jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Min Ying Tsang | Shun Tokuda | Po‐Chun Han | Zaoming Wang | Alexandre Legrand | Marina Kawano | Masahiko Tsujimoto | Yuki Ikeno | Kenji Urayama | Kevin C.‐W. Wu | Shuhei Furukawa
Source: ChemRxiv (preprint, 2021-11-02)
Field: Materials Science — Materials Chemistry

Controlled sequential assembly of metal-organic polyhedra into colloidal gels with high chemical complexity Assembling many chemical components into a material in a controlled manner is one of the biggest challenges in chemistry. Particularly porous materials with multivariate character within their scaffolds are expected to demonstrate synergistic properties. In this study, we show a synthetic strategy to construct porous networks with multiple chemical components. By taking advantage of the hierarchical nature of a colloidal system based on metal-organic polyhedra (MOPs), we developed a two-step assembly process to form colloidal networks; assembling of MOPs with the organic linker to the formation of MOP network as a colloidal particle, followed by further connecting colloids by additional crosslinkers, leading to colloidal networks. This synthetic process allows not only for the use of different organic linkers for connecting MOPs and colloidal particles, respectively, but for assembling different colloidal particles formed by various MOPs. The proof-of-concept of this tuneable multivariate colloidal gel system offers an alternative to developing functional porous soft materials with multifunction. Colloid ; Polyhedron ; Nanotechnology ; Porosity ; Linker ; Particle (ecology) ; Materials science ; Porous medium ; Well-defined ; Colloidal particle ; Process (computing) ; Metal-organic framework ; Chemistry ; Chemical engineering ; Computer science ; Organic chemistry ; Adsorption ; Engineering ; Mathematics Pickering emulsions and particle stabilization ; Advanced Polymer Synthesis and Characterization ; Hydrogels: synthesis, properties, applications
Authors: Niels R. M. Reintjens | Liubov Yakovlieva | Nittert Marinus | Johan Hekelaar | Francesca Nuti | Anna Maria Papini | Martin D. Witte | Adriaan J. Minnaard | Marthe T. C. Walvoort
Source: ChemRxiv (preprint, 2021-03-18)
Field: Chemistry — Organic Chemistry

Site-Selective Palladium-Catalyzed Oxidation of Glucose in Glycopeptides Here we report a novel method of site-selective oxidation of glucose moieties on individual glycopeptides and on a mixture of tryptic glycopeptides. The organometallic catalyst [(neocuproine)PdOAc]2OTf2, that was previously shown to perform regioselective C3-oxidation of glucosides, was used in the scope of this work. The selectivity of the catalyst towards glucose and the sensitivity of specific amino acid residues to oxidation was explored by screening a select panel of glycopeptides in the oxidation reactions. We reveal that glucosylated peptides are more readily oxidized compared to galactosylated peptides, and Thr/Ser-oxidation is a concomitant side-reaction. The oxidation methodology was also applied to the complex mixture of tryptic glucopeptides that was generated from the fragment of Haemophilus influenzae adhesin glycoprotein. The resulting keto-group of the glucose was further transformed into an oxime functionality, which allows introduction of various groups of interest. The methodology outlined in this work will allow to perfrom late-stage modification of glucopeptides as well as selective oxidation and functionalization of tryptic glucopeptides for proteomics analysis. Chemistry ; Glycopeptide ; Regioselectivity ; Combinatorial chemistry ; Catalysis ; Alcohol oxidation ; Oxime ; Selectivity ; Organic chemistry ; Biochemistry Carbohydrate Chemistry and Synthesis ; Glycosylation and Glycoproteins Research ; Chemical Synthesis and Analysis
Authors: Paul Chatelain
Source: SPIRE - Sciences Po Institutional REpository (preprint, 2021-05-03)
Field: Chemistry — Organic Chemistry

The Suzuki cross-coupling of aryl sulfones and sulfonyl fluorides The Suzuki coupling is one of the preferred methods for the formation of carbon-carbon bonds. Since its discovery in 1979, much effort has been made to extend its scope to new, alternative electrophiles. This thesis describes the coupling of robust sulfur-based electrophiles: sulfones and sulfonyl fluorides. These functional groups present favorable properties that are not seen in electrophiles previously used in this reaction. Sulfones can be used as a directing group on arenes for selective ortho- meta- and para-functionalization and have a reactivity complementary to existing electrophiles, permitting the straightforward synthesis of terphenyls from polysubstituted arenes. Sulfonyl fluorides are mainly used in SuFEx chemistry, a branch of click chemistry used to form S–N, S–O and S–C bonds. The present method forms C–C bonds from sulfonyl fluorides, turning this functional group into a branching point for divergent synthetic schemes. Sulfonyl ; Aryl ; Sulfone ; Coupling (piping) ; Chemistry ; Materials science ; Polymer chemistry ; Organic chemistry ; Composite material Sulfur-Based Synthesis Techniques ; Catalytic Cross-Coupling Reactions
Authors: Sebastian B. Beil | Max von Delius
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2021-04-01)
Field: Chemistry — Organic Chemistry

Supramolecular Approaches for Taming the Chemo- and Regiochemistry of C60 Addition Reactions The chemo- and regioselective functionalization of fullerenes is a long-standing problem of organic synthesis. Over the past five years, this fundamental challenge has gained technological relevance, because studies on single bis-adduct isomers in new-generation solar cells have demonstrated that the widespread use of isomer mixtures leads to suboptimal power conversion efficiencies. Herein, we review recent work on supramolecular approaches for achieving chemo- and regioselective syntheses of multiply functionalized derivatives of C60. Regioselectivity ; Supramolecular chemistry ; Chemistry ; Fullerene ; Combinatorial chemistry ; Organic chemistry ; Molecule ; Catalysis Fullerene Chemistry and Applications ; Molecular Junctions and Nanostructures ; Chemistry and Chemical Engineering
Authors: Shi‐Qiang Wang | Shaza Darwish | Debobroto Sensharma | Michael J. Zaworotko
Source: ChemRxiv (preprint, 2021-11-28)
Field: Chemistry — Inorganic Chemistry

Tuning the switching pressure in square lattice coordination networks by metal cation substitution Coordination networks that undergo guest-induced switching between “closed” nonporous and “open” porous phases are of increasing interest as the resulting stepped sorption isotherms can offer exceptional working capacities for gas storage applications. For practical utility, the gate ad/desorption pressures (Pga/Pgd) must lie between the storage (Pst) and delivery (Pde) pressures and there must be fast switching kinetics. Herein we study the effect of metal cation substitution on the switching pressure of a family of square lattice coordination networks [M(4,4’-bipyridine)2(NCS)]n (sql-1-M-NCS, M = Fe, Co and Ni) with respect to CO2 sorption. The Clausius-Clapeyron equation was used to correlate Pga/Pgd and temperature. At 298 K, Pga/Pgd values were found to vary from 31.6/26.7 bar (M = Fe) to 26.7/20.9 bar (M = Co) and 18.5/14.6 bar (M = Ni). The switching event occurs within 10 minutes as verified by dynamic CO2 sorption tests. In addition, in situ synchrotron PXRD and molecular simulations provided structural insight into the observed switching event, which we attribute to layer expansion of sql-1-M-NCS via intercalation and inclusion of CO2 molecules. This study could pave the way for rational control over Pga/Pgd in switching adsorbent layered materials and enhance their potential utility in gas storage applications. Sorption ; Desorption ; Intercalation (chemistry) ; Materials science ; Bar (unit) ; Synchrotron ; Metal ; Adsorption ; Chemical engineering ; Chemistry ; Inorganic chemistry ; Physical chemistry ; Metallurgy ; Physics Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Magnetism in coordination complexes
Authors: Matteo Costantini | Abraham Mendoza
Source:  (preprint, 2021-06-22)
Field: Chemistry — Organic Chemistry

Modular Enantioselective Synthesis of cis-Cyclopropanes through Redox-Active Carbene Transfer and Stereoselective Photo-Decarboxylation Chiral cis-cyclopropanes are strained rigid analogs of alkyl chains, whose study and application is still limited by their difficult synthesis. A modular approach for the synthesis of this challenging structures from abundant olefins is enabled by the discovery of the electron donor-acceptor (EDA) interaction between 2-substituted benzothiazolines and N-hydroxyphtalimide esters. These complexes are activated by visible light without photocatalysts. In this system, the benzothiazoline reagent plays a triple role as photoreductant, stereoselective hydrogen atom donor and Brønsted acid. Beyond the enantioselective synthesis of cis-cyclopropanes, these results introduce benzothiazolines as accessible and easily tunable self-sensitized photoreductants. Enantioselective synthesis ; Chemistry ; Decarboxylation ; Combinatorial chemistry ; Stereoselectivity ; Carbene ; Stereochemistry ; Alkyl ; Catalysis ; Organic chemistry Cyclopropane Reaction Mechanisms ; Catalytic C–H Functionalization Methods ; Radical Photochemical Reactions
Authors: Moritz Pott | Matthias Tinzl | Takahiro Hayashi | Yusuke Ota | Daniel L. Dunkelmann | Peer R. E. Mittl | Donald Hilvert
Source: ChemRxiv (preprint, 2021-01-17)
Field: Chemistry — Organic Chemistry

Noncanonical Heme Ligands Steer Carbene Transfer Reactivity in an Artificial Metalloprotein Changing the primary metal coordination sphere is a powerful strategy for modulating metalloprotein properties. Taking advantage of this approach, we have replaced the proximal histidine ligand in myoglobin with the histidine analogues Nd-methylhistidine (NMH), 5‑thiazoylalanine (5ThzA), 4-thiazoylalanine (4ThzA) and 3-(3-thienyl)alanine (3ThiA) by amber stop codon suppression using engineered pyrrolysyl-tRNA synthetases, including two newly evolved enzymes. In addition to tuning the heme redox potential over a >200 mV range, these noncanonical ligands modulate the protein’s promiscuous carbene transfer activity with ethyl diazoacetate. Myoglobin variants with increased reduction potentials (NMH and 5ThzA) proved superior for cyclopropanation and N-H insertion, especially under aerobic conditions, and could even promote these reactions in the absence of reducing agent. In contrast, the variants with the lowest Eo values (4ThzA and 3ThiA) exhibit comparatively high S-H insertion activity even though the respective histidine surrogates do not coordinate the heme iron. Given the important functional roles played by histidine in many enzymes, these genetically encoded histidine analogues represent valuable tools for probing mechanism and enabling new chemistries in metalloproteins. Histidine ; Metalloprotein ; Myoglobin ; Chemistry ; Heme ; Ligand (biochemistry) ; Stereochemistry ; Carbene ; Hemeprotein ; Alanine ; Biochemistry ; Enzyme ; Combinatorial chemistry ; Amino acid ; Catalysis Cyclopropane Reaction Mechanisms ; Hemoglobin structure and function ; Metalloenzymes and iron-sulfur proteins
Authors: Emőke Rédai | Orsolya E. Kovács | Zoltán Szabó | Attila Gergely | Paula Antonoaea | Nicoleta Todoran | Robert Vlad | Adriana Ciurba | Gabriella Dónáth-Nagy | Emese Sipos
Source: Acta Poloniae Pharmaceutica - Drug Research (article, 2021-10-25)
Field: Materials Science — Biomaterials

Fluoxetin containing PVP-based electrospun nanofibers Fluoxetine hydrochloride is a selective serotonin reuptake inhibitor used in the treatment of depression and obsessive-compulsive disorder. The aim of this study is represented by developing fluoxetineloaded polyvinylpyrrolidone-based fibers by uniaxial electrospinning. The effect of flow rate and needle to collector distance on fiber morphology and performance was monitored at 20 kV constant voltage. Fiber diameters, determined by scanning electron microscopy (SEM) varied between 462-833 nm. The drug content of the prepared electrospun fiber mats was monitored by UV spectroscopy and good correlations were found between the obtained and theoretical values. Tracking the changes in solid-state upon electrospinning were carried out by differential scanning calorimetry (DSC). The obtained DSC curves indicated the amorphization of crystalline fluoxetine during fiber formation. The release of the active ingredient happens in a burst manner and after five minutes dissolution of the fluoxetine is complete. The results presented herein could pave the way for a buccal, easy-to-use formulation of the antidepressant drug with greater patient compliance. Nanofiber ; Electrospinning ; Materials science ; Nanotechnology ; Chemical engineering ; Composite material ; Polymer ; Engineering Electrospun Nanofibers in Biomedical Applications
Authors: Marco Beaumont | Caio G. Otoni | Bruno D. Mattos | Tetyana V. Koso | Roozbeh Abidnejad | Bin Zhao | Anett Kondor | Alistair W. T. King | Orlando J. Rojas
Source:  (preprint, 2021-06-28)
Field: Materials Science — Biomaterials

Regioselective and Water-Promoted Surface Esterification of Never-Dried Cellulose Fibers Towards Nanofibers with Adjustable Surface Energy A new regioselective route is introduced for surface modification of biological colloids in the presence of water. Taking the case of cellulose nanofibers (CNFs), we demonstrate a site-specific (93% selective) reaction between the primary surface hydroxyl groups (C6-OH) of cellulose and acyl imidazoles. Cellulose nanofibers bearing C6-acetyl and C6-iso-butyl groups, with a degree of substitution of up to 1 mmol·g–1 are obtained upon surface esterification, affording CNFs of adjustable surface energy. The morphological and structural features of the nanofibers remain largely unaffected, but the regioselective surface reactions enable tailoring the interfacial interactions, as demonstrated in oil/water Pickering emulsions. Our method precludes the need for drying or exchange with organic solvents for surface esterification, otherwise needed in the synthesis of esterified colloids and polysaccharides. Moreover, the method is well suited for application at high-solid content, opening the possibility for implementation in reactive extrusion and compounding. The proposed acylation is introduced as a sustainable approach that benefits from the presence of water and affords a high chemical substitution selectivity. Regioselectivity ; Cellulose ; Nanofiber ; Surface modification ; Acylation ; Chemical engineering ; Organic chemistry ; Surface energy ; Chemistry ; Colloid ; Chemical modification ; Polymer chemistry ; Materials science ; Catalysis ; Nanotechnology ; Composite material Advanced Cellulose Research Studies ; Pickering emulsions and particle stabilization ; Electrospun Nanofibers in Biomedical Applications
Authors: Min Cao | Hai Deng
Source: Journal of Photopolymer Science and Technology (article, 2021-06-11)
Field: Materials Science — Materials Chemistry

Synthesis of Ordered Fluorinated BCPs with One Block Composed of Random Copolymer A series of fluorinated block copolymers (BCPs), with one block composed of random vinyl copolymers were synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization. Despite of the hugely different properties of the two monomers in the random copolymer block, highly ordered lamellar structure with sub-10 nm resolution was observed by SAXS after 160 ºC annealing for 24 h. Each micro-domain consisted of two uniformly distributed monomers, with a low Tg down to 24 ºC. Copolymer ; Materials science ; Raft ; Lamellar structure ; Monomer ; Chain transfer ; Small-angle X-ray scattering ; Polymer chemistry ; Polymerization ; Annealing (glass) ; Chemical engineering ; Scattering ; Polymer ; Radical polymerization ; Composite material Block Copolymer Self-Assembly ; Advanced Polymer Synthesis and Characterization ; Machine Learning in Materials Science
Authors: Zhenjing Jiang | Shibin Qi | Chengwei Gao | Xiangyu Li | Yanfei Zhang | Yuanzheng Yue
Source: ChemRxiv (preprint, 2021-06-22)
Field: Materials Science — Polymers and Plastics

Water Boosts the Performances of Glass Anodes for Lithium-Ion Batteries Owing to their disordered open network structure, oxide glasses are a promising class of anode materials for Lithium-Ion Batteries (LIBs). However, the relatively low capacities of glass anodes severely limit their practical application for large energy storage devices. Here we show an unconventional novel approach, which significantly enhances the electrochemical performances of glass anodes for LIBs. Specifically, we incorporated water into an electrochemically active glass system, i.e., TeO2-V2O5-P2O5 (TVP) glass powder via humidity treatment, and then mix the hydrated powder with additives to fabricate anode. The optimized humidity treatment led to the structural modification of the TVP glass powder, which boosted the capacity of the TVP anode by more than 200%, and maintained the reversible capacity for extra-long cycles. The boosted performances are associated both with the depolymerized structural network for Li+ diffusion and with the hydration-induced nanocrystals. These findings help develop superior glass electrodes in an economically effective way. Anode ; Materials science ; Lithium (medication) ; Electrochemistry ; Glass recycling ; Diffusion ; Ion ; Chemical engineering ; Humidity ; Electrode ; Composite material ; Chemistry Transition Metal Oxide Nanomaterials ; Advancements in Battery Materials ; Ga2O3 and related materials
Authors: Yung Yi Cheng | Chin Yu Liu | Cheng Tung Lin | Li Huang | Sheng Chu Kuo | Kuo Hsiung Lee | Chi Hung Huang
Source: UNC Libraries (article, 2021-07-02)
Field: Chemistry — Organic Chemistry

Mechanistic Studies on Regioselective Dephosphorylation of Phosphate Prodrugs during a Facile Synthesis of Antitumor Phosphorylated 2-Phenyl-6,7-methylenedioxy-1H-quinolin-4-one Phosphorylation of 2-(3-hydroxy-5-methoxyphenyl)-6,7-methylenedioxy-1 H-quinolin-4-one ( 1) afforded diphosphate 2. We found that, upon treatment with methanol under mild conditions, 2 can undergo facile and highly regioselective dephosphorylation to give the monophosphate 3, with a phosphate group remaining on the phenyl ring. The details of the dephosphorylation process were postulated and then probed by LC-MS and HPLC analyses. Furthermore, as a preliminary study, the water soluble monophosphate prodrug 4 was tested for antitumor activity against a MCF-7 xenograft nude mice model. Regioselectivity ; Methylenedioxy ; Dephosphorylation ; Prodrug ; Chemistry ; Phosphate ; Phosphorylation ; Stereochemistry ; Combinatorial chemistry ; Organic chemistry ; Biochemistry ; Catalysis ; Phosphatase Organophosphorus compounds synthesis ; Phosphorus compounds and reactions ; Synthesis and Reactivity of Sulfur-Containing Compounds
Authors: Manasvi Kumar
Source: Gutenberg Open Science (article, 2021-01-01)
Field: Materials Science — Polymers and Plastics

Role of Interface in Ferroelectric Polymer based Memory Diodes Organic electronic devices have the potential to alter our everyday lives with their unique characteristics, such as flexibility, stretchability and low-cost. Among the envisioned devices are non-volatile memories for applications in contactless identification transponders and smart labels. This thesis investigates the operation of such a memory device that uses phase-separated blends of a ferroelectric and semiconducting polymer in a diode configuration. The blend film is composed of columns of semiconductor domains that run continuously through the ferroelectric polymer matrix from the bottom to the top electrode. Polarization of the ferroelectric polymer upon application of appropriate electric fields (greater than coercive field), leads to the modulation of the injection barrier at the metal-semiconductor contact.28 The diode exhibits a bistable rectifying current-voltage characteristic. Numerical models have been proposed to describe the device physics of the memory diodes. This thesis provides a potential solution for ambient processing and operation of the memory diodes along with providing the experimental proof of the proposed operation mechanism of the memory diodes. Moreover, current driven memory devices have been demonstrated. Based on tuneable injection barrier, MEMOLED, a light emitting diode with an inherent ferroelectric switch, has been demonstrated. The advantage of a built-in rectifying switch in the construction of the MEMOLED is to present a non-emissive OFF state and an emissive non-volatile ON state. However, the current efficiency is low as compared to that of pristine semiconductor polymer based OLEDs, and the retention time of the emissive state is short. Here, it is shown that charge trapping in the ferroelectric phase could be a possible reason for the lower performance of the MEMOLEDs. Finally, organic ferroelectric tunnel junctions, based on ultra-thin film of P(VDF-TrFE), with colossal tunneling electroresistance are demonstrated. Materials science ; Interface (matter) ; Ferroelectricity ; Diode ; Optoelectronics ; Computer science ; Composite material ; Dielectric ; Wetting Conducting polymers and applications ; Analytical Chemistry and Sensors ; Phase-change materials and chalcogenides
Authors: Aiting Kai | Benjamin D. Egleston | Marc A. Little | Rob Clowes | Michael E. Briggs | Andrew I. Cooper | Rebecca L. Greenaway
Source: ChemRxiv (preprint, 2021-06-03)
Field: Materials Science — Materials Chemistry

Modular Type III Porous Liquids based on Porous Organic Cage Microparticles The dispersion of particulate porous solids in size-excluded liquids has emerged as a method to create Type III porous liquids, mostly using insoluble microporous materials such as metal-organic frameworks (MOFs) and zeolites. Here, we present the first examples of Type III porous liquids based on porous organic cages (POCs). By exploiting the solution processability of the POCs, racemic and quasiracemic cage microparticles were formed by chiral recognition. Dispersion of these porous microparticles in a range of size-excluded liquids, including oils and ionic liquids, formed stable POC-based Type III porous liquids. The flexible pairing between the solid POC particles and a carrier liquid allows the formation of a range of compositions, pore sizes, and other physicochemical properties to suit different applications and operating conditions. For example, we show that it is possible to produce porous liquids with relatively low viscosities (7-14 mpa∙s) or high thermal stability (325 °C). A 12.5 wt. % Type III porous liquid comprising racemic POC microparticles and an ionic liquid, [BPy][NTf2], shows a CO2 working capacity (104.30 μmol/gL) that is significantly higher than the neat ionic liquid (37.27 μmol/gL) between 25 °C and 100 °C. This liquid is colloidally stable and can be recycled at least 10 times without loss of CO2 capacity. Porosity ; Microporous material ; Ionic liquid ; Chemical engineering ; Dispersion (optics) ; Materials science ; Porous medium ; Thermal stability ; Chemistry ; Organic chemistry ; Composite material ; Catalysis Covalent Organic Framework Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Supramolecular Chemistry and Complexes