jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Min Chen | Changle Chen
Source: Chinese Journal of Chemistry (article, 2019-12-16)
Field: Materials Science — Biomaterials

Controlling the Ring‐Opening Polymerization Process Using External Stimuli Through the incorporation of stimuli‐responsive units, the properties of ring‐opening polymerization catalysts can be efficiently modulated using external stimuli. This article summarizes some of the recently reported strategies that control the ring‐opening polymerization of cyclic type monomers, using allosteric, redox, Lewis acid/base, supramolecular, electrochemical and light stimuli. These strategies enable the fine tuning of the polymerization process and the microstructure/composition of the final polymeric products. Chemistry ; Polymerization ; Monomer ; Ring (chemistry) ; Polymer chemistry ; Catalysis ; Supramolecular chemistry ; Photochemistry ; Chemical engineering ; Combinatorial chemistry ; Polymer ; Organic chemistry ; Molecule biodegradable polymer synthesis and properties ; Carbon dioxide utilization in catalysis ; Advanced Polymer Synthesis and Characterization
Authors: Zhuxiu Zhang | Yue Xiao | Mifen Cui | Jihai Tang | Zhaoyang Fei | Qing Liu | Xian Chen | Xu Qiao
Source: Dalton Transactions (article, 2019-01-01)
Field: Chemistry — Inorganic Chemistry

Modulating the basicity of Zn-MOF-74 <i>via</i> cation exchange with calcium ions The fine-tuning of metal-based molecular building blocks in Zn-MOF-74 through post-synthetic cation exchange with Ca2+ significantly enhances its basicity and corresponding catalytic performance. The resulting material, exemplified by Ca/Zn-MOF-74, is shown through Knoevenagel condensation to give an improved product yield over the parent Zn-MOF-74 and Ni/Zn-MOF-74. Chemistry ; Knoevenagel condensation ; Yield (engineering) ; Ion exchange ; Calcium ; Inorganic chemistry ; Zinc ; Ion ; Condensation ; Nuclear chemistry ; Catalysis ; Organic chemistry ; Materials science ; Metallurgy Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Chemical Synthesis and Characterization
Authors: Marcelo Echeverri | Sergio Gámez‐Valenzuela | Rafael C. González‐Cano | Jordy Guadalupe | Sandra Cortijo-Campos | Juan T. López Navarrete | Marta Iglesias | M. Carmen Ruiz Delgado | Berta Gómez‐Lor
Source: Chemistry of Materials (article, 2019-07-02)
Field: Materials Science — Materials Chemistry

Effect of the Linkage Position on the Conjugation Length of Truxene-Based Porous Polymers: Implications for Their Sensing Performance of Nitroaromatics Four highly porous truxene-based organic polymers have been synthesized via C–C cross coupling methodologies (under Yamamoto and Suzuki–Miyaura conditions) starting from two different brominated hexamethyltruxene isomers (2,7,12- and 3,8,13-tribromohexamethyltruxene). We have found that the linkage position in these polymers has a strong influence not only on the porosity but also on the absorption and light emitting properties of the final materials. We have performed a joint theoretical and experimental investigation to shed light on the role of the positional isomeric effect of the monomers on the degree of π-conjugation of the final materials. Our study indicates that the 2,7,12 linkage significantly enhances the electronic communication between the covalently linked building units, thus strongly influencing the conjugation length and the position of the energy levels of the final materials. The result of this work provides us with a new design tool to fine-tune the electronic properties of conjugated porous polymers with important implications for their potential applications, as demonstrated by their sensing performance for the detection of nitroaromatic compounds. Polymer ; Conjugated system ; Monomer ; Materials science ; Covalent bond ; Porosity ; Linkage (software) ; Absorption (acoustics) ; Porous medium ; Chemical engineering ; Chemistry ; Organic chemistry ; Composite material Covalent Organic Framework Applications ; Luminescence and Fluorescent Materials ; Metal-Organic Frameworks: Synthesis and Applications
Authors: Vytor Oliveira | Bruna L. Marcial | Francisco B. C. Machado | Elfi Kraka
Source: Materials (article, 2019-12-20)
Field: Chemistry — Physical and Theoretical Chemistry

Metal–Halogen Bonding Seen through the Eyes of Vibrational Spectroscopy Incorporation of a metal center into halogen-bonded materials can efficiently fine-tune the strength of the halogen bonds and introduce new electronic functionalities. The metal atom can adopt two possible roles: serving as halogen acceptor or polarizing the halogen donor and acceptor groups. We investigated both scenarios for 23 metal-halogen dimers trans-M(Y<sub>2</sub>)(NC<sub>5</sub>H<sub>4</sub>X-3)<sub>2</sub> with M = Pd(II), Pt(II); Y = F, Cl, Br; X = Cl, Br, I; and NC<sub>5</sub>H<sub>4</sub>X-3 = 3-halopyridine. As a new tool for the quantitative assessment of metal-halogen bonding, we introduced our local vibrational mode analysis, complemented by energy and electron density analyses and electrostatic potential studies at the density functional theory (DFT) and coupled-cluster single, double, and perturbative triple excitations (CCSD(T)) levels of theory. We could for the first time quantify the various attractive contacts and their contribution to the dimer stability and clarify the special role of halogen bonding in these systems. The largest contribution to the stability of the dimers is either due to halogen bonding or nonspecific interactions. Hydrogen bonding plays only a secondary role. The metal can only act as halogen acceptor when the monomer adopts a (quasi-)planar geometry. The best strategy to accomplish this is to substitute the halo-pyridine ring with a halo-diazole ring, which considerably strengthens halogen bonding. Our findings based on the local mode analysis provide a solid platform for fine-tuning of existing and for design of new metal-halogen-bonded materials. Halogen bond ; Halogen ; Density functional theory ; Acceptor ; Ring (chemistry) ; Dimer ; Crystallography ; Chemistry ; Hydrogen bond ; Materials science ; Metal ; Computational chemistry ; Molecule ; Organic chemistry ; Physics Crystallography and molecular interactions ; Inorganic Fluorides and Related Compounds ; X-ray Diffraction in Crystallography
Authors: Gökçen Akgül | Daniel Iglesias | P. Ocón | Eduardo Moreno‐Jiménez
Source: BioEnergy Research (article, 2019-08-06)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Valorization of Tea-Waste Biochar for Energy Storage Biochar ; Pyrolysis ; Physisorption ; Fourier transform infrared spectroscopy ; Carbon fibers ; Chemical engineering ; Materials science ; Thermogravimetric analysis ; Environmentally friendly ; Biomass (ecology) ; Energy storage ; Chemistry ; Catalysis ; Organic chemistry ; Composite material Supercapacitor Materials and Fabrication ; Graphene research and applications ; Advancements in Battery Materials
Authors: Hemant Hegde | Chella Santhosh | Rajeev K. Sinha
Source: Materials Research Express (article, 2019-08-21)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Seed mediated synthesis of highly stable CTAB capped triangular silver nanoplates for LSPR sensing Triangular silver nanoplates synthesized using conventional method with trisodium citrate as capping agent shows degradation of its sharp edges over a period of time making them suitable for use only in a limited time-frame. In this work, we present a new approach to synthesize triangular nanoplates using seed mediated method and cetyltrimethylammonium bromide (CTAB) as a single capping agent in very low concentration of 0.4 mM. The seed nanoparticles as well as nanoplates synthesized in this work showed higher stability over an observation period of ten days. Also, the method allows the fine tuning of nanoplate size by tuning the seed volume in the synthesis process. The synthesized nanoplates were examined morphologically as well as through UV–vis spectroscopy utilizing lab-built setup. These nanoplates also show good bulk refractive index sensitivity of 167 nm/RIU for ∼45 nm edge length triangular nanoplates. Bromide ; Materials science ; Trisodium citrate ; Chemical engineering ; Template ; Nanotechnology ; Frame work ; Refractive index ; Degradation (telecommunications) ; Optoelectronics ; Inorganic chemistry ; Chemistry ; Computer science Gold and Silver Nanoparticles Synthesis and Applications ; Nanocluster Synthesis and Applications ; Advanced Nanomaterials in Catalysis
Authors: Marco Carroli | Duc T. Duong | Ester Buchaca-Domingo | Andrea Liscio | Karl Börjesson | Martin Herder | Vincenzo Palermo | Stefan Hecht | Natalie Stingelin | Alberto Salleo | Emanuele Orgiu | Paolo Samorı́
Source: Advanced Functional Materials (article, 2019-11-18)
Field: Materials Science — Materials Chemistry

The Role of Morphology in Optically Switchable Transistors Based on a Photochromic Molecule/p‐Type Polymer Semiconductor Blend Abstract The correlation between morphology and optoelectronic performance in organic thin‐film transistors based on blends of photochromic diarylethenes (DAE) and poly(3‐hexylthiophene) (P3HT) is investigated by varying molecular weight ( M w = 20–100 kDa) and regioregularity of the conjugated polymer as well as the temperature of thermal annealing (rt‐160 °C) in thin films. Semicrystalline architectures of P3HT/DAE blends comprise crystalline domains, ensuring efficient charge transport, and less aggregated regions, where DAEs are located as a result of their spontaneous expulsion from the crystalline domains during the self‐assembly. The best compromise between field‐effect mobility ( μ ) and switching capabilities is observed in blends containing P3HT with M w = 50 kDa, exhibiting μ as high as 1 × 10 −3 cm 2 V −1 s −1 combined with a &gt;50% photoswitching ratio. Higher or lower M w than 50 kDa are found to be detrimental for field‐effect mobility and to lead to reduced device current switchability. The microstructure of the regioregular P3HT blend is found to be sensitive to the thermal annealing temperature, with an increase in μ and a decrease in current modulation being observed as a response to the light‐stimulus likely due to an increased P3HT‐DAE segregation, partially hindering DAE photoisomerization. The findings demonstrate the paramount importance of fine tuning the structure and morphology of bicomponent films for leveraging the multifunctional nature of optoelectronic devices. Materials science ; Photochromism ; Annealing (glass) ; Optoelectronics ; Polymer ; Transistor ; Photoisomerization ; Crystallinity ; Thin film ; Chemical engineering ; Nanotechnology ; Isomerization ; Composite material ; Organic chemistry Photochromic and Fluorescence Chemistry ; Organic Electronics and Photovoltaics ; Advanced Memory and Neural Computing
Authors: Anna S. Vikulina | André G. Skirtach | Dmitry Volodkin
Source: Langmuir (review, 2019-02-06)
Field: Materials Science — Surfaces, Coatings and Films

Hybrids of Polymer Multilayers, Lipids, and Nanoparticles: Mimicking the Cellular Microenvironment Here we address research directions and trends developed following novel concepts in 2D/3D self-assembled polymer structures established in the department led by Helmuth Möhwald. These functional structures made of hybrids of polymer multilayers, lipids, and nanoparticles stimulated research in the design of the cellular microenvironment. The composition of the extracellular matrix (ECM) and dynamics of biofactor presentation in the ECM can be recapitulated by the hybrids. Proteins serve as models for protein-based biofactors such as growth factors, cytokines, hormones, and so forth. A fundamental understanding of complex intermolecular interactions and approaches developed for the externally IR-light-triggered release offers a powerful tool for controlling the biofactor presentation. Pure protein beads made via a mild templating on vaterite CaCO<sub>3</sub> crystals can mimic cellular organelles in terms of the compartmentalization of active proteins. We believe that an integration of the approaches developed and described here offers a strong tool for engineering and mimicking both extra- and intracellular microenvironments. Extracellular matrix ; Nanotechnology ; Nanoparticle ; Compartmentalization (fire protection) ; Chemistry ; Biophysics ; Materials science ; Biology ; Biochemistry Polymer Surface Interaction Studies ; Surface Modification and Superhydrophobicity ; Diatoms and Algae Research
Authors: Elisabetta Alberico | Saskia Möller | Moritz Horstmann | Hans‐Joachim Drexler | Detlef Heller
Source: Catalysts (article, 2019-06-30)
Field: Chemistry — Inorganic Chemistry

Activation, Deactivation and Reversibility Phenomena in Homogeneous Catalysis: A Showcase Based on the Chemistry of Rhodium/Phosphine Catalysts In the present work, the rich chemistry of rhodium/phosphine complexes, which are applied as homogeneous catalysts to promote a wide range of chemical transformations, has been used to showcase how the in situ generation of precatalysts, the conversion of precatalysts into the actually active species, as well as the reaction of the catalyst itself with other components in the reaction medium (substrates, solvents, additives) can lead to a number of deactivation phenomena and thus impact the efficiency of a catalytic process. Such phenomena may go unnoticed or may be overlooked, thus preventing the full understanding of the catalytic process which is a prerequisite for its optimization. Based on recent findings both from others and the authors’ laboratory concerning the chemistry of rhodium/diphosphine complexes, some guidelines are provided for the optimal generation of the catalytic active species from a suitable rhodium precursor and the diphosphine of interest; for the choice of the best solvent to prevent aggregation of coordinatively unsaturated metal fragments and sequestration of the active metal through too strong metal–solvent interactions; for preventing catalyst poisoning due to irreversible reaction with the product of the catalytic process or impurities present in the substrate. Rhodium ; Catalysis ; Phosphine ; Chemistry ; Homogeneous catalysis ; Solvent ; Organic chemistry ; Metal ; Combinatorial chemistry Asymmetric Hydrogenation and Catalysis ; Chemical Synthesis and Analysis ; Catalytic Cross-Coupling Reactions
Authors: Anna Rovira | Albert Gandioso | Marina Goñalons | Alex Galindo | Anna Massaguer | Manel Bosch | Vicente Marchán
Source: The Journal of Organic Chemistry (article, 2019-01-10)
Field: Chemistry — Organic Chemistry

Solid-Phase Approaches for Labeling Targeting Peptides with Far-Red Emitting Coumarin Fluorophores Fluorophores based on organic molecules hold great potential for ligand-targeted imaging applications, particularly those operating in the optical window in biological tissues. In this work, we have developed three straightforward solid-phase approaches based on amide-bond formation or a Cu(I)-catalyzed azide-alkyne click (CuAAC) reaction for labeling an octreotide peptide with far-red emitting coumarin-based COUPY dyes. First, the conjugatable versions of COUPY fluorophores incorporating the required functional groups (e.g., carboxylic acid, azide, or alkyne) were synthesized and characterized. All of them were found fully compatible with Fmoc/ tBu solid-phase peptide synthesis, which allowed for the labeling of octreotide either through amide-bond formation or by CuAAC reaction. A near quantitative conversion was obtained after only 1 h of reaction at RT when using CuSO<sub>4</sub> and sodium ascorbate independently of the click chemistry approach used (azido-COUPY/alkynyl-peptide resin or alkynyl-COUPY/azido-peptide resin). COUPY-octreotide conjugates were found stable in cell culture medium as well as noncytotoxic in HeLa cells, and their spectroscopic and photophysical properties were found similar to those of their parent coumarin dyes. Finally, the potential bioimaging applications of COUPY-octreotide conjugates were demonstrated by confocal microscopy through the visualization of living HeLa cells overexpressing the somatostatin subtype-2 receptor. Chemistry ; Click chemistry ; Peptide bond ; Combinatorial chemistry ; Peptide ; HeLa ; Conjugate ; Azide ; Alkyne ; Peptide synthesis ; Solid-phase synthesis ; Amide ; Coumarin ; Sodium azide ; Somatostatin receptor ; Phosphoramidite ; Organic chemistry ; Receptor ; Biochemistry ; Cell ; Catalysis ; Oligonucleotide Click Chemistry and Applications ; Monoclonal and Polyclonal Antibodies Research ; Nanoplatforms for cancer theranostics
Authors: Amine Achour | Mohammad Islam | Sorin Vizireanu | Iftikhar Ahmad | Muhammad Aftab Akram | Khalid Saeed | Gheorghe Dinescu | Jean‐Jacques Pireaux
Source: Nanomaterials (article, 2019-05-23)
Field: Materials Science — Materials Chemistry

Orange/Red Photoluminescence Enhancement Upon SF6 Plasma Treatment of Vertically Aligned ZnO Nanorods Although the origin and possible mechanisms for green and yellow emission from different zinc oxide (ZnO) forms have been extensively investigated, the same for red/orange PL emission from ZnO nanorods (nR) remains largely unaddressed. In this work, vertically aligned zinc oxide nanorods arrays (ZnO nR) were produced using hydrothermal process followed by plasma treatment in argon/sulfur hexafluoride (Ar/SF<sub>6</sub>) gas mixture for different time. The annealed samples were highly crystalline with ~45 nm crystallite size, (002) preferred orientation, and a relatively low strain value of 1.45 × 10<sup>-3</sup>, as determined from X-ray diffraction pattern. As compared to as-deposited ZnO nR, the plasma treatment under certain conditions demonstrated enhancement in the room temperature photoluminescence (PL) emission intensity, in the visible orange/red spectral regime, by a factor of 2. The PL intensity enhancement induced by SF<sub>6</sub> plasma treatment may be attributed to surface chemistry modification as confirmed by X-ray photoelectron spectroscopy (XPS) studies. Several factors including presence of hydroxyl group on the ZnO surface, increased oxygen level in the ZnO lattice (<i>O<sub>L</sub></i>), generation of F-OH and F-Zn bonds and passivation of surface states and bulk defects are considered to be active towards red/orange emission in the PL spectrum. The PL spectra were deconvoluted into component Gaussian sub-peaks representing transitions from conduction-band minimum (CBM) to oxygen interstitials (<i>O<sub>i</sub></i>) and CBM to oxygen vacancies (<i>V<sub>O</sub></i>) with corresponding photon energies of 2.21 and 1.90 eV, respectively. The optimum plasma treatment route for ZnO nanostructures with resulting enhancement in the PL emission offers strong potential for photonic applications such as visible wavelength phosphors. Nanorod ; Photoluminescence ; Materials science ; X-ray photoelectron spectroscopy ; Analytical Chemistry (journal) ; Crystallite ; Oxide ; Passivation ; Zinc ; Oxygen ; Nanotechnology ; Chemical engineering ; Chemistry ; Optoelectronics ZnO doping and properties ; Ga2O3 and related materials ; Gas Sensing Nanomaterials and Sensors
Authors: Francesco Copes | Pascale Chevallier | Caroline Loy | Daniele Pezzoli | Francesca Boccafoschi | Diego Mantovani
Source: Frontiers in Bioengineering and Biotechnology (article, 2019-04-09)
Field: Materials Science — Biomaterials

Heparin-Modified Collagen Gels for Controlled Release of Pleiotrophin: Potential for Vascular Applications A fast re-endothelialization, along with the inhibition of neointima hyperplasia, are crucial to reduce the failure of vascular bypass grafts. Implants modifications with molecules capable of speeding up the re-endothelialization process have been proposed over the last years. However, clinical trials of angiogenic factor delivery have been mostly disappointing, underscoring the need to investigate a wider array of angiogenic factors. In this work, a drug release system based on a type I collagen hydrogel has been proposed for the controlled release of Pleiotrophin (PTN), a cytokine known for its pro-angiogenetic effects. Heparin, in virtue of its ability to sequester, protect and release growth factors, has been used to better control the release of PTN. Performances of the PTN drug delivery system on endothelial (ECs) and smooth muscle cells (SMCs) have been investigated. Structural characterization (mechanical tests and immunofluorescent analyses of the collagen fibers) was performed on the gels to assess if heparin caused changes in their mechanical behavior. The release of PTN from the different gel formulations has been analyzed using a PTN-specific ELISA assay. Cell viability was evaluated with the Alamar Blue Cell Viability Assay on cells directly seeded on the gels (direct test) and on cells incubated with supernatant, containing the released PTN, obtained from the gels (indirect test). The effects of the different gels on the migration of both ECs and SMCs have been evaluated using a Transwell migration assay. Hemocompatibility of the gel has been assessed with a clotting/hemolysis test. Structural analyses showed that heparin did not change the structural behavior of the collagen gels. ELISA quantification demonstrated that heparin induced a constant release of PTN over time compared to other conditions. Both direct and indirect viability assays showed an increase in ECs viability while no effects were noted on SMCs. Cell migration results evidenced that the heparin/PTN-modified gels significantly increased ECs migration and decreased the SMCs one. Finally, heparin significantly increased the hemocompatibility of the collagen gels. In conclusion, the PTN-heparin-modified collagen here proposed can represent an added value for vascular medicine, able to ameliorate the biological performance, and integration of vascular grafts. Pleiotrophin ; Chemistry ; Viability assay ; Heparin ; Cell migration ; Cell biology ; Cell ; Growth factor ; Biochemistry ; Biology Collagen: Extraction and Characterization ; Proteoglycans and glycosaminoglycans research ; Protease and Inhibitor Mechanisms