Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• -containing macrocycles and metalloporphyrins. Despite the impressive progress in photoredox catalysis, due to their most intensive electronic absorption band at 420 nm (Soret band, extinction coefficient of 105 M−1 cm−1), most porphyrin photocatalysts reported so far have been mainly utilized under blue

Extension of the π-system of monoaryl-substituted norbornadienes with acetylene bridges: influence on the photochemical conversion and storage of light energy

• Robin Schulte,
• Dustin Schade,
• Thomas Paululat,
• Till J. B. Zähringer,
• Christoph Kerzig and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 3061–3068, doi:10.3762/bjoc.20.254

• -bromonorbornadiene and the corresponding arylacetylenes. The norbornadienes showed absorption maxima in the range of 310–345 nm and long-wavelength zero onsets of up to 420 nm. The photoisomerization quantum yields were as high as 59% per photoisomerization event and the resulting quadricyclanes showed half-lives of

• converted into photoisomers with higher energy upon absorption of light. In turn, this reaction is reversible, thus allowing to release the stored chemical energy as heat in a specifically triggered back reaction [7][8][10][11][12][13]. For a practicable MOST system, some key parameters have to be ensured

• , such as absorption in the range of the solar spectrum, a high quantum yield of the photoreaction, long half-lives of the photoproducts, and a high energy storage density [7][8][12][13][14]. In this context, several different MOST systems have been explored, including, for example, anthracenes [15

Cyclodextrin-based rotaxanes for polymer materials: challenge on simultaneous realization of inexpensive production and defined structures

• Yosuke Akae

Beilstein J. Org. Chem. 2024, 20, 3026–3049, doi:10.3762/bjoc.20.252

• conventional synthesis. A similar [2]rotaxane molecule bearing a Co complex exhibited ICD derived from the chirality of CD on the absorption band of the cobalt complex [37]. Afterward, numerous CD-based rotaxane syntheses were reported; they generally contained noncovalent-bond moieties on the dumbbell

• ]. Polyrotaxanes were prepared with a coverage ratio of 18, 46, 64, and 71%, and the conjugative polymer without any CD coverage showed a decrease of the UV–vis absorption and its broadening at around 40–55 °C than those at 25 °C, while this spectral change became weaker according to the increase of the coverage

• ratio. Namely, the inclusion of CD prevented the aggregate formation of the conjugative polymer backbone, which usually induces a change in the absorption wavelength. Similarly, in fluorescence spectroscopy, the restriction of the nonradiative deactivation was caused by the inclusion structure

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• Table S1 and Figure S1, Supporting Information File 1). The electronic absorption spectra were characterized by a pronounced maximum in the visible region centered at 431–448 nm. Emission maxima of compound 1c were more significantly affected by the change of polarity and ranged from 475 nm (blue-green

• dimethylamino group, were studied (Table 1 and Figure 3). It was found that in most solvents, compound 1i was characterized by a single pronounced absorption maximum in the range of 503–525 nm that red-shifted upon increasing the solvent polarity. In formic acid, due to the protonation of the dimethylamino

• two observed absorption maxima: the first almost coincided with the corresponding maximum of the solution in formic acid, and the second one was in the same region as with other aprotic solvents. The emission maxima of stilbazole 1i were within a very wide range of 264 nm and covered almost the entire

Advances in radical peroxidation with hydroperoxides

• Oleg V. Bityukov,
• Pavel Yu. Serdyuchenko,
• Andrey S. Kirillov,
• Gennady I. Nikishin,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

• Sondos A. J. Almahmoud,
• Joseph Cameron,
• Dylan Wilkinson,
• Michele Cariello,
• Claire Wilson,
• Alan A. Wiles,
• Peter J. Skabara and
• Graeme Cooke

Beilstein J. Org. Chem. 2024, 20, 2921–2930, doi:10.3762/bjoc.20.244

• dicyanomethylene-functionalised violanthrone derivatives (3a, 3b and 3c) featuring different alkyl substituents. It is found that the introduction of the electron-deficient dicyanomethylene groups significantly improves the optical absorption compared to their previously reported precursors 2a–c. All compounds are

• intermolecular interactions which might result in a narrower HOMO–LUMO gap than that of PDI, and an absorption band extending to the near-infrared (NIR) region [26]. This makes violanthrone and its derivatives potential candidates for NIR optoelectronic applications. In fact, the intrinsic semiconducting

• ). Optical studies The UV–vis absorption spectra of 3a, 3b, and 3c are presented in Figure 5, and were carried out in dichloromethane solution (1 × 10−5 mol L−1). The absorption properties are summarised in Table 1. The UV–vis absorption spectra of the materials show a wide absorption band from 530 nm to 860

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

• , 117.1 (CAr), 91.1 (CN), 56.8, 29.4, 20.9 (CAliphatic), respectively. In its mass spectrum, the calculated value matched the found value m/z 419 calculated for [M]+ C28H25N3O. In the IR spectrum, the absorption peak index in 2213 is related to the CN group. For final confirmation, the derivative 4h was

• their suitable fluorophores [49][50][51]. The UV–vis absorption and emission spectra of products 4 and 6 were studied in ethanol at 298 K. The absorption range (λabs) was 400–225 nm, and the emission range (λem) was 560–400 nm. These findings are shown in Figure S3 in Supporting Information File 1. An

• interesting trend for the absorption of the synthesized derivatives 4 and 6 was observed when electron-donating substituents were present in the phenyl ring, which led to an increase in the intensity of the absorption and emission wavelengths (Supporting Information File 1, Figure S3). As is evident in

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• exhibit an absorption at 618 nm and show a blue color. In contrast to biologically inactive indigo, akashines A–C are active against various human tumor cell lines (CNCL SF268, LCL H460, MACL, colon carcinoma CCL HT29, melanoma MEXF 514L, lung carcinoma LXFA 526L and LXFL 529L, breast cancer MCF-7, kidney

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

• magnetic resonance (1H NMR) spectra was recorded on a Bruker DRX400 spectrometer operating at 400 MHz. High-resolution mass spectrometry (HRMS) was performed using a Bruker BioApex 47e FTMS with an analytical electrospray source employing NaI for accurate mass calibration (ESI). UV–vis absorption spectra

• equation; LoD = yB + 3sB. yB is the signal associated with the blank and sB corresponds to the standard deviation of the blank [22][23]. LoD: [Tb.1·3Cu]3+ 0.63 μM, λem = 544 nm. Previously reported lanthanide complexes [12][16][17]. Absorption (red line), excitation (yellow line, λem = 615 nm), and

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• desired pharmacological properties. Therefore, the design and synthesis of new compounds of this class with improved ADMET (absorption, distribution, metabolism, excretion, toxicity) pharmacological properties is an urgent task. Molecular docking was carried out to identify potential binding positions of

Mechanochemical difluoromethylations of ketones

• Jinbo Ke,
• Pit van Bonn and
• Carsten Bolm

Beilstein J. Org. Chem. 2024, 20, 2799–2805, doi:10.3762/bjoc.20.235

• absorption of mechanical energy and they are influenced by several factors, including the lack of solvation, changes in morphology and rheology of the reaction mixtures during the milling, and variations in concentration and dielectric environment. Consequently, an increased reactivity can be achieved

C–C Coupling in sterically demanding porphyrin environments

• Liam Cribbin,
• Brendan Twamley,
• Nicolae Buga,
• John E. O’ Brien,
• Raphael Bühler,
• Roland A. Fischer and
• Mathias O. Senge

Beilstein J. Org. Chem. 2024, 20, 2784–2798, doi:10.3762/bjoc.20.234

• ][5]. Nonplanar porphyrins offer a marked difference in chemical and physical properties when compared to their planar compatriots [6], with relatively smaller HOMO–LUMO gaps resulting in an observed bathochromic shift in the UV–vis absorption spectrum [7]. The phenomenon of nonplanarity results from

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

• dependency on the amount of PyBA added. The absorption spectra of catC60-lip and C60-lip were compared in PBS(–) (Figure 3). At two different concentrations, no significant change was observed in catC60-lip, whereas broadening and a red shift were observed in C60-lip at higher concentrations (10 mol equiv

• 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

• samples dispersed in phosphate-buffered saline (PBS(–)). UV–vis absorption spectra of liposomes (1 mM phospholipid) with C60 (a) or a cationic derivative of C60 (catC60) (b) added at various molar equivalents (mol equiv) to phospholipid. The equivalent of C60 added in C60-loaded liposomes (C60-lip) was

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

• , we postulated that blue light was not the optimal one. Since, the absorption spectrum of the mixture showed better absorption at higher wavelengths (see Supporting Information File 1), we repeated the synthesis by irradiating with white LEDs, succeeding in isolating product 3j in acceptable yield

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

• 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

• displayed in Figure 3. The corresponding photophysical data and quantum yields are described in Table 2. The analysis of the absorption spectra revealed well-resolved bands for derivatives 5a, 5d, 5f, 5g, and 5i for short wavelengths (250–300 nm). At higher wavelength (300–450 nm) broad absorption bands

• with a certain fine-structure for compounds 5a, 5g, and 5i and structure-less absorption features for compounds 5d, 5f, and 5h containing electron-donating functional groups are observed. In addition, the presence of strongly electron-donating N,N-dimethylamino groups leads to increased extinction

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

• fluorophore 1c. The absorption wavelengths and spectral shapes in the ultraviolet (UV)–visible absorption spectra of the PMMA films containing 1 wt % of 1a and 1c or 1f as representative examples (Figure S2 in Supporting Information File 1) were similar to those in the corresponding excitation spectra, which

• absorption spectrum of 1a in the two-component film. This result also clearly suggests an energy transfer from 1a to 1c. The fluorescence resonance energy transfer efficiency (EFRET) [30][31] was calculated from the ratio of the fluorescence lifetimes of the two- and high-energy-component films (Equation 1

• 80:20 ratio was also consistent with the corresponding absorption spectrum of 1a (Figure S2h in Supporting Information File 1). This result clearly indicates an energy transfer from 1a to 1f. Next, we evaluated the PL properties of the PMMA film blended in a 95:5 ratio, which had a higher weight

Transition-metal-free decarbonylation–oxidation of 3-arylbenzofuran-2(3H)-ones: access to 2-hydroxybenzophenones

• Bhaskar B. Dhotare,
• Seema V. Kanojia,
• Chahna K. Sakhiya,
• Amey Wadawale and
• Dibakar Goswami

Beilstein J. Org. Chem. 2024, 20, 2655–2667, doi:10.3762/bjoc.20.223

• -absorbing as well as photo-antioxidant properties via an intramolecular hydrogen transfer [5]. The structure–activity relationship between the substituents of 2-hydroxybenzophenones and their UV-absorption properties has been reported previously [6]. It was concluded that the ability to absorb UV light and

• earlier, 5-substituted-2-hydroxybenzophenones showed a better photoantioxidant ability, and can be an alternative to the commercially used UV-absorbers. Towards this, the UV absorption properties of the synthesized compounds were evaluated (Figure 6 and Figure S30 in Supporting Information File 1). UV

• absorption spectra of the most promising compounds (4aa, 4cb, 4eb, and 4fb) are depicted in Figure 6. The abilities of the synthesized compounds for use as a protector from UV radiation were evaluated based on several parameters as tabulated in Table 2. Initially, the λmax values for different absorption

Synthesis and cytotoxicity studies of novel N-arylbenzo[h]quinazolin-2-amines

• Battini Veeraiah,
• Kishore Ramineni,
• Dabbugoddu Brahmaiah,
• Nangunoori Sampath Kumar,
• Hélène Solhi,
• Rémy Le Guevel,
• Chada Raji Reddy,
• Frédéric Justaud and
• René Grée

Beilstein J. Org. Chem. 2024, 20, 2592–2598, doi:10.3762/bjoc.20.218

• used to hold mp samples for capillary mp determination. FTIR spectra were recorded on a Bruker Alpha apparatus with spectra further analysed with spectragryph 1.2.4 version. The absorption bands were reported in cm−1. High-resolution mass spectra were recorded in the Centre Régional de Mesures

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

• introduction of N-aryl units during the synthesis is rendered difficult owing to steric hindrances. For example, N-phenyl-substituted TATA+ cation 1b+ (Figure 1) [26] exhibited slightly red-shifted absorption and emission, with a higher quantum efficiency compared to those of N-alkyl-substituted TATA+ cations

• 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

• (Figures S22–25 in Supporting Information File 1) [31]. The absorption band at 524 nm was blue-shifted by 4 nm compared to that of N-phenyl-substituted 1b+-BF4− [15]. This can be ascribed to the lesser conjugation of the core TATA+ unit with the introduced 2,6-dimethylphenyl moieties owing to the more

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• changes. This is confirmed by the appearance of an absorption maximum in the UV–visible spectrum at λ = 490 nm, which is characteristic of thiolated o-benzoquinones. This absorption band corresponds to intramolecular charge transfer between the thioether group and the o-benzoquinone fragment [36][62][63

• oxidation was confirmed during a controlled potential microelectrolysis of compound 6 at 1.30 V (2 h, 0.8 F/mol). A similar electrochemical picture is observed for electrolysis products of catechol 6 as in the case of catechol 3. The recorded absorption spectra after the electrolysis display an intense

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

• spectrum shape (Supporting Information File 1, Figure S10). On the other hand, the UV–vis spectrum of the DAntM cation, generated from 3 in TFA solution, showed an intense absorption band at 890 nm, which is the opposite trend compared to the DAntM radical. Conclusion The synthesis and characterization of

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

• outer side (in-out-ts), but the thermodynamically stable final product is a regioselective “in-in” adduct, i.e., compound 6a. Optical properties Absorption and emission spectra of 6a were measured in CH2Cl2 (Figure 5). The conjugation is changed and a highly-twisted macrocyle forms by the double azide

• 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

• were almost independent of solvents. For example, the λem in CHCl3 and THF was 514 nm (Figure S11 in Supporting Information File 1). The double benzyl azide adduct of DBA-OHex displayed similar absorption and emission spectra with a λmax of 247 nm and λem of 539 nm in CH2Cl2. Since the Stokes shift of

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

• . A strong band with absorption maxima at 308.94 nm besides two more bands at ca. 280.29 nm, and 297.44 nm were observed for truxene-based mono-DPM 14. On the other hand, a very broad band for example at 334.41 nm was observed in the case of diacetyltruxene derivative 15. Moreover, for the same

Efficacy of radical reactions of isocyanides with heteroatom radicals in organic synthesis

• Akiya Ogawa and
• Yuki Yamamoto

Beilstein J. Org. Chem. 2024, 20, 2114–2128, doi:10.3762/bjoc.20.182

• * orbital). Such an n–σ* transition usually indicates the maximum absorption in the near-UV region, and the absorption cutoff reaches the visible region, especially in the case of highly periodic E–E. Therefore, interelement compounds E–E with groups 15–17 heteroatoms have isolated electron pairs, and E