jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Geriene O. LaBine | Philip P. Molloy | Jennie R. Christensen
Source: Applied Spectroscopy (article, 2021-03-30)
Field: Chemistry — Analytical Chemistry

Determination of Elemental Composition in Soft Biological Tissue Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry: Method Validation Determination of elemental concentrations in biological tissue is fundamental to many environmental studies. Analytical methods typically used to quantify concentrations in such studies have minimum sample volumes that necessitate lethal or impactful collection of tissues. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) has small sample volume requirements and offers environmental practitioners an opportunity to employ low-impact sample collection methods. Environmental applications of LA-ICP-MS are limited by the lack of validated methods, partly due to the need for dry samples and scarcity of matrix-matched certified reference materials (CRMs). This study validates an LA-ICP-MS method to determine concentrations of 30 elements in soft biological tissue (fish ovary and muscle). Tissue samples (median: 0.48 grams (g); inter-quartile range: 0.30 g to 0.56 g wet weight) were dehydrated, powdered, compressed into pellets (weighing approximately 0.03 g) and analyzed using LA-ICP-MS alongside three matrix-matched CRMs. The method yielded concentration determinations for CRM elements that were typically accurate to within 30% of theoretical concentrations, and precise (relative standard deviation <20%). These results were repeatable: accuracy rarely deviated from theoretical values by more than 20%, and precision rarely exceeded 33%. Determinations for biological samples were replicable irrespective of tissue (ovary or muscle). There was good linearity between analyte signal strength and theoretical concentration (median R<sup>2 </sup>≥ 0.981 for all elements) across ranges typically encountered in environmental studies. Concentrations could not be consistently obtained (i.e., determined concentrations were typically below detection limits) for boron, vanadium, molybdenum, and cadmium in muscles, and arsenic in both ovaries and muscles; however, detection limits were sufficiently low for most environmental contexts. Further methodological refinement could include the incorporation of spiked standards to extend linear ranges, and fine-tuning instrument parameters to obtain smoother signal intensities for rare elements. The method presented promotes the use of low-impact sample collection methods while enabling high-quality determinations of elemental concentrations in biological tissues. Certified reference materials ; Chemistry ; Inductively coupled plasma mass spectrometry ; Analyte ; Repeatability ; Analytical Chemistry (journal) ; Biological tissue ; Matrix (chemical analysis) ; Sample preparation ; Mass spectrometry ; Pellets ; Detection limit ; Chromatography ; Materials science ; Biomedical engineering Analytical chemistry methods development ; Heavy metals in environment ; Mercury impact and mitigation studies
Authors: Dóra Lakk-Bogáth | Patrik Török | Flóra Viktória Csendes | Soma J. Keszei | Beatrix Gantner | József Kaizer
Source: Molecules (article, 2021-07-26)
Field: Chemistry — Inorganic Chemistry

Disproportionation of H2O2 Mediated by Diiron-Peroxo Complexes as Catalase Mimics Heme iron and nonheme dimanganese catalases protect biological systems against oxidative damage caused by hydrogen peroxide. Rubrerythrins are ferritine-like nonheme diiron proteins, which are structurally and mechanistically distinct from the heme-type catalase but similar to a dimanganese KatB enzyme. In order to gain more insight into the mechanism of this curious enzyme reaction, non-heme structural and functional models were carried out by the use of mononuclear [Fe<sup>II</sup>(L<sub>1-4</sub>)(solvent)<sub>3</sub>](ClO<sub>4</sub>)<sub>2</sub> (<b>1</b>-<b>4</b>) (L<sub>1</sub> = 1,3-bis(2-pyridyl-imino)isoindoline, L<sub>2</sub> = 1,3-bis(4'-methyl-2-pyridyl-imino)isoindoline, L<sub>3</sub> = 1,3-bis(4'-Chloro-2-pyridyl-imino)isoindoline, L<sub>4</sub> = 1,3-bis(5'-chloro-2-pyridyl-imino)isoindoline) complexes as catalysts, where the possible reactive intermediates, diiron-perroxo [Fe<sup>III</sup><sub>2</sub>(μ-O)(μ-1,2-O<sub>2</sub>)(L<sub>1</sub>-L<sub>4</sub>)<sub>2</sub>(Solv)<sub>2</sub>]<sup>2+</sup> (<b>5</b>-<b>8</b>) complexes are known and well-characterized. All the complexes displayed catalase-like activity, which provided clear evidence for the formation of diiron-peroxo species during the catalytic cycle. We also found that the fine-tuning of iron redox states is a critical issue, both the formation rate and the reactivity of the diiron-peroxo species showed linear correlation with the Fe<sup>III</sup>/Fe<sup>II</sup> redox potentials. Their stability and reactivity towards H<sub>2</sub>O<sub>2</sub> was also investigated and based on kinetic and mechanistic studies a plausible mechanism, including a rate-determining hydrogen atom transfer between the H<sub>2</sub>O<sub>2</sub> and diiron-peroxo species, was proposed. The present results provide one of the first examples of a nonheme diiron-peroxo complex, which shows a catalase-like reaction. Isoindoline ; Chemistry ; Reactivity (psychology) ; Hydrogen peroxide ; Heme ; Redox ; Catalysis ; Catalase ; Catalytic cycle ; Stereochemistry ; Enzyme ; Solvent ; Medicinal chemistry ; Photochemistry ; Organic chemistry Metal-Catalyzed Oxygenation Mechanisms ; Metal complexes synthesis and properties ; Porphyrin and Phthalocyanine Chemistry
Authors: Ehsan Moharreri | Tahereh Jafari | Dinithi Rathnayake | Harshul S. Khanna | Chung‐Hao Kuo | Steven L. Suib | Partha Nandi
Source: Scientific Reports (article, 2021-09-28)
Field: Chemistry — Inorganic Chemistry

Role of catalytic nitrile decomposition in tricopper complex mediated direct partial oxidation of methane to methanol Synthetic homogeneous system known to date performing methane to methanol conversion using O<sub>2</sub> as terminal oxidant is unique and based on copper complex with piperazine-based ligand (Cu<sub>3</sub>L in Fig. 1) in a medium of acetonitrile. Prior work have shown that in order to achieve catalytic turnover, hydrogen peroxide is needed to regenerate the active site. We show in this paper that reaction solvent based on organic nitrile decompose concurrently with methane activation and that in the absence of either acetonitrile, Cu complex or hydrogen peroxide, the catalytic turnover does not happen. We show in this manuscript that the direct methane oxidation to methanol might have been mediated by catalytic Radziszewski oxidation between acetonitrile and H<sub>2</sub>O<sub>2</sub>. Additionally we have discovered that in the absence of methane, peroxide mediated acetonitrile decomposition also makes methanol via a background reaction which was hitherto unknown. Acetonitrile ; Nitrile ; Methanol ; Catalysis ; Chemistry ; Hydrogen peroxide ; Anaerobic oxidation of methane ; Methane ; Inorganic chemistry ; Decomposition ; Photochemistry ; Solvent ; Combinatorial chemistry ; Organic chemistry Metal-Catalyzed Oxygenation Mechanisms ; Microbial metabolism and enzyme function ; Oxidative Organic Chemistry Reactions
Authors: Deanna M. D’Alessandro | Pavel M. Usov
Source: Australian Journal of Chemistry (article, 2021-01-21)
Field: Chemistry — Electrochemistry

Spectroelectrochemistry: A Powerful Tool for Studying Fundamental Properties and Emerging Applications of Solid-State Materials Including Metal–Organic Frameworks Spectroelectrochemistry (SEC) encompasses a broad suite of electroanalytical techniques where electrochemistry is coupled with various spectroscopic methods. This powerful and versatile array of methods is characterised as in situ, where a fundamental property is measured in real time as the redox state is varied through an applied voltage. SEC has a long and rich history and has proved highly valuable for discerning mechanistic aspects of redox reactions that underpin the function of biological, chemical, and physical systems in the solid and solution states, as well as in thin films and even in single molecules. This perspective article highlights the state of the art in solid-state SEC (ultraviolet–visible–near-infrared, infrared, Raman, photoluminescence, electron paramagnetic resonance, and X-ray absorption spectroscopy) relevant to interrogating solid state materials, particularly those in the burgeoning field of metal–organic frameworks (MOFs). Emphasis is on developments in the field over the past 10 years and prospects for application of SEC techniques to probing fundamental aspects of MOFs and MOF-derived materials, along with their emerging applications in next-generation technologies for energy storage and transformation. Along with informing the already expert practitioner of SEC, this article provides some guidance for researchers interested in entering the field. Nanotechnology ; Chemistry ; Solid-state ; Field (mathematics) ; Resonance Raman spectroscopy ; Raman spectroscopy ; Materials science ; Physical chemistry ; Physics Electrochemical Analysis and Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Conducting polymers and applications
Authors: Marc Camats | Isabelle Favier | Sonia Mallet‐Ladeira | Daniel Plá | Montserrat Gómez
Source: Organic & Biomolecular Chemistry (article, 2021-11-26)
Field: Chemistry — Organic Chemistry

Understanding Cu(<scp>ii</scp>)-based systems for C(sp<sup>3</sup>)–H bond functionalization: insights into the synthesis of aza-heterocycles Herein we report the synthesis of imidazo[1,5-<i>a</i>]pyridine heterocycles <i>via</i> a Cu(II)-mediated functionalization of α'-C(sp<sup>3</sup>)-H bonds of pyridinylaldimines and subsequent cyclization. This strategy exploits the inherent directing ability of heteroleptic aldimine and pyridine groups in the substrate yielding the C-H functionalization of α'-methylene groups in a regioselective fashion over distant methyl or methylene groups in β or γ positions. The observed correlation between the nature of the anionic ligands (halide <i>vs.</i> carboxylate) bonded to copper and the chemoselectivity of the C(sp<sup>3</sup>)-H activation process points to a concerted metalation-deprotonation pathway prior to cyclization to furnish the corresponding imidazo[1,5-<i>a</i>]pyridine derivative. This copper-mediated C(sp<sup>3</sup>)-H bond functionalization reaction works for a variety of substrates incorporating linear alkyl chains (from 3 to 12 carbon atoms), and good functional group tolerance (aryl, ether and ester groups). Cu-Catalyzed C(sp<sup>2</sup>)-H cyanation on the imidazole ring can then take place selectively under oxidative conditions. Chemistry ; Metalation ; Surface modification ; Chemoselectivity ; Pyridine ; Regioselectivity ; Aryl ; Deprotonation ; Medicinal chemistry ; Methylene ; Ether ; Alkyl ; Combinatorial chemistry ; Stereochemistry ; Organic chemistry ; Catalysis Catalytic C–H Functionalization Methods ; Synthesis and Catalytic Reactions ; Cyclopropane Reaction Mechanisms
Authors: Francisco G. Cirujano | Nuria Martín | Neyvis Almora‐Barrios | Carlos Martí‐Gastaldo
Source: Catalysis Science & Technology (article, 2021-01-01)
Field: Chemistry — Inorganic Chemistry

Catalytic activity of a CuGHK peptide-based porous material The CuGHK peptide-based porous material acts as a heterogeneous organocatalyst in the Henry reaction due to a periodic distribution of pockets decorated with lysine side chain active sites. Catalysis ; Peptide ; Lysine ; Chemistry ; Porosity ; Porous medium ; Combinatorial chemistry ; Distribution (mathematics) ; Side chain ; Chemical engineering ; Polymer chemistry ; Organic chemistry ; Amino acid ; Biochemistry ; Polymer ; Mathematics ; Engineering Metal-Organic Frameworks: Synthesis and Applications ; Chemical Synthesis and Analysis ; Supramolecular Self-Assembly in Materials
Authors: Ramyaa Shri | Srinivasan Narasimhan | Ramachandran Murugesan | Shoba Narayan | E Smith | P Yelick | H Sun | T Jin | Q Yu | F Chen | M Miura | S Gronthos | M Zhao | B Lu | L Fisher | P Robey | S Shi | Shed | Y Park | Y Lee | Y Seo | H Seo | J Park | H Bae | G Huang | K Shagramanova | S Chan | D Cui | J Xiao | Y Zhou | X Zhou | Y Liu | Y Peng | Y Yu | H Li | Q Yuan | M Zhang | S Ni | X Zhang | J Lu | S Gao | Y Yang | Z Wang | Y Li | S Shrestha | A Diogenes | A Kishen | J Oliveira | N Kotobuki | M Tadokoro | M Hirose | J Mano | R Reis | H Ohgushi | R Moonesi Rad | D Atila | E Akgn | Z Evis | D Keskin | A Tezcaner | S Duailibi | M Duailibi | W Zhang | R Asrican | J Vacanti | M.-V Ciocilteu | O.-L Filip | C Valentin | O.-E Manda | I Neacu | A Ficai | I.-M Buzatu | C Nicolicescu | O Croitoru | J Neamu | I Neacsu | A Serban | A Nicoara | R Trusca | V Ene | F Iordache | L Arsenie | I Ardelean | N Mihailescu | I Mihailescu | C Ristoscu | C Bleotu | E Andronescu | H Tan | K Marra | Injectable | A Barth | S Ryglova
Source: Biointerface Research in Applied Chemistry (article, 2021-05-03)
Field: Materials Science — Polymers and Plastics

Fabrication of Dexamethasone-Silver Nanoparticles Entrapped Dendrimer Collagen Matrix Nanoparticles for Dental Applications A bioengineered tooth is a well-studied subject. However, it is a challenge when seamless integration of various functionalities is required. In the case of teeth, integrating stem cell differentiating agents, regenerating the dentin tissue, and arresting the biofilm formation are three aspects that call for attention. Dental pulp stem cell differentiation to odontoblasts can be facilitated by dexamethasone (Dex). The ideal scaffold for regeneration applications – collagen (Col), has several advantages but also has no inherent rigidity. Silver nanoparticles (AgNps) are found to be an ideal material for preventing biofilm formation, with challenges arising from their stability and cytotoxicity. The route was chosen based on the successful demonstration of various platforms is the PAMAM (Den) dendrimers. The platform encompassing all the ingredients – AgNp@Den@Dex@Col had a max at 622 nm. FTIR studies revealed the presence of all components, and scaffold degradation temperature improved. A linked morphology was observed under TEM, and the zone of inhibition (MIC) was 3.5 mm, indicating good antibacterial activity. There was also a 60% reduction in biofilm formation against Staphylococcus aureus and 40% against Klebsiella pneumoniae by the fabricated nanocomposite AgNp@Den@Dex@Col. In essence, this work reports a platform where three functions of stem cell differentiation, regeneration, and biofilm formation are integrated. Biofilm ; Silver nanoparticle ; Chemistry ; Odontoblast ; Scaffold ; Cytotoxicity ; Regeneration (biology) ; Nanoparticle ; Nanotechnology ; Chitosan ; Materials science ; Dentin ; Biomedical engineering ; Biochemistry ; Bacteria ; Cell biology ; In vitro ; Biology ; Composite material Dendrimers and Hyperbranched Polymers ; Collagen: Extraction and Characterization ; Periodontal Regeneration and Treatments
Authors: Jochen C. Lauer | Bernd Kohl | Felix Braun | Frank Röminger | Michael Mastalerz
Source: European Journal of Organic Chemistry (article, 2021-11-09)
Field: Chemistry — Organic Chemistry

A Hexagonal Shape‐Persistent Nanobelt of Elongated Rhombic Symmetry with Orthogonal π‐Planes by a One‐Pot Reaction Abstract Triptycenes with their predefined D 3h ‐symmetry are excellent molecular building blocks to construct shape‐persistent nanobelts having π‐orbitals orthogonal to the ring plane. However, up to now, there are only a very few examples of fused and rigid iptycene nanobelts synthesized in several consecutive steps in overall yields below 1 %. Here we present the simple one‐step one‐pot approach to an iptycene nanobelt, which forms in &gt;2 % and can readily be isolated from the polymeric by‐product by gel‐permeation chromatography. Symmetry (geometry) ; Chemistry ; Hexagonal crystal system ; Crystallography ; Product (mathematics) ; Ring (chemistry) ; Plane (geometry) ; Simple (philosophy) ; Atomic orbital ; Geometry ; Organic chemistry ; Physics ; Mathematics ; Quantum mechanics Synthesis and Properties of Aromatic Compounds ; Supramolecular Chemistry and Complexes ; Supramolecular Self-Assembly in Materials
Authors: Hongna Zhang | Ian Weiss | Indranil Rudra | Won Jun Jo | Simon Kellner | Georgios Katsoukis | Elena Galoppini | Heinz Frei
Source: ACS Applied Materials & Interfaces (article, 2021-05-13)
Field: Materials Science — Materials Chemistry

Controlling and Optimizing Photoinduced Charge Transfer across Ultrathin Silica Separation Membrane with Embedded Molecular Wires for Artificial Photosynthesis Ultrathin amorphous silica membranes with embedded organic molecular wires (oligo(<i>p</i>-phenylenevinylene), three aryl units) provide chemical separation of incompatible catalytic environments of CO<sub>2</sub> reduction and H<sub>2</sub>O oxidation while maintaining electronic and protonic coupling between them. For an efficient nanoscale artificial photosystem, important performance criteria are high rate and directionality of charge flow. Here, the visible-light-induced charge flow from an anchored Ru bipyridyl light absorber across the silica nanomembrane to Co<sub>3</sub>O<sub>4</sub> water oxidation catalyst is quantitatively evaluated by photocurrent measurements. Charge transfer rates increase linearly with wire density, with 5 nm<sup>-2</sup> identified as an optimal target. Accurate measurement of wire and light absorber densities is accomplished by the polarized FT-IRRAS method. Guided by density functional theory (DFT) calculations, four wire derivatives featuring electron-donating (methoxy) and -withdrawing groups (sulfonate, perfluorophenyl) with highest occupied molecular orbital (HOMO) potentials ranging from 1.48 to 0.64 V vs NHE were synthesized and photocurrents evaluated. Charge transfer rates increase sharply with increasing driving force for hole transfer from the excited light absorber to the embedded wire, followed by a decrease as the HOMO potential of the wire moves beyond the Co<sub>3</sub>O<sub>4</sub> valence band level toward more negative values, pointing to an optimal wire HOMO potential around 1.3 V vs NHE. Comparison with photocurrents of samples without nanomembrane indicates that silica layers with optimized wires are able to approach undiminished electron flux at typical solar intensities. Combined with the established high proton conductivity and small-molecule blocking property, the charge transfer measurements demonstrate that oxidation and reduction catalysis can be efficiently integrated on the nanoscale under separation by an ultrathin silica membrane. Materials science ; Photocurrent ; Molecular wire ; Artificial photosynthesis ; Density functional theory ; Electron transfer ; Membrane ; Photochemistry ; HOMO/LUMO ; Chemical physics ; Molecule ; Optoelectronics ; Catalysis ; Photocatalysis ; Computational chemistry ; Chemistry ; Organic chemistry Porphyrin and Phthalocyanine Chemistry ; Molecular Junctions and Nanostructures ; CO2 Reduction Techniques and Catalysts
Authors: Daniel M. Balazs | N. Deniz Erkan | Michelle Quien | Tobias Hanrath
Source: Nano Research (article, 2021-12-28)
Field: Materials Science — Materials Chemistry

Inkjet printing of epitaxially connected nanocrystal superlattices Access to a blossoming library of colloidal nanomaterials provides building blocks for complex assembled materials. The journey to bring these prospects to fruition stands to benefit from the application of advanced processing methods. Epitaxially connected nanocrystal (or quantum dot) superlattices present a captivating model system for mesocrystals with intriguing emergent properties. The conventional processing approach to creating these materials involves assembling and attaching the constituent nanocrystals at the interface between two immiscible fluids. Processing small liquid volumes of the colloidal nanocrystal solution involves several complexities arising from the concurrent spreading, evaporation, assembly, and attachment. The ability of inkjet printers to deliver small (typically picoliter) liquid volumes with precise positioning is attractive to advance fundamental insights into the processing science, and thereby potentially enable new routes to incorporate the epitaxially connected superlattices into technology platforms. In this study, we identified the processing window of opportunity, including nanocrystal ink formulation and printing approach to enable delivery of colloidal nanocrystals from an inkjet nozzle onto the surface of a sessile droplet of the immiscible subphase. We demonstrate how inkjet printing can be scaled-down to enable the fabrication of epitaxially connected superlattices on patterned sub-millimeter droplets. We anticipate that insights from this work will spur on future advances to enable more mechanistic insights into the assembly processes and new avenues to create high-fidelity superlattices. Nanocrystal ; Nanotechnology ; Superlattice ; Materials science ; Epitaxy ; Quantum dot ; Fabrication ; Nanomaterials ; Inkwell ; Optoelectronics ; Layer (electronics) Quantum Dots Synthesis And Properties ; Pickering emulsions and particle stabilization ; Nanomaterials and Printing Technologies
Authors: Andrea Daolio | Andrea Pizzi | Giancarlo Terraneo | Maurizio Ursini | Antonio Frontera | Giuseppe Resnati
Source: Angewandte Chemie (article, 2021-04-20)
Field: Chemistry — Physical and Theoretical Chemistry

Anion⋅⋅⋅Anion Coinage Bonds: The Case of Tetrachloridoaurate Abstract Interactions in crystalline tetrachloridoaurates of acetylcholine and dimethylpropiothetine are characterized by Au ⋅⋅⋅ Cl and Au ⋅⋅⋅ O short contacts. The former interactions assemble the AuCl 4 − units into supramolecular anionic polymers, while the latter interactions append the acetylcholine and propiothetine units to the polymer. The distorted octahedral geometry of the bonding pattern around the gold center is rationalized on the basis of the anisotropic distribution of the electron density, which enables gold to behave as an electrophile (π‐hole coinage‐bond donor). Computational studies prove that gold atoms in negatively charged species can function as acceptors of electron density. The attractive nature of the Au ⋅⋅⋅ Cl/O interactions described here complement the known aurophilic bonds involved in gold‐centered interactions. Supramolecular chemistry ; Chemistry ; Crystallography ; Ion ; Polymer ; Octahedron ; Electrophile ; Chemical physics ; Counterion ; Computational chemistry ; Crystal structure ; Organic chemistry Crystallography and molecular interactions ; Metal complexes synthesis and properties ; Organometallic Compounds Synthesis and Characterization
Authors: Réka Mokrai | Rózsa Szűcs | Matthew P. Duffy | Vincent Dorcet | Thierry Roisnel | Zoltán Benkő | László Nyulászi | Pierre‐Antoine Bouit | Muriel Hissler
Source: New Journal of Chemistry (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

Topologically diverse polycyclic aromatic hydrocarbons from pericyclic reactions with polyaromatic phospholes Topologically divers PAHs with planar, twisted and negatively curved topologies were obtained from polycyclic phospholes using pericyclic reactions. Pericyclic reaction ; Chemistry ; Computational chemistry ; Photochemistry Synthesis and Properties of Aromatic Compounds ; Graph theory and applications ; Axial and Atropisomeric Chirality Synthesis