jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Maurizio Chiminelli | Gabriele Scarica | Davide Balestri | Luciano Marchiò | Nicola Della Ca’ | Giovanni Maestri
Source: Tetrahedron Chem (article, 2023-11-10)
Field: Chemistry — Organic Chemistry

The visible-light-promoted intermolecular para-cycloadditions of allenamides on naphthalene The preparation of bridged bicyclooctadienes through the dearomatization of simple arenes is an interesting synthetic tool to access a vast chemical space of elegant molecular architectures from a wide range of simple and cheap building blocks. However, the energetic toll due to the loss of the aromatic stabilization has greatly limited the development of para-cycloadditions, especially with respect to intermolecular processes. We report herein the first general approach for the selective dearomatization of simple naphthalene. The visible-light-promoted reaction occurs under mild conditions over an ample range of substrates and it involves the initial sensitization of an acylallenamide. Moreover, complete control on the difunctionalization of either the internal or the terminal C–C double bond is observed depending on the substrate functionalization. Naphthalene ; Intermolecular force ; Chemistry ; Combinatorial chemistry ; Cycloaddition ; Substrate (aquarium) ; Surface modification ; Chemical space ; Photochemistry ; Nanotechnology ; Computational chemistry ; Molecule ; Organic chemistry ; Materials science ; Drug discovery ; Catalysis ; Physical chemistry Radical Photochemical Reactions ; Catalytic C–H Functionalization Methods ; Sulfur-Based Synthesis Techniques
Authors: Veit Dippold | Sarah Vogl | Julia Grüneberg | Arne Thomas
Source: Macromolecular Rapid Communications (article, 2023-04-07)
Field: Materials Science — Materials Chemistry

Linker Exchange as Facile Method for Post‐Synthetic Modification of β‐Ketoenamine‐linked Covalent Organic Frameworks Post-synthetic linker exchange performed on covalent organic frameworks (COFs) has become an important method to introduce functional building blocks into their backbone and thus to tune their chemical and physical properties. However, the linker exchange method has so far only been described for COFs with relatively weak linkages like imines. Herein, it is shown that this method can be also used for a post-synthetic linker exchange reaction on a β-ketoenamine linked COF. The time needed to achieve considerable linker exchange is much prolonged compared to other COFs with less stable linkages, however, this enables to achieve very good control on the ratio of the respective building blocks within the framework. Linker ; Covalent bond ; Materials science ; Combinatorial chemistry ; Chemistry ; Nanotechnology ; Computer science ; Organic chemistry Covalent Organic Framework Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Luminescence and Fluorescent Materials
Authors: Samuel Nees | Henrik Beer | Philip Just | Leon Teichmeier | Leif E. Christoffer | Ailina Guljam | Kushik Kushik | Holger Braunschweig | Christian Hering‐Junghans
Source: ChemPlusChem (article, 2023-02-24)
Field: Chemistry — Inorganic Chemistry

On the Reactivity of Mes*P(PMe<sub>3</sub>) towards Aluminum(I) Compounds – Evidence for the Intermediate Formation of Phosphaalumenes Phosphaalumenes are the heavier isoelectronic analogs of alkynes and have eluded facile synthesis until recently. We have reported that the combination of a phosphinidene transfer agent, <sup>Ar</sup> TerP(PMe<sub>3</sub> ) (<sup>Ar</sup> Ter=2,6-Ar<sub>2</sub> -C<sub>6</sub> H<sub>3</sub> ), with (Cp*Al)<sub>4</sub> (Cp*=C<sub>5</sub> (CH<sub>3</sub> )<sub>5</sub> ) afforded the phosphaalumenes <sup>Ar</sup> TerPAlCp* as isolable, violet, thermally stable compounds. In here we describe attempts to utilize Mes*P(PMe<sub>3</sub> ) (Mes*=2,4,6-tBu<sub>3</sub> -C<sub>6</sub> H<sub>2</sub> ) as a phosphinidene source in combination with different Al(I) precursors, namely <sup>Dip</sup> NacnacAl (<sup>Dip</sup> Nacnac=HC[C(Me)NDip]<sub>2</sub> , Dip=2,6-iPr<sub>2</sub> -C<sub>6</sub> H<sub>3</sub> ), (Cp*Al)<sub>4</sub> and Cp<sup>3t</sup> Al (Cp<sup>3t</sup> =1,2,4-tBu<sub>3</sub> -C<sub>5</sub> H<sub>2</sub> ). In all cases the formation of phosphaalumenes was not observed, however, their intermediate formation is indicated by formation of the dimer [Cp*Al(μ-PMes*)]<sub>2</sub> (2) and C-H-bond activation products along the putative P=Al bond, giving unusual 1,2-P,Al-tetrahydronaphtalene derivatives 1 and 4, clearly underlining the role the sterically demanding group on phosphorus plays in these transformations. The reactivity studies are supported by theoretical studies, demonstrating a thermodynamic preference for the C-H activation products. Additionally, we show that there are potential pitfalls in the synthesis of Cp*<sub>2</sub> AlH, the precursor to make (Cp*Al)<sub>4</sub> and give recommendations how to circumvent these. Phosphinidene ; Chemistry ; Reactivity (psychology) ; Steric effects ; Dimer ; Stereochemistry ; Medicinal chemistry ; Organic chemistry Synthesis and characterization of novel inorganic/organometallic compounds ; Organophosphorus compounds synthesis ; Organometallic Complex Synthesis and Catalysis
Authors: Nzar Rauf Abdullah | Hunar Omar Rashid | Botan Jawdat Abdullah | Chi‐Shung Tang | Viðar Guðmundsson
Source: Materials Chemistry and Physics (article, 2023-01-19)
Field: Materials Science — Materials Chemistry

Planar buckling controlled optical conductivity of SiC monolayer from Deep-UV to visible light region: A first-principles study Monolayer ; Planar ; Materials science ; Conductivity ; Optoelectronics ; Buckling ; Visible spectrum ; Nanotechnology ; Optics ; Composite material ; Chemistry ; Computer science ; Physics Boron and Carbon Nanomaterials Research ; ZnO doping and properties ; Nanowire Synthesis and Applications
Authors: Churna Bhandari | Durga Paudyal
Source: Physical Review Applied (article, 2023-08-07)
Field: Materials Science — Materials Chemistry

Giant Magnetic and Optical Anisotropy in Cerium-Substituted M-Type Strontium Hexaferrite Driven by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mn>4</mml:mn><mml:mi>f</mml:mi></mml:math> Electrons By performing density-functional calculations, we find a giant magnetocrystalline anisotropy (MCA) constant in abundant element cerium ($\mathrm{Ce}$) substituted M-type hexaferrite, in the energetically favorable strontium site, assisted by a quantum confined electron transfer from $\mathrm{Ce}$ to a specific iron ($2a$) site. Remarkably, the calculated electronic structure shows that the electron transfer leads to the formation of ${\mathrm{Ce}}^{3+}$ and ${\mathrm{Fe}}^{2+}$ at the $2a$ site producing an occupied $\mathrm{Ce}$($4{f}^{1}$) state below the Fermi level that adds a significant contribution to MCA and magnetic moment. A half $\mathrm{Ce}$ substitution forms a metallic state, while a full substitution retains the semiconducting state of the strontium hexaferrite (host). In the latter, the band gap is reduced due to the formation of charge-transferred states in the gap region of the host. The optical absorption coefficient shows an enhanced anisotropy between light polarization in parallel and perpendicular directions. Calculated formation energies, including the analysis of probable competing phases, and elastic constants confirm that both compositions are chemically and mechanically stable. With successful synthesis, the $\mathrm{Ce}$ hexaferrite can be an alternative high-performing critical-element-free permanent magnet material adapted for use in devices such as automotive traction drive motors. Cerium ; Materials science ; Strontium ; Electron transfer ; Density functional theory ; Magnetic moment ; Anisotropy ; Condensed matter physics ; Physics ; Chemistry ; Physical chemistry ; Optics ; Quantum mechanics Magnetic Properties and Synthesis of Ferrites ; Advancements in Battery Materials ; Heusler alloys: electronic and magnetic properties
Authors: Joyshree Maji | Sanjeev Kumar Pandey | S. Basu
Source: Biotechnology Notes (article, 2023-01-01)
Field: Materials Science — Materials Chemistry

The electrical transport and antibacterial properties of Fe doped MgO nanoparticles synthesized by a soft chemical technique Fe doped MgO nanoparticles were synthesized using a straightforward soft chemical method. We conducted a comprehensive examination of the electrical properties of Fe-doped MgO nanoparticles with a crystalline size range of 7-10 nm. Simultaneously, we explored their antibacterial capabilities. Our findings indicate that an increase in the concentration of Fe-doped MgO correlates with an enhanced bactericidal effect. To gain a deeper understanding of charge transfer processes, the AC conductivity and dielectric characteristics of the samples across various temperatures and frequencies was studied.The antibacterial activity was studied utilising the MIC methodology, the live count (LC) method, and the agar cup technique in addition to the electrical characteristics. After exposure to nanoparticles, we observed the disruption of pathogenic cell walls through transmission electron microscopy (TEM) analysis. These results suggest that Fe-doped MgO nanoparticles hold promise for the development of novel, more effective antibacterial drugs. The ½ MIC for <i>E.coli</i> was found to be 2.75 μg/ml, while for <i>Bacillus</i> sp., it was 1.75 μg/ml when exposed to Fe-doped MgO nanoparticles. This dosage level may find applications in the medical field. However, further investigations are required to assess potential toxicity and long-term environmental and human health effects. If successful in vivo tests follow, Fe-doped MgO nanoparticles could emerge as valuable antibacterial agents. Nanoparticle ; Doping ; Materials science ; Antibacterial activity ; Transmission electron microscopy ; Dielectric ; Nanotechnology ; Chemical engineering ; Nuclear chemistry ; Chemistry ; Bacteria ; Optoelectronics Magnesium Oxide Properties and Applications ; Nanoparticles: synthesis and applications ; Copper-based nanomaterials and applications
Authors: Luca Spiridigliozzi | Mauro Bortolotti | Gianfranco Dell’Agli
Source: Materials (article, 2023-03-10)
Field: Materials Science — Materials Chemistry

On the Effect of Standard Deviation of Cationic Radii on the Transition Temperature in Fluorite-Structured Entropy-Stabilized Oxides (F-ESO) It is confirmed that Fluorite-structured Entropy-Stabilized Oxides (F-ESO) can be obtained with multicomponent (5) equimolar systems based on cerium, zirconium, and other rare earth elements, selected according to the predictor already proposed by the authors. Indeed, in the present study, three different samples owning a standard deviation (SD in the following) of their cationic radii greater than the threshold value (i.e., SD > 0.095 with cationic radii measured in Å) needed to ensure the formation of the single-phase fluorite structure, were prepared via co-precipitation method. After a calcination step at 1500 °C for 1 h, the entropy-driven transition from multiple phases to single-phase fluorite-like structure has been actually confirmed. Thus, with the aim of defining the temperature at which such entropy-driven transition occurred, and identifying possible relation between such temperature and the actual value of SD, the phase evolution of all the prepared samples as a function of temperature (ranging from 800 °C to 1300 °C) was analyzed by in situ High Temperature X-ray Diffraction. An apparent inverse correlation between the standard deviation and the entropy-driven transition temperature has been identified, i.e., the higher the former, the lower the latter. These results, based on the conducted basic structural analysis, provide further support to the SD-based empirical predictor developed by the authors, suggesting that high values of SD could bring additional contribution to the overall entropy of the system, other than the configurational one. Thus, this SD-driven entropy contribution directly increases with the increasing of the standard deviation of the cationic radii of a given F-ESO. Fluorite ; Cationic polymerization ; Standard deviation ; Standard molar entropy ; Materials science ; Thermodynamics ; Entropy (arrow of time) ; Relative standard deviation ; Chemistry ; Enthalpy ; Physics ; Mathematics ; Polymer chemistry ; Metallurgy ; Statistics ; Chromatography Thermal Expansion and Ionic Conductivity ; Magnetic and transport properties of perovskites and related materials ; High Entropy Alloys Studies
Authors: Jonathan Hopkins | Daniel Ta | Antonio Lauto | Carly Baker | J. Daniels | Paweł Wagner | Klaudia Wagner | Nigel Kirby | Claudio Cazorla | David L. Officer | Damia Mawad
Source: Advanced Materials Technologies (article, 2023-06-27)
Field: Materials Science — Polymers and Plastics

Impact of Side Chain Extension on the Morphology and Electrochemistry of Phosphonated Poly(Ethylenedioxythiophene) Derivatives Abstract One factor with great bearing on the electrochemical performance of conjugated polymers is the film morphology. A balance between crystalline and amorphous domains needs to be achieved for the polymer to have an optimal ionic‐electronic conductance. Herein, the morphological and electrochemical properties of poly(ethylenedioxythiophene) polymers functionalized with phosphonate groups separated by methylene and butylene alkyl spacers from the backbone are compared. Extending the spacer from methylene to butylene increases structural ordering in the solid state as revealed by grazing‐incidence wide‐angle X‐ray scattering. However, the ordered domains are only short range, suggestive of a paracrystalline morphology in which ordered regions are separated by amorphous regions. This has a negative impact on the intermolecular charge transport. The longer spacer appears to have impeded the uptake of hydrated counterions, seen by the increase in the ionization potential and energy requirement for electrochemical switching, as well as the decrease in the volumetric capacitance. These results elucidate the advantages of having the phosphonate pendant group close to the backbone, separated only by a methylene spacer. This synthetic design likely facilitates hydrated counterions to accumulate around the polar phosphonate groups, close to the doped backbone where they can easily compensate the charge carriers formed upon oxidation. Phosphonate ; Side chain ; Materials science ; Alkyl ; Electrochemistry ; Methylene ; Counterion ; Polymer ; Polymer chemistry ; Amorphous solid ; Crystallography ; Chemical engineering ; Chemistry ; Organic chemistry ; Composite material ; Ion ; Physical chemistry ; Electrode Conducting polymers and applications ; Advanced Battery Materials and Technologies ; Supercapacitor Materials and Fabrication
Authors: Amr Ghazy | Mika Lastusaari | Maarit Karppinen
Source: Journal of Materials Chemistry C (article, 2023-01-01)
Field: Materials Science — Materials Chemistry

White-light emitting multi-lanthanide terephthalate thin films by atomic/molecular layer deposition ALD/MLD enables multi-lanthanide organic thin films in which different lanthanide species are optimally combined through organic linkers to yield warm white light photoluminescence. Materials science ; Lanthanide ; Atomic layer deposition ; Layer (electronics) ; Atomic layer epitaxy ; Deposition (geology) ; White light ; Thin film ; Nanotechnology ; Chemical engineering ; Optoelectronics ; Organic chemistry ; Ion Lanthanide and Transition Metal Complexes ; Organic Light-Emitting Diodes Research ; Nanocluster Synthesis and Applications
Authors: Antoine Brézault | Véronique Schmitt | Valérie Ravaine | Patrick Perrin | Nicolas Sanson
Source: Macromolecular Chemistry and Physics (article, 2023-11-28)
Field: Materials Science — Materials Chemistry

A “Limited Aggregation Model” to Predict the Size of Acrylamide‐Based Microgels Synthesized with Ionic Surfactants Abstract The size of acrylamide‐based microgels can be decreased by addition of ionic surfactants during the classical dispersion polymerization. Nevertheless, the mechanism of such syntheses is not well understood yet. Here, a “Limited Aggregation Model” is proposed by analogy with the limited coalescence mechanism occurring for Pickering emulsion stabilization. In such a model, nuclei aggregate until a constant, high enough surfactant surface coverage is reached, which ensures colloidal stability. Consequently, the total surface of the growing particles, linked to the inverse of their size, is linearly dependent on the surfactant concentration. This law is verified if the surfactant/polymer particle interaction is high enough to guarantee a “total adsorption” of the surfactants onto the particles. This simple model fits very well with all the data extracted from the literature, including very different synthesis conditions. Finally, it not only permits to predict the microgels size, but it is also an interesting tool to investigate the role of each synthesis parameter like initiator, solvent or polymer. For instance, it shows that the surfactant role is not linked to its charge, proving that a phenomenon complementary to the electrostatic repulsion, related to the surfactant tail, ensures the colloidal stability of the growing collapsed microgels. Pulmonary surfactant ; Emulsion polymerization ; Chemical engineering ; Polymer ; Chemistry ; Coalescence (physics) ; Ionic bonding ; Dispersion (optics) ; Colloid ; Polymerization ; Dispersion polymerization ; Particle size ; Polymer chemistry ; Surface tension ; Materials science ; Thermodynamics ; Organic chemistry ; Physical chemistry ; Physics ; Ion Pickering emulsions and particle stabilization ; Surfactants and Colloidal Systems ; Advanced Polymer Synthesis and Characterization
Authors: Daria Novikova | Ammar Al Mustafa | Tatyana A. Grigoreva | Светлана В. Ворона | Stanislav I. Selivanov | Vyacheslav G. Tribulovich
Source: Molecules (article, 2023-09-12)
Field: Chemistry — Organic Chemistry

NMR-Verified Dearomatization of 5,7-Substituted Pyrazolo[1,5-a]pyrimidines Tetrahydropyrazolo[1,5-a]pyrimidine (THPP) is an attractive scaffold for designing biologically active compounds. The most obvious way to obtain such compounds is to reduce pyrazolopyrimidines with complex hydrides, because the pyrimidine ring is reduced in the preference over the pyrazole ring. The presence of substituents at positions five and seven of pyrazolo[1,5-a]pyrimidines complicates the set of reaction products but makes it more attractive for medicinal chemistry because four possible stereoisomers can be formed during reduction. However, the formation of only <i>syn</i>-isomers has been described in the literature. This article is the first report on the formation of <i>anti</i>-configured isomers along with <i>syn</i>-isomers in the reduction of model 5,7-dimethylpyrazolo[1,5-a]pyrimidine, which was confirmed by NMR. The bicyclic core in the <i>syn</i>-configuration was shown to be conformationally stable, which was used to estimate the long-range interproton distances using NOESY data. At the same time, long-range dipole-dipole interactions corresponding to a distance between protons of more than 6 Å were first registered and quantified. In turn, the bicyclic core in the <i>trans</i>-configuration represents a conformationally labile system. For these structures, an analysis of conformations observed in solutions was carried out. Our results indicate the significant potential of <i>trans</i>-configured tetrahydropyrazolo[1,5-a]pyrimidines for the development of active small molecules. While possessing structural lability due to the low energy of the conformational transition, they have the ability to adjust to the active site of the desired target. Chemistry ; Pyrimidine ; Bicyclic molecule ; Ring (chemistry) ; Stereochemistry ; Two-dimensional nuclear magnetic resonance spectroscopy ; Molecule ; Lability ; Cis–trans isomerism ; Computational chemistry ; Organic chemistry Synthesis and Reactivity of Heterocycles ; Synthesis and Reactions of Organic Compounds ; Quinazolinone synthesis and applications
Authors: Alberto F. Garrido‐Castro | Yu̅ta Hioki | Yoshifumi Kusumoto | Kyohei Hayashi | Jeremy Griffin | Kaid C. Harper | Yu Kawamata | Phil S. Baran
Source: Angewandte Chemie (article, 2023-09-01)
Field: Chemistry — Organic Chemistry

Scalable Electrochemical Decarboxylative Olefination Driven by Alternating Polarity** Abstract A mild, scalable (kg) metal‐free electrochemical decarboxylation of alkyl carboxylic acids to olefins is disclosed. Numerous applications are presented wherein this transformation can simplify alkene synthesis and provide alternative synthetic access to valuable olefins from simple carboxylic acid feedstocks. This robust method relies on alternating polarity to maintain the quality of the electrode surface and local pH, providing a deeper understanding of the Hofer‐Moest process with unprecedented chemoselectivity. Decarboxylation ; Chemoselectivity ; Polarity (international relations) ; Alkene ; Electrochemistry ; Scalability ; Chemistry ; Carboxylic acid ; Combinatorial chemistry ; Alkyl ; Organic chemistry ; Electrode ; Catalysis ; Computer science Radical Photochemical Reactions ; CO2 Reduction Techniques and Catalysts ; Catalytic C–H Functionalization Methods
Authors: Sreejith Sudhakaran Jayabhavan | Geethanjali Kuppadakkath | Krishna K. Damodaran
Source: ChemPlusChem (article, 2023-07-05)
Field: Materials Science — Biomaterials

The Role of Functional Groups in Tuning the Self‐Assembly Modes and Physical Properties of Multicomponent Gels We have analyzed the nature and role of functional groups on the self-assembly modes and the physical properties of multicomponent gels with structurally similar individual components. The gelation properties of individual and mixed enantiomeric compounds of biphenyl bis-(amides) of alanine (BPA) or phenylalanine (BPP) methyl ester were analyzed in various solvent/solvent mixtures. Multicomponent gels were formed by mixing the enantiomeric BPP compounds at a lower concentration, but a higher concentration was required for mixed alanine-based BPA gels. The comparison of the mechanical strength of the individual and mixed BPP compounds indicated that the mixed BPP gels displayed enhanced mechanical strength (∼2-fold increase) in p-xylene, but a weaker gel was observed in DMSO/water. However, a reverse trend was observed for BPA gels, indicating the role of functional groups in the gel network formation. X-ray diffraction analysis of the gelator and the xerogels in the solid state confirmed the formation of co-assembled networks in mixed enantiomeric gels. The stability of the gels towards anions was evaluated by analyzing the anion induced stimuli-responsive properties. These results indicate the effective modeling of the functional groups of the individual components could lead to multicomponent gels with tunable properties. Chemistry ; Solvent ; Enantiomer ; Alanine ; Chemical engineering ; Self-assembly ; Polymer chemistry ; Organic chemistry ; Amino acid Supramolecular Self-Assembly in Materials ; Polydiacetylene-based materials and applications ; Luminescence and Fluorescent Materials