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

• –i, 9a, and 10a, a band with a maximum at 260–265 nm is observed, which has a shoulder at 300–305 nm. These signals seem to correspond to π–π* and n–π* transitions. In the luminescence spectra of compounds 4a–i, 9a, and 10a, there is one broadened band with an emission maximum at 409–440 nm (Figure 2

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• SCE for N-(diphenylmethylene)-1-phenylmethanamine) [78]. Spectroscopic investigations later revealed that the change in absorption and luminescence of deaerated solutions of [Ir1]+ and Et3N were neither related to i) the formation of [Ir1]0 via a single-excitation reductive quenching photocatalytic

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

• emitters [32][33]. However, the most popular optical spectroscopic methods previously used in this area, such as the very often used transient photoluminescence spectral measurement or the luminescence lifetime measurement, are unable to detect the dark states of the TADF emitters, i.e., the 3LE and 3CS

• Supporting Information File 1), the fluorescence intensity is less dependent on the atmosphere. Moreover, we suggest that the reduced luminescence of the oxidized molecules in air may be caused by the quenching effect of oxygen to the S1 state. According to this experimental phenomenon, we preliminarily

• time, in this process, the triplet features of 3LE start to appear (460 nm). Since the relaxed CS state and CR evolve within 7.92 ns, this is in agreement with the TADF luminescence studies (ca. 8 ns, Figure 4a), thus the decay of the 1CS state in aerated solution takes ca. 7.92 ns. Then, the system

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• to the molecules which cannot be superimposed on their own mirror image. Nanomaterials with chiroptical properties have shown potential applications in different fields such as optical devices, polarization-based information encryption, circularly polarized luminescence (CPL) lasers, or biosensing

• compound at 200 °C for 5 h, which gives a lower limit to the barrier of racemization of ΔG > 38.3 kcal mol−1 at 473 K. The circularly polarized luminescence (CPL) of these structures were also evaluated with the luminescence dissymmetry factors (glum) values of 4 × 10−4 for compound 11 and 7 × 10−4 for

• , respectively by DFT calculation. The enantiopure isomers of the π-extended helicenes were evaluated as excellent circularly polarized luminescence (CPL) emitters with a glum of 7.44 × 10−3 for 37, which is around 10-fold higher than 35. Chiral “HBC-dimers” and “HBC trimers” The combination of two or more HBCs

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• luminescence (CPL). The exciplex (excited heterodimer) formed intramolecularly proved to be conformationally rigid and consequently was not sensitive to solvent or temperature [8]. Further, pyrenoimidazole-fused phenanthridines have been reported recently, developed as fluorescence emitters for optoelectronic

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

• can be controlled. The singlet oxygen quantum yield (ΦΔ) of NI-PTZ is moderate in n-hexane (HEX, ΦΔ = 19%). TADF was observed for the dyads, the biexponential luminescence lifetime are 16.0 ns (99.9%)/14.4 μs (0.1%) for the dyad and 7.2 ns (99.6%)/2.0 μs (0.4%) for the triad. Triplet state was

• lifetime is 16.0 ns (99.9%)/14.4 μs (0.1%) in deaerated n-hexane (Figure 4a). In aerated solution, the luminescence lifetime is reduced to 7.6 ns (99.8%)/0.19 μs (0.2%) (Figure 4d). These are footprints for TADF. Similar features were reported for an analogous NI-PTZ dyad [20]. NI-PTZ2 displays similar

• the PTZ moiety (for NI-PTZ-O) or by using a longer linker (NI-Ph-PTZ and NI-PhMe2-PTZ), leads to a normal fluorescence decay. Specifically, the luminescence lifetimes of NI-PTZ-O and NI-Ph-PTZ are 3.1 ns (99%)/22.1 ns (1%) and 1.2 ns (77%)/4.5 ns (23%), respectively (Figure 4c and 4f). The

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

• new ionic TADF emitters were designed and synthesized for LEECs application using a known MR-TADF emitter DiKTa. Our MR-TADF green emitter, DiKTa-OBuIm exhibited efficient green luminescence and TADF in 1 wt % mCP film (λPL = 499 nm, FWHM = 66 nm, ΦPL = 71%, τd = 317 μs, kRISC = 2.85 × 103 s−1). This

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

• thermally activated delayed fluorescence (TADF) characteristics are emerging due to the potential applications in optoelectronic devices, time-resolved luminescence imaging, and solid-phase sensing. Herein, we synthesized two (4-bromobenzoyl)pyridine (BPy)-based donor–acceptor (D–A) compounds with varying

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

• twisting results in a slight increase in the HOMO and a slight lowering of the LUMO. The twisting effect is much smaller than the conjugation effect of the MeO group. Absorption spectra of all the substituted DBC derivatives also showed a red-shift as compared to that for DBC-H. Concerning the luminescence

• HOMO to LUMO and HOMO-1 to LUMO+1 (see Tables S1–S6 in Supporting Information File 1). The trend for the order of optical band gap is roughly consistent with that of the HOMO–LUMO gap obtained from DFT calculation [52]. In the photoluminescence spectra, the luminescence of DBC-Br was very weak. On 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

• ) [6][7]. In 2012, Adachi et al. first reported purely organic thermally activated delayed fluorescent (TADF) materials, which achieved nearly 100% exciton utilization via reverse intersystem crossing (RISC) [8]. Meanwhile, novel materials based on new luminescence mechanisms such as hybridized local

• multiple molecules [13]. The exciplex contains new excited states through charge transfer between a donor molecule and an acceptor molecule. This provides a simple way to create new luminescence processes through the intermolecular interactions of existing molecules [14]. It has been reported that new

• emitters can be realized by adding a Lewis acid to a fluorescent conjugated compound [15][16]. Lewis acids are common complexing agents [17] and are frequently used to dope conjugated polymers to enhance their conductivity while the luminescence is completely quenched [18][19]. In contrast, in the presence

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

• carbohelicenes has led to the synthesis of double, triple, quadruple, quintuple, and sextuple molecules, the chiro-optical properties of these molecules, such as their circular dichroism (CD) and circularly polarized luminescence (CPL), have also been widely studied [1][2][3][4][5][6][7][8]. The development of

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• luminescence in an OLED is achieved through the radiative decay of electrically generated excitons, high-efficiency devices must be able to harvest both the 25% singlet and 75% triplet excitons to produce light [3]. Distinct from phosphorescent compounds, TADF molecules harvest triplet excitons by converting

• luminescence spectroscopy was used to measure a for solution processed films of 20 wt % DICzTRZ in CzSi. The data were then analyzed via optical simulation to yield and anisotropy factor of 0.53, which disappointingly implies that the emitter presents a strongly vertical orientation (Figure 6); the

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• macrocycles [31][32]. Moreover, polypyrrolic systems are of extensive interest in numerous areas namely optics, medicine, and supramolecular chemistry in addition to the materials sciences and technology. Fascinatingly, in luminescence as well as fluorescence-based sensors, pyrrole derivatives play a vital

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• incomparable chelating ability towards selected transition metals, and the corresponding complexes were applied in various areas such as chemical-sensor materials, tunable redox-potential complexes, polymer hybrid luminescence materials, building blocks for multinuclear complexes, and as catalysts for cross

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

• luminescence with glum values of +0.0021, and −0.0025, respectively. The second way to fabricate the rac-TBPP-based CPL-active material is to co-gel the fluorescent rac-TBPP with a chiral ᴅ-glutamic acid gelator DGG by co-assembly strategy. At the molar ratio of rac-TBPP/DGG = 1:80, the glum value of the co

• -gel was about three times higher than the glum values of R2N-TBPP and S2N-TBPP enantiomers. Interestingly, the CPL handedness of the rac-TBPP/DGG co-gel could be adjusted effectively by changing their stoichiometric ratios. Keywords: circularly polarized luminescence; chiral resolution; co-gelation

• and applied in practice [4][5][6]. Among them, the fluorescent materials emitting circularly polarized luminescence (CPL) have attracted intensive interest owing to their wide applications in various researching fields including 3D displays, chiroptical materials, and so on [7][8][9][10]. Circular

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

• have led to promising applications of helicenes. The latter have been studied with respect to conductivity [12][13][14][15], nonlinear optics [16][17], circularly polarized luminescence [18][19][20][21][22][23][24], organocatalysis [25][26][27][28][29], conformational analysis [30], chirality sensing

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• liposomes (molar ratio 12/13 = 1:9, total monomer concentration = 10.0 μM, 25 °C) in 10.0 mM DMSO/TBS (v/v = 1:4, pH 7.4). The insets show the normalized fluorescence intensity at 515 nm vs the concentration of LPS (0–3.6 μM) and the fluorescence turn-on; C) confocal luminescence image for E. coli DH5α

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• -containing substituents such as NMe2 possess more electron-donating ability than the S-based moieties such as SMe. Moreover, it was found that NMe2 showed higher luminescence quantum yields (ΦF) in comparison to SMe, indicating that N-substituted groups could enhance the fluorescence intensity. Therefore

• strategies to overcome ACQ. Up to date, various AIE materials with efficient luminescence have been synthesized for diverse applications [28][29][30][31][32]. The discovery of AIE and especially aggregation-induced emission enhancement fluorogens (AIEEgens) further incentivized the synthesis and analysis of

• that H, Me, t-Bu, OMe, SMe and NMe2 represent excellent candidates as DSEgens. The combination of luminescence in both solutions and aggregated state enables future applications, such as data encryption, anti-counterfeiting [43] and non-invasive imaging for 3D tumor spheroids, considering that AIEgens

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• reversibility was achieved by the addition of the rhodium porphyrin 19 that reversed the system reviving the state SelfSORT-I. Since both self-sorted states exhibited a distinct fluorescence due to the changes at the zinc porphyrin sites, luminescence was used for the selective detection of DABCO in a mixture

• innovative catch–release system with multiple functions combined the ON/OFF-adjustment of silver(I) catalysis and fluorescence monitoring [59]. Actually, the ratiometric luminescence response allowed the exact monitoring of the catalytic activity. In the initial incomplete self-sorting (state SelfSORT-I

• reversed back to the initial state (Figure 15b). Here, all translocations happen in an off-equilibrium system. Since the kinetic evolution of the lithium pulses was followed by color and luminescence changes of the lithium-sensitive probe 36, the system is suited for a multitude of new applications

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• multiple imidazolium groups to overcome the high hydration enthalpy of phosphates and b) the imidazolium groups are connected to aromatic moieties such as anthracene, pyrene, etc. The variation in the luminescence of the aromatic moieties signals the binding event and furthermore, they provide additional

• buffer and produced nanoaggregates with surface exposed positive charges. Interestingly, the aggregates displayed cyanic green luminescence which originated from the excimeric emission of the stacked pyrenes [57][58][59]. In a recent work, we have demonstrated that self-assembled nanofibrous aggregates

NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• be detected by its luminescence [77][78][79]. Overall, while crystal structures provide fantastic insight into molecular interactions of such supramolecular ligands, they do not necessarily reflect the binding situation in solution. Furthermore, to our knowledge no protein co-crystal structures with

• indeed recognize the highly positively charged area on cytochrome c (Cyt c) that binds Cyt c peroxidase. The inhibition of this protein–protein interaction was demonstrated as well using a luminescence quenching assay. The protein surface recognition of two porphyrin ligands bearing carboxylate

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

• solutions in DMSO. Therefore, they showed potential to be utilized as colorimetric and luminescence pH sensors. The second-order nonlinear optical (NLO) responses of the dyes were measured by the electric field-induced second harmonic (EFISH) generation method. The highest μβ values were obtained for the

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• non-radiative transitions can be achieved by the host–guest method [50][51][52] or by crystallization [53][54][55][56][57]. In difference to the liquid phase, the highly ordered packing and the restriction of molecular motions in the crystalline state favor a persistent luminescence. The promotion of

• , no luminescence was detected for the para derivatives. All ortho derivatives exhibited luminescence neither in solution nor in the solid-state [73]. These observations for the para- and ortho-bromobenzaldehydes indicate that the phosphorescence is quenched in these systems, yielding only a weak

4-Hydroxy-3-methyl-2(1H)-quinolone, originally discovered from a Brassicaceae plant, produced by a soil bacterium of the genus Burkholderia sp.: determination of a preferred tautomer and antioxidant activity

• Dandan Li,
• Naoya Oku,
• Yukiko Shinozaki,
• Yoichi Kurokawa and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1489–1494, doi:10.3762/bjoc.16.124

• extinction assay [41][42]. This assay quantifies the presence of the most detrimental ROS, hydroxy radical [43][44], as intensity of luminescence emitted by oxidation of luminol. Compound 1 at 10 μM, which is lower than a concentration in production liquid cultures (15 μM), decreased luminescence to 14% of

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

• -opening reaction of 4-fluoroisoxazoles and exhibited highly fluorescent luminescence and aggregation-induced emission (AIE), showing promise as a new fluorophore. Keywords: aggregation-induced emission; boron ketoiminates; fluorescent probe; α-fluorinated boron ketoiminates; 4-fluoroisoxazoles

• fluorescent luminescence characteristics of 4-fluoroisoxazoles, the synthesis of α-fluorinated boron ketoiminates (F-BKIs), and their photochemical properties. Results and Discussion Synthesis and optical properties of 4-fluorinated isoxazoles Although there is a large number of fluorescent molecules

• luminescence (FL) of the solutions of 6b and 9b exhibited an increase in the emission intensities with increasing water content. It was interesting to note that the excitation maximum of 9b in the aggregated state showed a red-shift by approximately 20 nm based on the incorporation of a single fluorine atom