jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Ziqi Yu | Min Shi | Yin Wei
Source: Molecules (article, 2024-02-29)
Field: Chemistry — Organic Chemistry

Mechanistic Studies on Rhodium-Catalyzed Chemoselective Cycloaddition of Ene-Vinylidenecyclopropanes: Water-Assisted Proton Transfer Rhodium-catalyzed cycloaddition reactions are a powerful tool for the construction of polycyclic compounds. Combined experimental and DFT studies were used to investigate the temperature-controlled chemoselectivity of cationic rhodium-catalyzed intramolecular cycloaddition reactions of ene-vinylidenecyclopropanes. After a series of mechanistic studies, it was found that trace amounts of water in the reaction system play an important role in generating the product with <i>endo</i> double bond located on a five-membered ring and revealed that trace amounts of water in the reaction system, including the rhodium catalyst, substrate and solvent, were sufficient to promote the formation of the product with <i>endo</i> double bond located on a five-membered ring, and additional water could not further accelerate the reaction. DFT calculation results show that the addition of water indeed significantly lowers the energy barrier of the proton transfer step, making the formation of the product with <i>endo</i> double bond located on a five-membered ring more likely to occur and confirming the rationality of water-assisted proton transfer occurring in the selective access to the product with <i>endo</i> double bond located on a five-membered ring. Cycloaddition ; Chemistry ; Rhodium ; Double bond ; Catalysis ; Intramolecular force ; Ene reaction ; Chemoselectivity ; Ring (chemistry) ; Cationic polymerization ; Photochemistry ; Medicinal chemistry ; Stereochemistry ; Organic chemistry Cyclopropane Reaction Mechanisms ; Catalytic Alkyne Reactions ; Catalytic C–H Functionalization Methods
Authors: Angel A. J. Torriero | K. M. Miller | Ashwin K. V. Mruthunjaya
Source: Inorganics (article, 2024-12-26)
Field: Chemistry — Spectroscopy

Beyond Cations: Expanding the Horizons of Ferrocene-Based Electrochemical Sensors for Neutral and Anionic Molecules Ferrocene (Fc) has long been celebrated for its remarkable redox properties and structural versatility, making it a cornerstone of electrochemical sensor development. While extensive research has focused on cation detection using Fc-based systems, the equally critical recognition of neutral and anionic molecules remains underexplored despite their significance in biological, environmental, and industrial contexts. This review addresses this gap by exploring the latest advancements in Fc-based electrochemical sensors designed to overcome the unique challenges posed by these species—including diverse geometries, high hydration enthalpies, and the absence of formal charge. Molecular architectures such as amide-functionalised receptors, urea derivatives, Lewis acid-containing receptors, triazolium, and carboxylic acid-containing systems are examined, highlighting how these sensors achieve high selectivity and sensitivity. Furthermore, the influence of solvent environments on sensor performance is discussed, providing a critical analysis of how different receptor functionalities and solvents affect sensor behaviour. Emphasising the advantages of redox-based detection, this review aims to inspire further innovation in developing Fc-based technologies for detecting neutral and anionic species. Ferrocene ; Electrochemistry ; Molecule ; New horizons ; Chemistry ; Inorganic chemistry ; Materials science ; Nanotechnology ; Electrode ; Physical chemistry ; Physics ; Organic chemistry ; Astronomy Molecular Sensors and Ion Detection ; Advanced biosensing and bioanalysis techniques ; Luminescence and Fluorescent Materials
Authors: Lotan Portal | Iryna Polishchuk | Maria Koifman Khristosov | Alexander Katsman | Boaz Pokroy
Source: Advanced Engineering Materials (article, 2024-09-08)
Field: Materials Science — Materials Chemistry

Morphology Control of Nanoporous Gold Through Selective Dissolution of Au–Ge Eutectic Microstructures The synthesis of nanoporous gold (np‐Au) through the conventional method of dealloying a more reactive element from AuTherma alloys has been extensively studied and applied in various fields, particularly catalysis. Herein, a novel approach to creating droplet‐like np‐Au through the selective dissolution of Au–Ge eutectic microstructures is explored. This work reveals that adjusting the undercooling of the eutectic melt during solidification allows for the tuning of pore and ligament sizes. It is demonstrated that this undercooling can be modified, either directly or indirectly, by adjusting either the cooling rate or the heterogeneous nucleation site density of the eutectic melt. The findings, aligned with the model based on classical theory for eutectic solidification, elucidate the connection between the tuning of pore and ligament sizes in the eutectic microstructure and the undercooling of the eutectic melt. Importantly, it is established that this phenomenon is applicable across a variety of compositions, including hypereutectic, eutectic, and hypoeutectic. The ability to regulate pore and ligament size in single crystals of np‐Au droplets offers a novel approach to synthesizing catalytic np‐Au crystals with enhanced mechanical and thermal stability compared to conventional methods. Materials science ; Eutectic system ; Nanoporous ; Microstructure ; Dissolution ; Morphology (biology) ; Metallurgy ; Chemical engineering ; Nanotechnology Nanoporous metals and alloys ; Electrocatalysts for Energy Conversion ; Anodic Oxide Films and Nanostructures
Authors: Sandra Hernández-Ibáñez | Juan F. Ortuño | Ana Sirvent | Carmén Nájera | José M. Sansano | Miguel Yus | Francisco Foubelo
Source: The Journal of Organic Chemistry (article, 2024-04-13)
Field: Chemistry — Organic Chemistry

Synthesis of Vicinal <i>anti</i>-Amino Alcohols from <i>N</i>-<i>tert</i>-Butanesulfinyl Aldimines and Cyclopropanols The stereoselective synthesis of vicinal amino alcohols derivatives from 1-substituted cyclopropanols and chiral <i>N</i>-<i>tert</i>-butanesulfinyl imines is described. Cyclopropanols are easily prepared from carboxylic esters upon reaction with ethylmagnesium bromide in the presence of titanium tetraisopropoxide and undergo carbon-carbon bond cleavage by means of diethylzinc to produce, upon base deprotonation, enolized zinc homoenolates, which react with chiral sulfinyl imines in a highly regio- and stereoselective manner. Chemistry ; Diethylzinc ; Aldimine ; Vicinal ; Stereoselectivity ; Deprotonation ; Organic chemistry ; Medicinal chemistry ; Carbon–carbon bond ; Bond cleavage ; Enantioselective synthesis ; Catalysis Asymmetric Synthesis and Catalysis ; Synthetic Organic Chemistry Methods ; Cyclopropane Reaction Mechanisms
Authors: Yohan Gisbert | Marco Ovalle | Charlotte N. Stindt | Romain Costil | Ben L. Feringa
Source: Angewandte Chemie International Edition (article, 2024-11-11)
Field: Chemistry — Organic Chemistry

Coupling Rotary Motion to Helicene Inversion within a Molecular Motor Towards complex coupled molecular motions, the remote handedness inversion of a helicene moiety was achieved by a rotary molecular motor. The use of a specifically engineered dynamic helicene stator in a novel overcrowded-alkene second-generation molecular motor based on a fluorinated dibenzofluorene fragment allows for an unprecedented control over helicity inversion. This is achieved by the mechanical coupling of the rotation of the rotor to the helicene inversion of the stator half via a remote chirality transmission process. Thus, the unidirectional rotary motion generated upon irradiation is used to invert the dynamic stereochemistry of a helicene, leading to a 6-step cycle with eight intermediates. In this cycle, both alternation between P and M configurations of the helicene stator and dynamic thermal interconversion (paddling motion) can be achieved. In-depth computational and spectroscopic studies were performed to support the associated mechanism. The control over coupled motion and dynamic helicity offers prospects for the development of complex responsive systems. Helicene ; Molecular motor ; Inversion (geology) ; Coupling (piping) ; Motion (physics) ; Computer science ; Physics ; Classical mechanics ; Engineering ; Nanotechnology ; Materials science ; Mechanical engineering ; Biology ; Quantum mechanics ; Molecule ; Paleontology Supramolecular Chemistry and Complexes ; Advanced NMR Techniques and Applications ; Microtubule and mitosis dynamics
Authors: Ahmed M. Elazzazy | Khawater Ali | Noor M. Bataweel | Maged Mostafa Mahmoud | Afra Mohammed Baghdadi
Source: Polymers (article, 2024-07-29)
Field: Materials Science — Biomaterials

Microbial Biosynthesis of Medium-Chain-Length Polyhydroxyalkanoate (mcl-PHA) from Waste Cooking Oil Waste cooking oil is a common byproduct in the culinary industry, often posing disposal challenges. This study explores its conversion into the valuable bioplastic material, medium-chain-length polyhydroxyalkanoate (mcl-PHA), through microbial biosynthesis in controlled bioreactor conditions. Twenty-four bacterial isolates were obtained from oil-contaminated soil and waste materials in Mahd Ad-Dahab, Saudi Arabia. The best PHA-producing isolates were identified via 16S rDNA analysis as <i>Neobacillus niacini</i> and <i>Metabacillus niabensis</i>, with the sequences deposited in GenBank (accession numbers: PP346270 and PP346271). This study evaluated the effects of various carbon and nitrogen sources, as well as environmental factors, such as pH, temperature, and shaking speed, on the PHA production titer. <i>Neobacillus niacini</i> favored waste cooking oil and yeast extract, achieving a PHA production titer of 1.13 g/L, while <i>Metabacillus niabensis</i> preferred waste olive oil and urea, with a PHA production titer of 0.85 g/L. Both strains exhibited optimal growth at a neutral pH of 7, under optimal shaking -flask conditions. The bioreactor performance showed improved PHA production under controlled pH conditions, with a final titer of 9.75 g/L for <i>Neobacillus niacini</i> and 4.78 g/L for <i>Metabacillus niabensis</i>. Fourier transform infrared (FT-IR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) confirmed the biosynthesized polymer as mcl-PHA. This research not only offers a sustainable method for transforming waste into valuable materials, but also provides insights into the optimal conditions for microbial PHA production, advancing environmental science and materials engineering. Polyhydroxyalkanoates ; Bioplastic ; Food science ; Biosynthesis ; Chemistry ; Pulp and paper industry ; Waste management ; Biotechnology ; Environmental science ; Business ; Biochemistry ; Bacteria ; Biology ; Enzyme ; Engineering biodegradable polymer synthesis and properties ; Electrospun Nanofibers in Biomedical Applications ; Carbon dioxide utilization in catalysis
Authors: Kristen L. Steffens | Danny Bialuschewski | Barbara Milow
Source: Journal of Sol-Gel Science and Technology (article, 2024-10-11)
Field: Chemistry — Spectroscopy

“Tuning density and morphology of organic-inorganic hybrid-silica aerogels through precursor dilution for lightweight applications” Abstract Organic-inorganic hybrid-silica aerogels can be made of methyltrimethoxysilane (MTMS, CH 3 Si(OCH 3 ) 3 ) and dimethyldimethoxysilane (DMDMS, Si(OCH 3 ) 2 (CH 3 ) 2 ) in a typical sol-gel process yielding flexible and hydrophobic structures. In this work, MTMS and DMDMS were condensed with an increasing amount of water, leading to a decrease in the final materials density from ∼ 0.110 g cm −3 down to ∼0.066 g cm −3 . The gels were synthesized in a one-pot synthesis and dried under ambient pressure conditions at 80 °C. While the topology of the network remained intact, the size of secondary particles decreased from roughly 8.2 to 3.3 μm. The inter-particle neck thickness remained unaffected with increasing aging time for higher dilutions. The measured thermal conductivities were all in similar range (∼ 32.5 mW (m K) −1 at 25 °C), showing very good insulation characteristics. In general, higher diluted samples exhibited increasing softness and decreasing Young’s modulus, even with increased aging times. Overall, our optimized recipe leads to hydrophobic aerogels with ultralow densities while demonstrating very low thermal conductivity and a flexible mechanical performance. Graphical Abstract Dilution ; Morphology (biology) ; Chemical engineering ; Aerogel ; Materials science ; Nanotechnology ; Geology Aerogels and thermal insulation ; Silicone and Siloxane Chemistry ; Surface Modification and Superhydrophobicity
Authors: Jessica Chavez | Ajmal Khan | Kenna R. Watson | Safeera Khan | Yaru Si | Alexandra Y. Deng | Grant Koher | Mmesoma S. Anike | Xianwen Yi | Zhenquan Jia
Source: Antioxidants (article, 2024-02-10)
Field: Materials Science — Materials Chemistry

Carbon Nanodots Inhibit Tumor Necrosis Factor-α-Induced Endothelial Inflammation through Scavenging Hydrogen Peroxide and Upregulating Antioxidant Gene Expression in EA.hy926 Endothelial Cells Carbon nanodots (CNDs) are a new type of nanomaterial with a size of less than 10 nanometers and excellent biocompatibility, widely used in fields such as biological imaging, transmission, diagnosis, and drug delivery. However, its potential and mechanism to mediate endothelial inflammation have yet to be explored. Here, we report that the uptake of CNDs by EA.hy926 endothelial cells is both time and dose dependent. The concentration of CNDs used in this experiment was found to not affect cell viability. TNF-α is a known biomarker of vascular inflammation. Cells treated with CNDs for 24 h significantly inhibited TNF-α (0.5 ng/mL)-induced expression of intracellular adhesion molecule 1 (<i>ICAM-1</i>) and interleukin 8 (<i>IL-8</i>). <i>ICAM-1</i> and <i>IL-8</i> are two key molecules responsible for the activation and the firm adhesion of monocytes to activated endothelial cells for the initiation of atherosclerosis. ROS, such as hydrogen peroxide, play an important role in TNF-α-induced inflammation. Interestingly, we found that CNDs effectively scavenged H<sub>2</sub>O<sub>2</sub> in a dose-dependent manner. CNDs treatment also increased the activity of the antioxidant enzyme NQO1 in EA.hy926 endothelial cells indicating the antioxidant properties of CNDs. These results suggest that the anti-inflammatory effects of CNDs may be due to the direct H<sub>2</sub>O<sub>2</sub> scavenging properties of CNDs and the indirect upregulation of antioxidant enzyme NQO1 activity in endothelial cells. In conclusion, CND can inhibit TNF-α-induced endothelial inflammation, possibly due to its direct scavenging of H<sub>2</sub>O<sub>2</sub> and the indirect upregulation of antioxidant enzyme NQO1 activity in endothelial cells. Tumor necrosis factor alpha ; Inflammation ; Antioxidant ; Downregulation and upregulation ; ICAM-1 ; Chemistry ; Cell biology ; Endothelial activation ; Endothelial stem cell ; Intercellular Adhesion Molecule-1 ; Cell adhesion molecule ; Endothelial dysfunction ; Hydrogen peroxide ; Biochemistry ; Immunology ; Biology ; In vitro ; Endocrinology Carbon and Quantum Dots Applications ; Heme Oxygenase-1 and Carbon Monoxide ; Graphene and Nanomaterials Applications
Authors: Izabela Kurowska | Maksym Odnoroh | Oleksandr Ivanchenko | Marc Guerre | Mathias Destarac
Source: Polymer Chemistry (article, 2024-01-01)
Field: Chemistry — Organic Chemistry

Synthesis of high molar mass all-(meth)acrylic thermoplastic elastomers by photo-iniferter RAFT polymerisation PMMA-P n BA-PMMA triblock copolymers with high molar masses ( M n ∼800 kg mol −1 ), low dispersities ( Đ &lt; 1.25) and thermoplastic elastomer properties were synthesised via photo-iniferter RAFT polymerisation. Thermoplastic elastomer ; Molar mass ; Copolymer ; Raft ; Elastomer ; Molar ratio ; Materials science ; Polymer chemistry ; Polymerization ; Molar ; Thermoplastic ; Meth- ; Chemistry ; Composite material ; Polymer ; Organic chemistry ; Acrylate ; Catalysis Advanced Polymer Synthesis and Characterization ; Synthesis and properties of polymers ; Synthetic Organic Chemistry Methods
Authors: Daniel Weissberger | Martina H. Stenzel | Luke Hunter
Source: Molecules (review, 2024-10-19)
Field: Materials Science — Biomaterials

Precious Cargo: The Role of Polymeric Nanoparticles in the Delivery of Covalent Drugs Covalent drugs can offer significant advantages over non-covalent drugs in terms of pharmacodynamics (i.e., target-binding properties). However, the development of covalent drugs is sometimes hampered by pharmacokinetic limitations (e.g., low bioavailability, rapid metabolism and toxicity due to off-target binding). Polymeric nanoparticles offer a potential solution to these limitations. Delivering covalent drugs via polymeric nanoparticles provides myriad benefits in terms of drug solubility, permeability, lifetime, selectivity, controlled release and the opportunity for synergistic administration alongside other drugs. In this short review, we examine each of these benefits in turn, illustrated through multiple case studies. Covalent bond ; Bioavailability ; Chemistry ; Nanoparticle ; Covalent binding ; Drug ; Combinatorial chemistry ; Drug delivery ; Solubility ; Pharmacokinetics ; Pharmacology ; Nanotechnology ; Materials science ; Organic chemistry ; Medicine Nanoparticle-Based Drug Delivery ; Innovative Microfluidic and Catalytic Techniques Innovation ; Advanced Drug Delivery Systems
Authors: Robert Thoran | Florian Puls | Hans‐Joachim Knölker
Source: Chemistry - A European Journal (article, 2024-01-25)
Field: Chemistry — Organic Chemistry

Synthesis of 1,1′‐Bicarbazoles by Sequential Iron(III)‐ and Palladium(II)‐Catalyzed Oxidative Coupling Reactions** The iron(III)-catalyzed oxidative coupling of diarylamines to 2,2'-bis(arylamino)-1,1'-biaryls and subsequent twofold palladium(II)-catalyzed oxidative cyclization provide a convergent synthetic route to 1,1'-bicarbazoles. Screening a range of different palladium(II) salts led to palladium(II) acetate, pivalate, and hexafluoroacetylacetonate as the most efficient catalysts. Remarkably, the twofold palladium(II)-catalyzed oxidative cyclization can also be performed under argon. The mechanism for the oxidative cyclization under an inert gas presumably involves regeneration of the catalytically active palladium(II) species by oxidative addition of pivalic acid. Palladium ; Chemistry ; Catalysis ; Pivalic acid ; Oxidative phosphorylation ; Oxidative coupling of methane ; Oxidative addition ; Medicinal chemistry ; Organic chemistry ; Biochemistry Catalytic C–H Functionalization Methods ; Catalytic Cross-Coupling Reactions ; Axial and Atropisomeric Chirality Synthesis
Authors: Patrícia Neves | Ana C. Gomes | Rodrigo P. Monteiro | Mirela J. Santos | Anabela A. Valente | André D. Lopes | Isabel S. Gonçalves | Martyn Pillinger
Source: Applied Organometallic Chemistry (article, 2024-03-15)
Field: Chemistry — Physical and Theoretical Chemistry

Inclusion complexes of cucurbit[<i>n</i>]urils (<i>n</i> = 7, 8) with <i>η</i><sup>5</sup>‐cyclopentadienyl methyl tricarbonyl molybdenum(II) and their use in epoxidation catalysis There are very few known examples of supramolecular compounds comprising molybdenum species hosted inside the portals/cavities of cucurbit[ n ]urils (CB n ). In this work, CB7 and CB8 macrocycles have been studied as hosts for the carbonyl complex [CpMo(CO) 3 Me] ( 1 ) (Cp = η 5 ‐C 5 H 5 ). Compounds were isolated in the solid state and characterized as genuine 1:1 inclusion complexes ( 1 @CB n ) by elemental and thermogravimetric analyses, powder X‐ray diffraction, scanning electron microscopy, 13 C{ 1 H} cross‐polarization magic‐angle spinning NMR, FT‐IR, Raman, and diffuse reflectance UV–Vis spectroscopies. The host–guest structures can act as supramolecular precatalysts for olefin epoxidation. Based on the model reaction of cis ‐cyclooctene with hydroperoxide oxidants ( tert ‐butylhydroperoxide or hydrogen peroxide), the structural features of 1 @CB n as well as the operating conditions influence the catalytic process. The metal species in 1 @CB n undergo oxidative decarbonylation in situ, giving oxidized metal species that are catalytically active for olefin epoxidation. The type of oxidant and solvent influences the catalytic activity and stability. 1 @CB8 was more stable than 1 @CB7 with regard to catalyst recycling and reuse. Based on the substrate scope investigation, for relatively large olefins, such as the fatty acid methyl ester methyl oleate, the size of the macrocyclic host may be a determining factor for catalytic activity. Chemistry ; Cyclopentadienyl complex ; Molybdenum ; Catalysis ; Inclusion (mineral) ; Medicinal chemistry ; Stereochemistry ; Polymer chemistry ; Organic chemistry ; Mineralogy Crystallography and molecular interactions ; Radioactive element chemistry and processing ; Supramolecular Chemistry and Complexes
Authors: Duy Thanh Cu | Hong‐Wei Wu | Hung-Pin Chen | Li‐Chen Su | Chien‐Cheng Kuo
Source: Sensors (article, 2024-02-01)
Field: Materials Science — Surfaces, Coatings and Films

Exploiting Thin-Film Properties and Guided-Mode Resonance for Designing Ultrahigh-Figure-of-Merit Refractive Index Sensors Guided-mode resonance (GMR) gratings have emerged as a promising sensing technology, with a growing number of applications in diverse fields. This study aimed to identify the optimal design parameters of a simple-to-fabricate and high-performance one-dimensional GMR grating. The structural parameters of the GMR grating were optimized, and a high-refractive-index thin film was simulated on the grating surface, resulting in efficient confinement of the electric field energy within the waveguide. Numerical simulations demonstrated that the optimized GMR grating exhibited remarkable sensitivity (252 nm/RIU) and an extremely narrow full width at half maximum (2 × 10<sup>-4</sup> nm), resulting in an ultra-high figure of merit (839,666) at an incident angle of 50°. This performance is several orders of magnitude higher than that of conventional GMR sensors. To broaden the scope of the study and to make it more relevant to practical applications, simulations were also conducted at incident angles of 60° and 70°. This holistic approach sought to develop a comprehensive understanding of the performance of the GMR-based sensor under diverse operational conditions. Figure of merit ; Grating ; Materials science ; Refractive index ; Optoelectronics ; Optics ; Resonance (particle physics) ; Sensitivity (control systems) ; Guided-mode resonance ; Diffraction grating ; Electronic engineering ; Physics ; Engineering Optical Coatings and Gratings ; Photonic and Optical Devices ; Advanced Fiber Optic Sensors