jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Pieter J. Swarts | Jeanet Conradie
Source: Molecules (article, 2020-06-01)
Field: Materials Science — Materials Chemistry

Synthesis, Spectroscopy, Electrochemistry and DFT of Electron-Rich Ferrocenylsubphthalocyanines A series of novel ferrocenylsubphthalocyanine dyads Y-BSubPc(H)<sub>12</sub> with ferrocenyl-carboxylic acids Y-H = (FcCH<sub>2</sub>CO<sub>2</sub>-H), (Fc(CH<sub>2</sub>)<sub>3</sub>CO<sub>2</sub>-H) or (FcCO(CH<sub>2</sub>)<sub>2</sub>CO<sub>2</sub>-H) in the axial position were synthesized from the parent Cl-BSubPc(H)<sub>12</sub> via an activated triflate-SubPc intermediate. UV/Vis data revealed that the axial ferrocenyl-containing ligand did not influence the Q-band maxima compared to Cl-BSubPc(H)<sub>12</sub>. A combined electrochemical and density functional theory (DFT) study showed that Fe group of the ferrocenyl-containing axial ligand is involved in the first reversible oxidation process, followed by a second oxidation localized on the macrocycle of the subphthalocyanine. Both observed reductions were ring-based. It was found that the novel Fc(CH<sub>2</sub>)<sub>3</sub>CO<sub>2</sub>BSubPc(H)<sub>12</sub> exhibited the lowest first macrocycle-based reduction potential (-1.871 V vs. Fc/Fc<sup>+</sup>) reported for SubPcs till date. The oxidation and reduction values of Fc(CH<sub>2</sub>)<sub>n</sub>CO<sub>2</sub>BSubPc(H)<sub>12</sub> (<i>n</i> = 0-3), FcCO(CH<sub>2</sub>)<sub>2</sub>CO<sub>2</sub>BSubPc(H)<sub>12</sub>, and Cl-BSubPc(H)<sub>12</sub> illustrated the electronic influence of the carboxyl group, the different alkyl chains and the ferrocenyl group in the axial ligand on the ring-based oxidation and reduction values of the SubPcs. Chemistry ; Electrochemistry ; Ligand (biochemistry) ; Trifluoromethanesulfonate ; Ring (chemistry) ; Crystallography ; Density functional theory ; Alkyl ; Redox ; Medicinal chemistry ; Stereochemistry ; Physical chemistry ; Inorganic chemistry ; Computational chemistry ; Organic chemistry ; Catalysis Porphyrin and Phthalocyanine Chemistry ; Surface Chemistry and Catalysis ; Molecular Junctions and Nanostructures
Authors: Xuefeng Yong | Weiwei Gao | Xiulian Lin | Chun‐Yu Ho
Source: Communications Chemistry (article, 2020-04-30)
Field: Chemistry — Organic Chemistry

NHC-Ni catalyzed 1,3- and 1,4-diastereodivergent heterocycle synthesis from hetero-substituted enyne Diastereodivergent heterocycle synthesis has been recognized as an important tool for drug discovery in recent years, yet strategies based on nickelacycle formation have not been established. Here, we report a NHC-Ni catalyzed highly 1,3- and 1,4-diastereodivergent heterocycle synthesis from enyne, which is achieved by manipulating the enyne N-substituent (allowing switching of selectivity from up to 2:98 to 98:2). The key to success is the efficient diastereodivergent formation of a nickelacyclopentene, with broad enyne scope at mild conditions, which subsequently provides reductive hydroalkenylation, acylation and silylation products on demand. Diastereoisomers which are sterically hard to distinguish or difficult to access by conventional routes are now accessible easily, including those with very similar 4°, contiguous and skipped stereocenters. Enyne ; Stereocenter ; Chemistry ; Substituent ; Catalysis ; Steric effects ; Acylation ; Combinatorial chemistry ; Stereochemistry ; Organic chemistry ; Enantioselective synthesis Catalytic Cross-Coupling Reactions ; Synthetic Organic Chemistry Methods ; Catalytic Alkyne Reactions
Authors: John C. Mergo | Jong Seto
Source: Frontiers in Materials (article, 2020-04-08)
Field: Materials Science — Biomaterials

On Simulating the Formation of Structured, Crystalline Systems via Non-classical Pathways Observations in crystal growth and assembly from recent in situ methods suggest alternative, non-classical crystallization pathways play an important role in the determination of the micro- and meso- structures in crystalline systems. These processes display parallels that cross-cut multiple disciplines investigating crystallization across four orders of magnitude in size scales and widely differing environments, hinting that alternative crystal growth pathways may be a fundamental scheme in natural crystal formation. Using a system of short-range attractive microbeads, we demonstrate that the addition of a small concentration of sub-species incommensurate with the lattice spacing of the dominant species results in a stark change in crystal size and morphology. These changes are attributed to the presence of fleeting, amorphous-like configurations of beads that ultimately change the melting and growth dynamics in preferred directions. From these real-time observations, we hypothesize the amorphous mineral precursors present in biological mineralized tissues undergo similar non-classical crystallization processes resulting in the complex structures found in biomineralization. Crystallization ; Biomineralization ; Amorphous solid ; Chemical physics ; Crystal growth ; Crystal (programming language) ; Materials science ; Molecular dynamics ; Nanotechnology ; Crystallography ; Chemistry ; Chemical engineering ; Computational chemistry ; Computer science Calcium Carbonate Crystallization and Inhibition ; Paleontology and Stratigraphy of Fossils ; Crystallization and Solubility Studies
Authors: Croix J. Laconsay | Dean J. Tantillo
Source: ChemRxiv (preprint, 2020-11-03)
Field: Chemistry — Organic Chemistry

Metal-Bound or Free Ylides as Reaction Intermediates in Metal-Catalyzed [2,3]-Sigmatropic Rearrangements? It Depends. Density functional theory calculations were applied to study four previously published metal-catalyzed [2,3]-rearrangements from onium ylide intermediates, in pursuit of generalizations about when, during these types of reactions, catalysts dissociate. Our results corroborate past studies where free ylide mechanisms were proposed to be operative. Calculations on case studies predict that the origin of metal-catalyst ‘falling off’ (dissociation) can be attributed primarily to the steric bulkiness of functional groups adjacent to the carbene carbon. Ylide ; Carbene ; Catalysis ; Chemistry ; Steric effects ; Density functional theory ; Sigmatropic reaction ; Metal ; Dissociation (chemistry) ; Onium ; Photochemistry ; Computational chemistry ; Medicinal chemistry ; Organic chemistry Cyclopropane Reaction Mechanisms ; Asymmetric Synthesis and Catalysis ; Synthetic Organic Chemistry Methods
Authors: Mario D. Martínez | Diego Ariel Riva | Cybele C. Garcı́a | Fernando Durán | Gerardo Burton
Source: Molecules (article, 2020-02-12)
Field: Chemistry — Organic Chemistry

Synthesis and Antibacterial Activity of Difluoromethyl Cinnamoyl Amides Series of novel amides of isoferulic acid, where the phenolic hydroxyl was replaced by a difluoromethyl group, were synthesized and their in vitro antibacterial activities assayed against fourteen bacterial strains (six Gram-positive and eight Gram-negative). A one-pot methodology was developed to obtain the 3'-(difluoromethyl)-4'-methoxycinnamoyl amides using Deoxofluor<sup>®</sup> as a fluorinating agent. The <i>N</i>-isopropyl, <i>N</i>-isopentyl, and <i>N</i>-(2-phenylethyl) amides <b>11b</b>, <b>11d</b> and <b>11g</b> were the most active and selective against <i>Mycobacterium smegmatis</i> (MIC = 8 µg/mL) with <b>11b</b> and <b>11g</b> displaying negligible or no cytotoxicity against HepG2 and A549 cells. Thirteen analogs of <i>N</i>-isopropylamide <b>11b</b> were also synthesized and their antibacterial activity assayed. Results show that the difluoromethyl moiety enhanced antibacterial activity and selectivity towards <i>M. smegmatis</i><i>,</i> changing the microorganism inhibition profile of the parent compound. The selectivity exhibited by some of the compounds towards <i>M. smegmatis</i> makes them potential leads in the search for new narrow spectrum antibiotics against <i>M. tuberculosis</i>. Moiety ; Chemistry ; Antibacterial activity ; Isopropyl ; Selectivity ; Mycobacterium smegmatis ; Stereochemistry ; Cytotoxicity ; In vitro ; Mycobacterium tuberculosis ; Combinatorial chemistry ; Bacteria ; Organic chemistry ; Biochemistry ; Tuberculosis ; Biology Synthesis and Biological Evaluation ; Fluorine in Organic Chemistry ; Fungal Plant Pathogen Control
Authors: Valeria Nori | Antonio Arcadi | Armando Carlone | Fabio Marinelli | Marco Chiarini
Source: Beilstein Journal of Organic Chemistry (article, 2020-05-20)
Field: Chemistry — Organic Chemistry

Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1( <i>2H</i> )-ones Cascade cyclocarbopalladation of the readily available aryl/alkyl-substituted propargylic amides containing an aryl iodide moiety, followed by Suzuki-Miyaura coupling with arylboronic acids, allowed an efficient regio- and stereoselective synthesis of tetrasubstituted 4-methylene-3,4-dihydroisoquinolin-1(2<i>H</i>)-ones. Moreover, cascade cyclocarbopalladation, followed by the reaction with 2-alkynyltrifluoroacetanilides, accomplished a double cyclization to afford challenging 4-methylene-3,4-dihydroisoquinolin-1(2<i>H</i>)-ones bearing a 3-indolyl substituent through aminopalladation/reductive elimination. Chemistry ; Stereoselectivity ; Moiety ; Methylene ; Aryl ; Iodide ; Substituent ; Palladium ; Alkyl ; Catalysis ; Medicinal chemistry ; Coupling reaction ; Combinatorial chemistry ; Stereochemistry ; Organic chemistry Chemical synthesis and alkaloids ; Catalytic C–H Functionalization Methods ; Catalytic Alkyne Reactions
Authors: Debora Caprara | Francesca Ripanti | Angela Capocefalo | Marina Ceccarini | C. Petrillo | P. Postorino
Source: International Journal of Biological Macromolecules (article, 2020-12-28)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Exploiting SERS sensitivity to monitor DNA aggregation properties DNA ; Raman spectroscopy ; Surface-enhanced Raman spectroscopy ; Nanotechnology ; Plasmon ; Base pair ; Chemistry ; Nanoscopic scale ; Nanoparticle ; Oligonucleotide ; Hybridization probe ; Materials science ; Raman scattering ; Physics ; Optoelectronics ; Biochemistry Gold and Silver Nanoparticles Synthesis and Applications ; Advanced biosensing and bioanalysis techniques ; Biosensors and Analytical Detection
Authors: Yasmine Grooten | Petra Riasová | Inês Isabel Ganco Salsinha | Debby Mangelings | Yvan Vander Heyden
Source: Analytical and Bioanalytical Chemistry (article, 2020-06-12)
Field: Chemistry — Spectroscopy

Stationary-phase optimized selectivity in supercritical fluid chromatography using a customized Phase OPtimized Liquid Chromatography kit: comparison of different prediction approaches Supercritical fluid chromatography ; Chromatography ; Chemistry ; Phase (matter) ; High-performance liquid chromatography ; Selectivity ; Elution ; Reversed-phase chromatography ; Stationary phase ; Supercritical fluid ; Analytical Chemistry (journal) ; Organic chemistry Analytical Chemistry and Chromatography ; Chromatography in Natural Products ; Microfluidic and Capillary Electrophoresis Applications
Authors: Daniel Andres‐Penares | Rodolfo Canet-Albiach | Jaume Noguera‐Gómez | Juan P. Martínez‐Pastor | Rafael Abargues | Juan F. Sánchez‐Royo
Source: Nanomaterials (article, 2020-07-18)
Field: Materials Science — Materials Chemistry

Two-Dimensional Indium Selenide for Sulphur Vapour Sensing Applications Surface-to-volume ratio in two-dimensional (2D) materials highlights among their characteristics as an inherent and intrinsic advantage taking into account their strong sensitivity to surface effects. For this reason, we have proposed in this work micromechanically exfoliated 2D nanosheets of InSe as an optical vapour sensor. As a proof of concept, we used 2-mercaptoethanol as the chemical analyte in vapour phase to monitor the change of the InSe photoluminescence (PL) before and after exposure to the analyte. For short vapour exposure times (at low analyte concentration), we found a PL enhancement of InSe nanosheets attributed to the surface localization of Se defects. For long vapour exposure times (or higher concentrations) a PL reduction is observed, probably due to the diffusion of molecules within the nanosheet. These results confirm the capability of 2D InSe as a photoluminescent sensor of vapours, because of its sensitivity to surface passivation or volume diffusion of molecules. Analyte ; Passivation ; Materials science ; Photoluminescence ; Indium ; Selenide ; Nanosheet ; Diffusion ; Vapours ; Molecule ; Nanotechnology ; Analytical Chemistry (journal) ; Chemical engineering ; Optoelectronics ; Chemistry ; Physical chemistry ; Layer (electronics) ; Organic chemistry 2D Materials and Applications ; Nanowire Synthesis and Applications ; Gas Sensing Nanomaterials and Sensors
Authors: Sayanti Chatterjee | Sridhar Banerjee | Rahul Dev Jana | Shrabanti Bhattacharya | Biswarup Chakraborty | Sergio A. V. Jannuzzi
Source: Dalton Transactions (article, 2020-12-23)
Field: Chemistry — Inorganic Chemistry

Tuning the stereoelectronic factors of iron(<scp>ii</scp>)-2-aminophenolate complexes for the reaction with dioxygen: oxygenolytic C–C bond cleavage <i>vs</i>. oxidation of complex Oxidative C-C bond cleavage of 2-aminophenols mediated by transition metals and dioxygen is a topic of great interest. While the oxygenolytic C-C bond cleavage reaction relies on the inherent redox non-innocent property of 2-aminophenols, the metal complexes of 2-aminophenolates often undergo 1e-/2e- oxidation events (metal or ligand oxidation), instead of the direct addition of O2 for subsequent C-C bond cleavage. In this work, we report the isolation, characterization and dioxygen reactivity of a series of ternary iron(ii)-2-aminophenolate complexes [(TpPh,Me)FeII(X)], where X = 2-amino-4-tert-butylphenolate (4-tBu-HAP) (1); X = 2-amino-4,6-di-tert-butylphenolate (4,6-di-tBu-HAP) (2); X = 2-amino-4-nitrophenolate (4-NO2-HAP)(3); and X = 2-anilino-4,6-di-tert-butylphenolate (NH-Ph-4,6-di-tBu-HAP) (4) supported by a facial tridentate nitrogen donor ligand (TpPh,Me = hydrotris(3-phenyl-5-methylpyrazol-1-yl)borate). Another facial N3 ligand (TpPh2 = hydrotris(3,5-diphenyl-pyrazol-1-yl)borate) has been used to isolate an iron(ii)-2-anilino-4,6-di-tert-butylphenolate complex (5) for comparison. Both [(TpPh,Me)FeII(4-tBu-HAP)] (1) and [(TpPh,Me)FeII(4,6-di-tBu-HAP)] (2) undergo regioselective oxidative aromatic ring fission reaction of the coordinated 2-aminophenols to the corresponding 2-picolinic acids in the reaction with dioxygen. In contrast, complex [(TpPh,Me)FeII(4-NO2-HAP)] (3) displays metal based oxidation to form an iron(iii)-2-amidophenolate complex. Complexes [(TpPh,Me)FeII(NH-Ph-4,6-di-tBu-HAP)] (4) and [(TpPh2)FeII(NH-Ph-4,6-di-tBu-HAP)] (5) react with dioxygen to undergo 2e- oxidation with the formation of the corresponding iron(iii)-2-iminobenzosemiquinonato radical species implicating the importance of the -NH2 group in directing the C-C bond cleavage reactivity of 2-aminophenols. The systematic study presented in this work unravels the effect of the electronic and structural properties of the redox non-innocent 2-aminophenolate ring and the supporting ligand on the C-C bond cleavage reactivity vs. the metal/ligand oxidation of the complexes. The study further reveals that proper modulation of the stereoelectronic factors enables us to design a well synchronised proton transfer (PT) and dioxygen binding events for complexes 1 and 2 that mimic the structure and function of the nonheme enzyme 2-aminophenol-1,6-dioxygenase (APD). Cleavage (geology) ; Chemistry ; Bond cleavage ; Stereochemistry ; Medicinal chemistry ; Catalysis ; Biochemistry ; Materials science Metal-Catalyzed Oxygenation Mechanisms ; Metal complexes synthesis and properties ; Porphyrin and Phthalocyanine Chemistry
Authors: Paula Kayser | Federico Serrano‐Sánchez | Óscar J. Durá | François Fauth | J. A. Alonso
Source: Journal of Materials Chemistry C (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Experimental corroboration of the thermoelectric performance of Bi<sub>2</sub>PdO<sub>4</sub> oxide and Pb-doped derivatives Predicted thermoelectric behaviour in Bi<sub>2</sub>PdO<sub>4</sub> is experimentally realized. Pb doping enhances the power factor, with additional reduction of thermal conductivity. Materials science ; Thermoelectric effect ; Doping ; Oxide ; Thermoelectric materials ; Nanotechnology ; Analytical Chemistry (journal) ; Engineering physics ; Chemical engineering ; Metallurgy ; Thermodynamics ; Optoelectronics ; Thermal conductivity ; Environmental chemistry ; Composite material ; Physics ; Chemistry Advanced Thermoelectric Materials and Devices ; Magnetic and transport properties of perovskites and related materials ; Gas Sensing Nanomaterials and Sensors
Authors: Alex James | Robert Dawson
Source: Macromolecular Rapid Communications (article, 2020-05-25)
Field: Materials Science — Materials Chemistry

Efficient and Tunable White‐Light Emission Using a Dispersible Porous Polymer A dispersible porous polymer (PEG<sub>113</sub> -b-DVB<sub>800</sub> -co-AA<sub>200</sub> ) based on the controlled radical polymerization of divinylbenzene and acrylic acid with a poly(ethylene glycol) (PEG) macrochain transfer agent (macro-CTA) is synthesized and postsynthetically modified with anthracene. This blue-emitting porous polymer is used to encapsulate the yellow-emitting fluorophore rhodamine B into its core, resulting in a white-light emitting dispersion with a quantum yield of 38% and commission internationale de l'éclairage coordinates of (X = 0.33, Y = 0.32). Materials science ; Quantum yield ; Divinylbenzene ; Polymer ; Fluorophore ; Copolymer ; Ethylene glycol ; Polymerization ; Rhodamine ; Polymer chemistry ; PEG ratio ; Acrylic acid ; Atom-transfer radical-polymerization ; Chemical engineering ; Porosity ; Rhodamine B ; Fluorescence ; Chemistry ; Photocatalysis ; Organic chemistry ; Styrene ; Composite material ; Catalysis ; Optics Covalent Organic Framework Applications ; Luminescence and Fluorescent Materials ; Perovskite Materials and Applications
Authors: Hebatallah M. Essam | Martin N. Saad | Eman S. Elzanfaly | Sawsan M. Amer
Source: Acta Chromatographica (article, 2020-07-22)
Field: Chemistry — Analytical Chemistry

Optimization and validation of Eco-friendly RP-HPLC and univariate spectrophotometric methods for the simultaneous determination of Fluorometholone and Tetrahydrozoline hydrochloride Abstract A sensitive RP-HPLC method is presented for the simultaneous quantification of Fluorometholone (FLM) and Tetrahydrozoline hydrochloride (THZ). The method has the advantages of being rapid, accurate, reproducible, ecologically acceptable and sensitive. The separation utilized C 8 Xbridge® column and mobile phase mixture of Acetonitrile/phosphate buffer pH 3 ± 0.1 (70:30, v/v) with UV detection at 230 nm. Stepwise optimization and factors affecting separation are properly discussed. Different factors were optimized such as stationary phase, selection of organic solvent and its content, buffer pH and concentration, flow rate, elution type and detection wavelength. The studied drugs were efficiently separated in 3.4 min with high resolution. Also, two univariate spectrophotometric methods have been optimized for the quantification of the studied drugs. Method 1: dual wavelength for THZ and iso-absorptive point for FLM, Method 2: ratio difference (RD) for THZ and first derivative FLM utilizing methanol as a solvent. These methods are accurate, precise with minimal data manipulation. Greenness of the methods was estimated using eco-scale tool where the presented methods were found to be excellent green with eco-score of 83 for HPLC and 80 for spectrophotometry. The methods are validated in conformance with ICH guidelines, with acceptable accuracy, precision, and selectivity. The suggested methods can be employed for the economic analysis of THZ and FLM in their pure form and binary ophthalmic formulation, that can be employed by quality control laboratories. Chemistry ; Chromatography ; High-performance liquid chromatography ; Resolution (logic) ; Pharmaceutical formulation ; Accuracy and precision ; Solvent ; Acetonitrile ; Selectivity ; Phosphate buffered saline ; Spectrophotometry ; Analytical Chemistry (journal) Analytical Methods in Pharmaceuticals ; Analytical Chemistry and Chromatography ; Analytical Chemistry and Sensors
Authors: Ana S. Luís | Chunsheng Jin | Gabriel Vasconcelos Pereira | Robert W. P. Glowacki | Sadie R. Gugel | Shaleni Singh | Dominic P. Byrne | Nicholas A. Pudlo | James A. London | Arnaud Baslé | Mark Reihill | Stefan Oscarson | Patrick A. Eyers | Mirjam Czjzek | Gurvan Michel | Tristan Barbeyron | Edwin A. Yates | Gunnar C. Hansson | Niclas G. Karlsson | Alan Cartmell | Eric C. Martens
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2020-11-21)
Field: Chemistry — Organic Chemistry

A single bacterial sulfatase is required for metabolism of colonic mucin <i>O</i> -glycans and intestinal colonization by a symbiotic human gut bacterium Summary Humans have co-evolved with a dense community of microbial symbionts that inhabit the lower intestine. In the colon, secreted mucus creates a physical barrier that separates these microbes from the intestinal epithelium. Some gut bacteria are able to utilize mucin glycoproteins, the main mucus component, as a nutrient source. However, it remains unclear which bacterial enzymes initiate the degradation of the highly complex O -glycans found in mucins. In the colon, these glycans are heavily sulfated, but the specific sulfatases that are active on colonic mucins have not been identified. Here, we show that sulfatases are essential to the utilization of colonic mucin O -glycans by the human gut symbiont Bacteroides thetaiotaomicron . We have characterized the activity of 12 different sulfatases encoded by this species, showing that these enzymes collectively are active on all of the known sulfate linkages in colonic O -glycans. Crystal structures of 3 enzymes provide mechanistic insight into the molecular basis of substrate-specificity. Unexpectedly, we found that a single sulfatase is essential for utilization of sulfated O -glycans in vitro and also plays a major role in vivo . Our results provide insight into the mechanisms of mucin degradation by gut bacteria, an important process for both normal microbial gut colonization and diseases such as inflammatory bowel disease (IBD). Sulfatase activity is likely to be a keystone step in bacterial mucin degradation and inhibition of these enzymes may therefore represent a viable therapeutic path for treatment of IBD and other diseases. Mucin ; Glycan ; Microbiology ; Sulfatase ; Biology ; Mucus ; Bacteria ; Bacteroides thetaiotaomicron ; Enzyme ; Intestinal mucosa ; Bacteroides ; Glycoprotein ; Biochemistry ; Medicine Carbohydrate Chemistry and Synthesis ; Microbial Metabolites in Food Biotechnology ; Probiotics and Fermented Foods