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density functional theory

Jingyu Pang, Yanhong Chao, Honghong Chang, Hongping Li, Jun Xiong, Minqiang He, Qi Zhang, Huaming Li, Wenshuai Zhu
In this paper, the carbon-doped boron nitride nanoplate (C-BNNP) was prepared by pyrolyzing the precursor under N2 and served as an excellent adsorbent for removal of Rhodamine B (RhB). The structure and composition of C-BNNP were characterized and its adsorption behavior for RhB was investigated. Compared with boron nitride nanoplate (BNNP) which was synthesized under NH3, C-BNNP displayed an enhancement of the adsorption capacity for RhB (833mg/g). The adsorption activity was comprehensibly studied by kinetics, isotherm and thermodynamics...
August 4, 2017: Journal of Colloid and Interface Science
Mehrnoosh Khodam Hazrati, Zahra Javanshir, Zargham Bagheri
It has been previously indicated that BN nanostructures may be nontoxic and biocompatible. Here the potential application of a B24N24 is explored as a drug delivery system for anti-cancer 5-fluorouracil based on the density functional theory. This drug prefers to attach via its oxygen atoms to the B atoms of the cluster with adsorption energy about -11.90kcalmol(-1) based on the dispersion corrected B3LYP level of theory. To make the cluster more appropriate for drug delivery, we replaced a B atom by Si or Al atom to improve the interaction strength...
August 9, 2017: Journal of Molecular Graphics & Modelling
Aleksandra Drzewiecka-Antonik, Paweł Rejmak, Marcin T Klepka, Anna Wolska, Piotr Pietrzyk, Karolina Stępień, Giuseppina Sanna, Marta Struga
The new Cu(II) complexes of 1/2/3-(bromophenyl)-3-(1,7,8,9-tetramethyl-3,5-dioxo-4-azatricyclo[,6)]dec-8-en-4-yl)thiourea derivatives have been synthesized. The spectroscopic studies together with density functional theory calculations of Cu(II) complexes revealed that two parent ligands coordinate to the copper cation in bidentate fashion via thiocarbonyl S and deprotonated N atoms forming rarely observed four-membered chelate ring, with nearly planar [CuN2S2] moiety. In solid state, the mononuclear complex is formed for thiourea derivative with 3-bromophenyl, whereas for Cu(II) connection with 2- and 4-bromophenyl-thioureas the formation of dinuclear complexes is observed, the latter formed by the stacking of mononuclear complexes...
August 9, 2017: Journal of Inorganic Biochemistry
Chun-Guang Liu, Meng-Xu Jiang, Zhong-Min Su
Geometrical structures, metal-support interactions, and infrared (IR) spectroscopy of a series of M1/POM (M = Cu, Zn, Ag, and Au; POM = [PW12O40](3-)) single-atom catalysts (SACs), and catalytic cycle for alkene epoxidation catalyzed by M1/POM SACs were studied using density functional theory (DFT) calculations. The calculations demonstrate that the most probable anchoring sties for the isolated single atoms studied here in the M1/POM SACs are the fourfold hollow sites on the surface of POM support. The bonding interaction between single metal atom and surface of POM support comes from the molecular orbitals with a mixture of d atomic orbital of metal and 2p group orbital of surface oxygen atoms of POM cage...
August 18, 2017: Inorganic Chemistry
Qiang Tan, Haiyan Zhu, Shengwu Guo, Yuanzhen Chen, Tao Jiang, Chengyong Shu, Shaokun Chong, Benjamin Hultman, Yongning Liu, Gang Wu
Deactivation of an anode catalyst resulting from the poisoning of COad-like intermediates is one of the major problems for methanol and ethanol electro-oxidation reactions (MOR & EOR), and remains a grand challenge towards achieving high performance for direct alcohol fuel cells (DAFCs). Herein, we report a new approach for the preparation of ultrafine cobalt-doped CeO2 dots (Co-CeO2, d = 3.6 nm), which can be an effective anti-poisoning promoter for Pd catalysts towards MOR and EOR in alkaline media. Compared to Pd/CeO2 and pure Pd, the hybrid Pd/Co-CeO2 nanocomposite catalyst exhibited a much enhanced activity and remarkable anti-poisoning ability for both MOR and EOR...
August 18, 2017: Nanoscale
Xiaowei Song, Matias R Fagiani, Sreekanta Debnath, Min Gao, Satoshi Maeda, Tetsuya Taketsugu, Sandy Gewinner, Wieland Schöllkopf, Knut R Asmis, Andrey Lyalin
The mechanism of dissociative D2 adsorption on Ti2O4(-), which serves as a model for an oxygen vacancy on a titania surface, is studied using infrared photodissociation spectroscopy in combination with density functional theory calculations and a recently developed single-component artificial force induced reaction method. Ti2O4(-) readily reacts with D2 under multiple collision conditions in a gas-filled ion trap held at 16 K forming a global minimum-energy structure (DO-Ti-(O)2-Ti(D)-O)(-). The highly exergonic reaction proceeds quasi barrier-free via several intermediate species, involving heterolytic D2-bond cleavage followed by D-atom migration...
August 18, 2017: Physical Chemistry Chemical Physics: PCCP
Zhongxu Wang, Jingxiang Zhao, Qinghai Cai
Searching for low-cost, efficient, and stable electrocatalysts for CO2 electroreduction (CO2ER) reactions is highly desirable for the reduction of CO2 emission and its conversion into useful products, but remains a great challenge. In this work, single transition metal atoms supported on porphyrin-like graphene catalysts, i.e., TMN4/graphene, acting as electrocatalysts for CO2 reduction were explored by means of comprehensive density functional theory (DFT) computations. Our results revealed that these anchored TM atoms possess high stability due to their strong hybridization with the unsaturated N atoms of the substrate and function as the active sites...
August 18, 2017: Physical Chemistry Chemical Physics: PCCP
Nathalie Camus, Nathalie Le Bris, Selbi Nuryyeva, Matthieu Chessé, David Esteban-Gómez, Carlos Platas-Iglesias, Raphaël Tripier, Mourad Elhabiri
The acid-base and copper(ii) coordination properties of three previously described cyclam derivatives are reported. Potentiometry, mass spectrometry, UV-vis absorption spectroscopy, electrochemistry and theoretical calculations were combined to investigate the protonation and binding properties of Bn-cyclam-EtOH (L1), oxo-cyclam-EtOH (L2) and oxo-Bn-cyclam-EtOH (L3). These three cyclams are C-functionalized by a hydroxyethyl pendant arm and display either one N-benzyl group and/or an amide replacing one macrocyclic secondary amine...
August 18, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Jingrun Zhu, Xiaoling Yang, Yihua Zhu, Yuanwei Wang, Jin Cai, Jianhua Shen, Luyi Sun, Chunzhong Li
Here we report the room-temperature, atmospheric synthesis of Mn-doped cesium lead halide (CsPbX3) perovskite quantum dots (QDs). The synthesis is performed without any sort of protection, and the dual-color emission mechanism is revealed by density functional theory. The Mn concentration reaches a maximum atomic percentage of 37.73 at%, which is significantly higher in comparison to those achieved in earlier reports via high temperature hot injection method. The optical properties of as-prepared nanocrystals (NCs) remain consistent even after several months...
August 21, 2017: Journal of Physical Chemistry Letters
Yousuke Ooyama, Toshiaki Enoki, Satoshi Aoyama, Joji Ohshita
We designed and developed a fused-bibenzo[c]thiophene, namely, 2,9-bis(tert-butyldimethylsilyl)phenanthro[9,8-bc:10,1-b'c']dithiophene (PHDT-Si), as a new π-building block in the emitters, photosensitizers and semiconductors for organic optoelectronic devices. Based on photophysical (photoabsorption, fluorescence and time-resolved fluorescence spectroscopy) and electrochemical measurements (cyclic voltammetry), and density functional theory (DFT) calculations, this work reveals that the fused-bibenzo[c]thiophene PHDT-Si, which is prepared by an efficient synthesis method, has a rigid, high planar and expanded π-conjugation structure, and possesses intense photoabsorption and fluorescence properties (λ = 598 nm (εmax = 41 000 M(-1) cm(-1)) and λ = 613 nm (Φf = 0...
August 18, 2017: Organic & Biomolecular Chemistry
Pei-Pei Zhao, Yong-Cheng Wang, Yang Sheng, Yi-Ming Jia
The reactions of Ni(+) with propionaldehyde in the gas phase have been systematically investigated using density functional theory at the B3LYP/def2-TZVP level. The decomposition reaction mechanism has been identified. Our calculations indicated that Ni(+) can assist decomposition of propionaldehyde to form Ni(+)CO and C2H6 through two types of reaction channel: C-C bond activation and C-H bond activation. In addition, charge decomposition analysis (CDA) was carried out to obtain a deeper understanding for orbital interaction of the initial complex...
August 15, 2017: Computational & Theoretical Chemistry
Jacek Kłos, Mijin Kim, Millard H Alexander, YuHuang Wang
The optical and electronic properties of atomically thin materials such as single-walled carbon nanotubes and graphene are sensitively influenced by substrates, the degree of aggregation, and the chemical environment. However, it has been experimentally challenging to determine the origin and quantify these effects. Here we use time-dependent density-functional-theory calculations to simulate these properties for well-defined molecular systems. We investigate a series of core-shell structures containing C60 enclosed in progressively larger carbon shells and their perhydrogenated or perfluorinated derivatives...
December 29, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
Tetsuya Takayanagi, Hirokazu Kimiya, Tatsushi Ohyama
We investigated aqueous solutions containing nitrite ions and DMPO (5,5-dimethyl-1-pyrroline-N-oxide) by ESR (Electron Spin Resonance) in the pH range from 1 to 6. A DMPO -OH signal was observed below pH 3.0 in the presence of nitrite ions, whereas in the absence of nitrite ion, an extremely weak signal was observed below pH 1.5. Addition of methanol, a hydroxyl radical scavenger, to this system did not lead to the appearance of a detectable DMPO-CH2OH signal. The possibility of this DMPO-OH signal being due to a genuine spin trapping process with hydroxyl radical was therefore ruled out...
August 17, 2017: Free Radical Research
Davide Migliorini, Helen Chadwick, Francesco Nattino, Ana Gutiérrez-González, Eric Dombrowski, Eric A High, Han Guo, Arthur L Utz, Bret Jackson, Rainer D Beck, Geert-Jan Kroes
Accurately simulating heterogeneously catalyzed reactions requires reliable barriers for molecules reacting at defects on metal surfaces, such as steps. However, first-principles methods capable of computing these barriers to chemical accuracy have yet to be demonstrated. We show that state-resolved molecular beam experiments combined with ab initio molecular dynamics using specific reaction parameter density functional theory (SRP-DFT) can determine the molecule-metal surface interaction with the required reliability...
August 22, 2017: Journal of Physical Chemistry Letters
Rafal Zuzak, Ruth Dorel, Mariusz Krawiec, Bartosz Such, Marek Kolmer, Marek Szymonski, Antonio M Echavarren, Szymon Godlewski
The on-surface synthesis of nonacene has been accomplished by dehydrogenation of an air-stable partially saturated precursor, which could be aromatized by using a combined scanning tunneling and atomic force microscope as well as by on-surface annealing. This transformation allowed the in-detail analysis of the electronic properties of nonacene molecules physisorbed on Au(111) by scanning tunneling spectroscopy measurements. The spatial mapping of molecular orbitals was corroborated by density functional theory calculations...
August 22, 2017: ACS Nano
Hua Jin, Hegen Zhou, Yongfan Zhang
The mechanism of CO oxidation on the WO₃(001) surface for gas sensing performance has been systematically investigated by means of first principles density functional theory (DFT) calculations. Our results show that the oxidation of CO molecule on the perfect WO₃(001) surface induces the formation of surface oxygen vacancies, which results in an increase of the surface conductance. This defective WO₃(001) surface can be re-oxidized by the O₂ molecules in the atmosphere. During this step, the active O₂(-) species is generated, accompanied with the obvious charge transfer from the surface to O₂ molecule, and correspondingly, the surface conductivity is reduced...
August 17, 2017: Sensors
Manoj Kumar, Joseph S Francisco
High-level coupled cluster theory with single and double excitation, and including a perturbative triples correction (CCSD(T)) method and a series of Dunning's augmented correlation consistent basis sets, aug-cc-pVXZ (X=D, T, Q and 5) was applied to examine the conformational landscape of SNO radical system. The basis set has an important effect on the relative stability of SNO radical isomers, and the NSO radical is the most stable member of SNO radical family. This is in contrast to previous density functional theory prediction suggesting SNO radical is the most stable isomer...
August 17, 2017: Journal of Physical Chemistry. A
Ziyad A Taha, Taher S Ababneh, Ahmed K Hijazi, Qutaiba Abu-Salem, Abdulaziz M Ajlouni, Shroq Ebwany
A pyridine-diacylhydrazone Schiff base ligand, L = 2,6-bis[(3-methoxy benzylidene)hydrazinocarbonyl]pyridine was prepared and characterized by single crystal X-ray diffraction. Lanthanide complexes, Ln-L, {[LnL(NO3 )2 ]NO3 .xH2 O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er)} were prepared and characterized by elemental analysis, molar conductance, thermal analysis (TGA/DTGA), mass spectrometry (MS), Fourier transform infra-red (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. Ln-L complexes are isostructural with four binding sites provided by two nitro groups along with four coordination sites for L...
August 17, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
Xing Huang, Travis Jones, Hua Fan, Marc-Georg Willinger
Void formation in semiconductors is generally considered to be deteriorating. However, for some systems, void formation and evolution are beneficial and can be used for the fabrication of novel nanostructures. In either scenario, the understanding of void formation and evolution is of both scientific and technical high importance. Herein, using ZnS ribbons as an example, we report real-time observations of void formation and the kinetics of growth at the nano- and atomic scales upon heating. Direct imaging reveals that voids, created by a focused electron beam in wurtzite (WZ) ribbons, have a rectangular shape elongated along the <0001> direction...
August 17, 2017: Nanoscale
Li-Fang Wang, Xiaolin Shu, Guang-Hong Lu, Fei Gao
An embedded-atom method potential has been developed for modeling hydrogen in body-centered-cubic (bcc) tungsten by fitting to an extensive database of density functional theory (DFT) calculations. Comprehensive evaluations of the new potential are conducted by comparing various hydrogen properties with DFT calculations and available experimental data, as well as all the other tungsten-hydrogen potentials. The new potential accurately reproduces the point defect properties of hydrogen, the interaction among hydrogen atoms, the interplay between hydrogen and a monovacancy, and the thermal diffusion of hydrogen in tungsten...
August 17, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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