Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• containing one or two exocyclic olefin units. Owing to the transformation of carbonyl groups, the resulting products exhibit several unique physical and chemical properties: (1) the enhancement of configurational stability, (2) the appearance of fluorescence, and (3) the reductive carbon–carbon-bond

• peripherally modified CBBC derivatives have also been prepared and were shown to have fascinating properties [17][18][19][20][21]. For example, carbazole-substituted donor–acceptor-type CBBC derivatives exhibit both efficient circularly polarized luminescence (CPL) and thermally activated delayed fluorescence

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

• fluorescence (TADF), and chiral sensing. Notably, recent developments have yielded π-extended, structurally robust, and stimuli-responsive azahelicenes exhibiting record-high dissymmetry factors (|gabs| and |glum|), elevated CPL brightness (BCPL), and efficient integration into CPL-OLEDs and redox-switchable

• absorption and emission maxima (λabs = 399 nm, λem = 405 nm), a fluorescence quantum yield (ΦF) of 0.13, and high dissymmetry factors (|gabs| = 1.9 × 10−2, |gabs| = 9.5 × 10−3 at 403 nm) [18] (Table 2). Miura and co-workers employed Pd(II)/Ag(I)-catalyzed cyclizations to construct azahelicenes, with compound

• intramolecular Scholl reactions [24] (Table 3). All compounds exhibited strong absorption in the UV–vis region (250–450 nm) and fluorescence emission between 400–550 nm. Among these, compound 11c, a saddle-shaped dibenzodiaza[8]circulene, was particularly noteworthy as the first example of its kind synthesized

Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds

• Lidia Zaharieva,
• Vera Deneva,
• Fadhil S. Kamounah,
• Nikolay Vassilev,
• Ivan Angelov,
• Michael Pittelkow and
• Liudmil Antonov

Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105

• crystal was used and the samples were scanned 128 times. The UV–vis spectra were measured on a Jasco V-570 UV–vis–NIR spectrophotometer using spectral grade solvents in the concentration range ≈10−5 mol/L. The steady-state fluorescence spectra were recorded with a FluoroLog 3-22 (HORIBA

N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B

• Joy E. Rajakulendran,
• Emmanuel Tope Oluwabusola,
• Michela Cerone,
• Terry K. Smith,
• Olusoji O. Adebisi,
• Adefolalu Adedotun,
• Gagan Preet,
• Sylvia Soldatou,
• Hai Deng,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103

• cell line are given below), after which the Alamar Blue cell viability reporter was added and the fluorescence recorded using an FLx 800 plate reader (BioTek) with excitation wavelength 535/540 nm and emission wavelength at 590/610 nm using Gen5 Reader Control 2.0 Software (BioTek). EC50 values were

• 20 μL Alamar Blue (0.125 mg/mL resazurin salt in PBS) was added to all wells and incubated for a further 6 hours before fluorescence recording. Structures of the pseudomonins D–G (1–4), pseudomonine (5), pseudomonin B (6) and salicylic acid (7). Key HMBC, 1H-1H COSY and NOE correlations. Extracted

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

• , it was reported that PAH 126 exhibits anti-Kasha fluorescence [80] from the S3 state in the range of 410–470 nm upon excitation at 370 nm. This was well verified by femtosecond time-resolved absorption spectroscopy (fs-TAS), with corresponding high-energy excited state absorption bands observed at

• optical absorption. The UV–vis absorption spectra, fluorescence properties and 1H NMR spectroscopy, indicate that 150 and 151 can be protonated to form the corresponding tropylium cation and consecutive dication under acidic conditions, with reversible protonation−deprotonation capabilities. Additionally

• benzenoid part of the precursor (Scheme 23) [106]. As a result, the reaction of precursor 177 with P(OEt)3 gave fused π-scaffold 178 in 40% yield. Compound 178 features a highly planar geometry, narrow optical band gaps, anti-Kasha fluorescence, and reversible stimuli-responsiveness to acid and base. Gao

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold

• Henry S. T. Smith,
• Ben Giuliani,
• Kanchana Wijesekera,
• Kah Yean Lum,
• Sandra Duffy,
• Aaron Lock,
• Jonathan M. White,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90

• °C in 5% CO2. At 6 h, 5 µL of 600 µM resazurin, diluted in growth media, was added. Plates were further incubated for 6 h and measured for fluorescence at 530 nm excitation and 595 nm emission. The % inhibition was calculated using 0.4% DMSO (no inhibition) and 50 μM puromycin (100% inhibition) data

Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts

• Valentina Benazzi,
• Arianna Bini,
• Ilaria Bertuol,
• Mariangela Novello,
• Federica Baldi,
• Matteo Hoch,
• Alvise Perosa and
• Stefano Protti

Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84

• tail extending to the visible region. The emission properties of the synthesized CDs were also investigated and the results are summarized in Table 2. The fluorescence quantum yield strongly depends on the nature of the starting substrates, as is apparent by comparison of the value obtained for

• product was detected. Conclusion The results arising from cyclic voltammetry analyses, along with the Stern–Volmer fluorescence quenching data and with the isolated products and the GC yields obtained when irradiating the carbon dots in the presence of triarylsulfonium salts, indicate that carbon dots are

• the examined CDs. Quenching constants of the CDs calculated on the fluorescence intensity. Light-mediated reduction of triarylsulfonium salts in the presence of the CDs examined in this work. Supporting Information Supporting Information File 22: Experimental details, photophysics of CDs, cyclic

Synthesis of pyrrolo[3,2-d]pyrimidine-2,4(3H)-diones by domino C–N coupling/hydroamination reactions

• Ruben Manuel Figueira de Abreu,
• Robin Tiedemann,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2025, 21, 1010–1017, doi:10.3762/bjoc.21.82

• Abstract A variety of pyrrolo[3,2-d]pyrimidine-2,4(3H)-diones were prepared by a combination of Sonogashira reaction and subsequent cyclization by domino C–N coupling/hydroamination reaction. The optical properties (UV–vis absorption and fluorescence) depend on the substitution pattern of the compounds

• amino group. The corresponding fluorescence quantum yields were also strongly affected by the substitution pattern of the pyrrolouracils. Compounds 4k and 4l show very high fluorescence quantum yields of 83% and 71%, respectively, what might be reasoned by the strong donor ability of the NMe2-functional

• groups of those compounds. In contrast, compounds 4a and 4m showed only weak fluorescence with quantum yields of 9 and 4%, respectively. Compound 4j exhibited almost no emission (Φ = 0.1%). [30]. Conclusion In summary, we developed a new methodology for the synthesis of pyrrolo[3,2-d]pyrimidine-2,4(3H

On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals

• Daniel Straub,
• Markus Gross,
• Mona E. Arnold,
• Julia Zolg and
• Alexander J. C. Kuehne

Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80

• perchlorotriphenylmethyl (PTM) or tris(2,4,6-trichlorophenyl)methyl (TTM) radicals degrades to half of their intensity within just a few minutes, while for their corresponding di- and multiradicals no fluorescence data is reported at all (see Figure 1a for chemical structures) [5][6]. However, research on fluorescent

• demonstration of LEDs with 100% internal quantum efficiency [8][12]. Modern approaches also incorporate light-emitting TTM radical derivatives into LEDs based on thermally activated delayed fluorescence to moderate excited triplet, doublet, and singlet states in an attempt to improve the overall device and

• mechanisms and reasons behind the fluorescence color and the fluorescence quantum yield and derive structure–optical property relationships. We will provide the reader with an overview of the perspectives and challenges of open-shell light-emitting radicals and discuss what to do to solve the remaining

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

• (RAFT) polymerization [18]. Moreover, in 2022, Zysman-Colman and collaborators showed that molecule 3, initially synthesized as a TADF (thermally activated delayed fluorescence) emitter [14], can be used as a PC under electron-transfer (ET) and energy-transfer (EnT) processes (Figure 1a) [19]. All the

• transfer (CT) character in scaffolds 4a and 6a can be attributed to the absence of a complete conjugated system. On the other hand, the fluorescence profile showed more differences in the analysis of the three members of the D–A family. Again, 5a revealed a bathochromic effect compared with the less

• experimentally in the solvatochromism study of fluorescence using solvents with diverse polarities (see Supporting Information File 1, Figure S9). Indeed, the density functional theory (DFT) calculation performed at WB97XD/Def2TZVP level of theory showed the lowest value for the HOMO–LUMO energy gap in compound

Orthogonal photoswitching of heterobivalent azobenzene glycoclusters: the effect of glycoligand orientation in bacterial adhesion

• Leon M. Friedrich and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2025, 21, 736–748, doi:10.3762/bjoc.21.57

• protocol [41], the fluorescent GFP (green fluorescent protein)-expressing strain PKL1162 was applied to mannan-coated microtiter plates. In this assay, fluorescence intensity correlates with the number of adhered bacterial cells. The photoswitches 1–5 (cf. Figure 1) were used as inhibitors of bacterial

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

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

• fluorination on the electronic features of phenacene molecules. F8-Phenacenes were conveniently synthesized by the Mallory photoreaction of the corresponding fluorinated diarylethenes as the key step. Upon fluorination on the phenacene cores, the absorption and fluorescence bands of the F8-phenacenes in CHCl3

• systematically red-shifted by ca. 3–5 nm compared to those of the corresponding parent phenacenes. The vibrational progressions of the absorption and fluorescence bands were little affected by the fluorination in the solution phase. In the solid state, the absorption band of F8-phenacenes appeared in the similar

• wavelength region for the corresponding parent phenacenes whereas their fluorescence bands markedly red-shifted and broadened. These observations suggest that the intermolecular interactions of excited-state F8-phenacene molecules are significantly different from those of the corresponding parent molecules

Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether

• Gianpaolo Gallo and
• Bartosz Lewandowski

Beilstein J. Org. Chem. 2025, 21, 541–546, doi:10.3762/bjoc.21.42

• binds free tryptophan selectively in aqueous media. Furthermore, it is capable of binding to tryptophan within model tripeptides. The naphthalene functionality in the glucose-derived receptor enables the study of guest binding using fluorescence spectroscopy. Keywords: amino acids; macrocyclic

• in water [21]. Crown ether 1 is particularly suited for the sensing of Trp methyl ester, which it binds with a higher affinity than the Phe and Tyr esters. Additionally, the binding of Trp-OMe results in a highly efficient fluorescence quenching of the naphthalene unit in the receptor. Herein, we

• acids in H2O by 1 was investigated by ITC measurements and titration experiments monitored by fluorescence spectroscopy. The results are summarized in Table 1. Receptor 1 binds tryptophan with the highest affinity among the investigated amino acids (entry 1, Table 1). The Ka of the complex between 1 and

Deep-blue emitting 9,10-bis(perfluorobenzyl)anthracene

• Long K. San,
• Sebastian Balser,
• Brian J. Reeves,
• Tyler T. Clikeman,
• Yu-Sheng Chen,
• Steven H. Strauss and
• Olga V. Boltalina

Beilstein J. Org. Chem. 2025, 21, 515–525, doi:10.3762/bjoc.21.39

• photostability compared to ANTH and 9,10-ANTH derivatives, and a simple synthetic access makes it an attractive material as a deep-blue OLED emitter and an efficient fluorescent probe. Keywords: anthracene; dibromoanthracene; electron poor polyaromatic systems; fluorescence; perfluoroalkylation

• to suppress undesirable fluorescence self-quenching [15]. Not only do bulky substituents disrupt intermolecular interactions of this type, they can also provide higher chemical stability and reduce or prevent the photodimerization and photo-oxidation to which all acenes are prone [13]. Furthermore

• because isolated electronically excited molecules are more likely to undergo fluorescence instead of non-radiative relaxation, as discussed in some literature [13]. At the same time, it should be noted that emission properties in the crystalline phase and amorphous films, which are often used in OLED

Unprecedented visible light-initiated topochemical [2 + 2] cycloaddition in a functionalized bimane dye

• Metodej Dvoracek,
• Brendan Twamley,
• Mathias O. Senge and
• Mikhail A. Filatov

Beilstein J. Org. Chem. 2025, 21, 500–509, doi:10.3762/bjoc.21.37

• promising strategy for synthesizing substituted cyclobutanes without the need for ultraviolet irradiation. Keywords: bimane; [2 + 2] cycloaddition; fluorescence; topochemical polymerization; X-ray crystallography; Introduction Topochemical polymerizations refer to polymerization reactions occurring in the

• "bimanes" is derived from the Latin ‘bi’ (two) and ‘manus’ (hand). syn-Bimanes are often characterized by high fluorescence quantum yields, ranging from 60% to 100% [17], while anti-isomers typically exhibit phosphorescence [18]. Figure 1b illustrates the two isomers along with their simplified naming

• ¹H NMR spectra remained unchanged compared to the neat compounds (Figures S1, S3, and S5, Supporting Information File 1), confirming that the reaction occurs selectively in the solid state. Cl2B was also irradiated in DCM with the same 405 nm LEDs, in a quartz fluorescence cuvette. A UV–vis spectrum

Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

• Yurii A. Sayapin,
• Eugeny A. Gusakov,
• Inna O. Tupaeva,
• Alexander D. Dubonosov,
• Igor V. Dorogan,
• Valery V. Tkachev,
• Anna S. Goncharova,
• Gennady V. Shilov,
• Natalia S. Kuznetsova,
• Svetlana Y. Filippova,
• Tatyana A. Krasnikova,
• Yanis A. Boumber,
• Alexey Y. Maksimov,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26

• -(1,1-Dimethyl-1H-benzo[e]indolin-2-yl)-5,6,7-trichloro-1,3-tropolone exhibited high in vitro cytotoxic activity against A431 skin cancer and H1299 lung cancer cell lines. Keywords: cytotoxic activity; fluorescence; o-chloranil; quantum chemical DFT calculations; 1,3-tropolones; X-ray diffraction

• (0.84) Å, H···O = 1.79 (1.83) Å, and N···O = 2.513 (2.518) Å, angle N–H–O 140.4° (138.0°). The electronic absorption spectra of compounds 7a,b and 8a,b in acetonitrile have long wavelength bands in the region of 425–432 nm (Table 2). They exhibit dual-maxima fluorescence at 476–530 nm with normal and

• -n-butylammonium salts (TBAX: F, Cl, Br, I, CN). Exclusively cyanide and fluoride anions lead to a naked-eye effect due to a change of the solution’s colour from yellow-orange to pale yellow (Figure 5). At the same time, a new fluorescence band appears at 420–440 nm. The Stokes shifts of fluorescence

Red light excitation: illuminating photocatalysis in a new spectrum

• Lucas Fortier,
• Corentin Lefebvre and
• Norbert Hoffmann

Beilstein J. Org. Chem. 2025, 21, 296–326, doi:10.3762/bjoc.21.22

• unsaturated ring structure derived from squaric acid [47], has attracted attention due to its ability to promote single-electron transfer [48]. These compounds exhibit significant NIR fluorescence, making them valuable in applications such as biomolecule probing. Additionally, squaraine derivatives are well

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

• Islam S. Marae,
• Jingyun Tan,
• Rengo Yoshioka,
• Zakaria Ziadi,
• Eugene Khaskin,
• Serhii Vasylevskyi,
• Ryota Kabe,
• Xiushang Xu and
• Akimitsu Narita

Beilstein J. Org. Chem. 2025, 21, 270–276, doi:10.3762/bjoc.21.19

• properties were investigated by UV–vis absorption and fluorescence spectroscopy in compassion to pristine BPP and its oxidation product, benzo[rst]pentaphene-5,8-dione (BPP-dione). BPP-OiPr exhibited a significantly enhanced photoluminescence quantum yield (PLQY), reaching 73% in comparison to pristine BPP

• micrometers, as demonstrated by SEM. These results provide not only an easy access to highly emissive BPP derivatives with potential as organic fluorescent materials, but also an insight to design derivatives of other PAHs with enhanced fluorescence and charge transfer character. Single crystal structure of

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

• Molecular photoswitches have been studied for a long time because their physicochemical properties such as refractive index [1][2], dipole moment [3][4], conductivity [5][6], magnetism [7][8], and fluorescence [9][10][11] can be spatiotemporally modulated by light without physical contact. Therefore

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• degassed solvent and light-shielding flask, the oxidative conversion of 12 to the imidate 18 proceeded smoothly. Notably, the transient intermediate 18, exhibiting a sky-blue fluorescence, further underwent a ring opening to afford the tetracyclic 14 with the simultaneous regeneration of both a nitrile and

Heteroannulations of cyanoacetamide-based MCR scaffolds utilizing formamide

• Marios Zingiridis,
• Danae Papachristodoulou,
• Despoina Menegaki,
• Konstantinos G. Froudas and
• Constantinos G. Neochoritis

Beilstein J. Org. Chem. 2025, 21, 217–225, doi:10.3762/bjoc.21.13

• , showing similar profiles across all the different scaffolds (Figure 2 and Supporting Information File 1). The compounds 5–7 exhibited a maximum absorbance (λmax) at 330 nm, 284 nm and 310 nm, respectively, which also corresponded to their excitation wavelength (λex). Upon excitation, fluorescence emission

• pyrimidine scaffold. Representative fluorescence spectrum of compounds 5b (λex = 330 nm) and 6e (λex = 430 nm) at 0.2 M in DMSO. Molecular geometry observed within the crystal structure of compound 7b (CCDC 2376493). Strategies towards targeted adducts: A) Niementowski quinazoline synthesis utilizing

• materials. The colored frames indicate the different scaffold types. Synthesis of N-substituted thienopyrimidones 5a–e by a Gewald three-component reaction employing 2-aminothiophenes 2a–e and formamide as C1 source. A characteristic fluorescence for compound 5a was reported (365 nm in DMSO). The reported

Hot shape transformation: the role of PSar dehydration in stomatocyte morphogenesis

• Remi Peters,
• Levy A. Charleston,
• Karinan van Eck,
• Teun van Berlo and
• Daniela A. Wilson

Beilstein J. Org. Chem. 2025, 21, 47–54, doi:10.3762/bjoc.21.5

• decreased slightly during the heating cycle, indicative of membrane dehydration (Figure 3c). Further proof for the changing membrane properties was shown by a fluorescence measurement of pyrene-PEG-OH in the presence of the PSar-PBLG vesicles. Pyrene is well-known for its sensitivity to environmental

• the PSar corona in which the pyrene resided. This change shifted the ratio between I1/I3 of pyrenes fluorescence, going down from 1.50 to 1.31 (Figure 3b). This is a clear indication of the environment of the pyrene probe becoming more hydrophobic. The information obtained from DSC, accompanied by the

Synthesis, characterization, and photophysical properties of novel 9‑phenyl-9-phosphafluorene oxide derivatives

• Shuxian Qiu,
• Duan Dong,
• Jiahui Li,
• Huiting Wen,
• Jinpeng Li,
• Yu Yang,
• Shengxian Zhai and
• Xingyuan Gao

Beilstein J. Org. Chem. 2024, 20, 3299–3305, doi:10.3762/bjoc.20.274

• ]. Compared to the traditional PO-containing moieties, PhFlOP possesses an enhanced rigid structure to reduce the possibility of nonradiative decay processes, which would improve optoelectronic properties [17][27]. Thermally activated delayed fluorescence (TADF) materials and devices have emerged rapidly in