jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: William I. Nicholson | Fabien Barreteau | Jamie A. Leitch | Riley Payne | Ian Priestley | Edouard Godineau | Claudio Battilocchio | Duncan L. Browne
Source: ChemRxiv (preprint, 2021-05-10)
Field: Chemistry — Physical and Theoretical Chemistry

Direct Amidation of Esters via Ball Milling &lt;p&gt;&lt;i&gt;The direct mechanochemical amidation of esters – enabled by ball-milling – is herein described. The operationally simple procedure requires inputs of ester, amine, and sub-stoichiometric KOtBu and is applicable to a preparation of a large and diverse library of 78 amide structures with modest to excellent efficiency. Heteroaromatic and heterocyclic components are specifically shown to be amenable to this mechanochemical protocol. This direct synthesis platform has been applied to the synthesis of API’s, agrochemicals, and its ability to deliver gram-scale synthesis of active pharmaceuticals and building blocks is demonstrated, all in the absence of a reaction solvent.&lt;/i&gt;&lt;/p&gt; Ball mill ; Stoichiometry ; Amine gas treating ; Amide ; Combinatorial chemistry ; Chemistry ; Solvent ; Organic chemistry ; Chemical engineering ; Engineering Crystallography and molecular interactions ; Venomous Animal Envenomation and Studies ; Plant-based Medicinal Research
Authors: Dragana Jovanovic | Jovana Stanojkovic | Dzeneta Halilovic | Rejhana Kolašinac | Tatjana J. Kop | Mira S. Bjelaković | Dragana R. Milić
Source: Journal of the Serbian Chemical Society (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

Fulleropyrrolidines with orthogonally flexible substituents - synthesis and electrochemical properties A large series of disubstituted fulleropyrrolidines was synthesized and analyzed by cyclic voltammetry. The three main groups of target compounds differ by a flexible N-chain, while their further diversity was achieved by the introduction of various rigid, aryl substituents at the pyrrolidine carbon. Some dialkyl analogues were also designed for comparison, A standard [3+2]- cycloaddition of in situ generated azomethine ylides to C60 afforded a variety of disubstituted fulleropyrrolidines. Furthermore, a set of dumbbell-shaped di(fulleropyrrolidine) derivatives containing rigid fumaryl or isophthaloyl diamide platform was prepared with the aim of investigating a long-range effect of the second fulleropyrrolidine moiety on their electrochemical properties. All compounds were fully characterized by comparative analysis of spectral data, while examination of electrochemical properties was performed on representative samples, distinguished by main structural subunits. All compounds expressed quite similar electron-accepting ability, lower than C60, but higher in comparison to structurally similar N-methylfulleropyrrolidine. Electrochemistry ; Chemistry ; Pyrrolidine ; Moiety ; Cycloaddition ; Cyclic voltammetry ; Combinatorial chemistry ; Stereochemistry ; Carbon fibers ; Polymer chemistry ; Organic chemistry ; Materials science ; Electrode ; Physical chemistry ; Composite number Fullerene Chemistry and Applications ; Diamond and Carbon-based Materials Research
Authors: Varshini J. Kumar | Jian‐Zhong Wu | Martyna Judd | Élodie Rousset | Marcus Korb | Stephen A. Moggach | Nicholas J. Cox | Paul J. Low
Source: ChemRxiv (preprint, 2021-11-16)
Field: Chemistry — Physical and Theoretical Chemistry

The syntheses, structures and spectroelectrochemical properties of 6-oxo-verdazyl derivatives bearing surface anchoring groups A series of 6-oxo verdazyl radicals functionalised at the 1- and 5-positions by methyl, thiomethyl and iodo groups were synthesised using conventional strategies. Facile Sonogashira cross-coupling reactions of terminal alkynes with the diiodo analogue were used for synthetic elaboration of the verdazyl core structure with π-conjugated ethynyl groups. The radicals were characterised by EPR spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry and optical spectroscopy. The chemically and electrochemically reversible oxidation and reduction of these radicals within a convenient redox window permitted further studies on the closed-shell cationic and anionic forms using spectroelectrochemical methods, supported by (TD-)DFT calculations. Sonogashira coupling ; Radical ; Chemistry ; Cationic polymerization ; Cyclic voltammetry ; Conjugated system ; Electron paramagnetic resonance ; Single crystal ; Photochemistry ; Spectroscopy ; Polymer chemistry ; Crystallography ; Electrochemistry ; Organic chemistry ; Palladium ; Catalysis ; Polymer ; Electrode ; Nuclear magnetic resonance Photochemistry and Electron Transfer Studies ; Oxidative Organic Chemistry Reactions ; Radical Photochemical Reactions
Authors: Sayak Subhra Panda | John D. Tovar
Source: Organic Materials (article, 2021-04-01)
Field: Materials Science — Biomaterials

Aqueous Self-Assembly of Peptide–Diketopyrrolopyrrole Conjugates with Variation of N-Alkyl Side Chain and π-Core Lengths Peptidic sequences when conjugated to π-electronic groups form self-assembled networks of π-electron pathways. These materials hold promise for bio-interfacing charge transporting applications because of their aqueous processability and compatibility. In this work, we incorporated diketopyrrolopyrrole (DPP), a well-established π-core for organic electronic applications, within the peptidic sequence. We embedded different numbers of thiophene rings (2 and 3) on both sides of the DPP to alter the length of the π-cores. We also varied the length of the N-alkyl side chains (methyl, butyl, hexyl) attached to the DPP core. These variations allowed us to explicitly study the effect of π-core and N-alkyl side-chain length on photophysical properties and morphology of the resulting nanomaterials. All of these molecules formed H-type aggregates in the assembled state. Longer π-cores have relatively red-shifted absorption maxima, whereas the N-alkyl variation did not present significant photophysical changes. Alkyl ; Side chain ; Conjugated system ; Aqueous solution ; Conjugate ; Molecule ; Polymer ; Materials science ; Chemistry ; Self-assembly ; Organic chemistry Supramolecular Self-Assembly in Materials ; Polydiacetylene-based materials and applications ; Luminescence and Fluorescent Materials
Authors: Elena Álvarez | María Romero‐Fernández | Diego Iglesias | Raúl Martínez‐Cuenca | Obinna Okafor | Astrid E. Delorme | Alex Conradie | Pedro Lozano | Peter Licence | Ruth Goodridge | Sergio Chiva | Francesca Paradisi | Darren A. Walsh | Víctor Sans
Source: ChemRxiv (preprint, 2021-10-05)
Field: Materials Science — Materials Chemistry

Electrochemical oscillatory baffled reactors fabricated with additive manufacturing for efficient continuous-flow oxidations Electrochemical continuous-flow reactors offer a great opportunity for enhanced and sustainable chemical syntheses. However, mass transport limitations typically hinder their performance, which requires a very short distance between electrodes for efficient performance. This imposes design limitations on the systems, in particular to integrate electrochemistry with other enabling technologies. Here we present a novel application of electrochemical continuous-flow oscillatory baffled reactors (ECOBRs) that combines advanced mixing features with electrochemical transformations to enable efficient electrochemical oxidations under continuous-flow at millimeter distance between electrodes. Different Additive Manufacturing techniques have been employed to rapidly fabricate the reactors. The electrochemical oxidation of NADH, a very sensitive substrate key for the regeneration of enzymes in biocatalytic transformations, has been employed as a benchmark reaction. The oscillatory conditions improved bulk mixing, facilitating the contact of reagents to the electrodes. Under oscillatory conditions, the ECOBR demonstrated higher effectivity and productivity than a parallel plate commercial flow cell. Electrochemistry ; Continuous flow ; Flow (mathematics) ; Materials science ; Chemical engineering ; Electrode ; Chemistry ; Mechanics ; Engineering ; Physics Anodic Oxide Films and Nanostructures ; Electrochemical Analysis and Applications ; Electrocatalysts for Energy Conversion
Authors: Joy Omini | Izabela Wojciechowska | Aleksandra Skirycz | Hideaki Moriyama | Toshihiro Obata
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2021-08-06)
Field: Materials Science — Materials Chemistry

Association of the malate dehydrogenase-citrate synthase metabolon is modulated by intermediates of the Krebs tricarboxylic acid cycle ABSTRACT Mitochondrial malate dehydrogenase (MDH)-citrate synthase (CS) multi-enzyme complex is a part of the Krebs tricarboxylic acid (TCA) cycle ‘metabolon’ which is enzyme machinery catalyzing sequential reactions without diffusion of reaction intermediates into a bulk matrix. This complex is assumed to be a dynamic structure involved in the regulation of the cycle by enhancing metabolic flux. Microscale Thermophoresis analysis of the porcine heart MDH-CS complex revealed that substrates of the MDH and CS reactions, NAD + and acetyl-CoA, enhance complex association while products of the reactions, NADH and citrate, weaken the affinity of the complex. Oxaloacetate enhanced the interaction only when it was presented together with acetyl-CoA. Structural modeling using published CS structures suggested that the binding of these substrates can stabilize the closed format of CS which favors the MDH-CS association. Two other TCA cycle intermediates, ATP, and low pH also enhanced the association of the complex. These results suggest that dynamic formation of the MDH-CS multi-enzyme complex is modulated by metabolic factors responding to respiratory metabolism, and it may function in the feedback regulation of the cycle and adjacent metabolic pathways. Citric acid cycle ; Citrate synthase ; Malate dehydrogenase ; Tricarboxylic acid ; Biochemistry ; NAD+ kinase ; Enzyme ; Metabolism ; Metabolic pathway ; Flux (metallurgy) ; Chemistry ; Catalytic cycle ; Biology Enzyme Structure and Function ; Metabolomics and Mass Spectrometry Studies ; Metabolism and Genetic Disorders
Authors: V.S. Oliveira | Gilberto S. Falk | Dachamir Hotza | Sergio Yesid Gómez González
Source: International Journal of Ceramic Engineering & Science (article, 2021-09-09)
Field: Materials Science — Materials Chemistry

Ultrafast reaction‐sintering of grain size‐controlled titanium niobate from TiO<sub>2</sub> and Nb<sub>2</sub>O<sub>5</sub> Abstract TiNb 2 O 7 is a promising alternative to graphite anodes currently employed in lithium‐ion batteries. The material offers a high specific capacity, good cycling stability, and better safety characteristics. The solid‐state reaction between TiO 2 and Nb 2 O 5 is the most straightforward synthesis route to prepare TiNb 2 O 7 . It has only been documented so far to be conducted at long periods of sintering time (&gt;10 h). In this work, we propose a fast‐firing approach to the solid‐state synthesis, which yields TiNb 2 O 7 in less than 2 min of furnace holding time, starting from tape‐cast titania ( d 50 = 0.26 μm) and niobia ( d 50 = 0.967 μm) green compacts. Besides significantly reducing processing time, fast‐firing enabled the hindering of grain growth, producing a material with grain size ∼0.5 μm (holding time of 2 min) and ∼1 μm (5–10 min). Materials science ; Grain size ; Sintering ; Graphite ; Solid-state ; Chemical engineering ; Grain growth ; Titanium ; Metallurgy ; Anode ; Nanotechnology ; Cycling ; Mineralogy ; Engineering physics ; Electrode ; Chemistry Ferroelectric and Piezoelectric Materials ; Advanced ceramic materials synthesis ; Advancements in Battery Materials
Authors: Cameron G. Copeland
Source: Digital Commons - USU (Utah State University) (article, 2021-10-08)
Field: Materials Science — Biomaterials

Production of Synthetic Spider Silk Fibers Orb-weaving spiders produce six different types of silks, each with unique mechanical properties. The mechanical properties of many of these silks, in particular the dragline silk, are of interest for various biomedical applications. Spider silk does not elicit an immune response, making it an ideal material for several applications in the medical field. However, spiders cannot be farmed for their silk as they are cannibalistic and territorial. The most reasonable alternative for producing spider silk fibers is to utilize genetic engineering to produce the proteins in a foreign host and then spin fibers from the synthetic protein. Spider silk-like proteins have been expressed in transgenic goats on a scale sufficient to spin synthetic fibers. To spin it, the protein is dissolved in a solvent to create a viscous spin dope. This spin dope is extruded into a coagulation bath where it forms a fiber. Fibers spun in this manner have poor mechanical properties and are water soluble, unlike natural spider silk. By applying a post-spin draw, the mechanical properties of the fibers improve and they are no longer water soluble. This increase occurs because β-sheets, important secondary structures, form and begin to align parallel to the fiber axis. In previous work, post-spin draw has been applied by hand to the fibers after initial spinning. This is not a viable method for the commercial production of synthetic spider silk. The first aim of this research was to design, test, and optimize a mechanical system that can create consistent, synthetic spider silk fibers. The second aim of this research was to discover how parameters such as solvents, temperature, spinning speed, additives, and post-spin draw, among other variables, affect the properties of synthetic spider-silk proteins purified from goat milk. As part of this research, a mechanical system that can perform these treatments while the fiber is being made was designed, built and tested. This system was built with the intent to inform the creation of a process for the creation of a synthetic on an industrial level. Spider silk ; Spider ; SILK ; Production (economics) ; Synthetic fiber ; Fiber ; Biology ; Zoology ; Materials science ; Economics ; Composite material Silk-based biomaterials and applications ; Silkworms and Sericulture Research ; Phytochemical compounds biological activities
Authors: Stephanie G. E. Amos | Diana Cavalli | Franck Le Vaillant | Jérôme Waser
Source: ChemRxiv (preprint, 2021-07-09)
Field: Chemistry — Organic Chemistry

From Photoredox Catalysis to the Direct Excitation ofEthynylBenziodoXolones: Accessing Alkynylated QuaternaryCarbons from Alcohols via Oxalates EthynylBenziodoXolones (EBXs) are commonly used as radical traps in photocatalytic alkynylations. Herein, we report their application in two complementary deoxygenation strategies allowing the synthesis of valuable alkynylated all-carbon quaternary centers from tertiary alcohols via stable oxalate salts. Our first approach involves a photocatalytic process using 4CzIPN as an organic dye to promote oxidative degradation of the oxalate and EBXs to trap the formed radical. In our second approach, we demonstrate the direct photoexcitation of an EBX, which then acts as both oxidant and radical trap, alleviating the need for a photocatalyst in several EBX-mediated alkynylation processes. Photocatalysis ; Chemistry ; Deoxygenation ; Oxalate ; Photoredox catalysis ; Photoexcitation ; Photochemistry ; Catalysis ; Radical ; Organic chemistry ; Excitation Radical Photochemical Reactions ; Sulfur-Based Synthesis Techniques ; Catalytic C–H Functionalization Methods
Authors: Jaideep B. Bharate | Jörgen Ådén | Anna L. Gharibyan | Dan E. Adolfsson | Sanduni Wasana Jayaweera | Pardeep Singh | Katarina Vielfort | Mohit Tyagi | Mari Bonde | Sven Bergström | Anders Olofsson | Fredrik Almqvist
Source: Organic & Biomolecular Chemistry (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>-mediated coupling of 6-amino-7-aminomethyl-thiazolino-pyridones with aldehydes to construct amyloid affecting pyrimidine-fused thiazolino-2-pyridones We herein present the synthesis of diversely functionalized pyrimidine fused thiazolino-2-pyridones <i>via</i> K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>-mediated oxidative coupling of 6-amino-7-(aminomethyl)-thiazolino-2-pyridones with aldehydes. The developed protocol is mild, has wide substrate scope, and does not require transition metal catalyst or base. Some of the synthesized compounds have an ability to inhibit the formation of Amyloid-β fibrils associated with Alzheimer's disease, while others bind to mature amyloid-β and α-synuclein fibrils. Chemistry ; Pyrimidine ; Substrate (aquarium) ; Catalysis ; Combinatorial chemistry ; Coupling (piping) ; Fibril ; Amyloid fibril ; Stereochemistry ; Amyloid β ; Biochemistry ; Disease Synthesis and biological activity ; Synthesis and Reactivity of Heterocycles ; Catalytic C–H Functionalization Methods
Authors: Yoshiaki Maeda | Kahori Watanabe | Ryosuke Kobayashi | Tomoko Yoshino | Chris Bowler | Mitsufumi Matsumoto | Tsuyoshi Tanaka
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2021-11-11)
Field: Materials Science — Biomaterials

Chromosome scale assembly of allopolyploid genome of the diatom <i>Fistulifera solaris</i> Abstract Microalgae including diatoms are of interest for environmentally-friendly manufacturing such as biofuel production. However, only a very few of their genomes have been elucidated owing to their diversified and complex evolutionary history. The genome of the marine oleaginous diatom Fistulifera solaris , an allopolyploid diatom possessing two subgenomes, has been analyzed previously by pyrosequencing. However, many unsolved regions and unconnected scaffolds remained. Here we report the entire chromosomal structure of the genome of F. solaris strain JPCC DA0580 using a long-read nanopore sequencing platform. From just one single run using a MinION flow-cell, the chromosome scale assembly with telomere-to-telomere resolution was achieved for 41 out of 44 chromosomes. Centromere regions were also predicted from the chromosomes, and we discovered conserved motifs in the predicted regions. The function of the motifs was experimentally confirmed by successful transformation of the diatom via bacterial conjugation. This discovery provides insights into chromosome replication, facilitating the rational design of artificial chromosomes for large-scale metabolic engineering of diatoms. The chromosome scale assembly also suggests the potential existence of multi-copy mini-chromosomes and tandemly repeated lipogenesis genes related to the oleaginous phenotype of F. solaris . The nanopore sequencing also solved the sequential arrangement of the repeat region in the F. solaris mitochondrial genome. Findings of this study will be useful to understand and further engineer the oleaginous phenotype of F. solaris . Biology ; Genome ; Nanopore sequencing ; Chromosome ; Centromere ; Genetics ; Minion ; Telomere ; Gene ; Computational biology ; Evolutionary biology Diatoms and Algae Research ; Genomics and Phylogenetic Studies ; Protist diversity and phylogeny
Authors: Srikanth Nayak | Raju R. Kumal | Ahmet Uysal
Source:  (preprint, 2021-10-05)
Field: Chemistry — Physical and Theoretical Chemistry

Spontaneous and Ion-Specific Formation of Inverted Bilayers at Air/Aqueous Interface Developing better separation technologies for rare earth metals is important for a sustainable economy. However, the chemical similarities between rare earths make their separations difficult. Identifying molecular scale interactions that amplify the subtle differences between the rare earths can be useful in developing new separation technologies. Here, we describe ion-dependent monolayer to inverted bilayer transformation of extractant molecules at the air/aqueous interface. The inverted bilayers form with Lu3+ ions but not with Nd3+. By introducing Lu3+ ions to preformed monolayers, we extract kinetic parameters corresponding to the monolayer to inverted bilayer conversion. Temperature-dependent studies show Arrhenius behavior with an energy barrier of 40 kcal/mol. The kinetics of monolayer to inverted bilayer conversion is also affected by the character of the background anion, although anions are expected to be repelled from the interface. Our results show the outsized importance of ion-specific effects on interfacial structure and kinetics, pointing to their role in chemical separation methods. Monolayer ; Bilayer ; Chemical physics ; Ion ; Aqueous solution ; Chemistry ; Kinetics ; Arrhenius equation ; Molecule ; Materials science ; Nanotechnology ; Physical chemistry ; Activation energy ; Membrane ; Organic chemistry Electrostatics and Colloid Interactions ; Micro and Nano Robotics ; Pickering emulsions and particle stabilization
Authors: Junsoo Park | Yi Xia | Vidvuds Ozoliņš | Anubhav Jain
Source: npj Computational Materials (preprint, 2021-03-25)
Field: Materials Science — Materials Chemistry

Optimal band structure for thermoelectrics with realistic scattering and bands Abstract Understanding how to optimize electronic band structures for thermoelectrics is a topic of long-standing interest in the community. Prior models have been limited to simplified bands and/or scattering models. In this study, we apply more rigorous scattering treatments to more realistic model band structures—upward-parabolic bands that inflect to an inverted-parabolic behavior—including cases of multiple bands. In contrast to common descriptors (e.g., quality factor and complexity factor), the degree to which multiple pockets improve thermoelectric performance is bounded by interband scattering and the relative shapes of the bands. We establish that extremely anisotropic “flat-and-dispersive” bands, although best-performing in theory, may not represent a promising design strategy in practice. Critically, we determine optimum bandwidth, dependent on temperature and lattice thermal conductivity, from perfect transport cutoffs that can in theory significantly boost z T beyond the values attainable through intrinsic band structures alone. Our analysis should be widely useful as the thermoelectric research community eyes z T &gt; 3. Scattering ; Thermoelectric effect ; Bandwidth (computing) ; Electronic band structure ; Anisotropy ; Thermoelectric materials ; Condensed matter physics ; Band gap ; Computational physics ; Physics ; Statistical physics ; Engineering physics ; Materials science ; Optics ; Computer science ; Telecommunications ; Quantum mechanics Advanced Thermoelectric Materials and Devices ; Thermal properties of materials ; Thermal Radiation and Cooling Technologies