Base-promoted deacylation of 2-acetyl-2,5-dihydrothiophenes and their oxygen-mediated hydroxylation

• Vladimir G. Ilkin,
• Margarita Likhacheva,
• Igor V. Trushkov,
• Tetyana V. Beryozkina,
• Vera S. Berseneva,
• Vladimir T. Abaev,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2026, 22, 192–204, doi:10.3762/bjoc.22.13

• presented in Figure 2. The formation of product 2a before water and acid were added also follows from the comparison of UV–vis spectra of crude mixture (a) and product 2a (b). According to the previously reported data [51], the absorption maximum in spectrum (a) at 220 nm is caused by the presence of

• )) and R1 = 0.0837, wR2 = 0.1768 (all data). Largest diff. peak/hole 0.29/−0.55 e−Å−3. HRMS analysis of the crude product. UV–vis spectra of the crude mixture (5.6 mg of the crude mixture was dissolved in 15 mL of methanol and the aliquot (100 µL) was diluted in 900 µL of methanol) (a) and purified

Improved synthesis and physicochemical characterization of the selective serotonin 2A receptor agonist 25CN-NBOH

• Adrian G. Rossebø,
• Hannah G. Kolberg,
• Anders E. Tønder,
• Louise Kjaerulff,
• Poul Erik Hansen,
• Karla A. Frydenvang,
• Jesper Østergaard and
• Jesper L. Kristensen

Beilstein J. Org. Chem. 2026, 22, 175–184, doi:10.3762/bjoc.22.11

• , respectively, while UV–vis spectra were recorded using the fiber optic probe (10 mm light path) of the inForm diode array spectrometer. The instrument control and data analysis were performed using the inForm software Version 1.1.3.6 (Sirius Analytical, Forest Row, UK). HPLC Samples from distribution

A new synthesis of Tyrian purple (6,6’-dibromoindigo) and its corresponding sulfonate salts

• Holly Helmers,
• Mark Horton,
• Julie Concepcion,
• Jeffrey Bjorklund and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2026, 22, 167–174, doi:10.3762/bjoc.22.10

• deprotonation. Examining the absorbance at 755 nm versus pH yields a second pKa value at 13.0 ± 0.11 (Supporting Information File 1, Figure S26). As shown in Figure 1B, the corresponding disulfonate of 6,6’-dibromoindigo, 9, shows similar UV–vis spectra to compound 10. Specifically, 9 shows a λmax at 606 nm and

• ) [26]. The UV–vis spectra of both 9 and 10 are similar to those of 5,5’-indigodisulfonic acid disodium salt (indigo carmine) and 5,5’,7-indigotrisulfonic acid trisodium salt, as shown in Table 1 [27][28]. When compared to the absorption maximum of 6,6’-dibromoindigo (1), di- and trisulfonation causes a

• , thereby creating water-soluble derivatives of this ancient dye. A) UV–vis spectra of 6,6’-dibromo-5,5’,7-indigotrisulfonic acid trisodium salt (10) (10 μM) in aqueous solution at different pH values. B) UV–vis spectra of 6,6’-dibromo-5,5’-indigodisulfonic acid disodium salt (9) (10 μM) in aqueous solution

Symmetrical D–π–A–π–D indanone dyes: a new design for nonlinear optics and cyanide detection

• Ergin Keleş,
• Alberto Barsella,
• Nurgül Seferoğlu,
• Zeynel Seferoğlu and
• Burcu Aydıner

Beilstein J. Org. Chem. 2026, 22, 131–142, doi:10.3762/bjoc.22.6

• Supporting Information File 16: Synthesis of compounds, copies of NMR, HRMS and UV–vis spectra and DFT results. Acknowledgements The numerical calculations reported in this paper were fully performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA resources). This study constitutes

Silica gel with covalently attached bambusuril macrocycle for dicyanoaurate sorption from water

• Michaela Šusterová and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2025, 21, 2604–2611, doi:10.3762/bjoc.21.201

• carried out in nitrogen atmosphere. The dicyanoaurate concentration in solution was determined according to UV–vis spectra recorded with a CARY 60 spectrophotometer (Agilent Technologies). NMR spectra were recorded on a Bruker Avance III 300 spectrometer (300.15 Hz, 298.15 K). Preparation of SG-NHCO-BU1

• ] (0.5 mM) with increasing amount of BU1. C) UV–vis spectra of K[Au(CN)2] (0.5 mM) before and after additions of supernatants obtained by treatment of SG-NHCO-BU1 and SG-BU1 with aqueous 1 M KOH. The efficiency of materials (blue SG-BU1, grey SG-NHCO-BU1) in sorbing dicyanoaurate from its water solution

Effect of a photoswitchable rotaxane on membrane permeabilization across lipid compositions

• Udyogi N. K. Conthagamage,
• Lilia Lopez,
• Zuliah A. Abdulsalam and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2498–2512, doi:10.3762/bjoc.21.192

• the LUVs at 10 mol % relative to the total lipid content. UV–vis spectra recorded before irradiation showed an absorption band around 372 nm, corresponding to the π→π* transition of the E isomer (Figure 3, left column, black trace). Upon irradiation at 370 nm for 1 minute, two new peaks appeared at

• rotaxane 1. LUVs containing rotaxane 1 were subjected to ten cycles of alternating irradiation at 370 nm and 467 nm, with UV–vis spectra recorded after each exposure. Figure 3 (right column) shows the changes in absorption at 365 nm, reflecting the photoswitching and photoreversibility of rotaxane 1 across

Conformational effects on iodide binding: a comparative study of flexible and rigid carbazole macrocyclic analogs

• Guang-Wei Zhang,
• Yong Zhang,
• Le Shi,
• Chuang Gao,
• Hong-Yu Li and
• Lei Xue

Beilstein J. Org. Chem. 2025, 21, 2369–2375, doi:10.3762/bjoc.21.181

• concentrations in CDCl3 (400 MHz, CDCl3, 25 °C); (A) WDG, (N) TBAI, and equimolar TBAI solutions at concentrations of (B) 0.25, (C) 0.50, (D) 0.75, (E) 1.00, (F) 1.25, (G) 1.5, (H) 1.75, (I) 2.00, (J) 3.00, (K) 5.00 equivalents. (a) UV–vis spectra of PBG (10 μM) in CHCl3 with TBAI concentration, (b) UV–vis

• spectra of WDG (10 μM) in CHCl3, (c) Fluorescence spectra of PBG (10 μM) in CHCl3 (λex: 303 nm), (d) Fluorescence spectra of WDG (10 μM) in CHCl3 (λex: 303 nm). Synthesis routes of PBG and WDG. Supporting Information Supporting Information File 32: Additional experimental data. Funding The project was

Photochemical reduction of acylimidazolium salts

• Michael Jakob,
• Nick Bechler,
• Hassan Abdelwahab,
• Fabian Weber,
• Janos Wasternack,
• Leonardo Kleebauer,
• Jan P. Götze and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2025, 21, 1973–1983, doi:10.3762/bjoc.21.153

• identity of the active light-absorbing species in the reaction mixture. UV–vis spectra of the benzoylazolium starting material 1 at different concentrations in the acetonitrile reaction solvent were accordingly measured. Although exhibiting maximum absorption at wavelengths significantly shorter than that

• efficiency observed upon switching from blue to UV-A light irradiation. Nevertheless, alternative scenarios involving the potential formation of excited donor–acceptor (EDA) complexes between benzoylazolium species 1 and DIPEA were considered. Measurements of the UV–vis spectra in the presence of the amine

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

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

• types of CDs and aims to promote the use of these sustainable materials, it opens the way for further exploitation of such compounds in visible-light-catalyzed reactions. UV–vis spectra of the CDs. All the measurements have been performed in water, except for CD-a-GLU, where a H2O/acetonitrile 1:1

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

Substituent effects in N-acetylated phenylazopyrazole photoswitches

• Radek Tovtik,
• Dennis Marzin,
• Pia Weigel,
• Stefano Crespi and
• Nadja A. Simeth

Beilstein J. Org. Chem. 2025, 21, 830–838, doi:10.3762/bjoc.21.66

• 1H NMR spectrum. We compared these results to simply estimating the isomer distribution at the PSS (cf. Supporting Information File 1, section 3.1) from the UV–vis spectra and observed good agreement, meaning the results from UV–vis spectroscopy can be used for rough PSD estimation, due to good

• spectral separation of the isomers. Since we encountered fast back isomerization only for NAc-PAP-OH (vide infra), the PSDs could only be determined from the UV–vis spectra. NAc-PAPs showed high to quantitative formation of the Z-configurated isomers. For example, NAc-PAP-Br showed an isomerization

• equipment, experimental procedures, compound characterization, UV–vis spectra at different concentrations, photochemical experiments, thermal isomerization analysis, and NMR spectra. Funding We thank the Swedish Vetenskapsrådet for a Starting Grant (2021-05414 to SC and to 2023-04088 to NAS). This work was

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

• UV–vis spectra of the two photoswitchable units. This design laid the basis for a robust switching cycle comprising the EManEGlc, the EManZGlc, and the ZManZGlc isomer of 1 [24]. In this contribution, we address the question of how the different isomers of 1 perform as inhibitors of bacterial

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

• reference. The selected photophysical parameters are summarized in Table 1. The fluorescence excitation spectra were consistent with absorption spectra to unambiguously assign the fluorescence bands to the studied F8-phenacenes (Figure S1 in Supporting Information File 1). In the UV–vis spectra, a small

Semisynthetic derivatives of massarilactone D with cytotoxic and nematicidal activities

• Rémy B. Teponno,
• Sara R. Noumeur and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 607–615, doi:10.3762/bjoc.21.48

• well as detailed structure–activity relationships, to optimize massarilactone hemisynthetic derivatives for specific biological applications. Experimental General experimental procedures UV–vis spectra were recorded on a Shimadzu UV/Vis 2450 spectrophotometer. Optical rotations were obtained from an

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

• achieved due to chemical modification of ANTH [25][32]. Changes in the UV–vis spectra were typically used as an indication of the compounds’ decomposition. It is well established that ANTH is rapidly oxidized to form anthraquinone upon exposure to light in the presence of oxygen. Furthermore, endoperoxides

• irradiated with a 34 W incandescent bulb. The UV–vis spectra of ANTH monitored over time showed that new absorbance features began to appear, suggesting the formation of new products. In contrast, the UV–vis spectra of 9,10-ANTH(BnF)2 showed no new absorbance features over time, suggesting that either

• (C8F17)2 [36]. These results make it clear that monitoring photoirradiated solutions by UV–vis spectroscopy must be accompanied by complementary analyses to enable accurate interpretation of the changes in the UV–vis spectra and identification of the photoproducts. The next comparative photostability

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

• 1:1 (v/v) solution which was left to evaporate at room temperature over the course of a few days. Photophysical properties Fluorescence spectra were measured on a Horiba FluoroMax Plus spectrofluorimeter. UV–vis spectra were measured on a Shimadzu UV-1900i UV–vis spectrophotometer. Absorption and

Antibiofilm and cytotoxic metabolites from the entomopathogenic fungus Samsoniella aurantia

• Rita Toshe,
• Syeda J. Khalid,
• Blondelle Matio Kemkuignou,
• Esteban Charria-Girón,
• Paul Eckhardt,
• Birthe Sandargo,
• Kunlapat Nuchthien,
• J. Jennifer Luangsa-ard,
• Till Opatz,
• Hedda Schrey,
• Sherif S. Ebada and
• Marc Stadler

Beilstein J. Org. Chem. 2025, 21, 327–339, doi:10.3762/bjoc.21.23

• experimental methods Optical rotations at 20 °C were measured with an Anton Paar MCP 150 circular polarimeter (Anton Paar, Graz, Austria). UV–vis spectra spanning the 190–600 nm range were acquired using a Shimadzu UV2450 spectrophotometer (Shimadzu, Kyoto, Japan). Electronic circular dichroism (ECD) spectra

• were obtained using a J-815 spectropolarimeter (JASCO Pfungstadt, Germany). The optical rotation, ECD, and UV–vis spectra of the newly described secondary metabolites were assessed in MeOH (Uvasol, Merck, Darmstadt, Germany). Analytical HPLC chromatograms and electrospray ionization mass spectra (ESIMS

Surprising acidity for the methylene of 1,3-indenocorannulenes?

• Shi Liu,
• Märt Lõkov,
• Sofja Tshepelevitsh,
• Ivo Leito,
• Kim K. Baldridge and
• Jay S. Siegel

Beilstein J. Org. Chem. 2024, 20, 3144–3150, doi:10.3762/bjoc.20.260

• separately titrated in order to obtain the UV–vis spectra of the acids in neutral as well as in deprotonated forms. Then, the same titration is done with a mixture of measured acid (FIC or BFC) and a reference acid. Using the spectral data from the titrations of mixtures the dissociation levels α = [A−]/([A

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

• spectra of the products were obtained using an LS45 spectrometer from PerkinElmer. Elemental analyses were conducted using an Vario El CHN mode system from Elementar GmbH. The PL and the UV–vis spectra were obtained using a spectrofluorometer (LS45, PerkinElmer) and a Specord S 600 (Analytik Jena

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

• free PyBA. Data analysis, including calculation of the phase transition temperature, was performed using the MicroCal PEAQ-DSC Software. UV–vis absorption measurement UV–vis spectra of DMPC liposomes (1 mM DMPC) with or without catC60 or C60 were measured in PBS(–) using a UV-3600 Plus absorption

Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light

• Francesco Gambuti,
• Jacopo Pizzorno,
• Chiara Lambruschini,
• Renata Riva and
• Lisa Moni

Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230

• studies; description of photochemical equipment; characterization data of compounds (1H, 13C and 19F NMR spectra, IR and UV–vis spectra). Acknowledgements The University of Genova is kindly acknowledged for the contribution to the acquisition of an NMR instrument (D.R. 3404 19/7/2018). We thank Mr

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

• ), strong (s), medium (m), weak (w) or very weak (vw). UV–vis spectra were recorded on a Cary 60 UV–vis spectrophotometer and emission spectra were recorded on an Agilent Cary Eclipse fluorescence spectrophotometer. Basic and high-resolution mass spectra (MS/HRMS) were measured on instruments coupled to a

Synthesis and reactivity of the di(9-anthryl)methyl radical

• Tomohiko Nishiuchi,
• Kazuma Takahashi,
• Yuta Makihara and
• Takashi Kubo

Beilstein J. Org. Chem. 2024, 20, 2254–2260, doi:10.3762/bjoc.20.193

• and cathodic sides became smaller, resulting in a reversible redox wave (Figure 5b). This indicates that the generated DAntM radical rapidly decomposes during the CV measurement, leading to the irreversible redox wave at slow scan rate. The UV–vis spectra of the DAntM radical and cation were shown in

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

• parts per million (ppm) and the coupling constants (J) in hertz (Hz). UV–vis spectra were recorded on a Shimadzu UV-2501PC spectrophotometer using DMF as the solvent. The emission spectra were recorded with a Jasco FP-8300 spectrofluorometer using DMF as the solvent. Mass spectra were recorded using a

• 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

• spectra are very similar. These results indicate that substituents with different functional groups can be attached to DPP 2 without significant modification of their optical properties. The observed Stokes shifts for dyes 3 and 4 averaged in the range of 60–70 nm. All compounds exhibited high