We herein report the first use of thiosquaramides as polymerization catalysts, which are shown to be effective for the controlled ROP of lactide in the presence of an alcohol source and NEt3. Comparison of their catalytic performances with the less acidic squaramides are also discussed. The observed catalytic activity of variously N-substituted thiosquaramides suggest that a balanced NH Brønsted acidity is required for optimal performance. Most interestingly and rather unexpectedly, DFT-supported calculations on thiosquaramide-mediated lactide ROP catalysis suggest that secondary interactions between the thiosquaramide N-substituents and the incoming lactide (presently of type C-H…p-arene) are crucial for catalytic activity. Though this type of interactions is quite common in organo-catalysis, it has rarely been evidenced to play a key role in the area of organo-catalyzed polymerizations. Such catalyst substituents/substrate interactions may well play a significant role in the catalytic performances of various other systems.
Impact of Metabolic Stress on BeWo Syncytiotrophoblast Function
During placental formation, cytotrophoblasts (CTBs) fuse into multinucleate, microvilli-coated syncytiotrophoblasts (STBs), which contact maternal blood, mediating nutrient, metabolite, and gas exchange between mother and fetus, and providing a barrier against fetal infection. Trophoblasts remodel the surrounding extracellular matrix through the secretion of matrix metalloproteinases (MMPs). Maternal obesity and diabetes mellitus can negatively impact fetal development and may impair trophoblast function. We sought to model the impact of metabolic stress on STB function by examining MMP and hormone secretion. The BeWo CTB cell line was syncytialized to STB-like cells with forskolin. Cell morphology was examined by electron microscopy and immunofluorescence; phenotype was further assessed by ELISA and RT-qPCR. STBs were exposed to a metabolic stress cocktail (MetaC: 30 mM glucose, 10 nM insulin, and 0.1 mM palmitic acid). BeWo syncytialization was demonstrated by increased secretion of HCGβ and progesterone, elevated syncytin gene expression (ERVW-1 and ERVFRD-1), loss of tight junctions, and increased surface microvilli. MetaC strongly suppressed syncytin gene expression (ERVW-1 and ERVFRD-1), suppressed HCGβ and progesterone secretion, and altered both MMP-9 and MMP-2 production. Metabolic stress modeling diabetes and obesity altered BeWo STB hormone and MMP production in vitro.
Boronic acid functionalized silica‐coated Fe3O4 as a novel magnetically separable catalyst for the synthesis of hydrazinyl thiazoles
A novel silica-coated magnetite supported boronic acid functionalized nanocatalyst (Fe3O4@SiO2-Pr-N=CH-C6H4B(OH)2) was synthesized using a simple approach. The structure of the nanocatalyst was characterized using FT-IR, XRD, EDX, TGA-DTA, FE-SEM, TEM, and VSM techniques. The catalytic activity of Fe3O4@SiO2-Pr-N=CH-C6H4B(OH)2 was explored in the synthesis of hydrazinyl thiazoles via one-pot, the three-component reaction of phenacyl halide, thiosemicarbazide, and aryl aldehyde in EtOH:H2O (50:50, v/v) at room temperature. The catalyst was easily isolated using an external magnet from the reaction mixture and reused for the sixth run without significant loss of catalytic activity. The present approach offers the advantages of operational simplicity, shorter reaction time, ambient reaction condition, facile separation of catalyst, and higher yields of the products.
A novel silica-coated magnetite supported boronic acid functionalized nanocatalyst (Fe3O4@SiO2-Pr-N=CH-C6H4B[OH]2) was synthesized using a simple synthetic protocol. The catalyst was fully characterized by using Fourier transform-infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), thermogravimetric analysis-differential thermal analysis (TGA-DTA), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM) techniques. The structural investigations revealed that the catalyst is nano-sized (average crystallite size 13 nm), spherical, thermally stable, and magnetic in nature having a magnetic saturation of 51.26 emu/g. The catalytic activity of Fe3O4@SiO2-Pr-N=CH-C6H4B(OH)2 was explored in the synthesis of hydrazinyl thiazoles via one-pot, three-component reaction of phenacyl halide, thiosemicarbazide and aryl aldehyde in EtOH:H2O (50:50, v/v) at room temperature and it gave above 90% yields of hydrazinyl thiazoles. The catalyst being magnetically separable can be reused six times with the retention of catalytic activity. The present approach offers the advantages of operational simplicity, shorter reaction time, ambient reaction condition, facile separation of catalyst, and higher yields of the products.
Extremely Stable Perylene Bisimide‐Bridged Regioisomeric Diradicals and Their Redox Properties
Excellent stability is an essential premise for organic diradicals to be used in organic electronic and spintronic devices. Herein, we attach two tris(2,4,6-trichlorophenyl)methyl (TTM) radical building blocks to the two sides of perylene bisimide (PBI) bridges and obtain two regioisomeric diradicals (1,6-TTM-PBI and 1,7-TTM-PBI). Both of the isomers show super stability rather than the monomeric TTM under ambient conditions, due to the enlarged conjugation as well as the electron withdrawing effects from the PBI bridges. The diradicals show distinct and reversible multi-step redox processes, and the spectroelectrochemistry investigation reveals the generation of organic mixed-valence (MV) species during reduction processes. The two diradicals have singlet ground states, very small singlet−triplet energy gaps (ΔES-T) and a pure open-shell character (with diradical character y0 = 0.966 for 1,6-TTM-PBI and 0.967 for 1,7-TTM-PBI). This work opens a window to develop very stable diradicals and offers them opportunity of further applications in optical, electronic and magnetic devices.
Catalyst Engineering for the Selective Reduction of CO2 to CH4: A First‐Principles Study on X‐MOF‐74 (X = Mg, Mn, Fe, Co,Ni, Cu, Zn)
The conversion of carbon dioxide (CO2) into more valuable chemical compounds represents a critical objective for addressing environmental challenges and advancing sustainable energy sources. The CO2 reduction reaction (CO2RR) holds promise for transforming CO2 into versatile feedstock materials and fuels. Leveraging first-principles methodologies provides a robust approach to evaluate catalysts and steer experimental efforts. In this study, we examine the CO2RR process using a diverse array of representative cluster models derived from X-MOF-74 (where X encompasses Mg, Mn, Fe, Co, Ni, Cu, or Zn) through first-principles methods. Notably, our investigation highlights the Fe-MOF-74 cluster's unique attributes, including favorable CO2 binding and the lowest limiting potential of the studied clusters for converting CO2 to methane (CH4) at 0.32 eV. Our analysis identified critical factors driving the selective CO2RR pathway, enabling the formation CH4 on the Fe-MOF-74 cluster. These factors involve less favorable reduction of hydrogen to H2 and strong binding affinities between the Fe open-metal site and reduction intermediates, effectively curtailing desorption processes of closed-shell intermediates such as formic acid (HCOOH), formaldehyde (CH2O), and methanol (CH3OH), to lead to selective CH4 formation.
An Aryl‐ether‐linked Covalent Organic Framework Modified with Thioamide Groups for Selective Extraction of Palladium from Strong Acid Solutions
Efficient adsorption of palladium ions from acid nuclear waste solution is crucial for ensuring the safety of vitrification process for radioactive waste. However, the limited stability and selectivity of most current adsorbents hinder their practical applications under strong acid and intense radiation conditions. Herein, to address these limitations, we designed and synthesized an aryl-ether-linked covalent organic framework (COF-316-DM) grafted dimethylthiocarbamoyl groups on the pore walls. This unique structure endows COF-316-DM with high stability and exceptional palladium capture capacity. The robust polyarylether linkage enables COF-316-DM to withstand irradiation doses of 200 or 400 kGy of β/γ ray. Furthermore, COF-316-DM demonstrates fast adsorption kinetics, high adsorption capacity (147 mg g-1), and excellent reusability in 4 M nitric acid. Moreover, COF-316-DM exhibits remarkable selectivity for palladium ions in the presence of 17 interference ions, simulating high level liquid waste scenario. The superior adsorption performance can be attributed to the strong binding affinity between the thioamide groups and Pd2+ ions, as confirmed by the comprehensive analysis of FT-IR and XPS spectra. Our findings highlight the potential of COFs with robust linkers and tailored functional groups for efficient and selective capture of metal ions, even in harsh environmental conditions.
Interfacing Whole Cell Biocatalysis with a Biocompatible Pictet‐Spengler Reaction for One‐Pot Syntheses of Tetrahydroisoquiolines and Tryptolines
Biocatalytic processes are highly selective and specific. However, their utility is limited by the comparatively narrow scope of enzyme-catalysed transformations. To expand product scope, we are developing biocompatible processes that combine biocatalytic reactions with chemo-catalysis in single-flask processes. Here, we show that a chemocatalysed Pictet-Spengler annulation can be interfaced with biocatalysed alcohol oxidation. This two-step, one-pot cascade reaction converts tyramine and aliphatic alcohols to tetrahydroisoquinoline alkaloids in aqueous buffer at mild pH. Tryptamine derivatives are also efficiently converted to tryptolines. Optimization of stoichiometry, pH, reaction time, and whole-cell catalyst deliver the tetrahydroisoquinolines and tryptolines in >90% and >40% isolated yield, respectively, with excellent regioselectivity.
[ASAP] Rethinking SnSe Thermoelectrics from Computational Materials Science
Accounts of Chemical Research
DOI: 10.1021/acs.accounts.3c00490
Chemical Profiling of Nitraria roborowskii Kom. by UPLC‐Q‐Orbitrap‐MS and Their Hypolipidemic Effects in Vivo .
The Nitraria roborowskii Kom. (NRK) berries, as fruits of the genus Nitraria of the Zygophyllceae family, have been widely used as folk medicine. Modern pharmacological research has demonstrated that Nitraria berries had hypolipidemic, hypoglycemic, and immunomodulatory effects. However, more research needs to be reported on the chemical composition and biological activity of NRK. Hence, the phenolic compounds in the NRK berries were comprehensively analyzed and characterized by Ultra Performance Liquid Chromatography-Quadruple-Orbitrap MS system (UPLC-Q-Orbitrap MS) in this study. In total, 52 phenolics were identified, and all were reported for the first time. In addition, the hypolipidemic efficacy of NRK berries extract was studied in the hyperlipidemic mouse model. After treatment, the high dose group of NRK substantially reversed total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels. Through lipidomics technology, 27 potential biomarkers were characterized. And there was a significant callback at 25 of them after NRK treatment by using statistical analysis methods. Pathway analysis results demonstrated that NRK might exert therapeutic effects by regulating glycerophospholipid and glycerolipid metabolism pathways. This study could provide firsthand information on NRK berries for their phenolic compounds and potential application in preventing and treating hyperlipidemia.
Selective Fluorescent Sensing for Iron in Aqueous Solution by A Novel Functionalized Pillar[5]arene
![Selective Fluorescent Sensing for Iron in Aqueous Solution by A Novel Functionalized Pillar[5]arene](https://chemistry-europe.onlinelibrary.wiley.com/cms/asset/d46e629e-8810-4667-a130-634182ac65d8/open202300109-toc-0001-m.png)
An anthracene-appended water-soluble pillar[5]arene was prepared to construct a supramolecular fluorescent sensor system to accurately and selectively detect Fe3+ in water.
Abstract
Iron ion is one of the most physiologically important elements in metabolic processes, indispensable for all living systems. Since its excess can lead to severe diseases, new approaches for its monitoring in water samples are urgently needed to meet requirements. Here, we firstly report a novel and universal route for the synthesis of a series of pillar[n]arene derivates containing one benzoquinone unit by photocatalysis. With this in hand, an anthracene – appended water – soluble pillar[5]arene (H) with excellent fluorescence sensing potency was prepared. H enabled the ultrasensitive detection of iron ions in aqueous solution with limits of detection of 10−8 M. Over a wide range of metal ions, H exhibited specific selectivity toward Fe3+. More importantly, H could still properly operate in a simulated sewage sample, coexisting with multiple interference ions.