Synthesis of pyrrole-fused dibenzoxazepine/dibenzothiazepine/triazolobenzodiazepine derivatives via isocyanide-based multicomponent reactions

• Marzieh Norouzi,
• Mohammad Taghi Nazeri,
• Ahmad Shaabani and
• Behrouz Notash

Beilstein J. Org. Chem. 2024, 20, 2870–2882, doi:10.3762/bjoc.20.241

• , and triazolobenzodiazepine under solvent- and catalyst-free conditions. Purposefully, this approach produced various bioactive scaffolds using environmentally friendly, mild, and simple conditions. Due to their bioactive moieties, these compounds with exclusive fluorescence properties may attract

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

• eliminating short-lived background fluorescence. This unique capability enhances the sensitivity and reliability of trivalent lanthanide-based chemosensors, making them invaluable tools for our application in the detection of hydrogen sulfide. Our previously reported trivalent lanthanide-based chemosensors

• were measured at room temperature utilizing a Varian Cary 1E UV–vis spectrophotometer with a quartz cell of 10 mm path length. Luminescence emission spectra of aqueous solutions were captured at 23 °C using a Varian Cary-Eclipse fluorescence spectrophotometer set to phosphorescence mode, employing a

• 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.

Access to optically active tetrafluoroethylenated amines based on [1,3]-proton shift reaction

• Yuta Kabumoto,
• Eiichiro Yoshimoto,
• Bing Xiaohuan,
• Masato Morita,
• Motohiro Yasui,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2776–2783, doi:10.3762/bjoc.20.233

•  1a, 1, 2) [10][11][12], liquid crystals (Figure 1b, 3, 4) [13][14][15][16][17], fluorescence materials (Figure 1c, 5) [18][19], and so on, have been developed in recent years. In sharp contrast to the major development of such non-chiral tetrafluoroethylenated compounds, there have been only few

Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions

• Hayato Takagi,
• Çetin Çelik,
• Ryosuke Fukuda,
• Qi Guo,
• Tomohiro Higashino,
• Hiroshi Imahori,
• Yoko Yamakoshi and
• Tatsuya Murakami

Beilstein J. Org. Chem. 2024, 20, 2732–2738, doi:10.3762/bjoc.20.231

• physiologically relevant media [15]. The interaction between catC60 and PyBA in the liposomes was assessed by the fluorescence spectra of PyBA in catC60-lip [16]. The catC60-lip containing catC60 at 0, 5.4, and 54 µM were mixed with PyBA (50 µM) in PBS(–), and the fluorescence spectra were measured. As shown in

• Figure 4a, the intensity decreased upon increasing the concentration of the catC60 in the liposomes, showing the quench of PyBA fluorescence by catC60, presumably by interacting in the liposome membrane. The incomplete quenching after the addition of PyBA at a concentration comparable to that of catC60

• may be attributed to the presence of unembedded PyBA in the dispersion. To this PyBA-embedded catC60-lip system, methanol was added to completely destroy the liposome structures, resulting in the regain of the fluorescence intensity (Figure 4b). The results clearly demonstrate that PyBA interacts with

Synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones

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

Beilstein J. Org. Chem. 2024, 20, 2708–2719, doi:10.3762/bjoc.20.228

• was studied by UV–vis and fluorescence spectroscopy. Keywords: cross-coupling; cyclization; heterocycles; palladium; Introduction Nucleobases contain the coded information and give DNA and RNA their typical structure. As a nucleobase, uracil is involved in numerous vital processes and is therefore a

• -based benzo[f]quinazoline-1,3(2H,4H)-diones C [65]. Furthermore, optical properties were analysed by UV–vis and fluorescence spectroscopy. Results and Discussion Synthesis Our strategy for the synthesis of benzo[f]quinazoline-1,3(2H,4H)-diones is based on a four-step sequence and relies on a combination

• properties All synthesized compounds exhibit photoluminescence by excitation with UV light. Hence, we studied the photophysical properties of all obtained derivatives 5 by steady-state absorption and fluorescence spectroscopy. The influence of the substitution pattern on the photophysical properties is

5th International Symposium on Synthesis and Catalysis (ISySyCat2023)

• Anthony J. Burke and
• Elisabete P. Carreiro

Beilstein J. Org. Chem. 2024, 20, 2704–2707, doi:10.3762/bjoc.20.227

• fluorescence quantum yield, which is an important property for their potential application in the field of optoelectronics (particularly for energy and biological chemistry applications). In this thematic issue, Nieto et al. contributed a timely Review article on the chemical space of 2-phenethylamines

Photoluminescence color-tuning with polymer-dispersed fluorescent films containing two fluorinated diphenylacetylene-type fluorophores

• Kazuki Kobayashi,
• Shigeyuki Yamada,
• Motohiro Yasui and
• Tsutomu Konno

Beilstein J. Org. Chem. 2024, 20, 2682–2690, doi:10.3762/bjoc.20.225

• luminescent materials, particularly after the 2001 discovery of aggregation-induced emission. This study focuses on fluorinated diphenylacetylene-based luminescent molecules, revealing that specific molecular modifications can enhance fluorescence and achieve a wide range of photoluminescence colors. A simple

• diphenylacetylene structure as the π-conjugated core. As a part of our research projects, we have begun to explore diphenylacetylene-based luminescent molecules despite diphenylacetylene not exhibiting fluorescence at room temperature because it undergoes a πσ* excited state that rapidly forms a trans-bend

• short-axis direction of the electron-deficient aromatic ring significantly retards the internal conversion via the formation of H···F hydrogen bonds, leading to a marked blue fluorescence in the crystalline state (Figure 1b) [17][18][19][20]. Recently, the introduction of N,N-disubstituted amino groups

Applications of microscopy and small angle scattering techniques for the characterisation of supramolecular gels

• Connor R. M. MacDonald and
• Emily R. Draper

Beilstein J. Org. Chem. 2024, 20, 2608–2634, doi:10.3762/bjoc.20.220

• structures. Some of the key features and capabilities of these techniques are summarised in Table 1. CLSM is a fluorescence microscopy technique capable of acquiring high-resolution optical images at selected depths of the sample. This is achieved by exciting compounds with laser light and, by using a

• pinhole to select focal planes, allows fluorescence at various depths to be focused and imaged. The resulting 2D focal plane images can be stacked to yield a 3D fluorescence image of high resolution, allowing complex morphologies to be visualised (Figure 2) [11]. While CLSM provides in situ 3D imaging

• attached to the molecules themselves or is interacting with them. Introducing fluorescent dyes to self-assembling systems affects their chemical and mechanical stability as the hydrophobic features can destabilise the self-assembled network [18]. This reliance on fluorescence labels or dyes leading to a

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

• spectra were referenced to residual solvent. UV–visible absorption spectra were recorded on a Hitachi U-4500 spectrometer. Fluorescence spectra were recorded on a Hitachi F-4500 fluorescence spectrometer. MALDI–TOF MS was recorded on a Shimadzu Axima-CFRplus. TLC analyses were carried out on aluminum

Photoredox-catalyzed intramolecular nucleophilic amidation of alkenes with β-lactams

• Valentina Giraldi,
• Giandomenico Magagnano,
• Daria Giacomini,
• Pier Giorgio Cozzi and
• Andrea Gualandi

Beilstein J. Org. Chem. 2024, 20, 2461–2468, doi:10.3762/bjoc.20.210

• the cis-isomer. The optimal PC for the reaction was acridinium salt IV (Table 1, entry 1), while the Fukuzumi catalyst (I), commonly employed by Nicewicz et al., was less effective (Table 1, entry 9). 3CzClIPN, an organic dye belonging to the class of thermally activated delayed fluorescence (TADF

Improved deconvolution of natural products’ protein targets using diagnostic ions from chemical proteomics linkers

• Andreas Wiest and
• Pavel Kielkowski

Beilstein J. Org. Chem. 2024, 20, 2323–2341, doi:10.3762/bjoc.20.199

• -PAGE) and visualized by in-gel fluorescence scanning (Figure 6A). In this approach the tag is a suitable fluorophore. Previously, during an introduction period of a chemical proteomics workflow of activity-based protein profiling (ABPP), the resulting fluorescent bands might be simply cut out from the

• gel and subjected to MS analysis to identify the labeled proteins [77][78]. The in-gel analysis is often used for target validation with corresponding protein mutants or knockout cell lines, with loss of the identified probe–protein interaction leading to disappearance of the fluorescence band from

• the TAMRA-azide yields a mixture of labeled and unlabeled proteins. The proteins are then separated on SDS-PAGE by their molecular weight and fluorescence of the labeled proteins is recorded (Figure 6A). Due to the high sensitivity of fluorescence read-out, this allows to identify protein labeling

Cell-free protein synthesis with technical additives – expanding the parameter space of in vitro gene expression

• Tabea Bartsch,
• Stephan Lütz and
• Katrin Rosenthal

Beilstein J. Org. Chem. 2024, 20, 2242–2253, doi:10.3762/bjoc.20.192

• workflows [45]) and performance evaluation. This is convenient because product formation and even concentration can be easily quantified measuring the fluorescence intensity. To take advantage of this, fusion proteins with sfGFP can be constructed for CFPS performance evaluation [46]. Therefore, sfGFP was

• increase the synthesis yield, but the general influence of all additives will be investigated. Figure 1 shows the results of sfGFP synthesis with different technical additives. All values were normalized in relation to the fluorescence intensity of the reference with 2% PEG-8000. Macromolecular crowding is

• , as it provides a simple and robust readout, the fluorescence signal. As a result, the composition of the CFPS solution is optimized for the synthesis of GFP. In addition, larger and more complex enzymes are usually more difficult to synthesize with CFPS [56], although there are exceptions, such as

Metal-free double azide addition to strained alkynes of an octadehydrodibenzo[12]annulene derivative with electron-withdrawing substituents

• Naoki Takeda,
• Shuichi Akasaka,
• Susumu Kawauchi and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2024, 20, 2234–2241, doi:10.3762/bjoc.20.191

• addition. Thus, compound 6a shows an ultraviolet absorption peak at 249 nm (λmax) and no absorption in the visible region was observed. When excited at 249 nm, an emission band at 513 nm (λem) appeared in the spectrum with a fluorescence quantum yield (Φ) of 7.0%. The absorption and fluorescence spectra

• the double benzyl azide adduct of DBA-OHex was 21900 cm−1 and larger than that of 6a (20700 cm−1), the Φ was 4.3%. This result suggested that replacing the hexyloxy substituents with electron-withdrawing ones enhanced the fluorescence intensity by approximately 1.6 times. Crosslinker application Using

• previously reported electron-donating hexyloxy substituents. The addition pattern was experimentally investigated by 2D NMR, which was also supported by DFT calculations. The bistriazole product displayed fluorescence in the visible range with a fluorescence quantum yield of 7.0%. Finally, the developed

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

• –80%) along with their preliminary photophysical (absorption, emission and time resolved fluorescence lifetime) properties. The condensation reaction for assembling the required DPMs were catalyzed with trifluoroacetic acid (TFA) at 0 °C to room temperature (rt), and the stable dipyrromethanes were

• derivatives were successfully characterized and their structures were established by means of the 1H and 13C NMR spectroscopy, besides further confirmation by mass spectrometry (see Supporting Information File 1). The UV–vis absorption, emission and time-resolved fluorescence spectra Emission and absorption

• these compounds were found ranged from 350 to 508 nm, with a small shoulder in each case, which displays vibronic features (Figure 2). Exact values of the fluorescence maxima for these compounds are as follows: 12 (406.78, 428.93, and 457.04), 14 (406.42, 429.65, and 458.53), and 15 (406.42, 429.65, and

Computational toolbox for the analysis of protein–glycan interactions

• Ferran Nieto-Fabregat,
• Maria Pia Lenza,
• Angela Marseglia,
• Cristina Di Carluccio,
• Antonio Molinaro,
• Alba Silipo and
• Roberta Marchetti

Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180

• networks (NN), that allows the user to predict protein-glycan binding. Taking a glycan structure as input, this model is able to predict the strength of the interaction based on the relative fluorescence units (RFUs) measured in the Consortium for Functional Glycomics glycan arrays and extrapolating these

Cage-like microstructures via sequential Ugi reactions in aqueous emulsions

• Rita S. Alqubelat,
• Yaroslava A. Menzorova and
• Maxim A. Mironov

Beilstein J. Org. Chem. 2024, 20, 2078–2083, doi:10.3762/bjoc.20.179

• , which was monitored through the disappearance of isocyanide in the reaction medium using a color reaction [19]. Then the emulsion was applied to the glass surface and evaporated at a temperature of 50 °C. The resulting samples were analyzed using fluorescence microscopy at a wavelength of 490 nm. After

A new platform for the synthesis of diketopyrrolopyrrole derivatives via nucleophilic aromatic substitution reactions

• Vitor A. S. Almodovar and
• Augusto C. Tomé

Beilstein J. Org. Chem. 2024, 20, 1933–1939, doi:10.3762/bjoc.20.169

• region [3][4]. In turn, N-substituted DPP derivatives are soluble in common organic solvents, exhibit large molar extinction coefficients, Stokes shifts in the range of 10–70 nm and high fluorescence quantum yields [5][6][7]. Due to their outstanding photophysical properties, DPP-based dyes have been

• consistently displayed the protonated molecular ion [M + H]+ as the base peak. The UV–vis and fluorescence spectra of DPP derivatives 3a–f, 4a, 4d and 4f in DMF are presented in Figure 1, and their photophysical properties are summarized in Table 1. These compounds are highly fluorescent, and their UV–vis

• fluorescence quantum yields, ranging from 0.66 to 0.83, confirming their potential applications in fluorescence imaging, sensors, and optoelectronic devices. A comprehensive discussion of the potential uses of these fluorescent substances in areas such as materials science, biology, or chemistry may provide a

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

• on biological activities or photophysical properties (i.e., fluorescence) of GBB adducts. Another advantage is that, by replacing the amidine component (classically 2-aminopyridines) with other heterocycles, different scaffolds are obtained, and this is extremely efficient in diversity-oriented

• proof of concept, one of the GBB adducts was transformed into a N,C-palladacycle and was investigated as a potential catalyst for carbon–carbon bond-forming reactions. Furthermore, the authors studied in detail the fluorescence properties of the GBB adducts, that will be discussed in chapter 5. As

• economy (water was the only byproduct) and thermal stability as well as remarkable fluorescence properties. Multicomponent reaction can be also employed to prepare crystalline porous materials namely covalent organic frameworks (COFs). The structural diversity and functionality of COFs were assembled from

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides

• Adam D. Bass,
• Daniela Castellanos,
• Xavier A. Calicdan and
• Dennis D. Cao

Beilstein J. Org. Chem. 2024, 20, 1767–1772, doi:10.3762/bjoc.20.155

• has low fluorescence intensity (Φ = 0.006) [20], 7-Hex emits more efficiently with Φ = 0.41. Interestingly, 7-Ph has nearly no emission intensity, as evidenced by the low signal-to-noise ratio in the data and a near-zero quantum yield when excited at 400 nm. This fluorescence quenching is likely

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• (150 mM) before white-light irradiation and (b) DA11, (d) DA7, and (f) DA6 after white-light irradiation for 60 min. Macroscopic soft DAn scaffolds fabricated by the shear-flow method. Images taken during fluorescence microscopy. Photographs of freshly prepared (a) DA11, (c) DA10, (e) DA7, and (g) DA6

• , merged image of bright field and fluorescence with hBM-MSCs after 3 days of incubation. Fluorescence images of live cells in (b) DA11, (d) DA10, (f) DA7, and (h) DA6 after 3 days of incubation to observe the cell affinity on the hydrogel surface. Scale bar: 200 μm, applied for all panels. The large

Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• was applicable to various carboxylic acids with electron-donating as well as electron-withdrawing substituents but unfortunately, aliphatic acids were not effective in this reaction. In addition, several control experiments, such as fluorescence quenching and Stern–Volmer studies, were done to analyze

Domino reactions of chromones with activated carbonyl compounds

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1256–1269, doi:10.3762/bjoc.20.108

• chromone 9a and for the diene containing a methoxy group (R4 = OMe). The products proved to be interesting, due to their blue fluorescence. 3-Formylchromones Dimethyl acetone-1,3-dicarboxylate The reaction of 3 with 3-formylchromones 10a–d afforded benzophenones 19a–d in moderate to good yields (Scheme 5

Synthesis and optical properties of bis- and tris-alkynyl-2-trifluoromethylquinolines

• Stefan Jopp,
• Franziska Spruner von Mertz,
• Peter Ehlers,
• Alexander Villinger and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 1246–1255, doi:10.3762/bjoc.20.107

• steady state absorption and fluorescence spectroscopy which give insights of the influence of the substitution pattern and of the type of substituents on the optical properties. Keywords: alkynes; catalysis; fluorescence; heterocycles; palladium; Introduction Quinoline is a well-known core structure

• –10°. Optical properties Steady-state absorption and fluorescence measurements were carried out. Compounds 6a, 9a, and 12a were selected to study the impact of the position of the alkynyl group on the optical properties. Comparison of the absorption and emission features of 12a, 12b and 12c gives

• and applied to palladium-catalysed Sonogashira reactions. Optimised reaction conditions allow the synthesis of various bis- or tris-alkynylated products in one step. Products were generally obtained in high yields and intensive fluorescence. The photophysical properties of selected compounds were

Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• potentials of Aza-H and the substrates and initial steady-state fluorescence quenching experiments (Scheme 1, left), but detailed mechanistic insights and direct evidence of the transient radical ions could not be obtained yet [45]. Figure 1A illustrates the absorption and emission spectra of Aza-H in MeCN

• radical ions of polyazahelicenes. The moderate fluorescence quantum yield of 48% (in MeCN) [46] implies that a non-emissive triplet-excited state (at room temperature) could also be generated via intersystem crossing, potentially initiating electron transfer reaction sequences. 77 K emission measurements

• were thus carried out and they showed short-lived fluorescence and long-lived emission (phosphorescence) that was assigned to the triplet state of Aza-H with an energy of 2.32 eV (Figure 1A). Quantum mechanical computations of the Aza-H triplet state yielded a triplet energy of 2.17 eV (adiabatic

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

• isobenzofurans 2, 3 and 23 were studied by UV–vis and fluorescence spectroscopies (Figure 5). Compound 2 is devoid of ortho groups on its 1,3-diphenyl substituents and shows the longest wavelengths of absorption (λmax = 415 nm) and emission (emission λmax = 484 nm) in this series, consistent with a more highly

• -filled cuvette. Fluorescence spectra were measured on a FS5 spectrofluorometer (150 W CW Ozone-free xenon arc lamp) from Edinburgh Instruments. 1,3-Dimesitylisobenzofuran (3) To a round bottom flask was added 1,2-phenylenebis(mesitylmethanone) (21, 0.10 g, 0.27 mmol), zinc dust (0.70 g, 11 mmol) and 10

• ) level of theory using Spartan ’20 [8]. A structural rendering of 1,3-dimesitylisobenzofuran showing the requirement for non-planar mesityl groups in order to avoid steric repulsion between ortho-methyl groups and the nearest benzo hydrogen atoms. UV–vis (top) and fluorescence (middle) spectra for 10−6 M