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

• Guangdong Province, Shantou University, Shantou 518060, People’s Republic of China Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China 10.3762/bjoc.18.83 Abstract The changes in absorption and emission of fluorescent

• of nitrogen-containing heterocycles in the fluorescent materials, the addition of a Lewis acid tended to induce red-shifted absorption and emission, shedding light on the fact that the Lewis acid interacts easily with the nitrogen-containing fluorescent materials. This interaction mechanism is the

• Lewis acids, it was assumed that compound 14 formed a B–N coordination bond when doped with B(C6F5)3 and B(C6H5)3, respectively. Luminescent mechanisms In view of the phenomenon that Lewis acid–base coordination contributes to a decrease of the band gap and bathochromic shifts of absorption and emission

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• channels (Figures S4 and S8 in Supporting Information File 2), which is a suitable characteristic for helicene compounds used as supramolecular self-assembly units [34][35][36][37][38][39][40][41]. Spectroscopic features of DH-1–3 The UV–vis absorption spectra of DH-1–3 in dichloromethane are shown in

• Figure 4. In general, the UV–vis absorption spectra of DH-1–3 are generally similar in shape and exhibit three major absorption bands within 230–280 nm (band-I), 280–330 nm (band-II), and 304–414 nm (band-III) (Figure 4). Progressive red-shifts in the absorption spectra of band-I, band-II, and band-III

• occur with increasing number of selenium atoms. In band-I, compounds DH-1–3 show a maximum absorption peak at 232, 240, and 242 nm, respectively. In band-II and band-III, helical distortion and possible conjugation through heteroatoms (e.g., sulfur and selenium atoms) in DH-1–3 may increase π-electron

Synthesis of α-(perfluoroalkylsulfonyl)propiophenones: a new set of reagents for the light-mediated perfluoroalkylation of aromatics

• Durbis J. Castillo-Pazos,
• Juan D. Lasso and
• Chao-Jun Li

Beilstein J. Org. Chem. 2022, 18, 788–795, doi:10.3762/bjoc.18.79

• . Using 1,3,5-trimethoxybenzene (TMB, 9) as a model substrate, we optimized the perfluoroalkylation reaction under irradiation of a 300 W Xenon arc lamp (Table 2). Based on the UV–vis absorption of our reagents 1, we used long-pass filters at either 280 nm or 295 nm to avoid side reactions caused by

• perfluoroalkylsulfinates 2 and halogenated electrophilic partners. Left: isolated yields of synthesized perfluoroalkylating reagents: perfluorobutyl (1a), perfluorohexyl (1b), and perfluorooctyl (1c) analogues (after conversion of byproduct); middle: gram amounts of perfluorooctyl product 1c; right: UV–vis absorption of

Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• substituted with Ala or Phe generates an N-1 dealkylated product, which is non-enzymatically created from C21 hydroxylated products, as a major product. Based on these structural analyses, as well as an EPR analysis of the enzyme reaction of FtmOx1 and a transient ultraviolet–visible (UV–vis) absorption

• , including kinetic, UV–vis absorption, and EPR analyses of FtmOx1 wild type and its Y68F, Y74F, Y140F, and Y224F variants [70]. Their results revealed that the Y68F variant did not accumulate the initial tyrosyl radical and the formation of verruculogen was significantly decreased, while the Y224F variant

• these tyrosine residues [75]. The transient-kinetic, UV–vis absorption, and EPR analyses of FtmOx1 variants containing non-canonical Tyr analogs also indicated that Tyr68, rather than Tyr224, acts as the catalytic residue in the FtmOx1 reaction, supporting the CarC-like mechanism. NvfI: Nonheme iron

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• performance is characterized by the specific absorption rate (SAR) of the material. The tested materials showed high SAR values when brought into an electromagnetic field of 50 mT at a frequency of 54 kHz. Under these conditions the particles were able to catalyze the hydrogenation of CO. The presence of

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• (26) was chosen as a FRET acceptor as there is a considerable overlap in energy of the donor emission and acceptor absorption. Then, artificial LHSs were constructed with aggregates from 24b or 25b at a donor/acceptor ratio of 5:1 (Figure 6). Finally, the light harvesting materials (24b + 26) and (25b

Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties

• Masayori Hagimori,
• Tatsusada Yoshida,
• Yasuhisa Nishimura,
• Yukiko Ogawa and
• Keitaro Tanaka

Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60

• –vis spectra of all compounds were recorded in ethanol (EtOH), a polar solvent, and in dichloromethane (DCM), a non-polar solvent (see Figures S15–S17 in Supporting Information File 1). The maximum absorption peaks (λmax) shifted slightly to longer wavelengths in dichloromethane. Table 2 summarizes the

• structure of each compound owing to their high planarity in both the ground and excited states. The large overlap between these two frontier orbitals resulted in efficient absorption and emission. The calculated vertical excitation energies of compounds 3a, 4a, and 4e, along with their oscillator strengths

Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid

• Jannis A. Reich,
• Miriam Aßmann,
• Kristin Hölting,
• Paul Bubenheim,
• Jürgen Kuballa and
• Andreas Liese

Beilstein J. Org. Chem. 2022, 18, 567–579, doi:10.3762/bjoc.18.59

• were used (ECRKIT1, Purolite Lifetech, Duisburg, Germany). Three carriers that bind the enzyme through absorption (ECR1030M, ECR8806F, ECR1090M), two carriers with epoxy functional groups for covalent immobilization (ECR8204F, ECR8806F), and one amino-functionalized carrier for covalent immobilization

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• unit on the helicity of the polyacetylene was investigated by CD spectroscopy. Here, no chiral induction was observed for the ammonium species 32, while the N-acylated polymers 33 showed clear Cotton effects in the absorption range of the polymer main chain (490 nm), demonstrating an effective

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• to 200 meV), beneficial for efficient thermal triplet upconversion. Absorption and emission properties Absorption (10−5 M toluene solutions) and emission spectra (1 wt % PMMA films) of the carbazole–pyrimidine TADF compounds are shown in Figure 3 and details are enclosed in Table 2. The absorption

• spectra were rather similar for all compounds, described with, typical for tCbz units, vibronic progression-having peaks bellow ≈340 nm [41]. Molar absorption coefficients were in the range of 19700–34200 M−1 cm−1, being in line with DFT predicted S0→S1 oscillator strengths and LUMO energies. The

• toluene solutions as well as 1 wt % PMMA (poly(methyl methacrylate)) films. The solid-state samples were prepared by dissolving the compounds and polymer or host material at appropriate ratios in toluene solution and then wet-casting the solutions on quartz substrates. The absorption spectra were recorded

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• previously reported. Trichocitrinovirene A (1) was isolated as a colorless gum and had the molecular formula C15H22O5 on the basis of the HRESIMS peak at m/z 305.1359 [M + Na]+. The IR spectrum exhibited absorption bands at 3336, 1684, and 1649 cm−1 for hydroxy, conjugated carboxyl carbonyl, and double bond

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• compound 1 was fully characterized by 1H and 13C NMR and IR spectroscopy, MS spectrometry as well as elemental analysis (for the detailed data, see Supporting Information File 1). Steady-state PL spectra To reveal the photophysical properties of diluted solutions of compound 1, UV–vis absorption and steady

• concentration of the cyclohexane solution and the molar absorption coefficient ε were not determined. As is clearly seen from Figure 2, the absorption spectra were not affected by the dielectric constant of the solvents. In contrast, the emission peaks of the PL spectra drastically red-shifted from cyclohexane

• for generating the CT excited state. In comparison with the photophysical properties of the D–A–D compound, the absorption of 1 (λabs = 461 nm) is almost the same as that of POZ-DBPHZ (λabs = 463 nm) [17], while the PL emission peak appeared in a slightly blue-shifted region (λPL = 502 nm) from D–A–D

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• of solar energy [7]. In general, an effective supramolecular donor–acceptor system was employed to construct a photocatalytic system using FRET [6][8]. To fabricate a successful FRET system, the following key points need to be considered, i) the acceptor absorption spectrum should have good

• , respectively. Initially, we compared the overlapping efficiencies of both donor and acceptor systems by using UV–vis and fluorescence spectroscopy. The absorption band of the EsY acceptor shows good overlapping with the emission band of m-TPEWP5G donor (Figure 4a). We therefore speculated, that there may be an

• ) Normalized absorption and emission spectra of the EsY acceptor and the m-TPEWP5G donor assembly; (b) Fluorescence spectra of the m-TPEWP5G assembly with steadily increasing the equivalents of EsY in an aqueous medium (λex. = 320 nm). Inset: Photograph of m-TPEWP5G before and after the addition of EsY under

Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions

• Robin Schulte and
• Heiko Ihmels

Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41

• the borylation reaction (see above). Photochromism of naphthylnorbornadiene 6b The photoisomerization reaction of substrate 5b was monitored by absorption spectroscopy (Figure 1) and by 1H NMR-spectroscopic analysis (see Supporting Information File 1, Figure S51). In MeCN solution, norbornadiene 5b

• exhibits the lowest-energy maximum at 305 nm, which is comparable to the reported absorption spectra of known naphthyl-substituted norbornadiene derivatives [36][37]. Irradiation of 5b at 315 nm leads to a decrease of the absorption band with simultaneous formation of a blue-shifted maximum at 292 nm

• overlap of its absorption with the one of the norbornadiene. However, upon heating to 60 °C in MeCN solution the norbornadiene was regained after 25 h, as shown by photometric monitoring of the reaction (Scheme 3 and Figure 1, inset). These photochemical properties are comparable to the ones of literature

Glycosylated coumarins, flavonoids, lignans and phenylpropanoids from Wikstroemia nutans and their biological activities

• Meifang Wu,
• Xiangdong Su,
• Yichuang Wu,
• Yuanjing Luo,
• Ying Guo and
• Yongbo Xue

Beilstein J. Org. Chem. 2022, 18, 200–207, doi:10.3762/bjoc.18.23

• absorption bands at 325 and 293 nm indicated the presence of a coumarin-type chromophore. The IR spectrum of 1 demonstrated absorption bands characteristic for an hydroxy group (3266 cm−1), α,β-unsaturated carbonyl group (1739 and 1701 cm−1), and an aromatic ring (1624 and 1457 cm−1). The 1H NMR spectrum of

Multi-faceted reactivity of N-fluorobenzenesulfonimide (NFSI) under mechanochemical conditions: fluorination, fluorodemethylation, sulfonylation, and amidation reactions

• José G. Hernández,
• Karen J. Ardila-Fierro,
• Dajana Barišić and
• Hervé Geneste

Beilstein J. Org. Chem. 2022, 18, 182–189, doi:10.3762/bjoc.18.20

• reaction gave a mixture of 2c'', 2c', and 2c in a ratio of 79:16:5 vs a ratio of 80:12:7 in the absence of SiO2 (Scheme 2a). Moreover, the presence of SiO2 improved the absorption of reactants and rendered a reaction mixture physically more appropriate for the milling process, which in turn enabled a

Tenacibactins K–M, cytotoxic siderophores from a coral-associated gliding bacterium of the genus Tenacibaculum

• Yasuhiro Igarashi,
• Yiwei Ge,
• Tao Zhou,
• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku and
• Agus Trianto

Beilstein J. Org. Chem. 2022, 18, 110–119, doi:10.3762/bjoc.18.12

• three different seawater-based media, and butanolic extracts of the fermented cultures were subjected to HPLC/DAD analysis, which detected several unknown metabolites not present in our in-house UV database, showing UV end-absorption in the culture extract of A11M seawater medium. Purification of these

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• structural assignment of regiospecific compound 4a was readily deduced via detailed spectral data analysis. The IR spectrum of 4a contained characteristic absorption bands such as 1723 (C=O, ester), and 1687 (C=O, Boc) cm−1. The 1H NMR spectrum of compound 4a revealed a characteristic resonance for the Boc

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• , analysis of the structural diversity of the two isomers of P5 indicates that P5 cis (P5.1) is more disordered (see Supporting Information File 1, Table S3), which also correlates with a blue-shifted absorption minimum compared to P5 trans (P5.2). In the partially helical structures of aAxWt (i.e., second

Unsaturated fatty acids and a prenylated tryptophan derivative from a rare actinomycete of the genus Couchioplanes

• Shun Saito,
• Kanji Indo,
• Naoya Oku,
• Hisayuki Komaki,
• Masashi Kawasaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2939–2949, doi:10.3762/bjoc.17.203

• determined to be C10H16O2 on the basis of its NMR and HR–ESI–TOFMS data (m/z 191.1044 [M + Na]+, Δ + 0.1 mmu). Three degrees of unsaturation, calculated from the molecular formula, a UV absorption maximum at 264 nm, and IR absorption bands at 1679 and 2800–3200 cm−1, suggested dienone and hydroxy

• molecular formula was determined to be C18H22N2O3 based on its NMR and HR–ESI–TOFMS data (m/z 313.1556 [M – H]–, Δ – 0.2 mmu), corresponding to nine degrees of unsaturation. The UV spectrum, exhibiting the absorption maxima at 229 and 282 nm, was typical of an indole functionality. The IR absorption bands

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• coefficients of absorption and high ΦPL [15][16][17][18]. This led to OLEDs employing dual or multi emitter-designed compounds to show much improved EQEmax compared to devices with their single-emitter counterparts (Figure 1), albeit with a red-shifted emission [16][17][18][19]. The advantages of the dual

• stabilized compared to that predicted from DFT (EHOMO: −5.03 eV); however, the less positive oxidation potentials in DICzTRZ versus ICzTRZ does align with the predictions obtained by DFT. The UV–vis absorption spectrum of DICzTRZ, while slightly red-shifted and with higher molar absorptivity (as was the case

• similar to those associated with ICzTRZ. The two absorption bands located between 330 and 350 nm are ascribed to the LE transitions within the diindolocarbazole donor. The two lower energy and lower absorptivity bands at 390 nm and 410 nm are both assigned to CT-type transitions (Figure 4b

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Host–guest interaction and properties of cucurbit[8]uril with chloramphenicol

• Lin Zhang,
• Jun Zheng,
• Guangyan Luo,
• Xiaoyue Li,
• Yunqian Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 2832–2839, doi:10.3762/bjoc.17.194

• ] and CPE was investigated using UV–vis spectroscopy utilizing the molar ratio and Job's method under neutral conditions (Figure 3). Figure 3A shows that CPE has a strong absorption peak at λ = 278 nm and the absorption intensity gradually decreases after the continuous addition of Q[8]. When n(Q[8])/n

• (CPE) = 1:1, the absorbance exhibits an obvious turning point and further increasing the concentration of Q[8] does not change the absorption of the system. The spectrogram determined using Job's method is shown in Figure 3B. When n(Q[8])/[n(Q[8]) + n(CPE)] = 0.5, the maximum value of ΔA appears

• variation of the UV absorption intensity of CPE and CPE@Q[8] over time in simulated gastric juice (pH 1.2). Figure 7B shows the relationship between the UV absorption intensity of CPE and its inclusion complex in artificial intestinal fluid (pH 6.8) with time. The results show that CPE itself has high

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

• the series of compounds 3aa–fa and 3bb–be was carried out using chloroform (CHCl3), methanol (MeOH) or dimethyl sulfoxide (DMSO) solutions. As comparison, the UV–vis absorption spectra of compounds 3ea and 3be, which contain the nitro group in two different ring positions of the molecules recorded in

• the three solvents are depicted in Figure 3. The values of maximum molar absorption coefficients (in log ε) and wavelengths (nm) of all compounds are listed in Table 1. The absorption spectra of the studied Schiff base series presented electronic transitions in the 250–500 nm UV–vis region. In the

• the imine portion of the molecule. In comparison to the absorption spectra of aminoquinolines published by Kappenberg and co-workers [14], the Schiff bases studied here show similar absorption behavior, making it clear that these transitions originate mainly from the substituents (NH2, CF3, and R

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• Finnigan LTQ FT Ultra Fourier Transform Ion Cyclotron Resonance device at 250 °C for ESI. IR spectra were recorded on a Perkin Elmer FT-IR Paragon 1000 instrument as neat materials. Absorption bands were reported in wave numbers (cm−1), obtained on a ATR PRO450-S accessory (Jasco). Melting points were