jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Qaisar Abbas | Mojtaba Mirzaeian | Mohammad Ali Abdelkareem | Ahmed Al Makky | Arti Yadav | A.G. Olabi
Source: International Journal of Energy Research (article, 2021-12-14)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Structural tuneability and electrochemical energy storage applications of <scp>resorcinol‐formaldehyde</scp> ‐based carbon aerogels Extensive use of carbon-based materials has revolutionised the number of modern scientific areas such as transportation, electronic, material chemistry and electrochemical energy storage, mainly due to their outstanding characteristics such as excellent conductivity, mechanical strength, ease of availability and cost-effectiveness. However, it is difficult to fine-tune the physiochemical characteristics of naturally occurring carbonaceous materials according to desired applications. High purity carbon aerogels with control over porous structure prepared using synthetic chemistry techniques such as polymerisation can be a potential substitute carbon material due to their outstanding characteristics including superior conductivity, high level of porosity and chemical inertness. Designing tailored polymeric carbon materials according to their anticipated uses is advantageous and can be achieved by altering various synthesis parameters at the initial stages of preparation. This not only helps in fine tuning porous structure of carbon aerogels but can also assist in producing composite materials by introducing materials on the surface or within the bulk of produced carbons. Carbon fibers ; Materials science ; Porosity ; Electrochemistry ; Resorcinol ; Energy storage ; Nanotechnology ; Chemical engineering ; Porous medium ; Conductivity ; Polymerization ; Aerogel ; Composite number ; Polymer ; Composite material ; Chemistry ; Organic chemistry ; Electrode Supercapacitor Materials and Fabrication ; Aerogels and thermal insulation ; Catalytic Processes in Materials Science
Authors: James Nicolas Pagaduan | Nicholas Hight‐Huf | Avdhoot Datar | Yehiel Nagar | Michael D. Barnes | Doron Naveh | Ashwin Ramasubramaniam | Reika Katsumata | Todd Emrick
Source: ACS Nano (article, 2021-01-29)
Field: Materials Science — Materials Chemistry

Electronic Tuning of Monolayer Graphene with Polymeric “Zwitterists” Work function engineering of two-dimensional (2D) materials by application of polymer coatings represents a research thrust that promises to enhance the performance of electronic devices. While polymer zwitterions have been demonstrated to significantly modify the work function of both metal electrodes and 2D materials due to their dipole-rich structure, the impact of zwitterion chemical structure on work function modulation is not well understood. To address this knowledge gap, we synthesized a series of sulfobetaine-based zwitterionic random copolymers with variable substituents and used them in lithographic patterning for the preparation of negative-tone resists (<i>i.e.</i>, "zwitterists") on monolayer graphene. Ultraviolet photoelectron spectroscopy indicated a significant work function reduction, as high as 1.5 eV, induced by all polymer zwitterions when applied as ultrathin films (<10 nm) on monolayer graphene. Of the polymers studied, the piperidinyl-substituted version, produced the largest dipole normal to the graphene sheet, thereby inducing the maximum work function reduction. Density functional theory calculations probed the influence of zwitterion composition on dipole orientation, while lithographic patterning allowed for evaluation of surface potential contrast via Kelvin probe force microscopy. Overall, this polymer "zwitterist" design holds promise for fine-tuning 2D materials electronics with spatial control based on the chemistry of the polymer coating and the dimensions of the lithographic patterning. Graphene ; Work function ; Materials science ; Monolayer ; Kelvin probe force microscope ; Polymer ; Nanotechnology ; Density functional theory ; Zwitterion ; Optoelectronics ; Chemistry ; Organic chemistry ; Composite material ; Molecule ; Computational chemistry ; Layer (electronics) ; Atomic force microscopy Graphene research and applications ; 2D Materials and Applications ; Advanced Memory and Neural Computing
Authors: Margarita Bulatova | Daniil M. Ivanov | Matti Haukka
Source: Crystal Growth & Design (article, 2021-01-14)
Field: Chemistry — Physical and Theoretical Chemistry

Classics Meet Classics: Theoretical and Experimental Studies of Halogen Bonding in Adducts of Platinum(II) 1,5-Cyclooctadiene Halide Complexes with Diiodine, Iodoform, and 1,4-Diiodotetrafluorobenzene Complexes of PtX2COD (X = Cl, Br, I; COD = 1,5-cyclooctadiene) were cocrystallized with classical halogen-bond donors (CHI3, I2, and 1,4-diiodotetrafluorobenzene (FIB)), resulting in noncovalently bound supramolecular aggregates of various lengths—from heterotrimers to polymers. The influence of halides in the complexes on the geometry and strength of the halogen bond (XB) was studied both experimentally by single-crystal XRD and theoretically by quantum chemical methods such as noncovalent interaction plots (NCI-plot), electrostatic potential (ESP) surface analysis, and a combination of electron localization function (ELF) and quantum theory of atoms in molecules (QTAIM) analyses. It was shown that strength of XB interactions in the adducts increases in the order CHI3 > FIB > I2. Although halogen bonding was found to be the main preorganizing force in the structures, in the case of FIB adducts a rare Pt···I interaction was involved in additional stabilization of the structure. Hence, fine-tuning of halogen bonding can influence the length of the polymer, as well as the strength and directionality of interactions in the adduct. Halogen bond ; Chemistry ; Adduct ; Atoms in molecules ; Supramolecular chemistry ; Halide ; Halogen ; Molecule ; Non-covalent interactions ; Crystallography ; Crystal engineering ; Polymer ; Crystal structure ; Polymer chemistry ; Inorganic chemistry ; Organic chemistry ; Hydrogen bond ; Alkyl Crystallography and molecular interactions ; Chemical Thermodynamics and Molecular Structure ; Advanced Chemical Physics Studies
Authors: Zi‐Qi Li | Omar Apolinar | Ruohan Deng | Keary M. Engle
Source: Chemical Science (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

Directed Markovnikov hydroarylation and hydroalkenylation of alkenes under nickel catalysis We report a full account of our research on nickel-catalyzed Markovnikov-selective hydroarylation and hydroalkenylation of non-conjugated alkenes, which has yielded a toolkit of methods that proceed under mild conditions with alkenyl sulfonamide, ketone, and amide substrates. Regioselectivity is controlled through catalyst coordination to the native Lewis basic functional groups contained within these substrates. To maximize product yield, reaction conditions were fine-tuned for each substrate class, reflecting the different coordination properties of the directing functionality. Detailed kinetic and computational studies shed light on the mechanism of this family of transformations, pointing to transmetalation as the turnover-limiting step. Markovnikov's rule ; Transmetalation ; Regioselectivity ; Chemistry ; Catalysis ; Combinatorial chemistry ; Yield (engineering) ; Nickel ; Amide ; Ketone ; Substrate (aquarium) ; Lewis acids and bases ; Palladium ; Organic chemistry ; Materials science Catalytic C–H Functionalization Methods ; Sulfur-Based Synthesis Techniques ; Catalytic Alkyne Reactions
Authors: Xiushang Xu | Marco Di Giovannantonio | José I. Urgel | Carlo A. Pignedoli | Pascal Ruffieux | Kläus Müllen | Román Fasel | Akimitsu Narita
Source: Nano Research (article, 2021-04-23)
Field: Materials Science — Materials Chemistry

On-surface activation of benzylic C-H bonds for the synthesis of pentagon-fused graphene nanoribbons Abstract Graphene nanoribbons (GNRs) have potential for applications in electronic devices. A key issue, thereby, is the fine-tuning of their electronic characteristics, which can be achieved through subtle structural modifications. These are not limited to the conventional armchair, zigzag, and cove edges, but also possible through incorporation of non-hexagonal rings. On-surface synthesis enables the fabrication and visualization of GNRs with atomically precise chemical structures, but strategies for the incorporation of non-hexagonal rings have been underexplored. Herein, we describe the on-surface synthesis of armchair-edged GNRs with incorporated five-membered rings through the C-H activation and cyclization of benzylic methyl groups. Ortho -Tolyl-substituted dibromobianthryl was employed as the precursor monomer, and visualization of the resulting structures after annealing at 300 °C on a gold surface by high-resolution noncontact atomic force microscopy clearly revealed the formation of methylene-bridged pentagons at the GNR edges. These persisted after annealing at 340 °C, along with a few fully conjugated pentagons having singly-hydrogenated apexes. The benzylic methyl groups could also migrate or cleave-off, resulting in defects lacking the five-membered rings. Moreover, unexpected and unique structural rearrangements, including the formation of embedded heptagons, were observed. Despite the coexistence of different reaction pathways that hamper selective synthesis of a uniform structure, our results provide novel insights into on-surface reactions en route to functional, non-benzenoid carbon nanomaterials. Graphene ; Materials science ; Nanotechnology ; Annealing (glass) ; Conjugated system ; Crystallography ; Nanomaterials ; Graphene nanoribbons ; Scanning tunneling microscope ; Chemistry ; Chemical physics ; Polymer ; Composite material Graphene research and applications ; Molecular Junctions and Nanostructures ; Surface Chemistry and Catalysis
Authors: Ye Wang | Feng Li | Nan Bian | Xing Xiao
Source: Materials Science and Engineering A (article, 2021-05-04)
Field: Materials Science — Biomaterials

Coordinated control of preferred orientation and uniformity of AZ31 in accumulative alternating back extrusion Extrusion ; Materials science ; Microstructure ; Grain size ; Dynamic recrystallization ; Magnesium alloy ; Plasticity ; Recrystallization (geology) ; Composite material ; Material flow ; Metallurgy ; Hot working Magnesium Alloys: Properties and Applications ; Aluminum Alloys Composites Properties ; Microstructure and mechanical properties
Authors: Tamara Kharlamova | Margarita V. Salina | В. А. Светличный | M.A. Salaev | Andrey I. Stadnichenko | G. V. Mamontov
Source: Catalysis Today (article, 2021-08-31)
Field: Chemistry — Organic Chemistry

CeO2-supported Pt–Ag bimetallic catalysts for 4-nitrophenol reduction Bimetallic strip ; Calcination ; Catalysis ; Incipient wetness impregnation ; 4-Nitrophenol ; Metal ; Dispersion (optics) ; Reaction rate constant ; Chemistry ; Inorganic chemistry ; Materials science ; Nuclear chemistry ; Chemical engineering ; Selectivity ; Metallurgy ; Organic chemistry ; Kinetics Nanomaterials for catalytic reactions ; Catalytic Processes in Materials Science ; Ammonia Synthesis and Nitrogen Reduction
Authors: Meng Shi | Ratul Das | Sankara Arunachalam | Himanshu Mishra
Source: Physics of Fluids (article, 2021-12-01)
Field: Materials Science — Surfaces, Coatings and Films

Suppression of Leidenfrost effect on superhydrophobic surfaces The Leidenfrost phenomenon entails the levitation of a liquid droplet over a superheated surface, cushioned by its vapor layer. This vapor layer can obstruct boiling heat transfer in heat exchangers, thereby compromising energy efficiency and safety. For water, superhydrophobic surfaces are believed to reduce the Leidenfrost point (TL)—the temperature at which this phenomenon occurs. Therefore, superhydrophobic surfaces are not commonly utilized in thermal machinery despite their benefits such as reducing frictional drag. Here, we demonstrate that it is possible to achieve superhydrophobicity without lowering TL by surface engineering and fine-tuning liquid–solid adhesion. We demonstrate that TL of water on superhydrophobic surfaces comprising doubly reentrant pillars (DRPs) can exceed that on hydrophilic and even superhydrophilic surfaces. Via theory and computation, we disentangle the contributions of microtexture, heat transfer, and surface chemistry on the onset of the Leidenfrost phenomenon. Remarkably, coating-free and superhydrophobic DRP architecture can facilitate ∼300% greater heat transfer to water droplets at 200 °C in comparison with conventional superhydrophobic surfaces. These findings advance our understanding of the Leidenfrost phenomenon and herald technological applications of superhydrophobic surfaces in thermal machinery. Physics ; Leidenfrost effect ; Mechanics ; Classical mechanics ; Nucleate boiling ; Heat transfer Surface Modification and Superhydrophobicity ; Fluid Dynamics and Heat Transfer ; Icing and De-icing Technologies
Authors: Anish Rao | Soumendu Roy | Pramod P. Pillai
Source: Langmuir (article, 2021-01-27)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Temporal Changes in Interparticle Interactions Drive the Formation of Transiently Stable Nanoparticle Precipitates We demonstrate the power of fine-tuned interparticle interactions, emanating from appropriately functionalized surfaces, in creating self-assembled structures that show a transient switching between completely precipitated and redispersed stages of nanoparticles (NPs). The pH-dependent temporal changes in the strength of electrostatic interactions are explored to unveil a transient self-assembly response in plasmonic NPs. The assembly process was triggered by the electrostatic attraction between positively charged gold NPs (AuNPs) and an aggregating agent, ethylenediaminetetraacetic acid (EDTA). The autonomous changes in the pH and ionic strength of the solution, under the influence of atmospheric CO<sub>2</sub>, weaken the aggregating ability of EDTA and initiate the complete disassembly of [+] AuNP-EDTA precipitates. The use of a nondestructive mode of autonomous disassembly helped in achieving some of the desirable feats in the field of transient self-assembly such as easy removal of waste, formation of a transiently stable precipitate state, and negligible dampness in redispersion. The chemical strategy adopted in the present work, to introduce transientness, can act as a generic tool in creating the next generation of complex matter. Ethylenediaminetetraacetic acid ; Nanoparticle ; Transient (computer programming) ; Nanotechnology ; Ionic strength ; Chemical engineering ; Materials science ; Plasmon ; Chemical physics ; Chemistry ; Chelation ; Aqueous solution ; Inorganic chemistry ; Organic chemistry ; Computer science Gold and Silver Nanoparticles Synthesis and Applications ; Photochromic and Fluorescence Chemistry ; Pickering emulsions and particle stabilization
Authors: Junrong Huang | Min Yang | Chuan Dai | Yajun Zhou | Huilong Fang | Lizhi Zhu | Feng Yin | Zigang Li
Source: Frontiers in Chemistry (review, 2021-10-05)
Field: Chemistry — Organic Chemistry

Novel Strategies in C-H Oxidations for Natural Product Diversification—A Remote Functionalization Application Summary Selectively activating the distal inactive C-H bond for functionalization is one of the on-going challenge in organic synthetic chemistry. In recent years, benefiting from the development of selective synthesis methods, novel methodologies not only make it possible to break non-traditional chemical bonds and attain more diversity in inactive sites, but also provide more possibilities for the diversification of complex natural products. Direct C-H bond functionalization approaches make it feasible to explore structure-activity relationship (SAR), generate metabolites and derivatives, and prepare biological probes. Among them, direct oxidation of inert C-H bonds is one of the most common methods for natural product diversification. In this review, we focus on the application of remote functionalization of inert C-H bonds for natural products derivatization, including the establishment of oxidation methods, the regulation of reaction sites, and the biological activities of derivatives. We highlight the challenges and opportunities of remote functionalization of inert C-H bonds for natural product diversification through selected and representative examples. We try to show that inert C-H bond oxidation, properly regulated and optimized, can be a powerful and efficient strategy in both synthetic and medicinal chemistry. Surface modification ; Inert ; Natural product ; Chemistry ; Combinatorial chemistry ; Derivatization ; Diversification (marketing strategy) ; Organic chemistry ; Business Catalytic C–H Functionalization Methods ; Oxidative Organic Chemistry Reactions ; Alkaloids: synthesis and pharmacology
Authors: Yi Shen | Guodong Xue | Yasi Dai | Sergio Moles Quintero | Hanjiao Chen | Dongsheng Wang | Fang Miao | Fabrizia Negri | Yonghao Zheng | Juan Casado
Source: Nature Communications (article, 2021-10-29)
Field: Chemistry — Organic Chemistry

Normal &amp; reversed spin mobility in a diradical by electron-vibration coupling Abstract π−conjugated radicals have great promise for use in organic spintronics, however, the mechanisms of spin relaxation and mobility related to radical structural flexibility remain unexplored. Here, we describe a dumbbell shape azobenzene diradical and correlate its solid-state flexibility with spin relaxation and mobility. We employ a combination of X-ray diffraction and Raman spectroscopy to determine the molecular changes with temperature. Heating leads to: i) a modulation of the spin distribution; and ii) a “normal” quinoidal → aromatic transformation at low temperatures driven by the intramolecular rotational vibrations of the azobenzene core and a “reversed” aromatic → quinoidal change at high temperatures activated by an azobenzene bicycle pedal motion amplified by anisotropic intermolecular interactions. Thermal excitation of these vibrational states modulates the diradical electronic and spin structures featuring vibronic coupling mechanisms that might be relevant for future design of high spin organic molecules with tunable magnetic properties for solid state spintronics. Diradical ; Spintronics ; Chemical physics ; Intramolecular force ; Materials science ; Intermolecular force ; Spin (aerodynamics) ; Relaxation (psychology) ; Spin states ; Raman spectroscopy ; Chemistry ; Molecule ; Condensed matter physics ; Singlet state ; Atomic physics ; Physics ; Ferromagnetism ; Stereochemistry ; Organic chemistry ; Optics Synthesis and Properties of Aromatic Compounds ; Magnetism in coordination complexes ; Photochemistry and Electron Transfer Studies
Authors: Marcin Kobielusz | Akio Nitta | Wojciech Macyk | Bunsho Ohtani
Source: The Journal of Physical Chemistry Letters (article, 2021-03-18)
Field: Chemistry — Electrochemistry

Combined Spectroscopic Methods of Determination of Density of Electronic States: Comparative Analysis of Diffuse Reflectance Spectroelectrochemistry and Reversed Double-Beam Photoacoustic Spectroscopy The diffuse reflectance spectroelectrochemistry (SE-DRS) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) provide unique, complementary information on the density of electronic states (DOS) in the vicinity of the conduction band bottom. The measurements are performed under quite different conditions, representing the solid/liquid and solid/gas interfaces in SE-DRS and RDB-PAS, respectively. DOS profiles obtained from both types of measurements can be considered as unique "fingerprints" of the tested materials. The analysis of DOS profiles recorded for 16 different TiO<sub>2</sub> samples confirms that both methods similarly describe the shapes of DOS profiles around the conduction band edges. The states characterized by energy higher than VBT (valence-band top) + <i>E</i><sub>g</sub> can be considered as electronic states within the conduction band. Recognition of the potential of the conduction band bottom allows one to classify the electronic states as deep or shallow electron traps or conduction band states, which play different roles in photocatalysis. The comparative analysis shows that both methods provide very useful information which can be used in understanding and predicting the photo(electro)catalytic reactivity of semiconductors. Photoacoustic spectroscopy ; Diffuse reflectance infrared fourier transform ; Semimetal ; Spectroscopy ; Density of states ; Conduction band ; Semiconductor ; Chemistry ; Electronic structure ; Valence (chemistry) ; Diffuse reflection ; Materials science ; Quasi Fermi level ; Electron ; Analytical Chemistry (journal) ; Optoelectronics ; Band gap ; Optics ; Photoacoustic imaging in biomedicine ; Photocatalysis ; Condensed matter physics ; Physics ; Computational chemistry Electrochemical Analysis and Applications ; Gas Sensing Nanomaterials and Sensors ; Chalcogenide Semiconductor Thin Films
Authors: Yuchen Zhang | Xue Zhang | Shengming Ma
Source: Nature Communications (article, 2021-04-23)
Field: Chemistry — Organic Chemistry

Stretchable chiral pockets for palladium-catalyzed highly chemo- and enantioselective allenylation Pyrazolones are a vital class of heterocycles possessing various biological properties and much attention is paid to the diversified synthesis of enantiopure pyrazolone derivatives. We describe here the development of diphenylphosphinoalkanoic acid based chiral bisphosphine ligands, which are successfully applied to the palladium-catalyzed asymmetric allenylation of racemic pyrazol-5-ones. The reaction affords C-allenylation products, optically active pyrazol-5-ones bearing an allene unit, in high chemo- and enantioselectivity, with DACH-ZYC-Phos-C1 as the best ligand. The synthetic potential of the C-allenylation products is demonstrated. Furthermore, the enantioselectivity observed with DACH-ZYC-Phos-C1 is rationalized by density functional theory studies. Enantioselective synthesis ; Palladium ; Catalysis ; Nanotechnology ; Combinatorial chemistry ; Chemistry ; Materials science ; Organic chemistry Catalytic C–H Functionalization Methods ; Asymmetric Hydrogenation and Catalysis ; Asymmetric Synthesis and Catalysis
Authors: Pierre Gaffuri | Tatjana Dedova | Estelle Appert | Mati Danilson | Adrien Baillard | Odette Chaix‐Pluchery | Frank Güell | Ilona Oja Açik | Vincent Consonni
Source: Applied Surface Science (article, 2021-12-28)
Field: Materials Science — Materials Chemistry

Enhanced photocatalytic activity of chemically deposited ZnO nanowires using doping and annealing strategies for water remediation Photocatalysis ; Dopant ; Materials science ; Doping ; Annealing (glass) ; Nanowire ; Nanotechnology ; Chemical engineering ; Catalysis ; Optoelectronics ; Chemistry ; Metallurgy ; Organic chemistry ZnO doping and properties ; Advanced Photocatalysis Techniques ; Gas Sensing Nanomaterials and Sensors