rigidity, and π-conjugation. Nevertheless
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Published 31 Jul 2024
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  • LUMO orbitals for 3 and 23 and related compounds show reduced orbital densities on their aryl substituents, effectively reducing π-conjugation and raising HOMO–LUMO gaps. There appears little benefit to utilizing highly hindered 2’,4’,6’-triisopropylphenyl groups as in 24 or 2’,4’,6’-tri-tert
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Published 17 May 2024
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  • . A study confirmed that with appropriate molecular design, the π-conjugation relationship between the donor and acceptor moieties in TCBDs and DCNQs can be retained despite their non-planarity [14]. Diederich et al. synthesized a plethora of push–pull chromophores by employing anilino groups as EDGs
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Published 22 Jan 2024

Biphenylene-containing polycyclic conjugated compounds

  • Cagatay Dengiz

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

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  • 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
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Published 13 Dec 2023

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

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  • study raises a concern regarding the performance of dyes with tert-butyl substituted DPQ acceptors, either containing benzene (Qx74) or thiophene (Qx75) as a π-conjugation linker and their benzotriazole analogue. While the incorporation of the Qx enhances the interaction between the donor and acceptor
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Published 09 Nov 2023

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

Graphical Abstract
  • extended π-conjugation lengths which eventually favor the undesired formation of poorly emissive molecular aggregates must be overcome. Alternatively, donor–acceptor (D–A)-type organic fluorophores have been introduced and successfully exploited for the development of fluorophores with DR/NIR emissions
  • without lengthy extension of their π-conjugation systems due to a broadening of both the valence and the conduction bands and a consequent narrowing of the energy gap [22][23][24][25]. The D–A characters also offer a tunability of optoelectronic properties such as energy levels, optical bandgap (Eg), and
  • controlling the CT component in the HLCT state [54]. A suitable twisted angle (40–80°) allocated an appropriate tuning between the complete πconjugation and the pure CT transition character to form the HLCT state. As depicted in Figure 1a, the optimized structure of TPECNz revealed a twisted molecular
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Published 03 Nov 2023

Radical chemistry in polymer science: an overview and recent advances

  • Zixiao Wang,
  • Feichen Cui,
  • Yang Sui and
  • Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

Graphical Abstract
  • materials [74]. In 2000, they received the Nobel Prize in Chemistry. Typical conductive polymer structures have π-conjugation (Scheme 9A) [75]. They can be synthesized by various methods such as electrochemical and chemical methods. Oxidative polymerization and chain-growth polymerization are also good ways
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Published 18 Oct 2023

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

  • Alexander C. Brannan,
  • Elvie F. P. Beaumont,
  • Nguyen Le Phuoc,
  • George F. S. Whitehead,
  • Mikko Linnolahti and
  • Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

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  • benzoguanidine donor and compare it with the benchmark carbazole-based material (4CzIPN). Extended π-conjugation in 4BGIPN material results in yellow-green luminescence at 512 nm with a fast radiative rate of 5.5 × 10−5 s−1 and a photoluminescence quantum yield of 46% in methylcyclohexane solution. Such a
  •  1. Benzoguanidine has an extended π-conjugation compared with carbazole and is more nitrogen-rich (three N-atoms vs one in carbazole). Thompson et al. recently reported a series of carbene–metal–amide (CMA) (metal = Cu, Ag, Au) emitters employing a benzoguanidine ligand [10]. The extended π
  • , the LUMO isosurface in Figure 6, vide infra). Therefore, the higher reduction potential for 4BGIPN suggests that the benzonitrile core has a lower electron density, which is likely associated with extended π-conjugation and two additional electron withdrawing aza-type nitrogen atoms in the
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Published 07 Sep 2023

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

  • Chandra Sekhar Tekuri,
  • Pargat Singh and
  • Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

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  • spectroscopy. The preliminary photophysical results revealed a significant red-shift in their absorption and emission spectra as compared to the meso-tetrakis(4-methylphenyl)porphyrins due to the extended π-conjugation. Keywords: bathochromic shift; benzo[f]chromeno[2,3-h]quinoxalinoporphyrins; catalysis
  • other materials applications [4][5][6][7]. Among the previously synthesized synthetically modified porphyrinoids, β,β’-fused meso-tetraphenylporphyrins have gained a considerable importance because of their red-shifted absorption and emission due to the extended π-conjugation. In particular, β,β’-fused
  • ; Zn-TMPP, Soret band at 425 nm) due to the extended π-conjugation after the fusion of the benzo[f]chromeno[2,3-h]quinoxaline moiety at the β-pyrrolic positions of the porphyrin macrocycle. In the fluorescence spectra, free-base benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 9–13 showed emission bands at
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Published 11 Aug 2023

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

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  • for this kind of emitters is an electron donor–acceptor dyad, and the molecular geometry is usually orthogonal, i.e., the planes of the π-conjugation systems of the electron donor and acceptor are perpendicular to each other. As a result, the highest occupied molecular orbital (HOMO) and lowest
  • /Fc+) [49]. By directly connecting the NI and PTZ unit through a C–N single bond, the π-conjugation plane of the NI and PTZ units adopts a perpendicular geometry which is beneficial for SOCT-ICS (Scheme 1). Previously we observed TADF with an analogue of NI-PTZ-C5 (the difference of the molecular
  • N atom of the PTZ unit [59][60]. Further, the NI-PTZ-F-O and NI-PTZ-Ph-O compounds adopt an orthogonal geometry, and the N atom in the PTZ unit is not in π-conjugation with NI moiety due to a conformational restriction [55]. Thus, it is not the ordinary intramolecular charge transfer (ICT) state
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Published 19 Jul 2023

A fluorescent probe for detection of Hg2+ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

  • Xiaoqian Chen,
  • Naqin Yang,
  • Yue Ma,
  • Xinan Yang and
  • Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

Graphical Abstract
  • , which provides convenience for studying the host–guest chemistry of TMeQ[6] and constructing fluorescent probes in aqueous solution [37][38]. There is a π–π conjugation effect between the carbon–carbon double bond and the pyridine ring in 1,2-bis(4-pyridyl)ethene (G), which determines its ultraviolet
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Published 13 Jun 2023

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

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  • the extent of π-conjugation and the efficiency of particular donor–acceptor conjugation path in these new compounds. X-ray structures and absorption spectra of doubly protonated tetrafluoroborate salts of the oligomers are also discussed. Keywords: 1,8-bis(dimethylamino)naphthalene; cross-conjugated
  • which although conjugated to a third unsaturated center are not conjugated to each other” [16]. It is easy to see that there are two π-conjugation paths in molecules 5: a donor–acceptor conjugation path (Figure 2, highlighted in blue) and the π-conjugation of naphthalene rings through a butadiyne linker
  • , Figure 9). However, unlike salts 11a,c,d, methoxy derivative 11b demonstrates end absorption up to 415 nm and, thus, the lowest optical band gap in the series (2.99 eV). Evidently, protonation of 5b gives rise to a push–pull D–π–A–π–A–π–D system, in which the π-conjugation between the donating
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Published 15 May 2023

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

  • Kaiyue Ye,
  • Liyuan Cao,
  • Davita M. E. van Raamsdonk,
  • Zhijia Wang,
  • Jianzhang Zhao,
  • Daniel Escudero and
  • Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

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  • ). For NI-Ph-PTZ, the NI•− absorption bands in the 350–600 nm range are less resolved than for NI-PTZ. This likely comes from the effect of the π-conjugation of the phenyl ring with the NI moiety in NI-Ph-PTZ. In contrast, the PTZ•+ absorption band of NI-Ph-PTZ resembles the one of NI-PTZ, indicating
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Published 11 Oct 2022

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

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  • , which extends the degree of π-conjugation [1]. In this way, the HOMO–LUMO gap can be narrowed [2]. Low HOMO–LUMO gaps are desirable for organic solar cells as the maximum photoflux density of the sun is at ca. 700 nm, corresponding to 1.77 eV [3]. However, fused systems have the drawback of being prone
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Published 01 Aug 2022

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

  • Mengjie Wang,
  • Lanping Dang,
  • Wan Xu,
  • Zhiying Ma,
  • Liuliu Shao,
  • Guangxia Wang,
  • Chunli Li and
  • Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

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  • ; selenophene; thiophene; Introduction Given their esthetically pleasing helical structures, inherent helical chirality, and extended π-conjugation, helicenes have attracted extensive research attention. Helicenes are generally divided into carbohelicenes and heterohelicenes. The rapid development of
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Published 08 Jul 2022

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

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  • -type compound (λPL = 521 nm for POZ-DBPHZ) in cyclohexane. These data indicate that the effective length of π-conjugation is not affected by the number of donors, probably due to the right D–A dihedral angle for both compounds in the ground state. In contrary, the slight blue-shift of the PL spectra of
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Published 25 Apr 2022

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

  • Yelong Lei and
  • Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

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  • p–π conjugation. This stabilization is not possible with alkyl groups, explaining why 2-alkylaziridines did not generate the corresponding products. Intermediates C undergo an intramolecular nucleophilic attack to yield ethyl (oxazolidin-2-ylidene)alkanoates D, which further isomerize to more stable
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Published 05 Jan 2022
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