jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Anubhav Goswami | Romin Gogoi | Arpita Panda | Aakash Chandresh Sheth | Garima Jindal
Source: ChemRxiv (preprint, 2023-05-22)
Field: Chemistry — Organic Chemistry

The Role of Xantphos in forming an Elusive dirhodium-η1-allyl Intermediate in a Rh(II)-Catalyzed Allylic Alkylation: A Combined Computational and Experimental Study The use of dirhodium tetracarboxylate catalysts in multicomponent reactions involving allylic alkylation has been a formidable challenge to synthetic chemists. A unique strategy by means of catalyst structure modification in the presence of an external ligand, Xantphos, has recently enabled their efficient use in one-pot reactions involving carbene insertion into X–H bonds followed by allylic alkylation. However, the origin of the novel reactivity and the mechanism of such reactions remains unclear. Herein, we report a combined computational and experimental mechanistic study to shed light on the ligand enabled catalyst structure modification and its implication in catalysis. This unique reactivity is enabled by the dissociation of an octanoate bridge driven by κ2-Xantphos ligation to the dirhodium core of the catalyst. This, in turn, allows for the hitherto unknown oxidative addition with a Rh(II) catalyst resulting in a dirhodium-η1-allyl species. For the first time, we confirm the presence of such a species in solution through in situ NMR and cyclic voltammetry experiments in line with DFT calculations. Alongside, we study the role of the base and solvent in generating the nucleophilic partner that can trap the electrophilic allylic species. This study is expected to guide future catalyst design, including chiral variants for exploring newer modes of reactivity and selectivity using dirhodium catalysis. Xantphos ; Tsuji–Trost reaction ; Chemistry ; Nucleophile ; Allylic rearrangement ; Catalysis ; Reactivity (psychology) ; Electrophile ; Carbene ; Combinatorial chemistry ; Alkylation ; Medicinal chemistry ; Palladium ; Organic chemistry Cyclopropane Reaction Mechanisms ; Catalytic C–H Functionalization Methods ; Asymmetric Hydrogenation and Catalysis
Authors: Ming‐Shang Liu | Huan Meng | Wei Shu
Source: Research Square (preprint, 2023-08-18)
Field: Chemistry — Organic Chemistry

Unified Metal-Free Regioselective Heck-Type Sulfonylation, Cyanation, Amination, Amidation of Alkenes by Thianthrenation Cyanation ; Regioselectivity ; Amination ; Chemistry ; Organic chemistry ; Combinatorial chemistry ; Catalysis Sulfur-Based Synthesis Techniques ; Synthesis and Catalytic Reactions ; Catalytic C–H Functionalization Methods
Authors: Georg R. J. Artus | Davide Bottone | Stefan Seeger
Source: Small (article, 2023-06-14)
Field: Materials Science — Ceramics and Composites

Silicon Oxycarbide Coatings Consisting of Defined Bottom–Up‐Grown Nanostructures Silicon oxycarbide (SiOC) materials have arisen in the past few decades as a promising new class of glasses and glass-ceramics thanks to their advantageous chemical and thermal properties. Many applications, such as ion storage, sensing, filtering, or catalysis, require materials or coatings with high surface area and might benefit from the high thermal stability of SiOC. This work reports the first facile bottom-up approach to textured high surface area SiOC coatings obtained via direct pyrolysis of polysiloxane structures of well-defined shapes, such as nanofilaments or microrods. This work further investigates the thermal behavior of these structures by means of FT-IR, SEM, and EDX up to 1400 °C. The rods shrink in volume by ≈30% while their aspect ratio remains unaffected by pyrolysis until at least 1100 °C. The nano-sized filaments show signs of viscous flow already at a comparably low temperature of 900 °C which is very probably due to the nano-size effect. This might open a way to experimentally study the size-effect on the glass transition temperature of oxide glasses, an experimentally unexplored but very relevant topic. These structures have great potential, for example, as ion storage materials and supports in high temperature catalysis and CO<sub>2</sub> conversion. Materials science ; Nanostructure ; Nanotechnology ; Ceramic ; Silicon ; Pyrolysis ; Nanomaterials ; Thermal stability ; Oxide ; Catalysis ; Chemical engineering ; Thermal ; Composite material ; Metallurgy Advanced ceramic materials synthesis ; Diamond and Carbon-based Materials Research ; Semiconductor materials and devices
Authors: Marianna V. Kharlamova
Source:  (article, 2023-11-21)
Field: Materials Science — Materials Chemistry

Chemical Properties of Metallocene-Filled Carbon Nanotubes to Tailor Toxicity in Plants Metallocenes are toxic chemicals that are used for the growth of carbon nanotubes (CNTs). The study of the toxicity of metallocenes on plants is very important. It governs the issues of genetics. Toxicity studies should consider (I) the growth kinetics of carbon nanotubes, (II) the chemical reaction of metallocenes inside carbon nanotubes, and (III) investigations into the electronic properties of filled carbon nanotubes. Toxicity studies are influenced by the investigation of the growth processes of metallocene-filled carbon nanotubes, the evaporation of metals, and the formation of multiple-walled carbon nanotubes. Investigations into the modification of the Fermi level of filled carbon nanotubes also play a role in toxicity studies. Metallocenes are filled into carbon nanotubes through the various methods discussed here, including solution methods and gas-phase methods, each differing in methodology and requiring optimization. Many authors have published different methods of filling carbon nanotubes with metallocenes. They lead to high-filling ratios and allow future modifications of the electronic properties of carbon nanotubes. The kinetics of carbon nanotube growth are investigated with different methods. Environmental transmission electron microscopy is applied to studies with a time resolution of several nanoseconds. Here, we use Raman spectroscopy to study the growth process, which is revealed to have activation energies, growth rates, and temperature dependence. The dependence of growth temperature on the tube diameter and metallocene-type is revealed. It is shown that the growth temperature increases with the larger diameter of inner CNTs. The growth temperature increases for ferrocene compared to nickelocene and cobaltocene. With X-ray photoelectron spectroscopy, we show that the heating of metallocene-filled SWCNTs at 360–600 °C causes the n-doping of SWCNTs. Heating at higher temperatures results in p-doping. The obtained data are needed to tailor the toxicity issues of metallocene-filled carbon nanotubes on plants. Carbon nanotube ; Cobaltocene ; Materials science ; Carbon nanobud ; Ferrocene ; Carbon fibers ; Metallocene ; Chemical engineering ; Selective chemistry of single-walled nanotubes ; Raman spectroscopy ; Nanotechnology ; Mechanical properties of carbon nanotubes ; Optical properties of carbon nanotubes ; Nickelocene ; Nanotube ; Chemistry ; Composite material ; Physical chemistry ; Electrochemistry ; Polymerization ; Electrode Carbon Nanotubes in Composites ; Nanotechnology research and applications ; Chemical and Physical Properties of Materials
Source: Research outreach (article, 2023-06-28)
Field: Materials Science — Polymers and Plastics

Mechanochemistry A new route to sustainable polymer recycling lastic is one of the most common classes of man-made materials, finding various applications in a wide range of industries, from packaging to piping and plumbing, automobiles, toys, and furniture, to name but a few.Modern plastics are typically synthesised through relatively inexpensive processes starting from fossil fuel-based chemicals, like petroleum oil and natural gas.They form stable, lightweight, durable, and flexible materials, which can be moulded into solid objects of virtually any shape and size.Plastic is difficult to recycle due to the chemical bonds present in the polymer chains. Mechanochemistry ; Business ; Polymer ; Materials science ; Nanotechnology ; Composite material Polymer Science and PVC ; Polymer crystallization and properties
Authors: Guillaume Berionni
Source: Science (article, 2023-12-07)
Field: Chemistry — Organic Chemistry

Controlling precision on the ring Desired borylation of fluoroaromatic compounds is achieved with cobalt catalysts. Borylation ; Ring (chemistry) ; Cobalt ; Catalysis ; Chemistry ; Combinatorial chemistry ; Organic chemistry Catalytic C–H Functionalization Methods ; Catalytic Cross-Coupling Reactions ; Fluorine in Organic Chemistry
Authors: Bruno Lainer
Source: theses.fr (ABES) (article, 2023-12-20)
Field: Chemistry — Organic Chemistry

Approche multicatalytique de l'arylation énantio et diastéréosélective des alcools Alcohol moieties are present in a great diversity of valuable fine chemicals from nature and synthesis, therefore methods enabling their structural diversification are sought after. However, modifying the structure of alcohols at certain unreactive positions, even with the aid of catalysis, remains a challenge or requires tedious often wasteful multistep procedures. Recently, increased attention has been paid to multicatalysis, which combines multiple catalysts within one system, enabling the discovery of previously inaccessible reactivities or increasing the overall efficiency of multistep transformations. Described within are methods which enable the diastereo-, and enantioselective α-, and β-arylation of alcohols. By combining Ru- and Pd-based catalysts the unprecedented, enantioselective (and diastereodivergent in the case of alcohols already bearing stereocenters) β-arylation of primary alcohols can be carried out. Also, under sequential relay catalysis enantioenriched secondary benzylic alcohols can be obtained from a variety of available starting materials, such as primary alcohols, or alcohols bearing a double bond. Overall, these protocols demonstrate the potential of multicatalysis as a synthetic tool for diversifying alcohols. In a broader context, this thesis sets the stage for devising novel, multicatalytic strategies and methods for efficient synthesis. Enantioselective synthesis ; Variety (cybernetics) ; Catalysis ; Alcohol ; Primary (astronomy) ; Diversification (marketing strategy) Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods ; Asymmetric Hydrogenation and Catalysis
Authors: Yuanhui Pan | Ching-Hwa Ho | Francesco Paesani | Raja Ghosh
Source: ChemRxiv (preprint, 2023-03-06)
Field: Materials Science — Materials Chemistry

Engineering flat and dispersive bands in 2D layered COFs via interlayer stacking and donor-acceptor strategy Covalent organic frameworks (COFs) are an emergent class of two-dimensional (2D) crystalline organic materials that exhibit unique electronic, optical, and transport properties. In this study, we employ density functional theory (DFT) and the multiparticle Holstein formalism (MHF) to investigate the electronic structure and two-dimensional coherence of polarons in donor-acceptor COFs as a function of interlayer stacking arrangement. We show that simple modifications in the interlayer stacking arrangement have a profound impact on the transport properties, which can range from metallic behavior with vanishing band gap to highly localized states having completely flat bands. The extent of charge delocalization is found to be sensitive to the type of stacking arrangement and the precise arrangement of the donor and acceptor fragments within the COF structure. The results from the DFT calculations are consistent with MHF-based simulations, demonstrating that stacking-induced interlayer interac- tions facilitate better in-plane charge delocalization. As a consequence, we find that interlayer interactions help circumvent defect-induced trap states to enhance overall charge delocalization. Based on these analyses, we conclude that interlayer stacking can be exploited to guide the design of new 2D layered COF structures with potential applications in organic electronics. Stacking ; Delocalized electron ; Acceptor ; Materials science ; Density functional theory ; Chemical physics ; Molecular physics ; Electronic structure ; Condensed matter physics ; Nanotechnology ; Computational chemistry ; Chemistry ; Physics Covalent Organic Framework Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Graphene research and applications
Authors: Danyu Wang | Zhe Li | Tian‐Yi Luo | Michael B. Schmithorst | Sunghwan Park | Wenqian Xu | Brandon C. Bukowski | Bradley F. Chmelka | Efrosini Kokkoli | Michael Tsapatsis
Source: ChemRxiv (preprint, 2023-01-10)
Field: Chemistry — Inorganic Chemistry

Enantioselective Catalysts Based on Metal-Organic Framework-Supported Nucleotides Adenosine triphosphate (ATP) and other nucleotides can be irreversibly bound to the metal-organic framework (MOF) MIL-101(Cr). Analysis of X-ray diffraction data suggests that the location of the adsorbed ATP molecule is in proximity of the Cr3 clusters. Solid-state NMR and DFT calculations indicate that ATP is bound to MIL-101(Cr) through linkages of the terminal phosphate group with Cr(III) of the framework. In the presence of Cu(II) ions, the MOF-supported nucleotides can function as stable and reusable enantioselective heterogeneous catalysts for reactions like Diels-Alder and Michael addition. Compared to the corresponding homogeneous nucleotide-based artificial metalloenzymes (ArMs), the MOF-supported nucleotide-based ArMs exhibit significantly enhanced activity and selectivity in certain cases, demonstrating their potential as a new class of enantioselective heterogeneous catalysts. Nucleotide ; Enantioselective synthesis ; Catalysis ; Chemistry ; Adenosine triphosphate ; Metal-organic framework ; Molecule ; Stereochemistry ; Combinatorial chemistry ; Adsorption ; Organic chemistry ; Biochemistry Metal-Organic Frameworks: Synthesis and Applications ; Peptidase Inhibition and Analysis ; Metal complexes synthesis and properties
Authors: Ekta Shandilya | Bhargav Rallabandi | Subhabrata Maiti
Source: ChemRxiv (preprint, 2023-04-19)
Field: Chemistry — Physical and Theoretical Chemistry

Spatiotemporally tuned colloidal phoretic leap in an altering multivalent interaction field Multivalency-mediated interactions play an important role in governing dynamicity and self-assembly in biological systems. Despite its significance in supramolecular material chemistry to biomedicine, the role of multivalency in modulating colloidal transport or phoresis remains largely unexplored. Here, combining theory and experiment, we report diffusiophoretic motion of a positively-charged catalytic microbead during its multivalent interactions with a gradient of adenosine mono-, di- and trinucleotides (AM/D/TP) both in micro- and macroscale regimes. We find that the extent of drift diminishes with increasing number of phosphates. Subsequently, we exhibit nucleotide-specificity of the colloid in catalyzing a proton-transfer reaction, which in turn alters its phoretic behaviour. Finally, we demonstrate spatiotemporal control over colloidal phoretic leap (a sudden increase in phoretic velocity) and population dynamics driven by enzymatic downregulation of multivalent interactivity, which has been achieved by controlling ATP hydrolysis in situ. These findings open up avenues for utilizing multivalent surface-mediated catalytic activity to achieve precise control of particle transport relevant to reaction-diffusion driven spatiotemporal processes. Chemistry ; Colloid ; Nanotechnology ; Chemical physics ; Supramolecular chemistry ; Population ; Catalysis ; Particle (ecology) ; Diffusion ; Biophysics ; Physics ; Materials science ; Biology ; Biochemistry ; Molecule ; Physical chemistry ; Ecology ; Thermodynamics Electrostatics and Colloid Interactions ; Lipid Membrane Structure and Behavior ; Nanopore and Nanochannel Transport Studies
Authors: Silvia Panarello | Aleix González-Díez | Alice E. Berizzi | Fanny Malhaire | Roser Borràs‐Tudurí | Xavier Rovira | Laurent Prézeau | Jean‐Philippe Pin | Cyril Goudet | Amadeu Llebaria | Xavier Gómez‐Santacana
Source:  (preprint, 2023-07-03)
Field: Materials Science — Materials Chemistry

Optogluram-2: a subtype-selective photoswitchable positive allosteric modulator for metabotropic glutamate receptor 4 Background and Purpose Metabotropic Glutamate Receptors (mGlu) regulate multiple functions in the nervous systems and are involved in multiple disorders. However, selectively targeting individual mGlu subtypes with spatiotemporal precision is still an unmet need. Photopharmacology can address this concern by means of photoswitchable compounds such as Optogluram, which is a positive allosteric modulator (PAM) of mGlu4 that enables to optically control physiological responses with a high precision. However, Optogluram is not fully selective and finding mGlu4 PAMs with subtype selectivity may be complicated. Experimental Approach New photoswitchable analogues of Optogluram were synthesised with the aim of obtaining photoswitchable PAMs selective for mGlu4 receptor and with improved photoisomerization properties. The photopharmacological profiles of these new compounds were assessed using spectroscopy, functional IP and cAMP assays and computational modelling. Key Results Optogluram-2 emerged as a new photoswitchable PAM for mGlu4 receptor and offered improved photoswitching properties and was selective for mGlu4. Optogluram-2 had activity as both PAM and allosteric agonist. The π-π stacking of the thiazole ring in the allosteric pocket of mGlu6 is hypothesised to be responsible of the mGlu4 selectivity. Conclusion and Implications. The enhanced photoswitching behaviour and improved selectivity of Optogluram-2 makes it an excellent candidate to study the role of mGlu4 with a high spatiotemporal precision that only photopharmacology can offer. Indeed, the use of Optogluram-2 in tissues where mGlu4 can be co-expressed with other mGlu receptors will help to unravel the complexity of mGlu receptors in neural transmission, pinpointing the role of mGlu4 in such systems. Allosteric regulation ; Metabotropic glutamate receptor ; Allosteric modulator ; Chemistry ; Receptor ; Agonist ; Neuroscience ; Biophysics ; Biology ; Biochemistry Photochromic and Fluorescence Chemistry ; Retinal Development and Disorders ; Receptor Mechanisms and Signaling
Authors: Faujdar | Pathania | Preet | Katyal
Source: Bulgarian Chemical Communications (article, 2023-08-25)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Responsive PNIPAM coated Au core-shell nanoparticle for optical sensing In this work, we analyze the optical properties of responsive poly (N-isopropylacrylamide) (PNIPAM) coated plasmonic Au core-shell nanoparticle for sensing application.With external chemical or physical stimuli, the responsive PNIPAM polymeric layer exhibits unique properties like variation of solvent concentration, density and subsequently a change in refractive index (RI).Mie theory-based calculation modeled the change in the position of the localized surface plasmon resonance (LSPR) peak with linear change in refractive index of PNIPAM-coated Au nanosystem with external stimuli like change in salt concentration in water, temperature, pH, etc.It paves the way for designing efficient PNIPAMcoated Au-based refractive index-based system for bio/chemical sensing/detection.We theoretically report the sensitivity (S) equal to ~65.8 nm/RIU and the corresponding figure of merit (RIU/nm) is~2 10 6 .3 RIU/nm.Present investigation can lead to the realization of efficient bio/chemical sensors and light harvesting structures/devices. Nanoparticle ; Optical sensing ; Optical imaging ; Polymer Gold and Silver Nanoparticles Synthesis and Applications ; Plasmonic and Surface Plasmon Research ; Laser-Ablation Synthesis of Nanoparticles
Authors: Xuanrui Zhang
Source: Applied and Computational Engineering (article, 2023-11-06)
Field: Materials Science — Materials Chemistry

Research on the influence of various factors on the fluorescence function of silver nanoclusters as biomarkers This review focuses on the impact of numerous conditions on the fluorescence function of silver nanoclusters (AgNCs) as biomarkers. Factors such as particle size, structure and different ligand types are explored. First off, differential stability, sensitivity, cellular uptake, and biodistribution as well as red or blue shifts in absorption and emission wavelengths are caused by varied particle sizes. Furthermore, in the context of detecting microRNA using AgNC-based probes, the presence of a mismatched self-dimer structure is also crucial for achieving a significant red emission. In the final section, the considerable influence of ligandsdivided into primary and secondary ligandson the photoluminescence (PL) characteristics of atomically accurate AgNCs is examined with a focus on Ag29 nanoclusters. Nanoclusters ; Fluorescence ; Context (archaeology) ; Photoluminescence ; Materials science ; Nanotechnology ; Particle size ; Dimer ; Chemistry ; Analytical Chemistry (journal) ; Optoelectronics ; Physics ; Physical chemistry ; Optics ; Chromatography ; Organic chemistry ; Biology Nanocluster Synthesis and Applications ; Advanced Nanomaterials in Catalysis ; Gold and Silver Nanoparticles Synthesis and Applications
Authors: Hema Kuntrapakam | Angela B. Grommet | Michał J. Białek | Jinhua Wang | Oksana Yanshyna | Yael Diskin‐Posner | Rafał Klajn
Source: ChemRxiv (preprint, 2023-08-07)
Field: Chemistry — Organic Chemistry

Guest Encapsulation Alters the Thermodynamic Landscape of a Coordination Cage The architecture of self-assembled host molecules can profoundly affect the properties of the encapsulated guests. For example, rigid capsules with small windows can efficiently protect their contents from the environment; in contrast, tube-shaped, flexible hosts with large openings and an easily accessible cavity are ideally suited for catalysis. Here, we report a “Janus” nature of a Pd6L4 coordination cage previously reported to tube isomer (T). We show that upon encapsulating various tetrahedrally shaped guests, T can reconfigure into a capsule-shaped host (C) in a quantitative yield. Extracting the guest affords the empty C, which is metastable and spontaneously relaxes to T, and the T⇄C interconversion can be repeated for multiple cycles. Reversible toggling between two vastly different isomers paves the way towards controlling functional properties of coordination cages “on demand”. Janus ; Metastability ; Cage ; Catalysis ; Chemistry ; Nanotechnology ; Chemical physics ; Materials science ; Crystallography ; Organic chemistry ; Structural engineering Supramolecular Chemistry and Complexes ; Magnetism in coordination complexes ; Supramolecular Self-Assembly in Materials