jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Russell Shelp | Patrick J. Walsh
Source:  (preprint, 2020-04-29)
Field: Chemistry — Organic Chemistry

New bicyclo[1.1.1]pentanes via anionic reactivity of [1.1.1]propellane To optimize the performance of bioactive molecules, medicinal chemists must fine-tune drug properties such as water solubility, metabolic stability, and permeability through the cell membrane. Towards this goal, bicyclo[1.1.1]pentanes (BCPs) have recently attracted significant attention as bioisosteres of benzene rings, an abundant feature in drug molecules. Despite three decades Propellane ; Bicyclic molecule ; Reactivity (psychology) ; Chemistry ; Medicinal chemistry ; Medicine Oxidative Organic Chemistry Reactions ; Porphyrin and Phthalocyanine Chemistry ; Radical Photochemical Reactions
Authors: Russell Shelp | Patrick Walsh
Source:  (preprint, 2020-04-29)
Field: Chemistry — Organic Chemistry

New bicyclo[1.1.1]pentanes via anionic reactivity of [1.1.1]propellane To optimize the performance of bioactive molecules, medicinal chemists must fine-tune drug properties such as water solubility, metabolic stability, and permeability through the cell membrane. Towards this goal, bicyclo[1.1.1]pentanes (BCPs) have recently attracted significant attention as bioisosteres of benzene rings, an abundant feature in drug molecules. Despite three decades Propellane ; Reactivity (psychology) ; Bicyclic molecule ; Chemistry ; Medicinal chemistry ; Medicine Oxidative Organic Chemistry Reactions ; Porphyrin and Phthalocyanine Chemistry ; Radical Photochemical Reactions
Authors: P. G. Kudryavtsev
Source: International Journal of Petrochemical Science & Engineering (article, 2020-09-14)
Field: Materials Science — Materials Chemistry

Modelling of kinetics and structure formation at sol-gel transition Sol-gel is a modern technological process that is widely used in production of inorganic sorbents, catalysts and catalyst carriers, synthetic zeolites, inorganic binders, ceramics with select physical, optical, magnetic, and electrical properties, glass, glass ceramics, fibers, etc. The creation of models of this process will make it possible to fine-tune the properties of the resulting materials. The sol-gel transition is a process of sol particle association accompanied by the formation of "an infinite aggregate". Two ways of constructing mathematical models are suggested. The first approach is based on the methods of statistical thermodynamics, and the second one is hydrodynamical. Both methods make it possible to obtain the inter- consistent equations describing the relationship between the gelation time and the macroscopic parameters. Kinetics ; Transition (genetics) ; Structure formation ; Materials science ; Chemical physics ; Chemistry ; Chemical engineering ; Statistical physics ; Physics ; Engineering ; Classical mechanics ; Astrophysics ; Biochemistry Crystallization and Solubility Studies
Authors: Солизода Иброхими Ашурали | Живулин Владимир Евгеньевич | Шерстюк Дарья Петровна | Стариков Андрей Юрьевич | Трофимов Евгений Алексеевич | Зайцева Ольга Викторовна | Винник Денис Александрович
Source: Вестник Южно-Уральского государственного университета. Серия: Химия (article, 2020-11-23)
Field: Materials Science — Materials Chemistry

СИНТЕЗ И СТРУКТУРА КЕРАМИКИ БИЗАМЕЩЕННОГО ГЕКСАФЕРРИТА M-ТИПА BAFE(11,5-X)TI0,5ALXO19 The development of scientific and technological progress is impossible without the creation of new functional materials. One of the classes of such materials are hexagonal ferrites. Their unique physical properties make them an irreplaceable material for the production of high-frequency electronics. The widespread introduction of high-frequency electronics into everyday life, over the past decade, has generated great interest in hexagonal ferrites. The number of publications devoted to the synthesis of mono- and bisubstituted ferrites noticeably increases every year. Modification of the chemical composition of a ferrite by replacing some of the iron atoms with another element, without changing its structure, leads to a change in physical properties of the material. Variation of the final ferrite properties, by changing its chemical composition, is of interest and is promising for fine tuning the material properties for a specific task. The aim of the present work is to experimentally study the possibility of synthesizing ferrite with a magnetoplumbite structure, in which the iron atoms are partially replaced by the Al and Ti atoms. A review of the scientific literature on this issue showed the absence of publications on ferrites with such a set of substitute elements. The X-ray phase and structural analysis, electron microscopy, and energy-dispersive X-ray spectroscopy were used as research methods in the present study. The article offers the results of an experimental study of the possibility of obtaining bisubstituted M-type ferrite of the BaFe(11.5-x)Ti0.5AlxO19 composition, where x (Al) = 0.1, 0.5, 1. Solid-phase synthesis has been used as a method for preparing samples. This method is devoid of technological difficulties and is promising from the point of view of its scaling for the synthesis of ferrite. The samples have been sintered at three different temperatures: 1300, 1350, and 1400 °C. It is shown that in the temperature range 1300–1400 ° C the formation of monophase samples occurs. The calculation of the parameters of the crystal lattice has been made. The influence of temperature and concentration of a substituting element on the change in the parameters of the crystal lattice of the material has been revealed. The study by the electron microscopy method made it possible to reveal the presence of latent microporosity of the samples. Ferrite (magnet) ; Hexagonal crystal system ; Materials science ; Chemical composition ; Engineering physics ; Crystallography ; Nanotechnology ; Chemistry ; Physics ; Composite material Magnetic Properties and Synthesis of Ferrites ; Pigment Synthesis and Properties
Authors: Mahboob Alam | Kefeng Ping | Rohit Bhadoria | Kaido Tammeveski | Nadežda Kongi | Pavel Starkov
Source: ECS Meeting Abstracts (article, 2020-11-23)
Field: Chemistry — Inorganic Chemistry

Fused Hybrid Linkers for Metal–Organic Frameworks-Derived Bifunctional Oxygen Electrocatalysts Noble metal free M-N-C oxygen electrocatalysts are generaly synthesized using inorganic salts, organometallic precursors, nanostructured carbon nanotubes, several dopants and carbonization under modifying environments such as NH 3 or H 2 . Reducing synthesis steps or bringing versatility in post product is quite rare. We have introduced a series of metal-organic frameworks using iron/benzimidazole as the only primary precursor to obtain a uniform material. By merging catechol and imidazole units together, we prepared efficient bifunctional oxygen electrocatalyst. The proposed material outperforms the Pt-based materials with respect to electrocatalytic properties in alkaline media (ORR: E on = 1.01 V, E 1/2 = 0.87 V vs. RHE in 0.1 M KOH; OER: 1.60 V @10 mA cm –2 in 0.1 M KOH; ΔE = 0.73 V). It was also established that fine-tuning of organic linker can help to modulate the electrochemical properties of the single precursor based electro-catalyst material. Bifunctional ; Electrocatalyst ; Catalysis ; Materials science ; Carbonization ; Oxygen evolution ; Electrochemistry ; Dopant ; Inorganic chemistry ; Metal ; Chemical engineering ; Chemistry ; Organic chemistry ; Electrode ; Doping ; Metallurgy ; Physical chemistry ; Composite material Metal-Organic Frameworks: Synthesis and Applications ; Polyoxometalates: Synthesis and Applications ; Chemical Synthesis and Reactions
Authors: Mahboob Alam | Kefeng Ping | Rohit Bhadoria | Valdek Mikli | Arvo Mere | Jaan Aruväli | Päärn Paiste | Mati Kook | Mihkel Rähn | Väino Sammelselg | Kaido Tammeveski | Nadežda Kongi | Pavel Starkov
Source: ECS Meeting Abstracts (article, 2020-05-01)
Field: Chemistry — Inorganic Chemistry

Fused Hybrid Linkers for Metal–Organic Frameworks-Derived Bifunctional Oxygen Electrocatalysts Noble metal free M-N-C oxygen electrocatalysts are generaly synthesized using inorganic salts, organometallic precursors, nanostructured carbon nanotubes, several dopants and carbonization under modifying environments such as NH 3 or H 2 . Reducing synthesis steps or bringing versatility in post product is quite rare. We have introduced a series of metal-organic frameworks using iron/benzimidazole as the only primary precursor to obtain a uniform material. By merging catechol and imidazole units together, we prepared efficient bifunctional oxygen electrocatalyst. The proposed material outperforms the Pt-based materials with respect to electrocatalytic properties in alkaline media (ORR: E on = 1.01 V, E 1/2 = 0.87 V vs. RHE in 0.1 M KOH; OER: 1.60 V @10 mA cm –2 in 0.1 M KOH; ΔE = 0.73 V). It was also established that fine-tuning of organic linker can help to modulate the electrochemical properties of the single precursor based electro-catalyst material. Bifunctional ; Electrocatalyst ; Catalysis ; Materials science ; Carbonization ; Oxygen evolution ; Electrochemistry ; Dopant ; Inorganic chemistry ; Metal-organic framework ; Metal ; Chemical engineering ; Chemistry ; Organic chemistry ; Electrode ; Doping ; Metallurgy Metal-Organic Frameworks: Synthesis and Applications ; Polyoxometalates: Synthesis and Applications ; Chemical Synthesis and Reactions
Authors: Gu Lingyue | Kévin Renault | Anthony Romieu | Jean‐Alexandre Richard | Rajavel Srinivasan
Source: ChemRxiv (preprint, 2020-04-06)
Field: Chemistry — Organic Chemistry

Synthesis and Spectral Properties of 6'-Triazolyl-Dihydroxanthene-Hemicyanine Fused Near-Infrared Dyes We describe the synthesis of a range of 6’-triazolyl-dihydroxanthene-hemicyanine (DHX-hemicyanine) fused dyes through an effective copper-catalyzed azide-alkyne cycloaddition (CuAAC) "click" reaction, with the dual aim of providing molecular diversity and fine tuning spectral properties of these near-infrared (NIR)-active materials. This was implemented by reacting 16 different aliphatic and aromatic azides with a terminal alkynyl-based-DHX-hemicyanine hybrid scaffold prepared in four steps and 35% overall yield from 4-bromosalicylaldehyde. The resulting triazole derivatives have been fully characterized and their optical properties determined both in organic solvents and simulated physiological conditions (phosphate buffered saline containing 5% of bovine serum albumin protein). This systematic study is a first important step towards the development of NIR-I fluorogenic "click-on" dyes or related photoactive agents for light-based diagnostic and/or therapeutic applications. Click chemistry ; Cycloaddition ; Azide ; Chemistry ; Combinatorial chemistry ; Yield (engineering) ; Near-infrared spectroscopy ; Alkyne ; Bovine serum albumin ; Photochemistry ; Organic chemistry ; Materials science ; Catalysis ; Chromatography Click Chemistry and Applications
Authors: Gu Lingyue | Kévin Renault | Anthony Romieu | Jean‐Alexandre Richard | Rajavel Srinivasan
Source: ChemRxiv (preprint, 2020-04-06)
Field: Chemistry — Organic Chemistry

Synthesis and Spectral Properties of 6'-Triazolyl-Dihydroxanthene-Hemicyanine Fused Near-Infrared Dyes We describe the synthesis of a range of 6’-triazolyl-dihydroxanthene-hemicyanine (DHX-hemicyanine) fused dyes through an effective copper-catalyzed azide-alkyne cycloaddition (CuAAC) "click" reaction, with the dual aim of providing molecular diversity and fine tuning spectral properties of these near-infrared (NIR)-active materials. This was implemented by reacting 16 different aliphatic and aromatic azides with a terminal alkynyl-based-DHX-hemicyanine hybrid scaffold prepared in four steps and 35% overall yield from 4-bromosalicylaldehyde. The resulting triazole derivatives have been fully characterized and their optical properties determined both in organic solvents and simulated physiological conditions (phosphate buffered saline containing 5% of bovine serum albumin protein). This systematic study is a first important step towards the development of NIR-I fluorogenic "click-on" dyes or related photoactive agents for light-based diagnostic and/or therapeutic applications. Click chemistry ; Cycloaddition ; Chemistry ; Azide ; Combinatorial chemistry ; Near-infrared spectroscopy ; Bovine serum albumin ; Photochemistry ; Organic chemistry ; Catalysis Click Chemistry and Applications
Authors: Daniel Bůžek | Soňa Ondrušová | Jan Hynek | Petr Kovář | Kamil Lang | Ján Rohlíček | Jan Demel
Source: ChemRxiv (preprint, 2020-01-13)
Field: Chemistry — Inorganic Chemistry

Robust Aluminium and Iron Phosphinate Metal-Organic Frameworks for Efficient Removal of Bisphenol A Herein, we introduce a new series of highly stable MOFs, constructed using Fe&lt;sup&gt;3+&lt;/sup&gt; and Al&lt;sup&gt;3+&lt;/sup&gt; metal ions and bisphosphinate linkers. The isoreticular design leads to ICR-2, ICR-4, ICR-6, and ICR-7 MOFs with a honeycomb arrangement of linear pores, surface areas up to 1360 m&lt;sup&gt;2&lt;/sup&gt; g&lt;sup&gt;-1&lt;/sup&gt;, and high solvothermal stability. In most cases, their sorption capacity is retained even after 24 h reflux in water. The choice of the linkers allows fine tuning of the pore sizes and the chemical nature of the pores. This feature can be utilized for optimization of host-guest interactions between molecules and pore walls. Water pollution by various endocrine disrupting chemicals has been considered as a global threat to public health. In this work, we proved that the chemical stability and the hydrophobic nature of the synthesized series of MOFs result in remarkable sorption properties of these materials for neurodisruptor bisphenol A.&lt;br&gt; Bisphenol A ; Sorption ; Chemistry ; Bisphenol ; Molecule ; Chemical engineering ; Metal ; Chemical stability ; Aluminium ; Inorganic chemistry ; Organic chemistry ; Adsorption ; Epoxy Metal-Organic Frameworks: Synthesis and Applications ; Dendrimers and Hyperbranched Polymers ; Covalent Organic Framework Applications
Authors: Mir M. Atiqullah
Source:  (article, 2020-09-04)
Field: Materials Science — Polymers and Plastics

Undergraduate Research on High Temperature Creep Behavior of Polymers Creep is very slow deformation of materials at constant temperature and under steady stress. It is a diffusion phenomenon accelerated by higher temperatures at stress level below yield strengths. Although the result of creep in all materials are similar but physical mechanisms of creep in metals and polymers are very different because of the difference in the atomic and crystal structures. Specific knowledge of creep deformation is necessary for design and application of polymer based products at elevated temperatures. A senior design group was assigned a project to design and build a high temperature tester for polymers. The tester was designed to utilize small standard dog bone specimens under tensile load inside a heated chamber. It was equipped with automated temperature control and instrumented for computerized monitoring and logging of both temperature and elongation over time. Successful tests on a limited set of industrial polymers demonstrated the functionality of the tester. The results provided good estimates of the creep behavior of the experimental polymers for design purposes that were not easily available in the literature. Two minority and two honors research students were also engaged to fine tune the hardware, install and test the data acquisition system, and finally perform a range of creep experiments on the tester. The data on creep rates and times to failure conform to the hypothesis that these would be affected proportionately as stress and temperature are changed. Not only the design and operation of the tester gave the students high level of creep awareness and knowledge but also the tester and the experimental process now provide opportunities for generating experimental creep data for design and research purposes. The design groiup and the research students were all very enthusiastic to be part of such a novel laboratory experience. A few upgrading ideas are being considered for improving the functioning, monitoring, and utility of the tester. Creep ; Materials science ; Composite material ; Stress (linguistics) ; Diffusion creep ; Polymer ; Slip (aerodynamics) ; Forensic engineering ; Engineering ; Microstructure Polymer crystallization and properties ; Polymer Nanocomposites and Properties ; Fiber-reinforced polymer composites
Authors: Caius Gibeily | Li P. H. | B. McCallion | Laurence Taylor Seeley | Yujung Kong
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2020-12-25)
Field: Chemistry — Physical and Theoretical Chemistry

Biochemical and Phenomenological Models For A Shinethanogen System This section of in silico molecular modelling effectively served as our experimental workbench, fine-tuning the shinethanogen system gene circuit and testing our approach to experimental design. The molecular model of the gene circuit behaviour was dissected, taking account of the designed properties we sought in the design and research section of our engineering cycle and the intrinsic properties of the system (diffusion rates, association/dissociation, promoter dynamics). Therefore, the ultimate target of this section was to paint a picture of the behaviour of the gene circuit overall. Systems of ODEs were built for the thanogen and shinogen independently and deterministic and stochastic models were produced using kinetic parameters derived from the literature and approximated where unavailable. Phenomenological model ; Psychology ; Epistemology ; Philosophy ; Physics thermodynamics and calorimetric analyses ; Nonlinear Dynamics and Pattern Formation ; Plant Reproductive Biology
Authors: Coralie Duchemin
Source: Infoscience (Ecole Polytechnique Fédérale de Lausanne) (article, 2020-01-01)
Field: Chemistry — Inorganic Chemistry

Tailoring Chiral Cyclopentadienyl Rhodium(III) Catalysts for Enantioselective Alkenyl C-H functionalizations Chiral cyclopentadienyl (Cpx) metal complexes have empowered the developement of challenging asymmetric C(sp2)-H activation transformations. However the preparation of competent atropchiral Cpx ligands is long and tedious. Moreover the range of application of chiral Cpx catalysts in asymmetric C-H functionalization is limited to aryl C-H bonds. This thesis presents the elaboration of a library of atropchiral Cpx group-9 metal complexes via concise syntheses. Structural data were systematically collected and a rational analysis highlighted the flexibility of Cpx ligand to adapt to the steric environment of the metal center. Newly synthesized chiral rhodium Cpx complexes were competent in benchmark asymmetric C-H activation/allylation of arenes. Additionally, a fine tuning of chiral Cpx catalysts enabled a controled chemoselectivity in the asymmetric functionalization of alkenyl C-H bonds. A set of N-enoxysuccinimides and alkenes engaged selectively in the enantioselective Rh(III)-catalyzed cyclopropanation or carboamination of olefins in mild conditions. Mannitol-derived Cpx rhodium catalyst yielded cyclopropanes in high enantioselectivities while a tailored Binol-derived CpxRh(III) catalyst afforded amino esters with excellent enantioselectivities. The methods were applied in the synthesis of valuable amino acids derivatives and biologically active molecules. Enantioselective synthesis ; Rhodium ; Cyclopentadienyl complex ; Catalysis ; Chemistry ; Stereochemistry ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Catalytic C–H Functionalization Methods ; Synthesis and Catalytic Reactions
Authors: M. Hima Bindu | Buduru Gowthami
Source: International Journal of Research in Pharmaceutical Sciences and Technology (article, 2020-09-11)
Field: Materials Science — Biomaterials

Utilization of Lipids, Polymers by Modern Techniques for Innovative Pharmaceutical Formulations and Medical Devices With advancing science and technology, new futuristic technologies have been upcoming that are having a greater impact on the pharmaceutical and biomedical fields. Many lipids and polymer of natural and synthetic origin have spread horizons enabling to reach in fabricating delivery systems for unmet medical needs. In this modern biomedicine era, we must outline and scrutiny the roles of these biomaterials and the modern technologies that are shaping up the advancing medicines. The real challenges in modulating, fine-tuning the biomaterials for their bioactive properties are vital for assessing the in-vivo performance of the developed systems. Therefore, the present review discusses the detailed analysis of the current research reported in the technologies of utilizing the lipids, polymers, and their role in delivering the drugs, genes, and designing advanced implantable medical devices. The scrutiny also focuses on key optimization tools, analytical methods, formulation, and biomedical techniques helpful in developing the solutions that can be administered different routes in different therapeutic indications. Scrutiny ; Biomedicine ; Nanotechnology ; Biomedical technology ; Medical device ; Biochemical engineering ; Computer science ; Systems engineering ; Risk analysis (engineering) ; Engineering ; Medicine ; Biomedical engineering ; Materials science ; Bioinformatics ; Mechanical engineering ; Biology ; Political science Nanoparticle-Based Drug Delivery ; Advanced Drug Delivery Systems ; Drug Solubulity and Delivery Systems
Authors: Inha Cho | Zhi‐Jun Jia | Frances H. Arnold
Source: ChemRxiv (preprint, 2020-01-03)
Field: Chemistry — Organic Chemistry

RETRACTED: Site-selective enzymatic C‒H amidation for synthesis of diverse lactams Please note that this work has been retracted by the authors.After publication of the Report “Site-selective enzymatic C‒H amidation for synthesis of diverse lactams” in Science (1, also linked in metadata), efforts to reproduce the work showed that the enzymes do not catalyze the reactions with the activities and selectivities claimed. Careful examination of the first author’s lab notebook then revealed missing contemporaneous entries and raw data for key experiments. The authors therefore have retracted the article from Science and are now retracting the preprint from ChemRxiv. The original paper can be accessed by selecting “Version 1” of the preprint below, or by accessing https://doi.org/10.26434/chemrxiv.7711418.v1. Inha Cho, Zhi-Jun Jia, Frances H. Arnold*Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.*Corresponding author. Email: frances@cheme.caltech.eduReferences1. I. Cho, Z.-J. Jia, F. H. Arnold, Science 364, 575 (2019). DOI: 10.1126/science.aaw9068*******************************************************************************************Directed evolution of cytochrome P450 enzymes fine-tunes site selectivity of new-to-nature C‒H amidation for modular, sustainable and scalable preparation of enantio-enriched β-, γ- and δ-lactams. Metadata ; Chemistry ; Scalability ; Stereochemistry ; Computer science ; Combinatorial chemistry ; World Wide Web ; Database Cyclopropane Reaction Mechanisms ; Synthesis and Catalytic Reactions ; Catalytic C–H Functionalization Methods