ChemistryOpen最新文献

Isophorone is a relatively small molecule with several neighboring reacting sites, making it susceptible to various competing reactions with aldehydes, including aldol, Baylis-Hillman (BH), aldol condensation, and Michael addition reactions. In the present work, we have designed a switchable 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed procedure, where the reaction of isophorone with aldehydes is guided chemoselectively toward either aldol, BH, or aldol condensation reactions, depending on the use of water and/or heat. This controllable divergency likely stems from the ability to tune the dual nucleophilicity/basicity characters of the DBU/H₂O medium. In other words, the nucleophilicity of DBU plays a crucial role in directing the process toward the formation of the BH adducts in the absence of water. At the same time, the aldol pathway dominates when water is present. The conditions were amenable for tandem processes, as demonstrated for an aldol condensation/Diels-Alder sequence.

A 90-membered macrocycle having two functional moiety, diphenyl-phenanthroline (dpp) and two tri-dentate pyridine-diamide (pda) as templating center has been synthesized from precursor molecules via amide bond formation in 10 steps. dpp and pda are arranged alternatively around the macrocycle in a sequence of dpp-pda-dpp-pda and demeostrated orthogonal behaviour, when treated with transition metal such as Cu(I) and Co(III): It forms figure of eight complexes selectively between dpp units and pda units respectively due to the geomtric preferance. This makes the macrocycle operates in bimodal manner. Interconversion between figure of eight complexes has been witnessed by metal-exchange via demetalation and subsequent re-metalation between orthogonal templating centres. Removal of Cu(I) template is performed using a common and less toxic reagent NH₂CH₂CH₂NH₂ and Co(III) by Zn/CH₃COOH at RT.

Oxidation-reduction (Redox) reactions are crucial for many biological processes, yet there is no method available to evaluate redox states in a non-invasive, continuous manner. Here we introduce a novel approach to distinguish between reduced and oxidized states of glutathione (GSH and GSSG, respectively) using aquaphotomics near-infrared (NIR) spectroscopy and multivariate analysis. We identified clear differences in NIR spectra reflecting not only glutathione itself, but different redox states of glutathione based on the spectral features of water molecular conformations interacting with the reaction site. Molecular dynamic simulations also revealed the difference in water molecule coordination and hydration numbers around the reaction site. This approach not only sheds light on the significance of water molecules in redox reactions but also enables non-destructive, continuous assessment of redox states, with potential applications for bioreactor optimization.

In this study, we report the synthesis of thieno[2,3-c]pyridine derivatives by a metal-free method via fused 1,2,3-triazoles. In the synthesis of this skeleton using a three-step method, we first obtained 1-(2,2-dimethoxyethyl)-5-(thiophen-2-yl)-1H-1,2,3-triazole through a one-pot triazolation reaction and in the next step, we synthesized the thieno[2,3-c][1,2,3]triazolo[1,5-ɑ]pyridine compound using a modified Pomeranz-Fritsch reaction. In the final step, the synthesis of thieno[2,3-c]pyridine derivatives was achieved in good yield via acid-mediated denitrogenative transformation reactions. This mild condition synthetic process has enabled access to the title compounds, of which limited examples have been reported until now in the literature. Thus, the syntheses of 7-(substituted methyl)thieno[2,3-c]pyridine, thieno[2,3-c]pyridine-7-ylmethyl esters, and imidazo[1,5-ɑ]thieno[2,3-c]pyridine derivatives have been successfully achieved.

Herein we report on the most stable structures adopted by piracetam, a nootropic drug, in isolated conditions. A chirped pulse Fourier transform microwave spectrometer (CP-FTMW) coupled with a laser ablation source has been employed to explore the broadband rotational spectrum of piracetam in the 6.0-14.0 GHz range. Two conformers have been observed. The most stable conformer of piracetam adopts an exo configuration of the ring and is mainly stabilized through a N-H⋅⋅⋅⋅⋅⋅O=C hydrogen bond between the amide group and the rings' carbonyl oxygen. The second conformer is close in stability and only differs in the endo disposition of the ring. The results show a low interconversion barrier between both conformers.

In the Front Cover, two futuristic-looking machines make use of their robotic limbs to assemble glowing aromatic fragments around a Nickel-porphyrin. In this way, the modular approach of the synthetic strategy toward π-extended porphyrin-PAH hybrids is underlined. The machine to the right also contains several five-ring motifs to further highlight the β-meso-fusion step the work is centered around. The cover art was designed and made by Christoph Oleszak. More details can be found in the Research article by Bernd Meyer, Norbert Jux, and co-workers (DOI: 10.1002/open.202400481).

Recent advancements in wearable electronics for fall detection have shown significant potential, yet challenges remain in developing reliable, energy-efficient systems capable of continuous monitoring in real-world conditions. In this work, a double-network (DN) conductive hydrogel, comprising NaCl-coordinated agarose and poly (2-hydroxyethyl acrylate-co-acrylic acid) (Agarose/P(HEA-co-AA)-Al/NaCl) (APA-hydrogel), was synthesized. The agarose forms a stable first network, while the second network is established by P(HEA-co-AA) through aluminum ion coordination. Immersion in NaCl solution leads to the formation of hydrated sodium ions ([Na(H₂O)n]⁺), which are anchored within the hydrogel matrix via hydrogen bonding and metal coordination. The resulting APA-hydrogel was applied as a triboelectric nanogenerator (APA-TENG), demonstrating excellent performance with an open-circuit voltage of 900 V, a short-circuit current of 73.42 μA, and a peak power output of 3.52 mW at a 3 MΩ load. APA-TENG shows strong potential for energy harvesting and powering low-power devices, as well as real-time sensing for motion and fall detection, making it highly suitable for wearable and assistive technologies powered by human activity.

Refractory sulfur compounds in fuel oils combust, releasing sulfur oxides (SOx) into the atmosphere, which is a significant source of pollution. In this study, we focused on comparing the surface properties and hydrodesulfurization (HDS) activity of CoMo-(L)/γ-Al₂O₃ containing chelating ligands (L), specifically acetic acid (AA), with those of ethylenediaminetetraacetic acid (EDTA), citric acid (CA). CoMo/γ-Al₂O₃, CoMo-AA/γ-Al₂O₃, CoMo-EDTA/γ-Al₂O₃ and CoMo/γ-Al₂O₃ were prepared by hydrothermal treatment of the mixtures of Co(NO₃)₂.6H₂O and (NH₄)₆Mo₇O₂₄.4H₂O with stoichiometric Co/Mo ratios and enriched with chelating ligands (L=AA, CA and EDTA). Based on the product distributions of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), a reaction pathway of dibenzothiophene (DBT) HDS was proposed to follow hydrogenation (HYD) and direct desulfurization (DDS) routes. In addition, the ligand modification of CoMo/γ-Al₂O₃ catalysts resulted in enhancement of surface properties and HDS activity which is in the order of CoMo-CA/γ-Al₂O₃ (98 %)> CoMo-AA/γ-Al₂O₃ (94 %) > CoMo-EDTA/γ-Al₂O₃ (90 %) > CoMo/γ-Al₂O₃ (43 %). CoMo-AA/γ-Al₂O₃ presented a higher HYD/DDS ratio compared to CoMo-CA/γ-Al₂O₃, CoMo-EDTA/γ-Al₂O₃, and CoMo/γ-Al₂O₃, respectively which makes it a promising HDS catalyst.

The long-known dinuclear complexes of the general formula [M(μ-X)(η⁵-Cp*)X]₂ (1-4; M=Rh or Ir, X=Br or I; HCp*=pentamethylcyclopentadiene) represent important intermediates for the preparation of biologically (e. g., anticancer or antimicrobial) and catalytically active half-sandwich rhodium(III) and iridium(III) complexes. Here we report the optimized rapid microwave-assisted syntheses of the mentioned dinuclear synthons 1-4. With respect to their following synthetic utilization, we examined their antiproliferative activity in the representative human cancer cell lines, where they did not show any relevant cytotoxicity. However, the iridium complexes 3 and 4 exhibited considerable catalytic activity in a model transfer hydrogenation of acetophenone using propan-2-ol as the hydrogen source. The obtained comprehensive data sets can be useful in the evaluation of the ligand effects in complexes prepared from 1-4 and used in e. g. bioinorganic and catalytic applications.

The present study focuses on the iodination of pyrazoles mediated by cadmium (II) acetate. The objects of research were compounds with pyrazole rings substituted by N-propargyl, C, N-alkyl groups. Depending on the molar ratios of the reagents effective ways of obtaining mono- and triiodo-substituted products with the participation of the propargylic fragment in DMSO were elucidated. Induced by the cadmium (II) acetate principles of electrophilic iodination of the C-4 position of the pyrazole ring containing electron-donating groups were revealed. The iodination of the pyrazole derivative with only propargylic substituent was found to target the CH-acidic center of the triple bond and to lead to the corresponding iodoalkyne. An iodo-substituted product with triple bond is more reactive and prone to further electrophilic iodination forming a triiodo-substituted derivative. The introduction of methyl groups in the pyrazole ring of derivatives with propargylic substituent contributed to the promotion of competitive iodination reactions due to the increase in nucleophilicity of the pyrazole ring. Dimerized pyrazole rings with carbon atoms in the 4-th position did not succeed in being iodinated by the mentioned way. Possible pathways for both triple bond and pyrazole ring iodination involving acetyl hypoiodite were proposed.