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

• absorption and emission maxima of 411 and 520 nm, respectively, with a mega Stokes shift of 109 nm and fluorescence quantum yields both in the solid state (41%) and in solution (86%). The optical properties were supported by computational chemistry using density functional theory for optimized geometry and

• (excitation at λmax), respectively, leading to a mega Stokes shift (>100 nm) of 109 nm, which could be explained to be due to a fast relaxation from the excited state to the ground state as a result of a powerful intramolecular energy transfer between the TPA and boron groups through the thieno[3,2-b

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

• , featuring no significant vibronic structure, and a considerably large Stokes shift of 140 nm. The UV–vis absorption and PL spectra of spin-coated films were similar to those of dilute solutions. Based on the onset energy of this UV–vis spectrum, the optical band gap (Egopt) was estimated to be 2.04 eV

• silica substrate and solid powder (insert: fluorescence images of the solution, thin film, and solid powder under UV light at 356 nm). a) Normalized UV–vis absorption/PL spectra in different solvents. b) Lippert–Mataga plot of Stokes shift vs solvent polarity function (Δf). c) Transient PL decay traces

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation–cyclization–iodination–alkylation sequence

• Nadia Ledermann,
• Alae-Eddine Moubsit and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2023, 19, 1379–1385, doi:10.3762/bjoc.19.99

• absorption maximum of indole derivative 8b appears at 309 nm with an absorption coefficient ε = 10700 M−1 cm−1 and the emission maximum is found at 423 nm with a Stokes shift of 8700 cm−1 (Figure 1A). Moreover, compound 8b emits intensively blue in both the solid state and solution (Figure 1B). Conclusion In

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

• Vladislav Yu. Shuvalov,
• Ekaterina Yu. Vlasova,
• Tatyana Yu. Zheleznova and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2023, 19, 1155–1160, doi:10.3762/bjoc.19.83

• ). Their diluted alcohol solutions luminesce with a quantum yield of 0.09–0.23. Pyrazolo[3,4-b]pyridinones 4a–i, 9a, and 10a are characterized by an abnormally high Stokes shift (107–152 nm, 1.07–1.49 eV, Table 2). Such luminophores, which are colorless in daylight but become colored when irradiated with

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• to a short-range charge transfer transition (SRCT) that is a hallmark characteristic in MR-TADF compounds [28]. The Stokes shift is 54 nm (2361 cm−1) for DiKTa-OBuIm. The lowest energy absorption band in DiKTa-DPA-OBuIm is red-shifted and less intense (ε = 6 × 103 M−1 cm−1) compared to DiKTa-OBuIm

• , in line with its decreased oscillator strength (vide supra). According to the calculations (vide supra), the S1 excited state is also SRCT, but with larger long-range charge transfer (LRCT) content. Owing to the relative flexibility around the DPA donor unit, the Stokes shift is larger at 75 nm (2761

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• ). The large Stokes shift and spectral broadening indicated a highly polarized ICT state in both compounds (Figure 1c and Figure 1d as well as Tables S3 and S4 in Supporting Information File 1) [30]. The excited-state CT characteristics were further probed using the Lippert–Mataga plot for both the

• compounds (Figure S2 and Tables S3–S5 in Supporting Information File 1) [29]. A larger Stokes shift and transient dipole (µE−µG) than in BPy-pTC were observed in BPy-p3C (Table S5, Supporting Information File 1). This indicated the relatively stronger excited-state CT interactions in BPy-p3C (Figure 1c and

• and to λem = 582 nm in polar DCM (Figure 1d). As compared to the absorption spectra, the significant solvatochromic shifts in the fluorescence spectra suggested the presence of a highly dipolar excited state with a stronger ICT character, in contrast to the ground state of the molecule. But the Stokes

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• appeared at 490 nm, which is a by 43 nm longer wavelength than that (λmax,fl = 447 nm) of OTK-2. The Stokes shift (SS) value of OTT-2 is estimated to be 3177 cm−1, which is higher than that (2945 cm−1) of OTK-2. In addition, the Φfl of OTT-2 is 0.41, which is higher than that (Φfl = 0.36) of OTK-2. Time

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

• Stokes shift for DBC-S(O)2Me was the largest, which is due to the electron-withdrawing nature of the S(O)2Me group. Conclusion The electrochemical and spectroscopic properties of DBC derivatives were investigated, and the effects of substituents and torsion of the naphthalene moiety were discussed based

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

• region. Also, the protonated polymer 61 showed strong fluorescence at 480 nm with a large Stokes shift of 155 nm. In 2015, Zhang, Liu, and co-workers [36] reported the synthesis of conjugated donor–acceptor (D–A)-type azulene-dithienyldiketopyrrolopyrrole (DPP) polymers 69, 71, and 72. The synthesis of

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• , including the maximum of absorption and emission, fluorescence quantum yield, stokes shift, onset of the absorption wavelengths and optical band gap are summarized in Table 3. Aiming to understand the impact of substituents at arylethynyl groups, spectra of diversely substituted tetrahydroacridines were

Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• self-absorption and a wider stokes shift [17]. Further, the steric hindrance and highly rigidity could reduce non-radiative transition and restrict the internal rotation [18]. More importantly, in the TB structure, its bridged methylene groups of the diazocine chiral nitrogen atoms prevent the

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• emission with the highest in the series λem = 561 nm and Stokes shift 128 nm. Conclusion In summary, novel carbazole-based [6]helicenes fused with an azine ring (pyridine, pyrazine or quinoxaline) have been prepared from commercially available 2,3-dihaloazines via a five-step synthetic sequence. Two key

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

• amines led to the increase in the Stokes shift and a significant red shift between the absorption and the emission maxima. This was due to the varying electronic contributions to the host structure induced by the heterocyclic amino constituents [50][51][52] (Figure 4). Hydroxide anion sensing properties

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• emission bands were at λem = 524 nm (λexc = 380 nm) and λem = 523 nm (λexc = 460 nm, see Supporting Information File 1, Figure S2). Then, a Stokes shift of 16 nm could be appreciated in agreement with data previously reported for PBA-BODIPY (1) [26][35]. Dynamic light scattering (DLS) measurements were

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• absorption, excitation, emission, Stokes shift, fluorescence quantum efficiency, molar extinction coefficient, and brightness. The photophysical data of the β-carboline C1 or C3-tethered benzothiophenone derivatives are summarized in Table 2, and their graphical data are depicted in Figure 3 and Figure 4

Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles

• Kazuyuki Sato,
• Akira Kawasaki,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2020, 16, 1411–1417, doi:10.3762/bjoc.16.117

• ][38], their optical properties feature a large Stokes shift and high molar absorption coefficients (ε) that are similar to the corresponding boron diketonates. The synthesis and properties of BKIs have been reported recently and they are easily accessible either from the corresponding 1,3-diketones 1

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• blue-shifted spectrum with lower Stokes Shift values, enabling a different frequency of light to be accessed. Overall, there is a significant difference in the HOMO–LUMO gap of the three porphyrin dimers. The meso–meso-linked dimer 19 has the largest gap of 2.21 eV, followed by the triptycene-linked

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• fluorescence quantum yields of 3a and 4a remain high (Φf = 0.95 and 0.56, respectively) and are comparable to that of 1a (Table 1). The smaller Stokes shift values of ≈178 cm−1 and longer emission lifetimes of ≈7.83 ns indicate the rigid scaffolds of α,α-disubstituted 4a in the excited state. In the case of β

• emission bands were observed with lowered quantum yields, Φf of 0.25 and 0.16, respectively (Figure 5b and Table 1). The larger Stokes shift and shorter emission lifetime suggest a rapid decay of the excited species after structural relaxation (vide infra, Table 1). Also, intersystem crossing to the

• significantly decreased with the geometry relaxation at the S1 state compared to that of the S0-state structure, which could be the origin of the large Stokes shift for 6a. Therefore, in comparison with the α-substituted compounds 3a and 4a, the less emissive character of the β-ethynyl-substituted derivatives

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• ) λmax [nm] (ε [L·mol−1·cm−1]): 274 (32000), 321 (18100), 428 (10000); emission (CH2Cl2) λmax [nm] (Stokes shift [cm−1]): 565 (5700); quantum yield (CH2Cl2) Φf: 0.01; Anal. calcd for C23H17F3N2O2 (410.1): C, 67.31; H, 4.18; N, 6.83; found: C, 67.50; H, 4.32; N, 6.70. Typical procedure for the

• ), 924 (w), 853 (m), 818 (s), 795 (m), 750 (m), 748 (m), 692 (s), 669 (m), 640 (m); UV–vis (CH2Cl2) λmax [nm] (ε [L·mol−1·cm−1]): 294 (18800), 482 (47300); emission (CH2Cl2) λmax [nm] (Stokes-shift [cm−1]): 567 (3100); quantum yield (CH2Cl2) Φf: 0.99; emission (solid) λmax [nm]: 694; quantum yield (solid

• ), 1248 (s), 1188 (w), 1169 (m), 1134 (m), 1113 (s), 1092 (m), 1067 (m), 1047 (m), 1028 (w), 1001 (w), 885 (m), 854 (m), 847 (w), 775 (w), 758 (s), 746 (m), 694 (m), 658 (w); UV–vis (CH2Cl2) λmax [nm] (ε [L·mol−1·cm−1]): 274 (20300), 324 (20100), 417 (7700); emission (CH2Cl2) λmax [nm] (Stokes shift [cm−1

Plasma membrane imaging with a fluorescent benzothiadiazole derivative

• Pedro H. P. R. Carvalho,
• Jose R. Correa,
• Karen L. R. Paiva,
• Daniel F. S. Machado,
• Jackson D. Scholten and
• Brenno A. D. Neto

Beilstein J. Org. Chem. 2019, 15, 2644–2654, doi:10.3762/bjoc.15.257

• noted in all tested solvents (134–173 nm), thus pointing to efficient stabilizations through intramolecular charge-transfer (ICT) processes from the excited states. The largest Stokes shift was noted in the aqueous solution, indicating the dye’s stability in this solvent. The solvatochromic analyses of

• 2,1,3-benzothiadiazole (BTD) core and its derivatives that are successfully applied in bioimaging experiments. (Left) UV–vis, (center) fluorescence emission and (right) solvatochromic effect (Stokes shift in wavenumbers versus solvent polarity in ETN) of the synthesized BTD-4APTEG (10 μM for all

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• compounds were nonemissive. The Stokes shift of the OFs of nonoxidized DAEs was always ca. 6000 cm−1, independent of the substitution pattern. For comparison, this value was much lower than the Stokes shift of the OF of compound 6 (10,700 cm−1) [4]. The Stokes shift of the CFs of oxidized DAEs varied

• between 3000 cm−1 and 5600 cm−1, which is comparable with the Stokes shift observed for the CF of 6 (4600 cm−1) [4]. In the case of oxidized DAEs, asymmetric compounds possessed higher Stokes shifts by ca. 1000 cm−1 than symmetric DAEs. Only compound AsOTh2 has a higher Stokes shift than the CF of

Aggregation-induced emission effect on turn-off fluorescent switching of a photochromic diarylethene

• Luna Kono,
• Yuma Nakagawa,
• Ayako Fujimoto,
• Ryo Nishimura,
• Yohei Hattori,
• Toshiki Mutai,
• Nobuhiro Yasuda,
• Kenichi Koizumi,
• Satoshi Yokojima,
• Shinichiro Nakamura and
• Kingo Uchida

Beilstein J. Org. Chem. 2019, 15, 2204–2212, doi:10.3762/bjoc.15.217

• is one of the examples which express the mechanisms of aggregation-induced emission (AIE). This compound emits orange fluorescence with a large Stokes shift derived from ESIPT in aprotic solvents such as THF or hexane, while it exhibits only a photochromic reaction in protic solvents such as methanol

• a large Stokes shift is indispensable for such a system. One of the possible choices to achieve such a large Stokes shift is to introduce the excited-state intramolecular proton transfer (ESIPT). The process of ESIPT is a fast process even comparable to the internal conversion [15][16]. This is

• because the proton transfer occurs through an intramolecular hydrogen bond. This is also an origin of a large Stokes shift (8,000–11,000 cm−1) in the emission from the ESIPT state. Consequently, yellow luminescence was observed by UV-excitation [17][18]. Mutai et al. reported an ESIPT luminescence of an

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• have only little influence on the optical properties but significantly modulate the solubility in DMF. This result agrees with other cNDIs in literature [47][48][58]. NDI 1 shows weak fluorescence in CH2Cl2 with a maximum at 384 nm and a quantum yield of 7%. The Stokes’ shift is small (413 cm−1). Based

• quantum yield of 48%. The Stokes’ shift is rather large (715 cm−1). The excitation energy E00 of cNDI 6 in the singlet state is approximately 1.98 eV and is significantly smaller than that of NDI 1 due to the visible light excitation which delivers less energy to the excited state. The redox potentials of

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• ] or its 4-isomer, as optimal fluorescent light-up probes characterized by high fluorimetric response (I/I0 of up to 550-fold), excellent selectivity with respect to double-stranded DNA or single-stranded RNA controls, high quantum yield in the presence of G4 analytes (up to 0.32), large Stokes shift

• the design of G4-based logic gates could also be envisaged. Taking into account the favorable optical properties, in particular high brightness and large Stokes shift, the same probes could be utilized to proceed to cellular imagining of G4 structures, certainly with caution regarding the inherent

• acid samples used in the first screening round. Optical parameters (absorption and emission maxima, Stokes shift, molar absorptivity coefficient at the absorption maximum, fluorescence quantum yield and brightness) of dyes 1p, 1u, 17a and 18a in the absence of DNA or in the presence of G4-DNA

Synthesis, photophysical and electrochemical properties of pyridine, pyrazine and triazine-based (D–π–)₂A fluorescent dyes

• Keiichi Imato,
• Toshiaki Enoki,
• Koji Uenaka and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2019, 15, 1712–1721, doi:10.3762/bjoc.15.167

• . Therefore, the fact explains our findings that OUJ-2 shows large bathochromic shifts of the fluorescence maxima in polar solvents, as well as the Stokes shift values of OUJ-2 in polar solvents are much larger than those in nonpolar solvents. The cyclic voltammetry of OUY-2, OUK-2 and OUJ-2 demonstrated that

• , the three dyes showed a bathochromic shift of the fluorescence band with increasing solvent polarity from toluene to DMF (i.e., positive fluorescence solvatochromism). Thus, the Stokes shift (SS) values of the three dyes increase with increasing solvent polarity. Compared with OUY-2, OUK-2 and OUJ-2

• can easily be evaluated from the slope of a plot of νst against Δf (the Lippert–Mataga plot), where νst is the Stokes shift (Table 1), ε0 is the vacuum permittivity, h is Planck’s constant, c is the velocity of light, a is the Onsager radius of the dye molecule (7.81 Å, 7.99 Å and 7.91 Å for OUY-2