jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Juner Zhang | Ailiena O. Maggiolo | Edwin Alfonzo | Runze Mao | Nicholas J. Porter | Nayla M. Abney | Frances H. Arnold
Source: ChemRxiv (preprint, 2022-10-11)
Field: Chemistry — Organic Chemistry

Chemodivergent C(sp3)–H and C(sp2)–H Cyanomethylation Using Engineered Carbene Transferases The ubiquity of C–H bonds presents an attractive opportunity to elaborate and build complexity in organic molecules. Methods for selective functionalization, however, often must differentiate among multiple chemically similar and, in some cases indistinguishable, C–H bonds within the same molecule. An advantage of enzymes is that they can be finely tuned using directed evolution to achieve control over divergent C–H functionalization pathways. Here, we present engineered enzymes that effect a new-to-nature C–H alkylation (C–H carbene insertion) with unparalleled selectivity: two complementary carbene C–H transferases derived from a cytochrome P450 from Bacillus megaterium deliver an α-cyanocarbene into the α-amino C(sp3)–H bonds or the ortho-arene C(sp2)–H bonds of N-substituted arenes. These two transformations proceed via different mechanisms, yet only minimal changes to the protein scaffold (nine mutations, less than 2% of the sequence) were needed to adjust the enzyme’s control over the site-selectivity of cyanomethylation. The X-ray crystal structure of the selective C(sp3)–H alkylase, P411-PFA, reveals an unprecedented helical disruption which alters the shape and electrostatics in the enzyme active site. Overall, this work demonstrates the advantages of using enzymes as C–H functionalization catalysts for divergent molecular derivatization. Carbene ; Chemistry ; Surface modification ; Selectivity ; Stereochemistry ; Alkylation ; Enzyme ; Molecule ; Derivatization ; Biocatalysis ; Bacillus megaterium ; Combinatorial chemistry ; Catalysis ; Organic chemistry ; Biology ; Reaction mechanism Cyclopropane Reaction Mechanisms ; Catalytic C–H Functionalization Methods ; Synthesis and Catalytic Reactions
Authors: Roger Machín Rivera | Nikolas R. Burton | Luke D. Call | Marshall A. Tomat | Vincent N. G. Lindsay
Source: ChemRxiv (preprint, 2022-05-03)
Field: Chemistry — Organic Chemistry

Synthesis of Highly Congested Tertiary Alcohols via the [3,3] Radical Deconstruction of Breslow Intermediates Pericyclic processes such as [3,3]-sigmatropic rearrangements leading to the rapid generation of molecular complexity constitute highly valuable tools in organic synthesis. Herein, we report the formation of particularly hindered tertiary alcohols via rearrangement of Breslow intermediates formed in situ from readily available N-allyl thiazolium salts and benzaldehyde derivatives. Experimental mechanistic studies performed suggest that the reaction proceeds via a close radical pair which recombine in a regio- and diastereoselective manner, formally leading to [3,3]-rearranged products. Pericyclic reaction ; Sigmatropic reaction ; Chemistry ; Benzaldehyde ; Organic synthesis ; Cope rearrangement ; Tertiary alcohols ; Reaction intermediate ; Organic chemistry ; Alcohol ; Catalysis Radical Photochemical Reactions ; Catalytic C–H Functionalization Methods ; Sulfur-Based Synthesis Techniques
Authors: Chiara M. A. Gangemi | Tania Maria Grazia Salerno | Anna Barattucci | Fabio Cucinotta | Paola Bonaccorsi | Giovanna Calabrese | Paola Poma | Maria Giovanna Rizzo | Sebastiano Campagna | Fausto Puntoriero
Source: International Journal of Molecular Sciences (article, 2022-08-23)
Field: Materials Science — Materials Chemistry

A Curcumin-BODIPY Dyad and Its Silica Hybrid as NIR Bioimaging Probes In this paper we describe the synthesis of a novel bichromophoric system in which an efficient photoinduced intercomponent energy transfer process is active. The dyad consists of one subunit of curcumin and one of BODIPY and is able to emit in the far-red region, offering a large Stokes shift, capable of limiting light scattering processes for applications in microscopy. The system has been encapsulated in MCM-41 nanoparticles with dimensions between 50 and 80 nm. Both the molecular dyad and individual subunits were tested with different cell lines to study their effective applicability in bioimaging. MCM-41 nanoparticles showed no reduction in cell viability, indicating their biocompatibility and bio-inertness and making them capable of delivering organic molecules even in aqueous-based formulations, avoiding the toxicity of organic solvents. Encapsulation in the porous silica structure directed the location of the bichromophoric system within cytoplasm, while the dyad alone stains the nucleus of the hFOB cell line. BODIPY ; Biocompatibility ; Curcumin ; Chemistry ; Nanoparticle ; Nanotechnology ; Molecule ; Aqueous solution ; Biophysics ; Materials science ; Fluorescence ; Organic chemistry Luminescence and Fluorescent Materials ; Porphyrin and Phthalocyanine Chemistry ; Nanoplatforms for cancer theranostics
Authors: Sarath D. Perera
Source: OUSL Journal (article, 2022-12-31)
Field: Chemistry — Organic Chemistry

Synthesis of Tricarbonyl Re(I) Complexes of N and P Donor Ligands Reaction of 1,10-phenanthroline-5,6-dione V with 1,3-diphenyl propan-2-one afforded the keto-alcohol VI. Treatment of VI with alkynes, di(3-thienyl) acetylene and di(4-tert-butylphenyl) acetylene yielded 5,8-diphenyl-6,7-di(3-thienyl)-1,12-diaza-triphenylene L1 and 6,7-di(4-tert-butylphenyl)-5,8-diphenyl-1,12-diazatriphenylene L2, respectively. [ReCl(CO)5] reacted with N^N-donor ligands L1-L6 to produce fac-tricarbonylrhenium(I) complexes (20)-(25) in good yields as coloured solids. Treatment of [ReCl(CO)5] with the bulky P^N ligand L7 formed the neutral complex fac-[ReCl(CO)3(L7)] (26) whilst with the azine diphosphine Z,Z-L8 afforded the cationic complex fac-[Re(CO)3(E,Z-L8)]Cl (27a), where L8 is a tridentate ligand. The chloride anion of the complex (27a) was replaced by treating it with NH4PF6 into fac-[Re(CO)3(E,Z-L8)]PF6 (27b). Above complexes were characterized by a combination of elemental analysis, IR, Mass and NMR spectroscopy. Open university ; Sri lanka ; Library science ; Publication ; Distance education ; Open access journal ; New delhi ; Peer review ; Sociology ; Political science ; Pedagogy ; Medicine ; Computer science ; MEDLINE ; Scopus Inorganic and Organometallic Chemistry ; Asymmetric Hydrogenation and Catalysis ; Metal complexes synthesis and properties
Authors: Elisabetta Rosadoni | Federico Banchini | Sara Bellini | Marco Lessi | Luca Pasquinelli | Fabio Bellina
Source: Preprints.org (preprint, 2022-11-15)
Field: Chemistry — Organic Chemistry

Ligandless Palladium-catalyzed Direct C-5 arylation of azoles Promoted by Benzoic Acid in Anisole Due to the widespread application of (hetero)arylazoles, the development of straightforward functional group-tolerant synthetic methods that enable selective heteroaromatic elaboration under mild conditions aroused considerable attention. Over the last years we were interested in studies aimed to broaden the substrate scope of the direct functionalization of azoles and, in particular, to develop efficient synthetic protocols for the carbon-carbon bond forming reaction by selective palladium-catalyzed Csp2-H bond activation of imidazole derivatives. During these studies, we discovered that the outcome of the Pd-catalyzed arylation of imidazoles with aryl bromides is deeply influenced by the nature of the reaction solvent. Specifically, it is well known that the Pd-catalyzed direct arylation of imidazoles with aromatic halides selectively leads to C-5 monoarylation products when polar aprotic solvents such as DMF (or DMA) are used as a reaction medium, but these solvents are coded as dangerous according to EHS (Environmental, Health, Safety) parameters. Instead, the use of aromatic solvents as the reaction medium for direct arylations, although some of them show good EHS values, is poorly reported, probably due to their low solvent power against reagents and their potential involvement in undesired side reactions. So, with the intention of filling this gap, in this paper, we have developed a selective C-5 arylation procedure in anisole as the solvent, discovering also the unprecedented role of benzoic acid as a promoter of the coupling. Anisole ; Chemistry ; Aryl ; Catalysis ; Reagent ; Palladium ; Combinatorial chemistry ; Benzoic acid ; Solvent ; Functional group ; Reactivity (psychology) ; Substrate (aquarium) ; Coupling reaction ; Organic chemistry ; Alkyl Catalytic C–H Functionalization Methods ; Catalytic Cross-Coupling Reactions ; Sulfur-Based Synthesis Techniques
Authors: Jeff M. Van Raden | Dimitris I. Alexandropoulos | Michael Slota | Simen Sopp | Taisuke Matsuno | Amber L. Thompson | Hiroyuki Isobe | Harry L. Anderson | Lapo Bogani
Source: ChemRxiv (preprint, 2022-02-28)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Singly- and Triply-Linked Magnetic Porphyrin Lanthanide Arrays The introduction of paramagnetic metal centers into a conjugated π-system is a promising approach towards engineering spintronic materials. Here, we report an investigation of two types of spin-bearing dysprosium(III) and gadolinium(III) porphyrin dimers: singly meso-meso-linked dimers with twisted conformations and planar edge-fused ,meso,-linked tapes. The rare-earth spin centers sit out of the plane of the porphyrin, so that the singly linked dimers are chiral, and their enantiomers can be resolved, whereas the edge-fused tape complexes can be separated into syn and anti stereoisomers. We compare the crystal structures, UV-vis-NIR absorption spectra, electrochemistry, EPR spectroscopy and magnetic behavior of these complexes. Low temperature SQUID magnetometry measurements reveal intramolecular antiferromagnetic exchange coupling between the GdIII centers in the edge-fused dimers (syn isomer: J = –51 ±2 MHz; anti isomer: J = –19 ±3 MHz), whereas no exchange coupling is detected in the singly-linked twisted complex. The phase memory times, Tm, are in the range 8–10 µs at 3 K, which is long enough to test quantum computational schemes using microwave pulses. The syn and anti Dy2 edge-fused tapes both exhibit single molecule magnetic hysteresis cycles at temperatures below 0.5 K with slow magnetization dynamics. Crystallography ; Porphyrin ; Intramolecular force ; Electron paramagnetic resonance ; Materials science ; Squid ; Antiferromagnetism ; Dysprosium ; Magnetization ; Chemistry ; Condensed matter physics ; Photochemistry ; Nuclear magnetic resonance ; Stereochemistry ; Magnetic field ; Inorganic chemistry Magnetism in coordination complexes ; Porphyrin and Phthalocyanine Chemistry ; Lanthanide and Transition Metal Complexes
Authors: Lyudmila V. Parfenova | Pavel V. Kovyazin | Almira Bikmeeva | Eldar R. Palatov | Pavel V. Ivchenko | Ilya E. Nifant’ev | Л. М. Халилов
Source: Preprints.org (preprint, 2022-12-07)
Field: Chemistry — Organic Chemistry

Catalytic Properties of Zirconocene-Based Systems in 1-Hexene Oligomerization and Structure of Metal Hydride Reaction Centers In spite of large-scale investigations of homogeneous single-site metallocene catalysts and systems based on them, the problem of controlling their activity, chemo- and stereoselectivity with the aim of developing efficient methods for the preparation of practically useful products of alkenes transformation, such as dimers, oligomers, and polymers, still remains topical. Here we studied catalytic activity of differently structured zirconocenes (10 examples of cyclopentadienyl and indenyl complexes) and co-catalysts activating the system, namely HAlBui2, MMAO-12 or (Ph3C)[B(C6F5)4] at low activator/Zr ratios in 1-hexene oligomerization reaction. The influence of catalyst structure and system composition on alkene conversion, type of products formed and reaction stereoselectivity was investigated. The composition of hydride intermediates forming in the systems L2ZrCl2 (L2= ansa-Me2CCp2)-HAlBui2-activator was studied by NMR and the participation of biszirconium hydride complex as the precursor of catalytically active sites of the alkene dimerization reaction was shown. Hydride ; Alkene ; Chemistry ; Metallocene ; Cyclopentadienyl complex ; Catalysis ; Stereoselectivity ; Hexene ; Metal ; Combinatorial chemistry ; Polymer chemistry ; Organic chemistry ; Polymerization ; Polymer ; Ethylene Synthetic Organic Chemistry Methods ; Organometallic Complex Synthesis and Catalysis ; Catalysis and Oxidation Reactions
Authors: Muhammad Aneeq Haq | Han-Saem Lee | Mi‐Hye Lee | Da‐Woon Jeong | Eom Nu Si A | Bin Lee | Yoseb Song | Bum Sung Kim
Source: Coatings (article, 2022-03-15)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Nd2Fe14B/FeCo Core–Shell Nanoparticle Synthesis Using Galvanic Substitution Based Electroless Plating Core–shell structured magnetic nanoparticles combine hard and soft phases to improve energy efficiency. The mutual interaction of the two phases can lead to the exchange spring effect, leading to higher magnetic energy. In this regard, synthesis of Nd2Fe14B-based core–shell-structured powders have proven to be elusive, due to the relatively reactive nature of this phase. In this study, a process has been established for successfully coating the surface of Nd2Fe14B powders with a FeCo layer using the galvanic displacement method. Initially, a binary phase magnetic powder was synthesized containing Nd2Fe14B and Nd2Fe17 phase. Subsequently, the powders were coated using a Co precursor at 303 K. During coating, the metastable Nd2Fe17 phase was dissolved, and the Fe ions were released into the solution. Subsequently, the Fe ions deposited together with the Co ions on the surface of Nd2Fe14B powder to form a FeCo shell. The deposited layer thickness and composition was confirmed using TEM analysis. Materials science ; Coating ; Nanoparticle ; Chemical engineering ; Galvanic cell ; Phase (matter) ; Single displacement reaction ; Layer (electronics) ; Ion ; Shell (structure) ; Metallurgy ; Composite material ; Nanotechnology ; Chemistry Magnetic Properties of Alloys ; Metallic Glasses and Amorphous Alloys ; Magnetic properties of thin films
Authors: Xiuyuan Wang
Source: Highlights in Science Engineering and Technology (article, 2022-12-30)
Field: Materials Science — Biomaterials

Applications of Polymeric Micelles for Drug Delivery Polymeric micelles have attracted more and more attention in the biomedical field due to their controlled synthesis and sustained drug release, where a diverse of different drug carriers based on the polymeric micelles have been developed in recent years. This research will analyze the application and development of polymeric micelles that derived from block copolymers in biomedicine. There are three processes in drug delivery of drug carriers prepared by polymeric micelles, including micellar drug loading, micellar drug release and targeted therapy. In the polymeric micelles system, the reason why the solubilization and stabilization of drugs are improved is that the hydrophobic interaction and forming of hydrogen bond between micelles-system and drugs. This research also gives basic mechanism for polymeric micelles for passive and active drug targeting. What makes micelles ideal hosts for hydrophobic anti-cancer drugs or other targeted drugs is the hydrophobic nature of its core. This can make the drug more stable. In addition, this research is written to cover the latest information on polymeric micelles and methods of synthesis for applications. The advantages and disadvantages of its use as a drug carrier are also included. And it highlights the conditions that polymeric micelles need to meet as specific delivery tools in various targeting situations. Micelle ; Drug delivery ; Drug ; Targeted drug delivery ; Copolymer ; Drug carrier ; Chemistry ; Nanotechnology ; Materials science ; Polymer ; Combinatorial chemistry ; Organic chemistry ; Aqueous solution ; Pharmacology ; Medicine Nanoparticle-Based Drug Delivery ; Nanoplatforms for cancer theranostics ; Advanced Drug Delivery Systems
Authors: M.A. del Valle | Marta Ximenis | Xabier Lopez de Pariza | Julian M. W. Chan | Haritz Sardón
Source: Angewandte Chemie (article, 2022-06-14)
Field: Chemistry — Organic Chemistry

Spotting Trends in Organocatalyzed and Other Organomediated (De)polymerizations and Polymer Functionalizations Abstract Organocatalysis has evolved into an effective complement to metal‐ or enzyme‐based catalysis in polymerization, polymer functionalization, and depolymerization. The ease of removal and greater sustainability of organocatalysts relative to transition‐metal‐based ones has spurred development in specialty applications, e.g., medical devices, drug delivery, optoelectronics. Despite this, the use of organocatalysis and other organomediated reactions in polymer chemistry is still rapidly developing, and we envisage their rapidly growing application in nascent areas such as controlled radical polymerization, additive manufacturing, and chemical recycling in the coming years. In this Review, we describe ten trending areas where we anticipate paradigm shifts resulting from novel organocatalysts and other transition‐metal‐free conditions. We highlight opportunities and challenges and detail how new discoveries could lead to previously inaccessible functional materials and a potentially circular plastics economy. Organocatalysis ; Polymerization ; Depolymerization ; Nanotechnology ; Chemistry ; Polymer ; Polymer science ; Combinatorial chemistry ; Materials science ; Catalysis ; Organic chemistry ; Enantioselective synthesis Advanced Polymer Synthesis and Characterization ; biodegradable polymer synthesis and properties ; Carbon dioxide utilization in catalysis
Authors: Denis Dochain | Antoine Van Den Daelen | Aleš Stýskalík | Vít Vykoukal | Damien P. Debecker
Source: ChemRxiv (preprint, 2022-10-20)
Field: Materials Science — Materials Chemistry

Aerosol-assisted sol-gel synthesis of mesoporous Ag-Ta-SiO2 catalysts for the direct upgrading of ethanol to butadiene The Lebedev process, or the direct catalytic conversion of bioethanol to butadiene, offers an up-and-coming sustainable alternative to the petrochemical route toward this high-demand C4 hydrocarbon. Since the reaction mechanism involves a cascade of dehydrogenation, hydrogen transfer and dehydration steps, a bifunctional catalyst is required, combining both redox (for the dehydrogenation reaction) and acid (for hydrogen transfer and dehydration reactions) functionalities. Multi-step preparation methods are typically implemented to obtain tailored bifunctional catalysts, and a challenge is to balance the two functions to maximize the BD yield. Here, we disclose a straightforward, one-step, and continuous preparation of Ta-doped SiO2 loaded with Ag nanoparticles by coupling sol-gel chemistry with aerosol processing. Combining tantalum ethoxide, silver nitrate, hydrolysed tetraethyl orthosilicate and Pluronic F127 as templating agent in the aerosol process leads to mesoporous bifunctional catalysts featuring a specific surface area between 310–370 m2 g–1, a pore volume of ca. 0.5 mL g–1 and an average pore diameter of 5 nm. As attested by a variety of characterization techniques, the method leads to the homogeneous incorporation of highly dispersed tantalum species in the silica matrix, thereby creating the required acidic sites. These new catalysts have higher dehydration activity, as compared to the corresponding reference catalysts prepared by classical impregnation. Concomitantly, relatively small silver nanoparticles are stabilized (~15 nm). The relative Ta and Ag loading can be tuned easily. In the ethanol to butadiene reaction, these aerosol-made catalysts achieve a butadiene yield of ca. 25 % by optimizing the relative loadings of Ta and Ag, outcompeting the corresponding formulations prepared by impregnation. Bifunctional ; Catalysis ; Tetraethyl orthosilicate ; Dehydrogenation ; Mesoporous material ; Materials science ; Chemical engineering ; Chemistry ; Inorganic chemistry ; Organic chemistry Mesoporous Materials and Catalysis ; Catalysis for Biomass Conversion ; Supercapacitor Materials and Fabrication
Authors: Jian‐Fei Bai | Jianbo Tang | Xiaolong Gao | Zhi‐Jiang Jiang | Jia Chen | Zhanghua Gao
Source: ChemRxiv (preprint, 2022-01-11)
Field: Chemistry — Organic Chemistry

Transition Metal Catalyst Free Cross-Coupling Reaction of Tertiary Propargylic Alcohols with Hetero-Areneboronic Acids We report a perfluorophenylboronic acid catalyzed cross coupling reaction of tertiary propargylic alcohols and hetero-areneboronic acids for valuable benzo[b]thiophene and cyclopenta[a]indene derivates. This coupling reaction proceeds efficiently with a wide array of substrates scope in up to 89% yield and excellent regioselectivity. A significant advantage of our protocol is the transition metal catalyst free and mild conditions needed. This strategy provides direct and facile access to medicinally important benzo[b]thiophene and cyclopenta[a]indene scaffold containing a quaternary carbon center. Indene ; Regioselectivity ; Catalysis ; Chemistry ; Transition metal ; Thiophene ; Yield (engineering) ; Quaternary carbon ; Coupling reaction ; Combinatorial chemistry ; Tertiary alcohols ; Organic chemistry ; Materials science ; Enantioselective synthesis Catalytic Alkyne Reactions ; Catalytic Cross-Coupling Reactions ; Synthetic Organic Chemistry Methods
Authors: Robert R. A. Bolt | Sarah E. Raby‐Buck | Katharine Ingram | Jamie A. Leitch | Duncan L. Browne
Source: ChemRxiv (preprint, 2022-07-18)
Field: Chemistry — Organic Chemistry

Temperature-Controlled Mechanochemistry for the Nickel-Catalyzed Suzuki-Miyaura-Type Coupling of Aryl Sulfamates via Ball Milling and Twin-Screw Extrusion The use of temperature-controlled mechanochemistry to enable the mechanochemical nickel-catalyzed Suzuki-Miyaura coupling is herein described. Transitioning from a capricious room-temperature protocol, through to a heated, PID-controlled programmable jar heater manifold was required to deliver an efficient method for the coupling of aryl sulfamates (derived from ubiquitous phenols) and aryl boronic acid species. Furthermore, this process is conducted using a base-metal nickel catalyst, in the absence of bulk solvent, and in the absence of air/moisture sensitive reaction set-ups. This methodology is showcased through translation to large-scale twin-screw extrusion methodology enabling 200-fold scale increase, producing decagram quantities of C-C coupled material. Mechanochemistry ; Ball mill ; Catalysis ; Extrusion ; Aryl ; Nickel ; Materials science ; Chemical engineering ; Chemistry ; Metallurgy ; Organic chemistry ; Nanotechnology ; Engineering Catalytic Cross-Coupling Reactions ; Organoboron and organosilicon chemistry ; Crystallography and molecular interactions