jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Henrik H. Sønsteby | Ola Nilsen | Helmer Fjellvåg
Source: Global Challenges (article, 2019-08-01)
Field: Materials Science — Materials Chemistry

Chemical Uniformity in Ferroelectric K<i><sub>x</sub></i>Na<sub>1−</sub><i><sub>x</sub></i>NbO<sub>3</sub> Thin Films Potassium sodium niobate (KNN) has long been considered a viable candidate for replacing lead-based materials in piezo- and ferroelectric devices. The introduction of KNN on an industrial scale is highly awaited; however, processing challenges still remain to be solved. The main obstacle is lack of reproducible growth of uniform boules or thin films at temperatures that facilitate monolithic device integration. Herein, atomic layer deposition (ALD) of KNN thin films, exhibiting high chemical uniformity over large areas, is reported. The cation composition can be controlled at a 1% level, enabling fine-tuning of the film stoichiometry across the morphotropic phase boundaries of the KNbO<sub>3</sub>-NaNbO<sub>3</sub> solid solution. The films are obtained as highly oriented on Pt (111)||Si (100)-substrates after annealing at temperatures as low as 550 °C. They exhibit converse piezoelectric effects with magnitudes in accordance with literature. It is believed that the successful development of the described ALD process represents a major step toward achieving lead-free piezo- and ferroelectrics on an industrial scale. Ferroelectricity ; Natural bond orbital ; Materials science ; Thin film ; Crystallography ; Mineralogy ; Condensed matter physics ; Physics ; Nanotechnology ; Chemistry ; Optoelectronics ; Dielectric Ferroelectric and Piezoelectric Materials ; Electronic and Structural Properties of Oxides ; Acoustic Wave Resonator Technologies
Authors: Miklós Nagy | Dávid Rácz | Zsolt László Nagy | Péter Pál Fehér | Sándor Kovács | Csaba Bankó | Zsolt Bacsó | Alexandra Kiss | Miklós Zsuga | Sándor Kéki
Source: Scientific Reports (article, 2019-06-03)
Field: Chemistry — Organic Chemistry

Amino-isocyanoacridines: Novel, Tunable Solvatochromic Fluorophores as Physiological pH Probes Amino-isocyanoacridines (ICAAcs), as first members of their class, turned out to be a novel, multifunctional acridine orange (AO) type dye family with a number of additional favorable properties. They have enhanced solvatochromic emission range, low quantum yields (Φ<sub>F</sub> = 2.9-0.4%) in water, reduced basicity (pK<sub>a</sub> = 7.05-7.58), and their optical behavior could be fine-tuned by complexation with Ag(I) ions, too. Based on both their vibronic absorption and the charge transfer bands, ICAAcs can be applied as stable pH-probes with great precision (2-3% error) in the physiological pH range of 6-8 using UV-vis and fluorescence detection. The dyes are also able to sense pH change in different microenvironments, such as the Stern layer, as it was demonstrated on sodium lauryl sulfate micelles. The optical behavior of the ICAAc derivatives is discussed based on high-level quantum chemical calculations. All three dyes are well-applicable with conventional epifluorescence imaging. Furthermore, at the blue excitation, diMICAAc is optimally suited as a whole-cell probe for both the conventional microscopic and the laser-illumination studies, like flow- and imaging cytometric, or confocal laser-scanning microscopic examinations. Solvatochromism ; Chemistry ; Photochemistry ; Molecule ; Organic chemistry Organic Chemistry Cycloaddition Reactions ; Photochromic and Fluorescence Chemistry ; Bioactive Compounds and Antitumor Agents
Authors: Jaume García‐Amorós | M. Cidália R. Castro | Santi Nonell | Susana Vílchez | Jordi Esquena | M. Manuela M. Raposo | Dolores Velasco
Source: The Journal of Physical Chemistry C (article, 2019-08-28)
Field: Materials Science — Materials Chemistry

Adaptable Photochromic Switches with Self-Aggregating Heterocyclic Azo Dyes It is well-known that the thermal isomerization kinetics of photochromic azo dyes can be modulated by subtle changes in their chemical architecture. However, the availability of an orthogonal input to control the thermal relaxation of azo dyes is essential to enable access to multifunctional and adaptive photochromic switches based on these particular organic chromophores. In this work, we have designed and synthesized a new family of green-light-activated heterocyclic azo derivatives that modify their switching capabilities as a function of concentration. In this line, we have investigated their self-assembly and the nature of the supramolecular aggregates formed by means of dynamic light scattering, polarized optical microscopy, and X-ray diffraction. Indeed, imparting control over the self-assembly of these organic dyes allows to fine-tune their thermal relaxation time and produce adaptable photochromic switches. Specifically, swapping the azo dye concentration between values located above and below the corresponding critical aggregation concentration modifies significantly the relaxation time up to 250 times, i.e., from the millisecond to the microsecond timescale. Moreover, the optical density of the system can be switched back and forth hundreds of times, for both diluted and concentrated solutions, without any sign of fatigue. Photochromism ; Molecular switch ; Chromophore ; Isomerization ; Microsecond ; Photochemistry ; Relaxation (psychology) ; Optical switch ; Supramolecular chemistry ; Materials science ; Light scattering ; Kinetics ; Millisecond ; Chemistry ; Chemical engineering ; Chemical physics ; Scattering ; Optoelectronics ; Optics ; Organic chemistry ; Molecule ; Catalysis ; Physics Photochromic and Fluorescence Chemistry ; Photoreceptor and optogenetics research ; Supramolecular Self-Assembly in Materials
Authors: Devarshi Kashyap | Surendra Singh Gaur | S. Kanagaraj
Source: Materials Today Communications (article, 2019-11-05)
Field: Materials Science — Polymers and Plastics

Development of hybrid shape memory polyurethane composites for endovascular applications Materials science ; Polyurethane ; Composite material ; Ultimate tensile strength ; Radiodensity ; Shape-memory alloy ; Filler (materials) ; Composite number ; Radiography Polymer composites and self-healing ; Intracranial Aneurysms: Treatment and Complications ; Vascular Malformations Diagnosis and Treatment
Authors: Ai‐Xin Zhu | Qing‐Yuan Yang | Soumya Mukherjee | Amrit Kumar | Chenghua Deng | Andrey A. Bezrukov | Mohana Shivanna | Michael J. Zaworotko
Source: Angewandte Chemie (article, 2019-10-07)
Field: Chemistry — Inorganic Chemistry

Tuning the Gate‐Opening Pressure in a Switching pcu Coordination Network, X‐pcu‐5‐Zn, by Pillar‐Ligand Substitution Abstract Coordination networks that reversibly switch between closed and open phases are of topical interest since their stepped isotherms can offer higher working capacities for gas‐storage applications than the related rigid porous coordination networks. To be of practical utility, the pressures at which switching occurs, the gate‐opening and gate‐closing pressures, must lie between the storage and delivery pressures. Here we study the effect of linker substitution to fine‐tune gate‐opening and gate‐closing pressure. Specifically, three variants of a previously reported pcu ‐topology MOF, X‐pcu‐5‐Zn , have been prepared: X‐pcu‐6‐Zn , 6 =1,2‐bis(4‐pyridyl)ethane (bpe), X‐pcu‐7‐Zn , 7 =1,2‐bis(4‐pyridyl)acetylene (bpa), and X‐pcu‐8‐Zn , 8 =4,4′‐azopyridine (apy). Each exhibited switching isotherms but at different gate‐opening pressures. The N 2 , CO 2 , C 2 H 2 , and C 2 H 4 adsorption isotherms consistently indicated that the most flexible dipyridyl organic linker, 6 , afforded lower gate‐opening and gate‐closing pressures. This simple design principle enables a rational control of the switching behavior in adsorbent materials. Linker ; Acetylene ; Chemistry ; Substitution (logic) ; Ligand (biochemistry) ; Topology (electrical circuits) ; Adsorption ; Nanotechnology ; Materials science ; Organic chemistry ; Computer science ; Electrical engineering ; Receptor Metal-Organic Frameworks: Synthesis and Applications ; Crystallography and molecular interactions ; Supramolecular Chemistry and Complexes
Authors: Francesco Zaccaria | Roberta Cipullo | Andrea Correa | Peter H. M. Budzelaar | Vincenzo Busico | Christian Ehm
Source: Processes (article, 2019-06-20)
Field: Chemistry — Organic Chemistry

Separating Electronic from Steric Effects in Ethene/α-Olefin Copolymerization: A Case Study on Octahedral [ONNO] Zr-Catalysts Four Cl/Me substituted [ONNO] Zr-catalysts have been tested in ethene/α-olefin polymerization. Replacing electron-donating methyl with isosteric but electron-withdrawing chlorine substituents results in a significant increase of comonomer incorporation. Exploration of steric and electronic properties of the ancillary ligand by DFT confirm that relative reactivity ratios are mainly determined by the electrophilicity of the metal center. Furthermore, quantitative DFT modeling of propagation barriers that determine polymerization kinetics reveals that electronic effects observed in these catalysts affect relative barriers for insertion and a capture-like transition state (TS). Comonomer ; Steric effects ; Reactivity (psychology) ; Electronic effect ; Catalysis ; Olefin fiber ; Polymerization ; Ligand (biochemistry) ; Chemistry ; Copolymer ; Electrophile ; Photochemistry ; Ethylene ; Organic chemistry Organometallic Complex Synthesis and Catalysis ; Carbon dioxide utilization in catalysis ; Asymmetric Hydrogenation and Catalysis
Authors: Esteban Araya‐Hermosilla | Marnix Roscam Abbing | José Catalán‐Toledo | Felipe Oyarzún-Ampuero | Andrea Pucci | Patricio Raffa | Francesco Picchioni | Ignacio Moreno‐Villoslada
Source: Polymer (article, 2019-01-29)
Field: Materials Science — Materials Chemistry

Synthesis of tuneable amphiphilic-modified polyketone polymers, their complexes with 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin, and their role in the photooxidation of 1,3,5-triphenylformazan confined in polymeric nanoparticles Porphyrin ; Amphiphile ; Polymer ; Chemistry ; Polymer chemistry ; Photodegradation ; Ethylenediamine ; Copolymer ; Organic chemistry ; Photocatalysis ; Catalysis Porphyrin and Phthalocyanine Chemistry ; Photodynamic Therapy Research Studies ; Luminescence and Fluorescent Materials
Authors: Andrea Longhi | Marco Baron | Marzio Rancan | Gregorio Bottaro | Lidia Armelao | Paolo Sgarbossa | Cristina Tubaro
Source: Molecules (article, 2019-06-21)
Field: Chemistry — Organic Chemistry

Possible Synthetic Approaches for Heterobimetallic Complexes by Using nNHC/tzNHC Heteroditopic Carbene Ligands The synthesis of heterobimetallic complexes remains a synthetic challenge in the field of organometallic chemistry. A possible approach in this regard might be the use of a bidentate heteroditopic bis(carbene) ligand that combines an imidazol-2-ylidene (<i>n</i>NHC) with a 1,2,3-triazol-5-ylidene (<i>tz</i>NHC) connected by an organic spacer. The optimized strategy to heterobimetallic complexes with this type of ligand involves a 3-step procedure: (i) Coordination of the <i>n</i>NHC, functionalized with a 1,2,3-triazole ring, to a metal center; (ii) formation of the triazolium ring by alkylation of the triazole N-3; (iii) deprotonation of the <i>tz</i>NHC precursor and coordination of the second metal center. Following this procedure, a novel Au(I)-Ag(I) dinuclear complex was isolated and its properties were compared to the analogous homobimetallic Ag(I)-Ag(I) and Au(I)-Au(I) complexes. The study was completed by the determination of the molecular structures of some synthetic intermediates. Carbene ; Deprotonation ; Chemistry ; Denticity ; Ring (chemistry) ; Ligand (biochemistry) ; Stereochemistry ; Metal ; Combinatorial chemistry ; Alkylation ; Triazole ; Organic chemistry ; Ion ; Catalysis N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Catalytic Cross-Coupling Reactions ; Catalytic Alkyne Reactions
Authors: Selene Acosta | Juan Casanova‐Cháfer | Ayrton Sierra Castillo | Eduard Llobet | Rony Snyders | Jean‐François Colomer | Mildred Quintana | Chris Ewels | Carla Bittencourt
Source: Applied Sciences (article, 2019-12-06)
Field: Materials Science — Materials Chemistry

Low Kinetic Energy Oxygen Ion Irradiation of Vertically Aligned Carbon Nanotubes Vertically aligned multiwalled carbon nanotubes (v-CNTs) were functionalized with oxygen groups using low kinetic energy oxygen ion irradiation. X-ray photoelectron spectroscopy (XPS) analysis indicates that oxygen ion irradiation produces three different types of oxygen functional groups at the CNTs surface: epoxide, carbonyl and carboxyl groups. The relative concentration of these groups depends on the parameters used for oxygen ion irradiation. Scanning electron microscopy (SEM) shows that the macroscopic structure and alignment of v-CNTS are not affected by the ion irradiation and transmission electron microscopy (TEM) proves tip functionalization of v-CNTs. We observed that in comparison to oxygen plasma treatment, oxygen ion irradiation shows higher functionalization efficiency and versatility. Ion irradiation leads to higher amount of oxygen grafting at the v-CNTs surface, besides different functional groups and their relative concentration can be tuned varying the irradiation parameters. X-ray photoelectron spectroscopy ; Irradiation ; Oxygen ; Surface modification ; Materials science ; Carbon nanotube ; Ion ; Scanning electron microscope ; Transmission electron microscopy ; Graphene ; Chemical engineering ; Analytical Chemistry (journal) ; Nanotechnology ; Chemistry ; Composite material ; Organic chemistry Carbon Nanotubes in Composites ; Ion-surface interactions and analysis ; Nanopore and Nanochannel Transport Studies
Authors: Vera Bosmans | Jordi Poater | Roel Hammink | Paul Tinnemans | F. Matthias Bickelhaupt | Jasmin Mecinović
Source: The Journal of Organic Chemistry (article, 2019-02-22)
Field: Chemistry — Physical and Theoretical Chemistry

Probing Through-Space Polar−π Interactions in 2,6-Diarylphenols Although it is well established that the acidity of phenol can be fine-tuned with substituents on its aromatic ring via through-bond effects, the role of through-space effects on the acidity of phenols is presently poorly understood. Here, we present integrated experimental and computational studies on substituted 2,6-diarylphenols that demonstrate the essential contribution from through-space OH-π interactions and O<sup>-</sup>-π interactions in the observed trends in proton affinities and acidities of 2,6-diarylphenols. Polar ; Space (punctuation) ; Phenols ; Phenol ; Affinities ; Ring (chemistry) ; Proton ; Chemistry ; Computational chemistry ; Chemical polarity ; Chemical space ; Chemical physics ; Combinatorial chemistry ; Stereochemistry ; Organic chemistry ; Physics ; Molecule ; Drug discovery ; Computer science ; Quantum mechanics ; Biochemistry Crystallography and molecular interactions ; Free Radicals and Antioxidants ; Spectroscopy and Quantum Chemical Studies
Authors: Shuang Liang | Yanmei Nie | Sang-Hao Li | Jian‐Liang Zhou | Jun Yan
Source: Molecules (article, 2019-02-22)
Field: Materials Science — Materials Chemistry

A Comprehensive Study on the Dye Adsorption Behavior of Polyoxometalate-Complex Nano-Hybrids Containing Classic β-Octamolybdate and Biimidazole Units Six new hybrids based on β-[Mo₈O<sub>26</sub>]<sup>4-</sup> polyoxometalates, [Ni(H₂biim)₃]₂[β-Mo₈O<sub>26</sub>]•8DMF(<b>1</b>); (DMA)₂[M(H₂biim)₂(H₂O)₂][β-Mo₈O<sub>26</sub>]•4DMF (M = Ni (<b>2</b>), Co (<b>3</b>)), DMA = dimethyl-ammonium, H₂biim=2,2'-biimidazole); [M(H₂biim)(DMF)₃]₂[β-Mo₈O<sub>26</sub>]•2DMF (M = Zn (<b>4</b>), Cu (<b>5</b>)); [(DMA)₂[Cu(DMF)₄][β-Mo₈O<sub>26</sub>]•2DMF]<sub>n</sub> (<b>6</b>), have been successfully synthesized and characterized. Compounds <b>2⁻5</b> show favorable capacity to adsorb methylene blue (MB) at room temperature, and they can selectively capture MB molecules from binary-mixture solutions of MB/MO (MO = Methyl Orange), or MB/RhB (RhB = Rhodamine B). Compound <b>3</b> can uptake up to 521.7 mg g<sup>-1</sup> MB cationic dyes rapidly, which perform the maximum adsorption in an hour among the reported materials as far as we know. The compounds are stable and still work very efficiently after three cycles. For compound <b>3</b>, the preliminary adsorption mechanism studies indicated that the adsorption is an ion exchange process and the adsorption behavior of polyoxometalate-complex can be benefited from additional exchangeable protons in the complex cations. Polyoxometalate ; Adsorption ; Cationic polymerization ; Methylene blue ; Rhodamine B ; Methyl orange ; Chemistry ; Ammonium ; Molecule ; Ion ; Selective adsorption ; Inorganic chemistry ; Nuclear chemistry ; Organic chemistry ; Catalysis Polyoxometalates: Synthesis and Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Advanced Nanomaterials in Catalysis
Authors: Oscar E. Bonilla-Manrique | Harald Moser | Pedro Martín‐Mateos | Bernhard Lendl | Marta Ruiz-Llata
Source: Journal of Sensors (article, 2019-03-14)
Field: Chemistry — Spectroscopy

Hydrogen Sulfide Detection in the Midinfrared Using a 3D-Printed Resonant Gas Cell A fast and reliable photoacoustic (PA) sensor for trace gas detection is reported. The sensor is based on a 3D-printed resonant cell in combination with a continuous wave mode-hop-free external cavity quantum cascade laser to rapidly acquire gas absorption data in the midinfrared range. The cell is designed so as to minimize the window PA background at a selected acoustic resonance. The goal is a resonant PA cell capable of detecting the traces of gases using wavelength modulation of the laser source and second harmonic detection. The versatility and enhancement of the limit of detection at sub-ppm levels are investigated by monitoring specific lines of hydrogen sulfide (H 2 S). The noise-equivalent absorption normalized to laser-beam power and detection bandwidth is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn>1.07</mml:mn><mml:mo>×</mml:mo><mml:mn>10</mml:mn></mml:math> -8 W cm -1 Hz -1/2 for H 2 S targeting the absorption line at 1247.2 cm −1 . These properties make the sensor suitable for various practical sensors for water quality applications. Detection limit ; Laser ; Materials science ; Hydrogen sulfide ; Hydrogen ; Analytical Chemistry (journal) ; Wavelength ; Absorption (acoustics) ; Optics ; Optoelectronics ; Chemistry ; Physics ; Sulfur Spectroscopy and Laser Applications ; Laser Design and Applications ; Atmospheric and Environmental Gas Dynamics
Authors: Martin Müller
Source: Molecules (article, 2019-06-06)
Field: Materials Science — Surfaces, Coatings and Films

The Anomalous Influence of Polyelectrolyte Concentration on the Deposition and Nanostructure of Poly(ethyleneimine)/Poly(acrylic acid) Multilayers The deposition and nanostructure of polyelectrolyte (PEL) multilayers (PEMs) of branched poly(ethyleneimine)/poly(acrylic acid) (PEI/PAA) onto silicon substrates was studied in terms of the dependence of pH and the PEL concentration (c<sub>PEL</sub>) in the individual adsorption steps z. Both a commercial automatic dipping device and a homebuilt automatic stream coating device (flow cell) were used. Gravimetry, SFM, transmission (TRANS) and in situ attenuated total reflection (ATR) FTIR spectroscopy were used for the quantitative determination of the adsorbed amount, thickness, chemical composition and morphology of deposited PEMs, respectively. Firstly, the combination of pH = 10 for PEI and pH = 4 for PAA, where both PEL were predominantly in the neutral state, resulted in an extraordinarily high PEM deposition, while pH combinations, where one PEL component was charged, resulted in a significantly lower PEM deposition. This was attributed to both PEL conformation effects and acid/base interactions between basic PEI and acidic PAA. Secondly, for that pH combination an exponential relationship between PEM thickness and adsorption step z was found. Thirdly, based on the results of three independent methods, the course of the deposited amount of a PEM-10 (<i>z</i> = 10) versus c<sub>PEL</sub> in the range 0.001 to 0.015 M at pH = 10/4 was non-monotonous showing a pronounced maximum at c<sub>PEL</sub> = 0.005 M. Analogously, for c<sub>PEL</sub> = 0.005 M a maximum of roughness and structure size was found. Fourthly, related to that finding, in situ ATR-FTIR measurements gave evidence for the release of outermost located PEI upon PAA immersion (even step) and of outermost PAA upon PEI immersion (odd step) under formation of PEL complexes in solution. These studies help us to prepare PEL-based films with a defined thickness and morphology for interaction with biofluids in the biomedical and food fields. Polyelectrolyte ; Ethyleneimine ; Acrylic acid ; Adsorption ; Chemical engineering ; Polymer chemistry ; Fourier transform infrared spectroscopy ; Nanostructure ; Allylamine ; Deposition (geology) ; Coating ; Chemistry ; Materials science ; Analytical Chemistry (journal) ; Chromatography ; Nanotechnology ; Organic chemistry ; Copolymer ; Polymer Polymer Surface Interaction Studies ; Dendrimers and Hyperbranched Polymers ; Molecular Junctions and Nanostructures
Authors: Therese Planke | Katarina Cirnski | Jennifer Herrmann | Rolf Müller | Andreas Kirschning
Source: Chemistry - A European Journal (article, 2019-12-13)
Field: Chemistry — Organic Chemistry

Synthetic and Biological Studies on New Urea and Triazole Containing Cystobactamid Derivatives Cystobactamids belong to the group of arene-based oligoamides that effectively inhibit bacterial type IIa topoisomerases. Cystobactamid 861-2 is the most active member of these antibiotics. Most amide bonds present in the cystobactamids link benzoic acids with anilines and it was found that some of these amide bonds undergo chemical and enzymatic hydrolysis, especially the one linking ring C with ring D. This work reports on the chemical synthesis and biological evaluation of thirteen new cystobactamids that still contain the methoxyaspartate hinge. However, we exchanged selected amide bonds either by the urea or the triazole groups and modified ring A in the latter case. While hydrolytic stability could be improved with these structural substitutes, the high antibacterial potency of cystobactamid 861-2 could only be preserved in selected cases. This includes derivatives, in which the urea group is positioned between rings A and B and where the triazole is found between rings C and D. Amide ; Chemistry ; Ring (chemistry) ; Urea ; Peptide bond ; Hydrolysis ; Triazole ; Stereochemistry ; Combinatorial chemistry ; Enzyme ; Organic chemistry Click Chemistry and Applications ; Cancer therapeutics and mechanisms ; Chemical Synthesis and Analysis