85,643 results match your criteria functional theory


Intelligent [email protected] heterostructures with enhanced photoabsorption and photoconversion efficiency for tri-modal imaging guided combinatorial cancer therapy by near-infrared Ⅱ light.

J Colloid Interface Sci 2022 Jun 10;625:614-627. Epub 2022 Jun 10.

Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China. Electronic address:

A novel nanoplatform that supports multimodal imaging has been designed for deep tumor therapy. In this study, [email protected] heterojunction nanocomposites with tunable spectral absorption, effective electron-hole separation and high photothermal conversion efficiency were prepared for the combination therapy of phototherapy (PT), chemodynamic therapy (CDT) and radiotherapy (RT). By adjusting the doping ratio, the heterojunction nanoparticles show obvious tunable ability of local surface plasmon resonance and the ability to promote electron-hole separation with significantly enhanced reactive oxygen species production capacity. Read More

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Adsorption and oxidation of ciprofloxacin by a novel layered double hydroxides modified sludge biochar.

J Colloid Interface Sci 2022 Jun 22;625:596-605. Epub 2022 Jun 22.

State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai 200092, China.

In this study, biochar derived from municipal sludge (SBC) was modified by CoFe-Layered double hydroxides (CoFe-LDH), and used as adsorbent and oxidant for the removal of ciprofloxacin (CIP) for the first time. Under the optimal conditions, the CIP removal rate is increased by 24% compared with the single SBC, while the removal rates of total organic carbon and total nitrogen in the modified one are increased by 24% and 27%, respectively. Mechanism investigation suggested that the specific surface area and adsorption sites of modified biochar increased, and more CIP was adsorbed to the composite surface and then oxidized by more environmental persistent free radicals contained in the [email protected], when the adsorbed CIP molecules was oxidized and degraded, the adsorption sites can be freed and thus new CIP could be adsorbed to the [email protected] Read More

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Resting-state network organisation in children with traumatic brain injury.

Cortex 2022 Jun 4;154:89-104. Epub 2022 Jun 4.

Amsterdam Reproduction and Development Research Institute, Amsterdam, the Netherlands; Emma Children's Hospital, Amsterdam UMC location University of Amsterdam, Department of Pediatrics, Emma Children's Hospital Amsterdam UMC Follow-Me program & Emma Neuroscience Group, Meibergdreef 9, Amsterdam, the Netherlands.

Children with traumatic brain injury are at risk of neurocognitive and behavioural impairment. Although there is evidence for abnormal brain activity in resting-state networks after TBI, the role of resting-state network organisation in paediatric TBI outcome remains poorly understood. This study is the first to investigate the impact of paediatric TBI on resting-state network organisation using graph theory, and its relevance for functional outcome. Read More

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Room-Temperature Photooxidation of CH to CHOH with Nearly 100% Selectivity over Hetero-ZnO/FeO Porous Nanosheets.

J Am Chem Soc 2022 Jun 28. Epub 2022 Jun 28.

Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.

The huge challenge for CH photooxidation into CHOH lies in the activation of the inert C-H bond and the inhibition of CHOH overoxidation. Herein, we design two-dimensional in-plane -scheme heterostructures composed of two different metal oxides, with efforts to polarize the symmetrical CH molecules and strengthen the O-H bond in CHOH. As a prototype, we first fabricate ZnO/FeO porous nanosheets, where high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy affirm their in-plane -scheme heterostructure. Read More

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Dearomatization of Benzenoid Arenes Triggered by Triplet Excited State Intramolecular Proton Transfer.

J Phys Chem A 2022 Jun 28. Epub 2022 Jun 28.

Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China.

The detailed mechanism of photoinduced dearomatization of benzenoid arenes is investigated using both the high-level method and density functional theory. The results suggest that the optically allowed singlet excited state (S) can quickly decay to the lowest triplet excited state (T) through a barrierless internal conversion and intersystem crossing. Importantly, we find a triplet excited state intramolecular proton transfer (T-ESIPT) pathway to produce a diradical triplet intermediate (M), which can trigger the subsequent [4 + 2] dearomatization reaction. Read More

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Correlation between C═O Stretching Vibrational Frequency and p Shift of Carboxylic Acids.

J Phys Chem B 2022 Jun 28. Epub 2022 Jun 28.

Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.

Identifying the p values of aspartic acid (Asp) and glutamic acid (Glu) in active sites is essential for understanding enzyme reaction mechanisms. In this study, we investigated the correlation between the C═O stretching vibrational frequency (ν) of protonated carboxylic acids and the p values using density functional theory calculations. In unsaturated carboxylic acids (e. Read More

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Improved Dispersibility of Graphene in an Aqueous Solution by Reduced Graphene Oxide Surfactant: Experimental Verification and Density Functional Theory Calculation.

Langmuir 2022 Jun 28. Epub 2022 Jun 28.

School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, PR China.

It is difficult to disperse graphene flakes well in an aqueous solution while maintaining conductivity due to its high hydrophobicity. Herein, we demonstrated that a well-dispersed state of graphene in an aqueous solution was realized by using reduced graphene oxide (rGO) with a suitable content of oxygen-functional groups. A rGO-dispersed graphene (rGO/G) film was fabricated from the graphene dispersion with good conductivity by using rGO with a C/O ratio of 2. Read More

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Deep-Red/Near-Infrared to Blue-Green Phosphorescent Iridium(III) Complexes Featuring Three Differently Charged (0, -1, and -2) Ligands: Structures, Photophysics, and Organic Light-Emitting Diode Application.

Inorg Chem 2022 Jun 28. Epub 2022 Jun 28.

School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China.

We have designed and synthesized a new family of neutral phosphorescent iridium(III) complexes (- featuring three differently charged (0, -1, and -2) ligands, in which biphenyl () is used as a dianionic (-2) ligand, 4,6-difluorophenylpyridine () or 1-phenylisoquinoline () is used as a monoanionic (-1) ligand, and 2,2'-bipyridyl (), 1,10-phenanthroline (), 1,2-bis(diphenylphosphanyl)benzene (), or 1,2-bis(diphenylphosphanyl)ethane () is used as a neutral (0) ligand. The X-ray structures confirm that three coordination carbon atoms of all complexes assume a facial geometry, which can be beneficial to the stability of the structure. More importantly, the emitting color of the complexes can be tuned from deep red/near-infrared (NIR) (680-710 nm) to blue-green (466-496 nm) with different monoanionic (-1) ligands and neutral (0) ligands. Read More

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Anthraquinone-1,8-Derived (Pseudo-) Crown and Lariat Ethers: Design and Applications as Fluorescent and Chromogenic Ion (Pair) Sensors.

Chem Asian J 2022 Jun 28. Epub 2022 Jun 28.

Shanghai University, College of Science, No.99 Shangda Road, 200444, Shanghai, CHINA.

Cyclic polyamine/ethers embedded with anthraquinone moieties and functional pendants, are structural analogues of crown ethers and (oxo-) cyclams, and could be utilized as sensitive and selective chemosensors towards metal cations. Those pseudo- (similar but geometrically distinct) crown and lariat ethers show various cation-binding patterns and stoichiometry, being modulated by donor type, cavity size and pendants' chelating ability. The luminescent and chromogenic properties also differ a lot along with the derivation of the parental macrocycle. Read More

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Modeling the spectral properties of poly(x-phenylenediamine) conducting polymers using a combined TD-DFT and electrostatic embedding approach.

J Comput Chem 2022 Jun 28. Epub 2022 Jun 28.

CNRS, Chimie ParisTech-PSL, Institute of Chemistry for Life and Health Sciences (i-CLeHS), Theoretical Chemistry and Modelling Group (CTM), PSL University, Paris, France.

The absorption spectra of polymers derived from ortho, meta and para phenylenediamines (o-PDA, m-PDA and p-PDA) have been simulated combining periodic density functional theory (DFT) calculations with time-dependent DFT simulations. These latter have been carried out on finite clusters embedded in a set of point charges devised to exactly reproduce the electrostatic potential of the periodic chains. The results are compared with those obtained for solvated o-PDA, m-PDA and p-PDA oligomers of increasing sizes extracted from the periodic structures. Read More

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Connecting Thermodynamics of Alkali Ion Exchange on the Quartz (101) Surface with Density Functional Theory Calculations.

J Phys Chem A 2022 Jun 28. Epub 2022 Jun 28.

Department of Geosciences, Georgia State University, Atlanta, Georgia 30303, United States.

Periodic plane-wave density functional theory (DFT) calculations were performed on the α-quartz (SiO) (101) surface to model exchange of adsorbed Li and either Na, K, or Rb in inner- and outer-sphere adsorbed, and aqueous configurations, which are charge-balanced with 2 Cl. SiO or SiOH groups represented the adsorption surface sites. The SiO models included 58 HO and 2 HO molecules to approximate an aqueous environment, whereas the SiOH models had 59 HO and 1 HO molecules. Read More

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Automated Bonding Analysis with Crystal Orbital Hamilton Populations.

Chempluschem 2022 Jun 7:e202200123. Epub 2022 Jun 7.

Université Catholique de Louvain, Institute of Condensed Matter and Nanosciences, Chemin des Étoiles 8, 1348, Louvain-la-Neuve, Belgium.

Understanding crystalline structures based on their chemical bonding is growing in importance. In this context, chemical bonding can be studied with the Crystal Orbital Hamilton Population (COHP), allowing for quantifying interatomic bond strength. Here we present a new set of tools to automate the calculation of COHP and analyze the results. Read More

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Improving the Efficiency of Variationally Enhanced Sampling with Wavelet-Based Bias Potentials.

J Chem Theory Comput 2022 Jun 28. Epub 2022 Jun 28.

Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.

Collective variable-based enhanced sampling methods are routinely used on systems with metastable states, where high free energy barriers impede the proper sampling of the free energy landscapes when using conventional molecular dynamics simulations. One such method is variationally enhanced sampling (VES), which is based on a variational principle where a bias potential in the space of some chosen slow degrees of freedom, or collective variables, is constructed by minimizing a convex functional. In practice, the bias potential is taken as a linear expansion in some basis function set. Read More

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Mechanistic Insight into the Ni-Catalyzed Kumada Cross-Coupling: Alkylmagnesium Halide Promotes C-F Bond Activation and Electron-Deficient Metal Center Slows Down β-H Elimination.

Authors:
Yuanyuan Li Jun Zhu

J Org Chem 2022 Jun 28. Epub 2022 Jun 28.

State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.

The Ni-catalyzed Kumada-Tamao-Corriu (KTC) cross-coupling between aryl fluorides and alkyl Grignard reagents has been used to achieve a highly selective Csp-Csp bond construction the carbon-fluorine (C-F) bond activation. However, the detailed mechanism of this groundbreaking KTC reaction remains unclear. Herein, we perform a series of analyses by density functional theory (DFT) calculations in order to understand the reaction mechanisms for the selective activation of a highly inert C-F bond by Ni catalysts with bidentate phosphorus ligands. Read More

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Antioxidant and copper-chelating power of new molecules suggested as multiple target agents against Alzheimer's disease. A theoretical comparative study.

Phys Chem Chem Phys 2022 Jun 28. Epub 2022 Jun 28.

Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, I-87136 Rende, CS, Italy.

In this study, the scavenging activity against OOH radicals and the copper-chelating ability of two new synthesized molecules (named and ) that can act as multiple target agents against Alzheimer's disease have been investigated at the density functional theory level. The p and molar fractions at physiological pH have been predicted. The main antioxidant reaction mechanisms in lipid-like and water environments have been considered and the relative rate constants determined. Read More

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Hydrogenation of Formate Species Using Atomic Hydrogen on a Cu(111) Model Catalyst.

J Am Chem Soc 2022 Jun 28. Epub 2022 Jun 28.

Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.

The reaction mechanism of the CHOH synthesis by the hydrogenation of CO on Cu catalysts is unclear because of the challenge in experimentally detecting reaction intermediates formed by the hydrogenation of adsorbed formate (HCOO). Thus, the objective of this study is to clarify the reaction mechanism of the CHOH synthesis by establishing the kinetic natures of intermediates formed by the hydrogenation of adsorbed HCOO on Cu(111). We exposed HCOO on Cu(111) to atomic hydrogen at low temperatures of 200-250 K and observed the species using infrared reflection absorption (IRA) spectroscopy and temperature-programmed desorption (TPD) studies. Read More

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Molecular Dynamic Insights into the Distinct Solvation Structures of Aromatic and Aliphatic Compounds in Monoethanolamine-Based Deep Eutectic Solvents.

J Phys Chem B 2022 Jun 28. Epub 2022 Jun 28.

Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.

Deep eutectic solvents (DESs) are developing as an alternate medium for aromatic extraction, especially benzene and thiophene from aliphatic hydrocarbon mixtures. In this work, molecular dynamics (MD) simulations were first used to investigate the solvation structure of benzene, thiophene, and -hexane in monoethanolamine-based DESs. It reveals the liquid structures in the adjacent neighbor shells, which is a function of electron-withdrawing sulfur attached to thiophene and the π-electron cloud of benzene. Read More

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A theoretical study of the role of the non-innocent phenolate ligand of a nickel complex in water oxidation.

Authors:
Ting Fan Yongfei Ji

Phys Chem Chem Phys 2022 Jun 28. Epub 2022 Jun 28.

School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China.

Water oxidation is the bottleneck of artificial photosynthesis. A novel nickel phenolate complex with a redox-active ligand has been designed to manage multiple electron transfers during water oxidation (D. Wang and C. Read More

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Electrochemically Triggered Energy Release from an Azothiophene-based Molecular Solar Thermal System.

ChemSusChem 2022 Jun 27. Epub 2022 Jun 27.

Friedrich Alexander University Erlangen Nuremberg: Friedrich-Alexander-Universitat Erlangen-Nurnberg, Interface Research and Catalysis, Erlangen Center for Interface Research and Catalysis, Egerlandstraße 3, 91058, Erlangen, GERMANY.

Molecular solar thermal (MOST) systems combine solar energy conversion, storage, and release in simple one-photon one-molecule processes. Here, we address the electrochemically triggered energy release from an azothiophene-based MOST system by photoelectrochemical infrared reflection absorption spectroscopy (PEC-IRRAS) and density functional theory (DFT). Specifically, we studied the electrochemically triggered back-reaction from the energy rich ( Z )-3-cyanophenylazothiophene to its energy lean ( E )-isomer using highly oriented pyrolytic graphite (HOPG) as the working electrode. Read More

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The relativistic Euler equations with a physical vacuum boundary: Hadamard local well-posedness, rough solutions, and continuation criterion.

Arch Ration Mech Anal 2022 10;245(1):127-182. Epub 2022 May 10.

Department of Mathematics, University of California at Berkeley, Berkeley, USA.

In this paper we provide a complete local well-posedness theory for the free boundary relativistic Euler equations with a physical vacuum boundary on a Minkowski background. Specifically, we establish the following results: (i) local well-posedness in the Hadamard sense, i.e. Read More

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Green Crop Yam-Derived Carbons: Off-Plane Active Sites for Oxygen Electroreduction Identified by First-Principles.

ACS Appl Mater Interfaces 2022 Jun 27. Epub 2022 Jun 27.

State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029, P. R. China.

Plant-derived nonprecious metal catalysts are considered one of the promising candidates of platinum for oxygen reduction reaction (ORR). In this work, the typical microscopic morphology of fresh green crop yam is first detected by cryoscanning electronic microscopy. Using the green and widely sourced yam with spherical starch in nature as a precursor, well-defined spherical carbons are prepared via hypersaline-assisted hydrothermal carbonization and NHactivation, featuring a high heteroatom doping level and a hierarchical porous structure. Read More

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Intrinsic ferroelectricity in Y-doped HfO thin films.

Nat Mater 2022 Jun 27. Epub 2022 Jun 27.

Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE, USA.

Ferroelectric HfO-based materials hold great potential for the widespread integration of ferroelectricity into modern electronics due to their compatibility with existing Si technology. Earlier work indicated that a nanometre grain size was crucial for the stabilization of the ferroelectric phase. This constraint, associated with a high density of structural defects, obscures an insight into the intrinsic ferroelectricity of HfO-based materials. Read More

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Planar π-extended cycloparaphenylenes featuring an all-armchair edge topology.

Nat Chem 2022 Jun 27. Epub 2022 Jun 27.

Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.

The [n]cycloparaphenylenes ([n]CPPs)-n para-linked phenylenes that form a closed-loop-have attracted substantial attention due to their unique cyclic structure and highly effective para-conjugation leading to a myriad of fascinating electronic and optoelectronic properties. However, their strained topology prevents the π-extension of CPPs to convert them either into armchair nanobelts or planarized CPP macrocycles. Here we successfully tackle this long-standing challenge and present the bottom-up synthesis and characterization of atomically precise in-plane π-extended [12]CPP on Au(111) by low-temperature scanning probe microscopy and spectroscopy combined with density functional theory. Read More

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Data-driven Interpretable Descriptors for Structure-Activity Relation of Surface Lattice Oxygen on Doped Vanadium Oxides.

Angew Chem Int Ed Engl 2022 Jun 27. Epub 2022 Jun 27.

Tianjin University, School of Chemical Engineering and Technology, Provost, Tianjin University, 135 Yaguan Road, Jinnan District, 300350, Tianjin, CHINA.

Understanding the structure-activity relation of surface lattice oxygen is critical but challenging to design efficient redox catalysts. This paper describes data-driven redox activity descriptors on doped vanadium oxides combining density functional theory and interpretable machine learning. We corroborate p-band center is the most crucial feature about the activity. Read More

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Tower Carbon: A new large-cell carbon allotrope.

J Phys Condens Matter 2022 Jun 27. Epub 2022 Jun 27.

Xi'an University of Architecture and Technology, 13 Yanta road, Xi'an, Shaanxi, 710055, CHINA.

The structural development of novel carbon materials has always been a hot spot in theoretical and experimental research, due to carbon possess a wide range of applications in the fields of industry and electronic technology. In this work, a sp3 hybrid carbon allotrope, named Tower carbon, is proposed and studied based on density functional theory (DFT), including its structure, stability, electronic and mechanical properties. The crystal structure of tower carbon is like a Chinese classical architectural tower, so it is named tower carbon, which belongs to the cubic crystal system and is stable in thermodynamics, dynamics, and mechanics. Read More

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Elucidating the Role of Antisolvents on the Surface Chemistry and Optoelectronic Properties of CsPbBrI Perovskite Nanocrystals.

J Am Chem Soc 2022 Jun 27. Epub 2022 Jun 27.

Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom.

Colloidal lead-halide perovskite nanocrystals (LHP NCs) have emerged over the past decade as leading candidates for efficient next-generation optoelectronic devices, but their properties and performance critically depend on how they are purified. While antisolvents are widely used for purification, a detailed understanding of how the polarity of the antisolvent influences the surface chemistry and composition of the NCs is missing in the field. Here, we fill this knowledge gap by studying the surface chemistry of purified CsPbBrI NCs as the model system, which in itself is considered a promising candidate for pure-red light-emitting diodes and top-cells for tandem photovoltaics. Read More

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Reactive Oxygen Species Sequestration Induced Synthesis of β-PbO and Its Polymorphic Transformation to α-PbO at Atomically Thin Regimes.

ACS Nano 2022 Jun 27. Epub 2022 Jun 27.

Sir Ian Potter NanoBioSensing Facility, NanoBiotechnology Research Laboratory (NBRL), School of Science, RMIT University, Melbourne, Victoria 3001, Australia.

The emergence of attractive properties in materials at atomically thin regimes has seen an ongoing interest in two-dimensional (2D) materials. An aspect that has lacked focused attention is the effect of 2D material thickness on its crystal structure. As several layered materials naturally exist in mixed metastable phases, it raises an important question of whether a specific polymorph of these mixed-phase materials will be favored at atomically thin limits. Read More

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Origin of the Unusual Ground-State Spin = 9 in a Cr Single-Molecule Magnet.

J Am Chem Soc 2022 Jun 27. Epub 2022 Jun 27.

Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain.

The molecular wheel [Cr(OMe)(OCCMe)], abbreviated {Cr}, with an unusual intermediate total spin = 9 and non-negligible cluster anisotropy, / = -0.045(2) K, is a rare case among wheels based on an even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state ( = 0). Herein, we unveil the origin of such a behavior. Read More

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An Adaptive Rhodium Catalyst to Control the Hydrogenation Network of Nitroarenes.

Angew Chem Int Ed Engl 2022 Jun 27. Epub 2022 Jun 27.

Max-Planck-Institut fur chemische Energiekonversion, Synergistic Organometallic Catalysis, Stiftstrasse 34 - 36, D - 45470, Mülheim an der Ruhr, GERMANY.

An adaptive catalytic system that provides control over the nitroarene hydrogenation network to prepare a wide range of aniline and hydroxylamine derivatives is presented. This system takes advantage of a delicate interplay between a rhodium(III) center and a Lewis acidic borane introduced in the secondary coordination sphere of the metal. The high chemoselectivity of the catalyst in the presence of various potentially vulnerable functional groups and its readiness to be deployed at a preparative scale illustrate its practicality. Read More

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Coordinating tiny limbs and long bodies: Geometric mechanics of lizard terrestrial swimming.

Proc Natl Acad Sci U S A 2022 Jul 27;119(27):e2118456119. Epub 2022 Jun 27.

School of Physics, Georgia Institute of Technology, Atlanta, GA 30332.

Although typically possessing four limbs and short bodies, lizards have evolved diverse morphologies, including elongate trunks with tiny limbs. Such forms are hypothesized to aid locomotion in cluttered/fossorial environments but propulsion mechanisms (e.g. Read More

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