Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst

• Jannis Ludwig,
• Julian Helberg,
• Hendrik Zipse and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179

• influence of the solvent on the switching efficiency was evaluated by UV–vis (Figure S2, Supporting Information File 1) and NMR experiments (Figure 2). It is important to note that there are two ways to define the switching efficiency of record player molecules: 1. the cis–trans isomerization of the

• ) in the PSS at 530 nm and 435 nm, determined by 1H NMR spectroscopy (600 MHz; for details, see Supporting Information File 1). a) UV–vis cuvette with a solution of porphyrin 1 (13.1 µM in THF) and the corresponding UV–vis spectra at 25 °C in the PSS at 530 nm (green) and 435 nm (blue). b) Signals of

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• molecular ground-state electrical dipole (µ = 7.04 D), which is an evidence for an intramolecular charge transfer (CT) character of the chromophore [34]. The predicted UV–vis spectra by TD-DFT are in excellent agreement with the experimental one (Figure 3, Table 1, the vibrational coupling is neglected

• ) with a UV–vis detector (UV 3702). The melting points (mp) of compounds were determined with an Olympus BX-41 polarization microscope equipped with a Linkam THMS 600 hot stage and a temperature controller unit. 1H and 13C NMR spectra were recorded in CD3OD, CDCl3, D2O or DMSO-d6 at 298 K on a Bruker

• , 18H), 2.14 (m, 4H); 13C NMR (DMSO-d6, 101 MHz) 161.1, 160.7, 137.6, 134.1, 127.0, 126.3, 122.5, 63.2, 52.2, 37.7, 21.4; HRMS-ESI+ (methanol, m/z): [M]2+ calcd for C26H32Cl2N4O4, 267.0900; found, 267.0900; UV–vis (MeOH) λ [nm] (ε [M−1 cm−1]) 397 (10300), 377 (10900), 357 (16000). Synthesis of (S)-N,N

Design, synthesis and application of carbazole macrocycles in anion sensors

• Alo Rüütel,
• Ville Yrjänä,
• Sandip A. Kadam,
• Indrek Saar,
• Mihkel Ilisson,
• Astrid Darnell,
• Kristjan Haav,
• Tõiv Haljasorg,
• Lauri Toom,
• Johan Bobacka and
• Ivo Leito

Beilstein J. Org. Chem. 2020, 16, 1901–1914, doi:10.3762/bjoc.16.157

• for MC002 with lactate and pivalate were obtained by UV–vis measurements as absolute values [31]. Five carboxylates were studied in the form of their tetrabutylammonium salts: pivalate, acetate, benzoate, lactate, and formate. The anions were titrated in DMSO-d6/H2O solvent systems of two proportions

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• measurement of UV–vis absorption and fluorescence emission of the samples, stock solutions of 1.0 mM concentration were prepared using analytical grade CHCl3 as the solvent, and diluted to the final concentration of 4.0 μM. Next, we carefully measured the photophysical properties at room temperature including

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

• triazole 45 in 83% yield. Photophysical properties Finally, we examined the photophysical properties of both the azides and the triazoles. UV–vis absorption measurements of para-bromobenzaldehyde 3 and ortho-bromobenzaldehyde 4 as well as the corresponding triazoles 33–40 were conducted in chloroform

• fluorescence. This may be owing to the azide moiety, either as a functional group or as part of the triazole heterocycle. Similar observations were already made for luminescent materials [74][75]. Fluorene derivatives were subjected to photophysical measurements as well. UV–vis absorption spectra of

• of the alkyl bridge between the arene and the azide are underway in our laboratories. Top: literature examples of organic compounds showing RTP in the crystalline state (a) and in solution (b). Bottom: azide-linked derivatives presented in this work. a) Normalized UV–vis absorption spectra of 3 (blue

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• monitored with in-line and on-line spectroscopies, such as UV–vis, FTIR, mass spectrometry, and NMR [63][64][65][66][67][68]. These systems can be automated to ensure consistency and to remove the need for laborious manual sampling. In-line and on-line monitoring is well aligned with automated synthesis and

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

• properties of BKIs and F-BKIs, we measured the optical properties of compounds 6 and 9 (Table 2). As shown in Figure 2, the UV–vis absorptions of 6b and 9b in THF decreased upon the addition of H2O, and white precipitates formed in samples exceeding 80% of water content. Concurrently, the fluorescent

• parent BKI. Further structural modifications of compounds 3 or 9 and applications to fluorescent bioprobes are currently under investigation. UV–vis and fluorescence (FL) spectra of compounds 3b and 3c. Photochemical properties comparisons of BKIs and F-BKIs. (a–c) BKI 6b: photograph (a), UV–vis (b), and

• FL (c) spectra at different solvent compositions of THF/H2O upon excitation at 365 nm (1.0 × 10−5 M); (d–f) F-BKI 9b: photograph (d), UV–vis (e), and FL (f) spectra at different solvent compositions of THF/H2O upon excitation at 380 nm (1.0 × 10−5 M). Selective fluorination of isoxazoles and one-pot

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• oxime 1g (Scheme 5). Oxime radical 16 is a pale blue crystalline compound that is stable at room temperature [35][62], whereas liquid neat di-tert-butyliminoxyl radical (8) decomposed within a week [59]. The di(1-adamantyl)iminoxyl radical (16) was characterized by IR, UV–vis, EPR, and NMR spectroscopy

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• . The theoretical UV–vis spectra of the derivatives had single absorption bands. The band at ca. 310 nm was characterized by a combination of various transitions towards several excited states. The theoretical UV spectrum of derivative 1 had a shoulder at 390 nm. In general, the experimental UV spectra

• the derivatives 1–3 correlated with electrochemically estimated ones and with the ionization potential values discussed above. The photophysical characteristics determined from the UV–vis absorption and photoluminescence spectra are collected in Table 2. The emission spectra of diluted toluene

• -based compounds 1–3, calculated at the B3LYP/6-31G (d, p) level of theory. Cyclic voltammograms of quinazoline-based compounds 1–3. UV–vis absorption spectra of compounds 1–3. a) Theoretical and b) experimental spectra of compounds 1–3 in THF solution. Fluorescence spectra (a) of dilute solutions and

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• components of F-1 were catalytically active, and hence that the reaction was partly catalyzed heterogeneously and partly promoted by the leached catalyst under the experimental conditions. To investigate this in more detail, studies on the solubility of F-1 in MeOH were conducted by UV–vis spectroscopy at

• ) ranging from 5.0 to 3.8. The solubility of F-1 in water was determined by UV–vis spectroscopy to be 0.9 g/L. This corresponded to approximately 50% of the catalyst F-1 being dissolved in the water phase of the reactions reported in Table 1, runs 12–14. The concentration of the ammonium groups was then 4.0

Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore

• Esteban P. Urriolabeitia,
• Pablo Sánchez,
• Alexandra Pop,
• Cristian Silvestru,
• Eduardo Laga,
• Ana I. Jiménez and
• Carlos Cativiela

Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98

• was obtained with 96% isolated yield. In order to understand the different reactivities of oxazolones 2 and complexes 3 towards light, the absorption UV–vis spectra of the oxazolones 2 and ortho-palladated complexes 3 (CH2Cl2, 5 × 10−4 M) were measured and this provided some clues. The positions of

• cyclobutanes 4 and reductive elimination. UV–vis spectra of 2 and 3: absorption maxima (λmax, nm). Supporting Information Supporting Information File 319: Complete experimental section; copies of NMR spectra of 2 and 3. Supporting Information File 320: Copies on NMR spectra of compounds 4 and 5

• the absorption maxima (λmax, nm) for both species are collected in Table 1. According to the data in Table 1, the maximum absorption for oxazolones 2 is located in the near UV region, in the range of 375–385 nm, and this is quite far from the irradiation wavelength (465 nm). In fact, at 465 nm the UV

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• Fluorescence and Absorbance Spectrometer. Each compound (7a/7b) displayed three distinctive absorption bands in the UV–vis spectra: high energy bands and mid energy bands were assigned to π–π* and n–π* transitions, whereas the low energy bands were assigned to an intramolecular charge transfer (ICT) transition

• the meta position to the carbazole ring. The photoluminescence (PL) properties of compounds 7a and 7b were investigated in dichloromethane using a Duetta Fluorescence and Absorbance Spectrometer. Compounds 7a and 7b gave emission maxima at 561 nm and 482 nm, respectively. The UV–vis and PL spectra of

• the compounds are given in Figure 4. Solvatochromism In general, ICT-based absorption and emission bands show solvent dependency. This is better known as solvatochromism. The ICT behaviour of compounds 7a and 7b was further investigated in different solvents. Normalised UV–vis spectra of compounds 7a

Aryl-substituted acridanes as hosts for TADF-based OLEDs

• Naveen Masimukku,
• Dalius Gudeika,
• Oleksandr Bezvikonnyi,
• Ihor Syvorotka,
• Rasa Keruckiene,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

• found in the range of 5.11–5.18 eV. The electron affinity values were deduced from the IPcv and energy gap (Egopt) obtained from the onsets of the UV–vis absorption spectra. The ionization potentials IPPES of the solid films of derivatives 3–6 were estimated by photoelectron emission spectrometry (PES

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• adequate tuning of the porphyrin properties can enable them to absorb light in almost all of the UV–vis spectral range. Porphyrins also have elevated molar absorptivity (ca 105 L·mol−1·cm−1) and appropriate electronic levels for both energy transfer (ET) and single electron transfer (SET) in many

A method to determine the correct photocatalyst concentration for photooxidation reactions conducted in continuous flow reactors

• Clemens R. Horn and
• Sylvain Gremetz

Beilstein J. Org. Chem. 2020, 16, 871–879, doi:10.3762/bjoc.16.78

• applying Beer’s law using a path length fixed at 0.04 cm and an extinction of 2, the molar extinction coefficient still needs to be calculated. Therefore, the molar extinction coefficient needs to be measured separately in a UV–vis spectrometer as the emission maximum of the LED source does, in most cases

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• precursors affords both enantiomers Δ-10 (from CuClO4) and Λ-10 from (Cu(CH3CN)4PF6). UV–vis and circular dichroism spectroscopic studies evidence that the helical chirality exhibited by these two catalysts could be reversed by redox stimuli. These complexes could perform enantioselective Michael addition

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• fluorescence quenching studies, UV–vis spectroscopy experiments, calculation of the quantum yield, a cutoff experiment below 400 nm, GC–MS analysis, and NMR spectroscopic mechanistic experiments. They also concluded that an energy transfer mechanism could not be possible since the solvent employed affected the

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• aromatic, which is in accordance with the resonance structure of 1 as shown in Figure 2e. The UV–vis absorption spectra of compounds 5 and 1 in DCM are compared in Figure 3a. The maximum absorption peak of 1 is significantly red-shifted compared to that of precursor 5, which can be attributed to the

• 1.78 eV from the onset of its UV–vis absorption spectrum. Similar to the cyclopenta-fused pyrene derivatives [28][29], compound 1 does not show detectable fluorescence emission. Furthermore, the electrochemical properties of 1 was probed by cyclic voltammetry (CV) in DCM (Figure 3b). According to the

• -membered ring B. The large difference between the LUMO and HOMO leads to an intramolecular charge transfer, resulting in broad absorption bands in the UV–vis spectrum (Figure 3a) [36]. In addition, the LUMO energy of 1 (−2.98 eV) is significantly lower than that of 6 (−2.38 eV), which is responsible for

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• evident linearity in these systems. Moreover, initial UV–vis and fluorescence studies show the promise of triptycene as a linker for electron transfer studies, showcasing its isolating nature. Keywords: BODIPY; Pd-catalyzed cross-coupling; porphyrins; Sonogashira cross-coupling; triptycene; Introduction

• linked which, theoretically, can cause a significant energy/charge sink. Moreover, the use of π-conjugated linkers in porphyrin arrays results in significantly altered UV–vis spectra, indicating very strong electronic coupling that causes the loss of individual unit characteristics through delocalization

• biological labelling and are known photostable substitutes for fluorescein, giving them applications in cell imaging [20]. Due to the conjugated π-electron system present in BODIPYs they are more electron rich than porphyrins and possess an intense UV–vis absorption at approximately 400 nm, making them ideal

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• and optical properties were investigated by single crystal X-ray analysis and UV–vis spectroscopy. In the synthesis of dioxole derivative 5b, the regioisomer 5c was also produced. The yield of 5c was increased by increasing the reaction temperature, indicating that the rearrangement might involve the

• expansion by Wagner–Meerwein rearrangement, followed by Pd-catalyzed annulation (Figure 1) [18]. An UV–vis spectroscopy study revealed that the electronic character of 1 rather resembled that of an indenopyrene moiety than that of benzopyrene. Our synthetic route allows to easily introduce substituents on

• hydrogen bonds (C37∙∙∙O1, C11∙∙∙O2, C40∙∙∙O4) (Figure 5c). Photophysical properties of the dialkoxides were investigated by UV–vis and emission spectroscopies (Figure 6). UV–vis spectra of 5a and 5b well reflected the electric property of 1, showing two strong bands observed at around 280–300 nm and 330

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• core is perfectly planar and forms a face-to-face stacking columnar structure with an interplanar distance of 3.40 Å along the a axis. The BO2 units are slightly tilted from the aromatic plane (6.7 and 20.3°). TB4 in toluene absorbs UV–vis light with an absorption maximum at 566 nm, and emits

• QB4 are pretty high among electron-rich compounds. Thus we tested the stability of TB4 and QB4 under air by means of UV–vis absorption spectroscopy. Surprisingly almost no spectral changes for both compounds were observed after 12 h, probably because the most reactive sites are protected by the steric

• -time-of-flight (MALDI–TOF) method on a JEOL SpiralTOF/JMS-S3000 spectrometer. X-ray crystallographic data were recorded at 103 K with a BRUKER-APEXII X-ray diffractometer using Mo Kα radiation equipped with a large area CCD detector. UV–vis absorption spectra were measured with a JASCO UV/Vis/NIR

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• ) 6a recorded in CDCl3 at 298 K. Asterisks indicate the residual solvent peak. UV–vis absorption spectra of the BODIPY derivatives, (a) 1a (green), 3a (blue), 4a (red), and (b) 1a (green), 5a (blue), 6a (red) in CH2Cl2. Insets show the photo images of the solutions taken under ambient light

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• the substituents in compounds 7 on their optical properties was studied by UV–vis spectroscopy (Figure 1). The UV–vis spectra of 7aa, 7bb, and 7ba were measured in chloroform, and the normalized UV–vis spectra are shown in Figure 1. These compounds showed similar peak patterns between 300 and 500 nm

• selectively by sequential chemoselective C–O and C–H arylations. The strategy developed in this study should be useful for the synthesis of PAH derivatives with multiple substituents having different properties. Normalized UV–vis absorption spectra of 7aa, 7bb, and 7ba. Effects of the concentration and the

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• ) side view). UV–vis absorption (solid lines) and fluorescence (dashed lines) spectra of compounds 8a–c. Syntheses of PAH-fused phospholes featuring a 7-hydroxybenzo[b]phosphole as a key intermediate. Synthesis of phosphole-fused ortho-teraryl compounds 7. Oxidative cyclization of phosphole-fused ortho

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• benzyl NHP esters. The products were obtained in good yields. The functional group tolerance of the process was excellent and was further demonstrated in the course of a robustness screen. Supported by mechanistic experiments, including UV–vis analysis, crossover studies, trapping with TEMPO, and the use