jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Zhenguang Zhao | Norman Metanis
Source: ChemRxiv (preprint, 2020-12-07)
Field: Chemistry — Organic Chemistry

Chemoselective Copper-Mediated Radical Modification of Selenocysteines in Peptides and Proteins Highly valuable bioconjugated molecules must be synthesized through efficient, chemoselective chemical modifications of peptides and proteins. Herein we report the chemoselective modification of peptides and proteins via a reaction between selenocysteine residues and aryl/alkyl radicals. In situ radical generation from hydrazine substrates and copper ions proceeds rapidly in neat aqueous buffer at near neutral pH (5-8), providing a variety of Se-modified linear and cyclic peptides and proteins conjugated to aryl and alkyl molecules, as well as to affinity label tag (biotin). This chemistry opens a new avenue for chemical protein modifications. Chemistry ; Combinatorial chemistry ; Radical ; Conjugated system ; Alkyl ; Aryl ; Molecule ; Aqueous solution ; Organic chemistry Radical Photochemical Reactions ; Chemical Synthesis and Analysis ; Organoselenium and organotellurium chemistry
Authors: Ayomide H. Labulo | Elijah T. Adesuji | Charles O. Oseghale | Elias E. Elemike | Usman Adamu | Akinola Kehinde Akinola | Enock Olugbenga Dare
Source: Journal of the Nigerian Society of Physical Sciences (article, 2020-11-15)
Field: Materials Science — Materials Chemistry

Effect of benzophenone on the physicochemical properties of N-CNTs synthesized from 1-ferrocenylmethyl (2-methylimidazole) catalyst Vertically-aligned nitrogen-doped carbon nanotubes (v-N-CNTs) were synthesized \textit{via} the chemical vapour deposition (CVD) technique. 1-ferrocenylmethyl(2-methylimidazole) was employed as the source of the Fe catalyst and was dissolved in different ratios of acetonitrile/benzophenone feedstock which served as both the carbon, nitrogen, and oxygen sources. The morphological difference in N-CNTs was as a result of increased oxygen concentration in the reaction mix and not due to water vapour formation as observed in the oxygen-free experiment, indicating specifically, the impact of oxygen. Raman and X-ray photoelectron spectroscopy (XPS) revealed surface defects and grafting of oxygen functional groups on the sidewall of N-CNTs. The FTIR data showed little or no effect as oxygen concentration increases. XPS analysis detected the type of nitrogen species (\textit{i.e.} pyridinic, pyrrolic, graphitic, or molecular nitrogen forms) incorporated in the N-CNT samples. Pyrrolic nitrogen was dominant and increased (from 8.6 to 11.8 at.\%) as oxygen concentration increases in the reaction precursor. An increase in N content was observed with the introduction of a lower concentration of oxygen, followed by a gradual decrease at higher oxygen concentration. Our result suggested that effective control of the reactant mixtures can manipulate the morphology of N-CNTs. X-ray photoelectron spectroscopy ; Catalysis ; Oxygen ; Benzophenone ; Nitrogen ; Chemistry ; Carbon nanotube ; Raman spectroscopy ; Fourier transform infrared spectroscopy ; Carbon fibers ; Acetonitrile ; Inorganic chemistry ; Nuclear chemistry ; Chemical engineering ; Polymer chemistry ; Materials science ; Organic chemistry ; Nanotechnology Carbon Nanotubes in Composites ; Graphene research and applications ; Advancements in Battery Materials
Authors: Michèle Chevrier | Jurgen Kesters | J.E. Houston | Niko Van den Brande | Sylvain Chambon | Sébastien Richeter | Bruno Van Mele | Thomas Arnold | Mehdi Ahmad | Roberto Lazzaroni | Philippe Dubois | Rachel C. Evans | Wouter Maes | Sébastien Clément
Source: ORBi UMONS (article, 2020-07-20)
Field: Materials Science — Surfaces, Coatings and Films

Phosphonium-based polythiophene conjugated polyelectrolytes with different surfactant counterions : thermal properties, self-assembly and photovoltaic performance peer reviewed Polythiophene ; Pulmonary surfactant ; Counterion ; Thermal ; Photovoltaic system ; Polyelectrolyte Polymer Surface Interaction Studies ; Conducting polymers and applications ; Dendrimers and Hyperbranched Polymers
Authors: Tabitha F. Miller
Source: eScholarship (California Digital Library) (article, 2020-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Synthesis and Applications of High Spin Paramagnetic Metal-Organic Cages Supramolecular self-assembled metal-ligand cages have been used as reaction containers, molecular switches, and sensors. While many diamagnetic cage complexes are known, studies into spin-state switching cage complexes have only recently begun to emerge. These magnetically active complexes have applications in information storage, electronic switches, and display devices. To create stable, robust high spin complexes, new ligand structures must be explored focusing on the chelating portion of the ligand to affect the spin state of the metal centers.This work analyzes the characteristics needed in ligands to form favorable paramagnetic cage complexes, using reversible multicomponent metal-ligand self-assembly methods. Using novel termini to interact as metal coordinators allows the formation of high spin Fe(II) metal centers. High spin Fe(II) can be obtained via two types of ligand interactions, either distortion of the octahedral coordination environment due to excess bulk at the metal center, or using a weak coordinator. The addition of steric bulk near the metal center requires a certain amount of flexibility in the ligand backbone to allow favorable coordination. The spin states of these paramagnetic systems were examined to determine their magnetic moments and define the relationship between the metal centers. Alternatively, spin state switching complexes can be formed by using novel heterocyclic chelators. Using new termini allowed creation of novel paramagnetic cages and subsequently the functional properties of these cages were investigated. Slight differences made it possible to tease out the relative favorability between the two seemingly energetically equivalent coordination positions of imidazole termini. Synthesis of novel ligands with amine termini was pursued to bestow a wider range of functionality on cage systems. New amine capped complexes were characterized and found to bind biological molecules of interest. Additionally, the amine-capped complexes were found to be much more sensitive to the counterion employed, distinctly limiting the number of isomers formed. Paramagnetism ; Ligand (biochemistry) ; Supramolecular chemistry ; Chemistry ; Steric effects ; Spin states ; Metal ; Crystallography ; Octahedron ; Diamagnetism ; Coordination complex ; Chemical physics ; Stereochemistry ; Inorganic chemistry ; Condensed matter physics ; Crystal structure ; Physics ; Organic chemistry Magnetism in coordination complexes ; Supramolecular Chemistry and Complexes ; Metal complexes synthesis and properties
Authors: Jesper Dahl Jensen | Niels Bisballe | Laura Kacenauskaite | Maria Storm Thomsen | Bo W. Laursen
Source: ChemRxiv (preprint, 2020-08-14)
Field: Chemistry — Organic Chemistry

Utilizing Selective Chlorination to Synthesize New Triangulenium Dyes with Redshifted Absorption and Emission Access to functionalization of a new site in the triangulenium core structure has been achieved at an early stageby chlorination with N-chlorosuccinimide (NCS), giving rise to two new triangulenium dyes (&lt;b&gt;1&lt;/b&gt; and &lt;b&gt;2&lt;/b&gt;). By introducing the chlorine functionalities in the acridinium precursor, positions complementary to those previously accessed by electrophilic aromatic substitution of the dyes are functionalized. The chlorination is highly selective giving only one regioisomer for both mono- and dichlorination. For the monochlorinated acridinium compound a highly selective ring-closing reaction was discovered generating only a single regioisomer of the cationic [4]helicene product. This discovery aspired further investigations into the mechanism of [4]helicene formation and to the first isolation of the previously proposed intermediate of the two-step S&lt;sub&gt;N&lt;/sub&gt;Ar reaction key to all aza bridged triangulenium and helicenium synthesis. The fully ring closed mono- and di-chlorinated triangulenium dyes &lt;b&gt;1 &lt;/b&gt;and &lt;b&gt;2&lt;/b&gt; show a redshift in absorption and emission relative to the non-chlorinated analogues, while still maintaining relative high quantum yields of 36% and 41 %, and long fluorescence lifetimes of 15 ns and 16 ns, respectively. Helicene ; Chemistry ; Structural isomer ; Cationic polymerization ; Ring (chemistry) ; Fluorescence ; Absorption (acoustics) ; Photochemistry ; Combinatorial chemistry ; Stereochemistry ; Medicinal chemistry ; Organic chemistry ; Molecule ; Materials science Synthesis and Properties of Aromatic Compounds ; Photochromic and Fluorescence Chemistry ; Supramolecular Chemistry and Complexes
Authors: Petra Bombicz | Nóra V. May | Dániel Fegyverneki | Avirmed Saranchimeg | Gergely O Szabó | Zita Makó | G. Tamás Gál | Laura Bereczki
Source: Acta Crystallographica Section A Foundations and Advances (article, 2020-08-02)
Field: Chemistry — Organic Chemistry

LabJack-like crystal structures of halogenated 2-phenylbenzimidazoles – are they isostructural? Isostructural ; Crystallography ; Materials science ; Crystal (programming language) ; Crystal structure ; Chemistry ; Computer science ; Programming language Synthesis and Reactions of Organic Compounds ; Synthesis and Characterization of Heterocyclic Compounds ; Synthesis and biological activity
Authors: Helen S. Summers | Magdalena B. Foreiter | William Lewis | Christopher J. Moody | Tracey D. Bradshaw | Malcolm F. G. Stevens
Source: ARKIVOC (article, 2020-04-28)
Field: Chemistry — Organic Chemistry

Modulation of the acidity of the 8-carboxamide group in the temozolomide family of antitumor imidazo[5,1-d][1,2,3,5]tetrazines Imidazo [5,1-d][1,2,3,5]tetrazines related in structure to the anticancer drugs temozolomide and mitozolomide with modification of the 8-carboxamide group, have been synthesized, N-nitrocarboxamides by direct nitration of the corresponding carboxamides, and N-cyanomitozolomide by sodium cyanamide acylation. The NH groups in the N-nitro-and N-cyano-carboxamides were considerably more acidic than the parent carboxamide, and readily formed salts with morpholine and imidazole. X-Ray crystallography revealed that the N-nitro compound existed as such rather than the nitronic acid tautomer. Preliminary evaluation showed that enhancing the acidity of the carboxamide NH in mitozolomide analogues was detrimental to the growth inhibitory activity. Chemistry ; Temozolomide ; Carboxamide ; Combinatorial chemistry ; Stereochemistry ; Medicinal chemistry ; Pharmacology ; Cancer research ; Glioblastoma Synthesis and Characterization of Heterocyclic Compounds ; bioluminescence and chemiluminescence research ; Synthesis of Tetrazole Derivatives
Authors: Giordano Pierozan Bernardes
Source: Lume (Universidade Federal do Rio Grande do Sul) (article, 2020-01-01)
Field: Materials Science — Biomaterials

Relação estrutura-propriedades-processamento de blendas compatibilizadas de PLA-TPE O poli(ácido láctico) (PLA) é um dos principais polímeros biodegradáveis, exibindo alto módulo elástico e biocompatibilidade. Porém, sua baixa tenacidade demanda a modificação com a adição de elastômeros termoplásticos (TPEs) para atender a requisitos de projetos. A baixa compatibilidade entre PLA e TPEs requer o uso de agente compatibilizante (AgC) para melhor interação entre fases e, consequentemente, suas propriedades mecânicas e viscoelásticas. O comportamento reológico, as propriedades de interface e a processabilidade governam a formação da fase dispersa em uma blenda, afetando seus comportamentos viscoelástico e mecânico. Neste trabalho investigou-se a modificação das características mecânicas, morfológicas e viscoelásticas do PLA pela incorporação dos TPEs poliuretano termoplástico (TPU) e elastômero de etileno (EEt) sem e com a presença do AgC terpolímero etileno-acrilato de butila-metacrilato de glicidila (EBG) por mistura física. As blendas PLA/TPEs foram preparadas nas proporções mássicas de 10 e 30% em misturador interno, sendo as blendas PLA/TPEs (70/30) aditivadas com 5%EBG, e a blenda PLA/TPU (70/30) aditivada com os teores com 2,5 e 7,5%EBG. PLA, TPEs e EBG foram caracterizados quanto ao comportamento reológico, propriedades de superfície e miscibilidade. As blendas PLA/TPEs (sem e com EBG) foram caracterizadas quanto à sua processabilidade, propriedades reológicas, térmicas, mecânicas, viscoelásticas, morfológicas e de interface. A compatibilização com EBG reduziu a tensão interfacial e aumentou a espessura da interface da blenda PLA/TPU. A adição de 10% de TPE aumentou a viscosidade do PLA de 2123 para até 2300 Pa.s, enquanto que 30% de TPE acresceu a viscosidade para até 2650 Pa.s. O uso de 7,5%EBG reduziu o diâmetro das partículas de TPU na blenda PLA/TPU (70/30) de 3,9 para 2,3 μm. O uso de baixo %EEt retardou a degradação térmica do PLA, enquanto a presença de EBG nas blendas PLA/TPU retardou a decomposição dos segmentos de TPU. A temperatura de transição vítrea no PLA (medida por DSC) foi 61 ºC, não tendo sido afetada pela presença/%TPE e de EBG. A Energia Mecânica Específica (EME) aumentou com o aumento do %TPE nas blendas PLA/TPE. A tan δdiminuiu com o aumento do %TPE, aumentando o caráter elástico do PLA. O PLA apresentou aumento da resistência ao impacto de 1,9 para 5,0 kJ/m² com 30%TPU e para 7,0 kJ/m² com 7,5%EBG. A presença de TPE promoveu aumento da deformação no escoamento e melhora no balanço módulo-tenacidade do PLA. EBG mostrou-se um compatibilizante efetivo para as blendas PLA/TPU, sendo o teor de 7,5% o mais adequado. Palavras-chave: PLA, TPE, EBG, blendas, compatibilização, tenacificante. Materials science ; Chemistry ; Polymer chemistry biodegradable polymer synthesis and properties
Authors: Maximilian R. Marsiske | Cristina Ruiz‐Agudo
Source: Goldschmidt Abstracts (article, 2020-01-01)
Field: Materials Science — Biomaterials

Magnesium-Silicate-Hydrate (M-S-H) Nucleation in Presence of Polymeric Additives Silicate ; Hydrate ; Nucleation ; Chemical engineering ; Magnesium ; Materials science ; Polymer ; Chemistry ; Inorganic chemistry ; Metallurgy ; Organic chemistry ; Composite material ; Engineering Clay minerals and soil interactions ; Planetary Science and Exploration ; Calcium Carbonate Crystallization and Inhibition
Authors: Bangile Noel Rolihlahla
Source: University of the Western Cape Electronic Theses and Dissertations Repository (University of the Western Cape) (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Electrochemistry and photophysics of carbon nanodots-decorated nigs(Ni(In, Ga)Se2) quantum dots Quantum dot ; Nanodot ; Nanotechnology ; Carbon quantum dots ; Electrochemistry ; Materials science ; Carbon fibers ; Chemistry ; Electrode ; Composite material Quantum Dots Synthesis And Properties ; Carbon and Quantum Dots Applications ; Chalcogenide Semiconductor Thin Films
Authors: Abdulhakim A. Ahmed | Mohamed A El-Hag Ahmed | Raed M Abouhaddaf
Source: International Journal of Advanced Chemistry Research (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Structural and electronic properties of nanoparticle: density functional study of small palladium clusters (pdn n=1-6) Structure and relative stability of Pdn clusters for n=1–6 were investigated using density functional methods at the B3PW91 level of theory. The structures of the optimized Palladium clusters were investigated and the results are compared with the available experimental values. Stability of the clusters was determined from their relative energy values, binding energies, HOMO-LUMO gap and electronic properties. The binding energy per atom also increases with cluster size. The study revealed that Pd4 and Pd6 are relatively more stable than their neighboring clusters. The most stable isomer for all clusters under investigation is the triplet. The Pd4 and Pd5 showed different Pd-Pd bond lengths due to Jahn-Teller distortion. Stability function and atom addition energy change predict that Pd4, and Pd6 are relatively more stable than their neighboring clusters. Electron affinity (EA), Ionization potential (IP) and electronegativity values suggest that larger clusters have stronger tendency to accept electrons, thereby supporting the relative stability of Pd4 and Pd6. Finally, Collision diameter increases as the cluster size increases. Electronegativity ; Binding energy ; Cluster (spacecraft) ; Atom (system on chip) ; Ionization energy ; Density functional theory ; Chemistry ; Electron affinity (data page) ; Palladium ; Atomic physics ; Ionization ; HOMO/LUMO ; Band gap ; Electronic structure ; Molecular physics ; Electron ; Chemical physics ; Computational chemistry ; Materials science ; Molecule ; Ion ; Physics ; Organic chemistry Catalytic Processes in Materials Science ; Nanocluster Synthesis and Applications ; Quantum Dots Synthesis And Properties
Authors: Soshi Nishino | Koji Hirano | Masahiro Miura
Source: Institutional Repositories DataBase (IRDB) (article, 2020-07-17)
Field: Chemistry — Organic Chemistry

Cu-Catalyzed Reductive gem-Difunctionalization of Terminal Alkynes via Hydrosilylation/Hydroamination Cascade: Concise Synthesis of α-Aminosilanes This is the accepted version of the following article: Nishino S., Hirano K., Miura M.. Cu-Catalyzed Reductive gem-Difunctionalization of Terminal Alkynes via Hydrosilylation/Hydroamination Cascade: Concise Synthesis of α-Aminosilanes. Chemistry - A European Journal 26, 8725 (2020), which has been published in final form at https://doi.org/10.1002/chem.202001799. This article may be used for non-commercialpurposes in accordance with the Wiley Self-ArchivingPolicy [https://authorservices.wiley.com/author-resources/Journal-Authors/licensing/self-archiving.html] Terminal (telecommunication) ; Reductive elimination ; Alkyne ; Sequence (biology) ; Chemical synthesis Organoboron and organosilicon chemistry ; Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods
Authors: Shilpi Jaiswal | Jyotsana Pathak | Abhijit Patra
Source: ChemRxiv (preprint, 2020-07-13)
Field: Materials Science — Materials Chemistry

Single-Component White Light Emitting CdSexSy Alloy Nanocrystals Through Phosphine-Free Route Semiconductor nanocrystals are promising for display and lighting devices. Herein, we report a facile one-pot synthetic route to fabricate white light emitting CdSexSy nanocrystals with enhanced quantum yield using CdO, S powder, and Se powder as precursors. The phosphine-free route was adopted, employing paraffin oil as the reducing agent and solvent for the fabrication. The optical properties can be effectively tailored by controlling the reaction time and the molar ratio of Se/S. The emission of pristine CdSexSy nanocrystals covered a broad visible range from 400 to 750 nm. The CdSexSy nanocrystals (Se/S = 0.4) exhibited white-light emission with quantum yield of 50 ± 3 % and Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.30, 0.31). The band-edge (~400-450 nm) to trap-state (~550-750 nm) emissions was tuned by controlling the Se/S ratio, and the different shades of white light were obtained. Furthermore, the quantum yield and CIE coordinates of the CdSexSy nanocrystals (Se/S = 0.4) were found to be similar even after 30 days of fabrication, showing the high stability of nanocrystals. The white light emission was retained in nanocrystals-embedded poly(methyl methacrylate) (PMMA) thin film and also in the hydrogel matrix. The one-pot, low-cost, scalable fabrication of white light emitting CdSexSy nanocrystals demonstrated in the present study offers promising scope in the solid-state display applications. Nanocrystal ; Quantum yield ; Materials science ; Chromaticity ; Fabrication ; Optoelectronics ; Nanotechnology ; Solid-state lighting ; Chemical engineering ; Light-emitting diode ; Optics ; Fluorescence Quantum Dots Synthesis And Properties ; Chalcogenide Semiconductor Thin Films ; Nanocluster Synthesis and Applications
Authors: Sungyeon Heo | Shin Hum Cho | Clayton J. Dahlman | Ankit Agrawal | Delia J. Milliron
Source: ChemRxiv (preprint, 2020-06-16)
Field: Materials Science — Polymers and Plastics

Influence of Crystalline and Shape Anisotropy on Electrochromic Modulation in Doped Semiconductor Nanocrystals Localized surface plasmon resonance (LSPR) modulation appearing in the near-infrared range in doped semiconductor nanocrystals enriches electrochromic performance. Although crystalline and shape anisotropies influence LSPR spectra, study of their impact on electrochromic modulation are lacking. Here, we study how crystalline anisotropy in hexagonal cesium-doped tungsten oxide nanorods and nanoplatelets affects essential metrics of electrochromic modulation—coloration efficiency (CE) and volumetric capacity—using different sizes of electrolyte cations (tetrabutylammonium, sodium, and lithium) as structurally sensitive electrochemical probes. Nanorod films show higher CE than nanoplatelets in all of electrolytes owing to low effective mass along the crystalline c-axis. When using sodium cations, which diffuse through one-dimensional hexagonal tunnels, electrochemical capacity is significantly greater for platelets than for nanorods. This difference is explained by the hexagonal tunnel sites being more accessible in platelets than in nanorods. Our work sheds light on the role of shape and crystalline anisotropy on charge capacity and CE both of which contribute to overall modulation. Nanorod ; Electrochromism ; Materials science ; Doping ; Nanocrystal ; Lithium (medication) ; Nanotechnology ; Anisotropy ; Semiconductor ; Surface plasmon resonance ; Electrolyte ; Electrochemistry ; Optoelectronics ; Optics ; Nanoparticle ; Electrode ; Chemistry Transition Metal Oxide Nanomaterials ; Conducting polymers and applications ; Gas Sensing Nanomaterials and Sensors
Authors: Valentina Abet | Filip Szczypiński | Marc A. Little | Valentina Santolini | Christopher D. Jones | R. L. Evans | Craig M. Wilson | Xiao‐Feng Wu | M. S. Thorne | Michael J. Bennison | Peng Cui | Andrew I. Cooper | Kim E. Jelfs | Anna G. Slater
Source: ChemRxiv (preprint, 2020-05-26)
Field: Chemistry — Organic Chemistry

Inducing Social Self-Sorting in Organic Cages to Tune the Shape of the Internal Cavity &lt;p&gt;Many interesting target guest molecules have low symmetry, yet most methods for synthesising hosts result in highly symmetrical capsules. Methods of generating lower-symmetry pores are thus required to maximise the binding affinity in host-guest complexes. Here, we use mixtures of tetraaldehyde building blocks to access low-symmetry imine cages. Whether a low-energy cage is isolated can be correctly predicted from the thermodynamic preference observed in computational models. The stability of the observed structures depends on the geometrical match of the aldehyde building blocks. One bent aldehyde stands out as unable to assemble into high-symmetry cages—and the same aldehyde generates low-symmetry socially self-sorted cages when combined with a linear aldehyde. We exploit this finding to synthesise a family of low-symmetry cages containing heteroatoms, illustrating that pores of varying geometries and surface chemistries may be reliably accessed through computational prediction and self-sorting.&lt;/p&gt; Symmetry (geometry) ; Aldehyde ; Bent molecular geometry ; Imine ; Crystallography ; Sorting ; Chemical physics ; Chemistry ; Molecule ; Topology (electrical circuits) ; Computational chemistry ; Materials science ; Stereochemistry ; Computer science ; Combinatorics ; Geometry ; Mathematics ; Algorithm ; Catalysis ; Organic chemistry Supramolecular Chemistry and Complexes ; Chemical Synthesis and Analysis ; Surface Chemistry and Catalysis