jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Soheila Behzadi | Enayatollah Sheikhhosseini | Sayed Ali Ahmadi | Dadkhoda Ghazanfari | Mohammadreza Akhgar
Source: Heterocyclic Communications (article, 2020-01-01)
Field: Chemistry — Organic Chemistry

Synthesis and characterization of novel biological tetracoumarin derivatives bearing ether moieties Abstract A series of novel tetracoumarin derivatives ( 3a-f ) were prepared using the reaction of ether functionalized dibenzaldehyde with 4-hydroxycoumarin in the presence of sodium acetate. The structure of compounds was validated by IR, NMR, and CHN analyzes. Antimicrobial (antibacterial and antifungal) activity was studied on the basis of the minimum bactericidal concentration, minimum inhibitory concentration and inhibitory zone diameter. Favorable biological activity was found in compound 3f . Chemistry ; Ether ; Minimum inhibitory concentration ; Antimicrobial ; Antifungal ; Antibacterial activity ; Biological activity ; Proton NMR ; Combinatorial chemistry ; Nuclear chemistry ; Organic chemistry ; Stereochemistry ; Bacteria ; In vitro ; Biochemistry ; Microbiology Synthesis and biological activity ; Plant chemical constituents analysis ; Multicomponent Synthesis of Heterocycles
Authors: Erfan Dashtimoghadam | Hamed Salimi‐Kenari | Rasool Nasseri | Kenneth D. Knudsen | Hamid Mirzadeh | Bo Nyström
Source: Colloids and Surfaces A Physicochemical and Engineering Aspects (article, 2020-01-20)
Field: Materials Science — Biomaterials

Tunable viscoelastic features of aqueous mixtures of thermosensitive ethyl(hydroxyethyl)cellulose and cellulose nanowhiskers Ethyl(hydroxyethyl) cellulose (EHEC) is known to form reversible hydrogels in water at elevated temperatures in the presence of an ionic surfactant. However, the toxicity of common ionic surfactants (like SDS and CTAB) hampers pharmaceutical and biomedical applications of EHEC-based thermogels. Addition of a nature-based material to EHEC solutions - in the form of negatively charged cellulose nanowhiskers (CNWs) - will introduce an internal electrostatic repulsion that could also produce the balanced swelling necessary for forming a stable gel at elevated temperatures (ca. 37 °C). This may therefore be an alternative way of designing low toxicity thermoresponsive hydrogels of high mechanical strength for pharmaceutical and biomedical applications without the use of ionic surfactants. The properties of the temperature-induced gelling systems (EHEC/CNW and EHEC/SDS/CNW) were characterized by rheological methods and rheo-small angle light scattering (rheo-SALS), whereas the structure and morphology of CNWs were examined by transmission electron microscope (TEM) and small angle neutron scattering (SANS). Oscillatory shear results for the EHEC/CNW system showed that the gel temperature (ca. 37 °C) was virtually unaffected by the amount of added CNWs, while the fractal dimension values (2.2–2.3) suggested the evolution of a tighter incipient gel network with increasing level of added CNWs. Furthermore, a threefold increase of the gel strength parameter was observed with increasing concentration of CNWs. For the EHEC/CNW/SDS system, a more open network evolved with increasing amount of CNWs, and for this system, higher values of the gel strength parameter were found. Pronounced shear-thinning, even at very low shear rates, was observed for the EHEC/CNW system at all levels of CNW addition, whereas for the EHEC/CNW/SDS system, Newtonian-like behavior was detected at low shear rates. Self-healing hydrogels ; Ionic strength ; Chemical engineering ; Materials science ; Cellulose ; Pulmonary surfactant ; Dynamic light scattering ; Small-angle neutron scattering ; Viscoelasticity ; Aqueous solution ; Rheology ; Small-angle X-ray scattering ; Swelling ; Neutron scattering ; Polymer chemistry ; Composite material ; Nanoparticle ; Chemistry ; Scattering ; Nanotechnology ; Organic chemistry ; Optics Advanced Cellulose Research Studies ; Polysaccharides and Plant Cell Walls ; Polysaccharides Composition and Applications
Authors: Michael Kuepfert | Peiyuan Qu | Aaron E. Cohen | Caroline B. Hoyt | Christopher W. Jones | Marcus Weck
Source: Chemistry - A European Journal (article, 2020-04-08)
Field: Materials Science — Materials Chemistry

Reversible Photoswitching in Poly(2‐oxazoline) Nanoreactors This contribution reports light responsive catalytic nanoreactors based on poly(2-oxazoline) diblock copolymers. The hydrophobic block of the copolymer is a random copolymer consisting of a spiropyran functionalized 2-oxazoline (SPOx) and 2-(but-3-yn-1-yl)-4,5-dihydrooxazole (ButynOx), while the hydrophilic block is based on 2-methyl-2-oxazoline (MeOx). The block copolymer is terminated with tris(2-aminoethyl) amine (TREN) that serves as catalyst in a Knoevenagel condensation. Four block copolymers with different ButynOx/SPOx and hydrophilic/hydrophobic ratios are synthesized and self-assembled through solvent exchange. Micelles and vesicles of various sizes are observed by TEM, which undergo morphological and size changes in response to irradiation with UV light. We hypothesize that these transformations in the nanostructures are caused by increases in the hydrophilicity of the hydrophobic block when spiropyran (SP) isomerizes to merocyanine (MC) in the presence of UV light. The reversible transition from micellar to vesicular nanoreactors resulted in increased reaction kinetics through improved substrate accessibility to the catalytic site, or termination of the catalytic reaction due to polymer precipitation. These nanoreactors present a promising platform towards photoregulating reaction outcomes based on changes in nanostructure morphology. Nanoreactor ; Copolymer ; Merocyanine ; Polymer chemistry ; Spiropyran ; Materials science ; Micelle ; Photochemistry ; Chemistry ; Polymer ; Nanoparticle ; Photochromism ; Organic chemistry ; Nanotechnology Photochromic and Fluorescence Chemistry ; Photoreceptor and optogenetics research ; Supramolecular Self-Assembly in Materials
Authors: Prabhakar Panzade | Giridhar Shendarkar | Deepak Kulkarni | Santosh Shelke
Source: Advanced Pharmaceutical Bulletin (article, 2020-09-22)
Field: Chemistry — Physical and Theoretical Chemistry

Solid State Characterization and Dissolution Enhancement of Nevirapine Cocrystals <b><i>Purpose:</i></b> Novel cocrystals of nevirapine (NP) were designed and prepared with salicylamide and 3-hydroxy benzoic acid (3-HBA). <b><i>Methods:</i></b> The cocrystals were prepared by solvent drop grinding method by adding few drops of acetone to enhance the solubility and dissolution. The drug and cocrystals were characterized by differential scanning calorimetry (DSC) and powder x-ray diffraction (PXRD). The solubility of NP, its wet ground form, and cocrystals were investigated at different pH. Moreover, the effect of surfactant on solubility of cocrystals was also studied. Finally, intrinsic dissolution rate (IDR) and stability of cocrystals was examined. <b><i>Results:</i></b> The characterization of cocrystals by DSC and PXRD revealed formation of new solid forms due to changes in thermogram and PXRD pattern. The cocrystal of NP with 3-HBA showed 4.5 folds greater solubility in pH 1.2 buffer and 5.5 folds in 1% Tween 80 as compared to original drug. IDR of cocrystals was higher than the pure drug in 0.1 N hydrochloric acid (HCl). Moreover, cocrystals were found physically stable after 3 months as evident from unchanged IDR. <b><i>Conclusion:</i></b> Hence, the present research indicates the new stable solid forms of NP with improved dissolution rate than pure drug. Solubility ; Dissolution ; Cocrystal ; Powder diffraction ; Differential scanning calorimetry ; Chemistry ; Nuclear chemistry ; Biopharmaceutics Classification System ; Solvent ; Active ingredient ; Materials science ; Organic chemistry ; Crystallography ; Molecule ; Hydrogen bond Crystallography and molecular interactions ; Crystallization and Solubility Studies ; Chemical Thermodynamics and Molecular Structure
Authors: Adi Azoulay | Jesús Barrio | Jonathan Tzadikov | Michael Volokh | Josep Albero | Christel Gervais | Pilar Amo‐Ochoa | Hermenegildo Garcı́a | Félix Zamora | Menny Shalom
Source: Journal of Materials Chemistry A (article, 2020-01-01)
Field: Chemistry — Inorganic Chemistry

Synthesis of metal-free lightweight materials with sequence-encoded properties A general synthesis of phosphorus–nitrogen–carbon materials with highly tunable elemental composition and spatial organization as well as structural, electronic, and thermal stability properties is reported. Sequence (biology) ; Thermal stability ; Carbon fibers ; Phosphorus ; Materials science ; Metal ; Nitrogen ; Nanotechnology ; Chemical engineering ; Chemistry ; Metallurgy ; Engineering ; Composite material ; Composite number ; Organic chemistry Inorganic Chemistry and Materials ; MXene and MAX Phase Materials ; Catalysis and Hydrodesulfurization Studies
Authors: Patrizia Andreozzi | Lorenza Tamberi | Elisamaria Tasca | Gina Elena Giacomazzo | Marta Martínez Moro | Mirko Severi | Marco Marradi | Stefano Cicchi | Sergio Moya | Giacomo Biagiotti | Barbara Richichi
Source: Beilstein Journal of Organic Chemistry (article, 2020-09-11)
Field: Materials Science — Materials Chemistry

The B &amp; B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY Mechanochemistry is an emerging and reliable alternative to conventional solution (batch) synthesis of complex molecules under green and solvent-free conditions. In this regard, we report here on the conjugation of a dextran polysaccharide with a fluorescent probe, a phenylboronic acid (PBA)-functionalized boron dipyrromethene (BODIPY) applying the ball milling approach. The ball milling formation of boron esters between PBA BODIPY and dextran proved to be more efficient in terms of reaction time, amount of reactants, and labelling degree compared to the corresponding solution-based synthetic route. PBA-BODIPY dextran assembles into nanoparticles of around 200 nm by hydrophobic interactions. The resulting PBA-BODIPY dextran nanoparticles retain an apolar interior as proved by pyrene fluorescence, suitable for the encapsulation of hydrophobic drugs with high biocompatibility while remaining fluorescent. BODIPY ; Phenylboronic acid ; Chemistry ; Dextran ; Boron ; Fluorescence ; Nanoparticle ; Biocompatibility ; Combinatorial chemistry ; Ball mill ; Mechanochemistry ; Organic chemistry ; Chemical engineering ; Nanotechnology ; Catalysis ; Materials science Luminescence and Fluorescent Materials ; Supramolecular Chemistry and Complexes ; Force Microscopy Techniques and Applications
Authors: Maria C. Cringoli | Silvia Marchesan | Michele Melchionna | Paolo Fornasiero
Source: Molecules (review, 2020-11-29)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Nanostructured Gels for Energy and Environmental Applications Nanostructured gels have emerged as an attractive functional material to innovate the field of energy, with applications ranging from extraction and purification to nanocatalysts with unprecedented performance. In this review we discuss the various classes of nanostructured gels and the most recent advancements in the field with a perspective on future directions of this challenging area. Nanomaterial-based catalyst ; Nanotechnology ; Field (mathematics) ; Materials science ; Perspective (graphical) ; Ranging ; Biochemical engineering ; Computer science ; Engineering ; Nanoparticle ; Artificial intelligence ; Telecommunications Supercapacitor Materials and Fabrication ; Solar-Powered Water Purification Methods ; Aerogels and thermal insulation
Authors: Stefan P.W. Govers | Nicky Alexander | Majdi Al-Masri | Jürgen Omeis | Leendert G.J. van der Ven | Gijsbertus de With | A. Catarina C. Esteves
Source: Progress in Organic Coatings (article, 2020-11-04)
Field: Materials Science — Surfaces, Coatings and Films

Surface segregation of polydimethylsiloxane-polyether block copolymers in coatings driven by molecular architecture Materials science ; Polydimethylsiloxane ; Contact angle ; Copolymer ; Coating ; X-ray photoelectron spectroscopy ; Chemical engineering ; Siloxane ; Polymer ; Propylene oxide ; Surface modification ; Molar mass ; Polymer chemistry ; Desorption ; Ethylene oxide ; Composite material ; Organic chemistry ; Adsorption Polymer Surface Interaction Studies ; Advanced Polymer Synthesis and Characterization ; Surface Modification and Superhydrophobicity
Authors: Willi Zeni | Marco Seifried | Christian Knoll | Jan M. Welch | Gerald Giester | Berthold Stöger | Werner Artner | M. Reissner | Danny Müller | P. Weinberger
Source: Dalton Transactions (article, 2020-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Bifunctional Fe(<scp>ii</scp>) spin crossover-complexes based on ω-(1<i>H</i>-tetrazol-1-yl) carboxylic acids To increase the supramolecular cooperativity in Fe(ii) spin crossover materials based on N1-substituted tetrazoles, a series of ω-(1H-tetrazol-1-yl) carboxylic acids with chain-lengths of C2-C4 were synthesized. Structural characterization confirmed the formation of a strong hydrogen-bond network, responsible for enhanced cooperativity in the materials and thus largely complete spin-state transitions for the ligands with chain lenghts of C2 and C4. To complement the structural and magnetic investigation, electronic spectroscopy was used to investigate the spin-state transition. An initial attempt to utilize the bifunctional coordination ability of the ω-(1H-tetrazol-1-yl) carboxylic acids for preparation of mixed-metallic 3d-4f coordination polymers resulted in a novel one-dimensional gadolinium-oxo chain system with the ω-(1H-tetrazol-1-yl) carboxylic acid acting as μ2-η2:η1 chelating-bridging ligand. Bifunctional ; Spin crossover ; Chemistry ; Carboxylic acid ; Medicinal chemistry ; Organic chemistry ; Catalysis ; Inorganic chemistry Magnetism in coordination complexes ; Lanthanide and Transition Metal Complexes ; Metal complexes synthesis and properties
Authors: Sanaz Mohammadpourasl | F.F. De Biani | Carmen Coppola | Maria Laura Parisi | Lorenzo Zani | Alessio Dessì | Massimo Calamante | Gianna Reginato | Riccardo Basosi | Adalgisa Sinicropi
Source: Energies (article, 2020-04-19)
Field: Chemistry — Organic Chemistry

Ground-State Redox Potentials Calculations of D-π-A and D-A-π-A Organic Dyes for DSSC and Visible-Light-Driven Hydrogen Production The prediction of ground-state redox potentials by quantum chemical methods has a prominent role in the rational design of novel organic photosensitizers both for dye-sensitized solar cells (DSSCs) and photocatalytic systems for the production of H2. Indeed, the ground-state redox potential of the photosensitizers is one of the key parameters to identify the most promising candidates for such applications. Here, the ground-state redox potentials of 16 organic donor-π-acceptor D-π-A and donor-acceptor-π-acceptor D-A-π-A dyes having a medium to large size of the conjugated scaffold are evaluated, using the methods of the Density Functional Theory (DFT), in terms of free energy differences between their neutral and oxidized ground-state forms. These results are compared to the available experimental data and to the computed highest occupied molecular orbital energy −ε(HOMO) values as an approximation of ground-state redox potentials according to Koopmans’ theorem. Using the MPW1K functional in combination with the 6-31+G* basis set, the strategy based on the free energy cycle, including solvent effects, reproduces with a good level of accuracy the observed values (mean absolute error (MAE) &lt; 0.2 eV) and trend of redox potentials within related families of dyes. On the other hand, the −ε(HOMO) values are only able to capture the experimental trends in redox potential values. Redox ; Chemistry ; Ground state ; Acceptor ; Density functional theory ; Conjugated system ; Photochemistry ; Basis set ; Half-reaction ; Computational chemistry ; Chemical physics ; Atomic physics ; Inorganic chemistry ; Organic chemistry ; Physics Free Radicals and Antioxidants ; Organic Chemistry Cycloaddition Reactions ; Advanced Photocatalysis Techniques
Authors: Ganesh Shimoga | Eun‐Jae Shin | Sang‐Youn Kim
Source: IEEE Access (article, 2020-01-01)
Field: Materials Science — Polymers and Plastics

Flexible Vibrotactile Actuator Based on Soft PVC Gel Embedded Polyaniline/Silicon Dioxide Nanoparticles Nanocomposite hybrid materials made of inorganic nanoparticles and organic polymers are fascinating to design high performance polymeric materials, customized in electronics and transportation sectors. In this concern, a soft and flexible PVC gel embedded with silicon dioxide nanoparticles (SDNs) coated with polyaniline (PANI) has been proposed as a dielectric interface in vibrotactile actuator. Soft PVC gels were achieved by plasticization using acetyltributylcitrate (ATBC), an ecofriendly green plasticizer. The optimization of plasticizer content to PVC was precisely controlled and the ratio was kept constant throughout the experiment. PANI was coated on SDN by using chemical oxidative polymerization technique in order to tune the dielectric/electronic properties and minimize the leakage current. Various quantities of PANI-SDNs were loaded to PVC; the behavior of nanocomposite PVC gels as soft vibrotactile actuators was investigated. All the composite materials were comprehensively investigated using different physico-chemical techniques and haptic performance of the optimized PANI-SDN-0.2 nanocomposite PVC gel was assessed. The following are available online at http://www.xxx.com/xxx/s1, Figure S1. Pictograph representing PANI-SDN-0.2 nanocomposite PVC gel, (a) a flat PANI-SDN-0.2 nanocomposite PVC gel, (b) demonstrating the flexibility of PANI-SDN-0.2 nanocomposite PVC gel, (c) a wavy-shaped PANI-SDN-0.2 nanocomposite PVC gel for actuator design (d) dimensions of the fabricated wavy-shaped PANI-SDN nanocomposite PVC gels. Figure S2. Illustration to demonstrate the fabrication process of the vibrotactile actuator (a) components of the vibrotactile actuator, (b) lower surface of the top layer, (c) assembled vibrotactile actuator, (d) cross-sectional image of the vibrotactile actuator. Figure S3. Experimental environment demonstrating the measurement of haptic performance of PANI-SDN nanocomposite PVC gels. Description: Instrumentation and Characterization Techniques. Figure S4. EDX spectra of PANI (Scale = 1 μm). Figure S5. EDX spectra of SDNs (Scale = 1 μm). Figure S6. EDX spectra of PANI-SDNs (Scale = 1 μm). Figure S7. EDX spectra of PANI-SDN-0.2 nanocomposite PVC gel (Scale = 1 μm). Figure S8. (a & b) FESEM micrographs of PANI-SDN-0.2 nanocomposite PVC gel with different magnitudes (Scale = 2 μm and 200 nm respectively). Figure S9. Acceleration performance of PANI-SDN-0.01, PANI-SDN-0.05, PANI-SDN-0.1, PANI-SDN-0.3, PANI-SDN-0.4 and PANI-SDN-0.5 nanocomposite PVC gel based actuators. Nanocomposite ; Materials science ; Polyaniline ; Plasticizer ; Composite material ; Polymer ; Nanoparticle ; Composite number ; Actuator ; Silicon dioxide ; Chemical engineering ; Polymerization ; Nanotechnology ; Computer science Conducting polymers and applications ; Advanced Sensor and Energy Harvesting Materials ; Dielectric materials and actuators
Authors: Janina A. Werra | Marius A. Wünsche | Patrick Rathmann | Paul Mehlmann | Pawel Löwe | Fabian Dielmann
Source: Zeitschrift für anorganische und allgemeine Chemie (article, 2020-04-23)
Field: Chemistry — Organic Chemistry

Effective Control of the Electron‐donating Ability of Phosphines by using Phosphazenyl and Phosphoniumylidyl Substituents Phosphoniumylidyl and phosphazenyl groups are effective substituents to increase the electron‐donating ability of tertiary phosphines. However, the influence of structural variations among those substituents on the electronic properties of the phosphines is little explored. Herein, we show that protonation of the ylidic carbon atom of phosphoniumylidyl phosphines increases the Tolman electronic parameter (TEP) by ΔTEP = 16.0–18.8 cm –1 . Furthermore, phosphazenyl phosphines were synthesized with isopropyl groups (NP{ i Pr} 3 ) and tetramethylguanidino groups (NP{tmg} 3 ) at the phosphonium center. Determination of their TEP values reveals a remarkable low substituent parameter of χ = –18.5 cm –1 for the NP(tmg) 3 group. In addition, we prepared the corresponding gold(I) complexes and determined their solid‐state structures using single‐crystal X‐ray diffraction studies to analyze the steric profile of the new phosphine ligands. Steric effects ; Phosphine ; Substituent ; Chemistry ; Protonation ; Phosphonium ; Isopropyl ; Electronic effect ; Carbon atom ; Medicinal chemistry ; Crystallography ; Stereochemistry ; Organic chemistry ; Alkyl ; Ion Organometallic Complex Synthesis and Catalysis ; Catalytic Alkyne Reactions ; Asymmetric Hydrogenation and Catalysis
Authors: Yasuchika Hasegawa | Katsumasa Koide | Makoto Tsurui | Yuichi Kitagawa | Takayuki Nakanishi | Yoshihiro Doi | Yukio Hinatsu | Koji Fushimi
Source: ChemPhysChem (article, 2020-08-07)
Field: Materials Science — Materials Chemistry

Circularly Polarized Absorption and Luminescence of Semiconductor Eu‐OCN Nanocrystals in the Blue Region of the Electromagnetic Spectrum Semiconductor nanomaterials with efficient polarized-light control in the blue region of the visible spectrum are promising candidates for modern and future photo-information technology, display devices, and optical sensing applications. New-type semiconductor Eu(OCN)<sub>2</sub> nanocrystals with circularly polarized absorption (CD: circular dichroism) and emission (CPL: circularly polarized luminescence) under an applied magnetic field are demonstrated here for the first time. The effective CD signal at 1.6 T was observed at approximately 440 nm. The dissymmetry factor of CPL under 100 K, g<sub>M-CPL,</sub> was estimated to be 0.01. These characteristic circularly polarized absorption and emission phenomena of Eu(OCN)<sub>2</sub> nanocrystals should be caused by combination between the "Faraday A and C terms" of the magnetic moment in the excited state. Polarized-light control using Eu(OCN)<sub>2</sub> nanocrystals in the blue-light region of the electromagnetic spectrum is a large first step into a new world of photo-functional semiconductor nanomaterials. Luminescence ; Nanocrystal ; Absorption (acoustics) ; Semiconductor ; Blueshift ; Absorption spectroscopy ; Photochemistry ; Materials science ; Optoelectronics ; Chemistry ; Nanotechnology ; Photoluminescence ; Optics ; Physics Luminescence Properties of Advanced Materials ; Magneto-Optical Properties and Applications ; Perovskite Materials and Applications