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

• – a chemoselective receptor for aromatic amino acid esters in water. Fluorescence emission spectra of receptor 1 (25 μM in H2O) upon addition of increasing amounts of tripeptide 2. The concentration of the guest corresponding to each curve is indicated on the right. The arrow marks the quenching of

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

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

• fluorescence emission spectroscopies reveal green photoluminescence with fluorescence quantum yields of up to 33% for the Fn derivatives. The J-aggregation for the inner fluorine-substituted dimers Gnm is energetically and stereoelectronically more favorable and G66 exhibits thin-film fluorescence with a large

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

• sulfonylation was confirmed as no product was found when carrying out the reaction in the presence of radical scavengers. Stern–Volmer studies indicated a significant fluorescence emission quenching of methylene blue by DIPEA, suggesting a reductive quenching of methylene blue during the reaction. Experiments

Investigation of a bimetallic terbium(III)/copper(II) chemosensor for the detection of aqueous hydrogen sulfide

• Parvathy Mini,
• Michael R. Grace,
• Genevieve H. Dennison and
• Kellie L. Tuck

Beilstein J. Org. Chem. 2024, 20, 2818–2826, doi:10.3762/bjoc.20.237

• Information Supporting Information File 16: Copies of HRMS, 1H NMR and fluorescence emission spectra. Acknowledgements The authors acknowledge the support of the School of Chemistry, Monash University and the Australian Department of Defence and Defence Science and Technology Group.

Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures

• Yohei Haketa,
• Takuma Matsuda and
• Hiromitsu Maeda

Beilstein J. Org. Chem. 2024, 20, 2567–2576, doi:10.3762/bjoc.20.215

• desorption ionization time-of-flight mass spectrometry (MALDI–TOF MS). The synthesized ion pairs showed similar electronic properties in solution state. In CH3CN, 2+-BF4− exhibited UV–vis absorptions at 273, 350, and 524 nm and fluorescence emission at 607 nm upon excitation at 524 nm. The absorption band at

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

• like 1H NMR, 13C NMR, and mass spectral data. The preliminary UV–vis absorption as well as fluorescence emission spectral data for thus prepared truxene-based compounds were recorded in chloroform and compared as well. Additionally, time-resolved fluorescence lifetime decays were also measured for thus

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• solutions of 1,3-diarylisobenzofurans 2, 3 and 23 in CH2Cl2 solvent. The vials of 2, 3 and 23 showing fluorescence emission (bottom) were excited at 365 nm. Calculated HOMO and LUMO orbitals for parent isobenzofuran (1) and 1,3-diarylisobenzofuran derivatives 2, 3, 23, 24 and 25 using a DFT method performed

Auxiliary strategy for the general and practical synthesis of diaryliodonium(III) salts with diverse organocarboxylate counterions

• Naoki Miyamoto,
• Daichi Koseki,
• Kohei Sumida,
• Elghareeb E. Elboray,
• Naoko Takenaga,
• Ravi Kumar and
• Toshifumi Dohi

Beilstein J. Org. Chem. 2024, 20, 1020–1028, doi:10.3762/bjoc.20.90

• benzoate in 70% yield (Scheme 6A). Furthermore, iodonium salt 7aj with an umbelliferone-3-carboxylate counterion displayed extremely weak blue fluorescence emission under 365 nm UV light compared to free carboxylic acid 6j. This unique property was utilized for tracing the counterion exchange process of

• the diaryliodonium(III) salt by irradiating with 365 nm UV light. The counterion exchange in umbelliferone carboxylate salt 7aj with trifluoroacetic acid was rapid, and after 30 s, the completion of the reaction was confirmed by the emergence of strong blue fluorescence emission due to the liberation

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• using a similar principle [24]. The protection from the solvent of the intercalated Pt guest enables its fluorescence emission and is accompanied by the induction of chirality in the resulting host–guest complex. A significant enhancement of the circular dichroism response of the chiral guest is

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• , angles, and important crystallographic parameters are given in Tables S6 and S7, Supporting Information File 1. Hydrogen atoms are omitted for clarity. a) UV–vis (solid lines) and fluorescence emission (λex = 365 nm, dashed) spectra of compounds 5a–c (toluene, c = 2 10−5 M, l = 1 cm). b) Solutions of

• compounds 5a–c in toluene before irradiation (no emission) and c) during irradiation (photoluminescence, λex = 365 nm) at room temperature. UV–vis (solid lines) and fluorescence emission (dashed, λex = 365 nm) spectra of compounds 6a,b in toluene (c = 2 10−5 M, l = 1 cm) at room temperature. UV–vis

• , fluorescence emission (λex = 500 nm), and fluorescence excitation (λobs = 590 nm) spectra of benzo[5,6][1,4]oxazino[2,3-b]phenothiazine 10c in toluene (c = 2 10−5 M (UV–vis) or c = 2 10−6 M (fluorescence), l = 1 cm) at room temperature. Synthesis of 6,8-di-tert-butyl-N-aryl-3H-phenoxazin-3-imines 3 [6] and 6,8

Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

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

• = 0.07), and compound 64 displayed almost no fluorescence emission (λmax,em = 497 nm, Φem = NA). Naphthazarin–biphenylene hybrid structures Taking the advantage of naphthazarin's bifunctional Diels–Alder reactivity, Swager and his team succeeded in the synthesis of POA-type structures incorporating

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

• energy gap between HOMO/LUMO hybrid orbits and drive fluorescence emission to longer wavelengths [48][49]. In this molecular design, the strong electron-deficient naphtho[2,3-c][1,2,5]thiadiazole (Nz) [13][50][51] as an acceptor and the strong electron-donating carbazole [52] as a donor unit were used in

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

• capability of the PTZ and NI moieties, respectively, by oxidation of the PTZ unit, or by using different aryl substituents attached to the NI unit. This tuning effect was manifested in the UV–vis absorption and fluorescence emission spectra, e.g., in the change of the charge transfer absorption bands. TADF

• by 1H NMR, 13C NMR, and HRMS spectra (Experimental section). UV–vis absorption and fluorescence emission spectra The UV–vis absorption spectra of the compounds were studied (Figure 1 and Figure S29 in Supporting Information File 1). For the compounds without an oxidized PTZ unit, there are

• that affects the fluorescence of these two dyads. Indeed, the highly solvent polarity dependent fluorescence emission intensity, and wavelength are different from the 4-amino NI derivatives, which are much less solvent polarity-dependent [59][61]. Since a TADF molecule is characterized by a stronger

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• fluorescence emission based on CS-TPE or TBTQ-C6/CS-TPE may find applications in various fields, including the development of visual oral drug delivery systems. Keywords: chitosan; nanoparticle; tetraphenylethylene; tribenzotriquinacene; Introduction Stimuli-responsive assemblies in aqueous media have drawn

• addition, the presence of TBTQ-C6 greatly enhanced the fluorescence emission of the nanoparticles and was able to maintain the fluorescence relatively stable at different pH values. Essentially, this work demonstrates the first study involving stimuli-responsive supramolecular polymeric nanoparticles based

• . The fluorescence properties of CS-TPE and TBTQ-C6/CS-TPE with three different Rf in aqueous medium were investigated by fluorescence spectrophotometry. The fluorescence emission of CS-TPE was significantly enhanced with the increase of its Rf/DL (Figure 7a). This may be caused by the increased

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

• simulations additionally supported the pronounced hypochromic effect (chapter Computational analysis). Fluorescence spectra Fluorescence emission of Phen-Py-1 and Phen-Py-2 measured at pH 5 and pH 7 (cacodylate buffer, Ic = 0.05 mol dm−3) was linearly dependent on the concentration up to 4 × 10−6 mol dm−3

• excimer formation characterized by a new fluorescence emission band at 475 nm, which is significantly red-shifted compared to either fluorescent emission of single phenanthridine (λmax = 400 nm) or pyrene (λmax = 378 and 400 nm) molecule (Supporting Information File 1, Figure S2, left pH 5.0; right pH 7.0

• DNA/RNA polynucleotides [37]. The monomer fluorescence emission at 400 nm was not changed except for titration with poly dGdC–poly dGdC where a small emission increase of emission at 400 nm was observed. At ratios of an excess of polynucleotide over compound (r[compound]/[polynucleotide] < 0.3

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• showed good fluorescence emission; thus, it could be used as a photodynamic therapy application. In 2013, Liu and colleagues [66] used a click chemistry approach to synthesize meso-tetratriazole-bridged Zn(II) porphyrin-boron dipyrromethane conjugates 164 in 85% yield by reacting porphyrin 146 with

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

• . The synthesis of the dyads is based on the ordinary derivatization of the NI and PTZ chromophores [20]. The molecular structures were confirmed by 1H NMR, 13C NMR, and HRMS methods (Experimental section). UV–vis absorption and fluorescence emission spectra The UV–vis absorption spectra of the

• processes of these dyads upon photoexcitation. Experimental General methods All the chemicals used in synthesis are analytical pure and were used as received without purification. UV–vis absorption spectra were measured on a UV-2550 spectrophotometer (Shimadzu Ltd., Japan). Fluorescence emission spectra

Computational model predicts protein binding sites of a luminescent ligand equipped with guanidiniocarbonyl-pyrrole groups

• Neda Rafieiolhosseini,
• Matthias Killa,
• Thorben Neumann,
• Niklas Tötsch,
• Jean-Noël Grad,
• Alexander Höing,
• Thies Dirksmeyer,
• Jochen Niemeyer,
• Christian Ottmann,
• Shirley K. Knauer,
• Michael Giese,
• Jens Voskuhl and
• Daniel Hoffmann

Beilstein J. Org. Chem. 2022, 18, 1322–1331, doi:10.3762/bjoc.18.137

• prediction of two C2 related, dominating binding sites on 14-3-3ζ that may bind to two of the supramolecular ligand molecules. Keywords: AIE luminophores; fluorescence emission; guanidiniocarbonyl-pyrrole; ligand binding; 14-3-3 protein; Introduction The 14-3-3 protein family was one of the first

• overcome this issue is to use fluorescence emission as a read-out tool, such as an emission “on” or “off” behavior [15]. Selective and sensitive fluorescent ligands have been proven to be essential tools for the study of biological systems by biosensing and imaging [16]. There is an increasing demand for

• , Figures S22–S25). This compound 1 was tested in initial binding assays using fluorescence emission as well as native gel electrophoresis. We could indeed show that 1 binds to 14-3-3ζ as detected by native gel electrophoresis and fluorescence titration (Supporting Information File 1). Experiments show that

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

• band, but also intense fluorescence emission both in solution and the solid state. Keywords: (D–π)2 structure; fluorescence; fluorescent dyes; photoabsorption; redox properties; Introduction The design and development of a new type of organic fluorescent dyes have been of considerable scientific and

• fluorescent dyes constructed of an electron-donating moiety (D) and an electron-withdrawing moiety (A), linked by a π-conjugated unit thanks to their intense photoabsorption and fluorescence emission characteristics originating from the intramolecular charge transfer (ICT) excitation from the D to the A

• photoabsorption band but also intense fluorescence emission both in solution and the solid state, compared to the (D–π)2Ph-type structure. The electrochemical properties of OTK-2 and OTT-2 (0.1 mM) were evaluated using CV in DMF containing 0.1 M tetrabutylammonium perchlorate (Bu4NClO4), in which the potentials

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

• Nisha Devi and
• Virender Singh

Beilstein J. Org. Chem. 2022, 18, 926–934, doi:10.3762/bjoc.18.92

• . Fluorescence studies Fluorescence studies of these C-3-substituted pyrido[3,4-b]indole derivatives were examined and various parameters (contact time, concentration and solvent) were optimized for obtaining the best results using 7dA as a model substrate. Fluorescence emission spectra for optimizing the

• . Further, the fluorescence emission profile of 7dA was recorded in chloroform at different concentrations viz. 1 × 10−6 M, 2 × 10−6 M, 3 × 10−6 M, 4 × 10−6 M and 5 × 10−6 M which indicated that fluorescence intensity was found to increase with increase in concentration and fluorescence spectra above this

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

• light, which confirmed that the emission was sensitive to BF3 concentration. Yang et al. used also TFA to shape the fluorescence emission based on the protonation effect between the dissociated H+ and the fluorescent material [32]. Lin et al. used the Lewis acids B(C6F5)3 and AlCl3 to regulate the

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• +, and Mn2+ (nitrate salts were used as cation sources) in DMF resulted in different degrees of quenching of the fluorescence emission of host 4. The results are collected in Figure 3 as the corresponding fluorescence quenching efficiency which was quantified using the equation ΔI = (I0 − I), where I is

• halide ions, especially the heavier iodide ion, to the macrocyclic sensor, slightly enhanced the fluorescence emission in CH2Cl2/CH3OH 4:1 (v/v) at 298 K, instead of quenching the fluorescence as predicted by the classic heavy-atom effect. The corresponding fluorescence enhancement efficiency of selected

• −1. In another perspective, the presence of the coordination of selected anions to the macrocyclic sensor enhanced the fluorescence emission in various degree, extremely contrary to the classic heavy-atom effect caused by a heavy atom. In general, this macrocyclic sensor showed high fluorescence

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• coefficients of the derivatives studied here. All absorption spectra are listed in Supporting Information File 1 (Figures S2–S7). The steady-state fluorescence emission spectra of the Schiff base compounds from their absorption in the UV–vis region was carried out. Derivatives 3aa–fa and 3bb–be were analyzed

• fluorescence yields (Φf) were calculated in order to prove the quantum efficiency of these derivatives in terms of fluorescence emission and thus discuss the influence of the different solvents and substituents. Firstly, by comparing the selected solvents, compound 3aa (R = Ph, R1 = H) presented an emission in

• showing coplanarity of the same system. Normalized absorption spectra in the UV–vis region of compounds (a) 3ea and (b) 3be in CHCl3, MeOH or DMSO solution, respectively ([ ] = 1.50 × 10−5 M). Normalized steady-state fluorescence emission spectra of compound 3aa (R = Ph, R1 = H) in CHCl3 (black solid line