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atomic structure

Maya S Nair, Samar D'Mello, Rashmi Pant, Krishna Mohan Poluri
Interactions of a natural stilbene compound, resveratrol with two DNA sequences containing AATT/TTAA segments have been studied. Resveratrol is found to interact with both the sequences. The mode of interaction has been studied using absorption, steady state fluorescence and circular dichroism spectroscopic techniques. UV-visible absorption and fluorescence studies provided the information regarding the binding constants and the stoichiometry of binding, whereas circular dichroism studies depicted the structural changes in DNA upon resveratrol binding...
April 18, 2017: Journal of Photochemistry and Photobiology. B, Biology
Van A Ngo, Laura L Perissinotti, Williams Miranda, S R Wayne Chen, Sergei Y Noskov
Ryanodine (Ryd) irreversibly targets ryanodine receptors (RyRs), a family of intracellular calcium release channels essential for many cellular processes ranging from muscle contraction to learning and memory. Little is known of the atomistic details about how Ryd binds to RyRs. In this study, we used all-atom molecular dynamics simulations with both enhanced and bidirectional sampling to gain direct insights into how Ryd interacts with major residues in RyRs that were experimentally determined to be critical for its binding...
April 25, 2017: Biophysical Journal
Qingqing Li, Zhen Huang, Pengfei Guan, Rui Su, Qi Cao, Yimin Chao, Wei Shen, Junjie Guo, Hualong Xu, Renchao Che
Oxide materials with redox capability have attracted worldwide attentions in many applications. Introducing defects into crystal lattice is an effective method to modify and optimize redox capability of oxides as well as their catalytic performance. However, the relationship between intrinsic characteristics of defects and properties of oxides has been rarely reported. Herein, we report a facile strategy to introduce defects by doping a small amount of Ni atoms (1.8 at.%) into ceria lattice at atomic level through the effect of microstructure of crystal on the redox property of ceria...
April 26, 2017: ACS Applied Materials & Interfaces
Yashika Sharma, Sevi Murugavel
We report deviations from an ideal behavior of binary chalcogenide glass composition Ge20Te80 with respect to its quenching rate on mass density and thermal parameters including glass transition temperature. In an ideal glass, the increase in quenching rate will decrease the characteristic relaxation time and correspondingly shift in the glass transition temperature (Tg) to higher temperature and result in lower density. This, however, holds only when the liquid structure remains same as in equilibrium glass structure independent of their quenching rate...
April 26, 2017: Journal of Physical Chemistry. B
Kei Murakami, Shuya Yamada, Takeshi Kaneda, Kenichiro Itami
Azines, which are six-membered aromatic compounds containing one or more nitrogen atoms, serve as ubiquitous structural cores of aromatic species with important applications in biological and materials sciences. Among a variety of synthetic approaches toward azines, C-H functionalization represents the most rapid and atom-economical transformation, and it is advantageous for the late-stage functionalization of azine-containing functional molecules. Since azines have several C-H bonds with different reactivities, the development of new reactions that allow for the functionalization of azines in a regioselective fashion has comprised a central issue...
April 26, 2017: Chemical Reviews
Baodui Wang, Yuting Luo, Yong Peng, Weisheng Liu, Fengjuan Chen
Self-assembly has emerged as a promising method to control the structure and properties of ensembles of inorganic nanoparticles (NPs) for exploiting their collective effects. However, the rational assembly of inorganic NPs into soluble porous architectures as homogenized heterogeneous catalyst has been less studied. Here, we show that inorganic NPs can be used for the assembly of soluble porous coordination frameworks (PCFs) by atom-scale interfacial coordination-driven assembly strategy. Given large pore size, high dispersity in solution, strong absorption in the near-infrared range (NIR), and a long living electron-hole pair, the obtained soluble framework can serve as a platform for homogenize heterogeneous photocatalysts, which exhibited excellent activity, high apparent quantum efficiency, and recyclability to catalyze the noble metal free Suzuki coupling reaction under NIR light at room temperature...
April 26, 2017: Chemistry: a European Journal
Johannes Klösener, Markus Wiesemann, Mark Niemann, Beate Neumann, Hans-Georg Stammler, Berthold Hoge
For (pentafluoroethyl)phenylstannanes, (C2F5)4-nSnPhn (n = 1-3), and dimethylbis(pentafluoroethyl)stannane, (C2F5)2SnMe2, a high yield synthesis was developed by the use of LiC2F5 as a C2F5 transfer reagent. The treatment of these products with gaseous hydrogen chloride or hydrogen bromide afforded (C2F5)4-nSnXn (X = Cl, Br; n = 1-3) in good yields. The (pentafluoroethyl)stannanes were fully characterized by 1H, 13C, 19F and 119Sn NMR, IR spectroscopy and mass spectrometry. The treatment of the (pentafluoroethyl)tin halides (C2F5)4-nSnXn with 1,10-phenanthroline (phen) led to the formation of the corresponding octahedrally coordinated complexes [(C2F5)4-nSnXn(phen)], the structures of which were elucidated by X-ray diffraction analyses...
April 26, 2017: Chemistry: a European Journal
Michał Wójcik, Jaroslaw Wrobel, Zuzanna Janczuk, Jozef Mieczkowski, Ewa Gorecka, Joonmyung Choi, Maenghyo Cho, Damian Pociecha
Embedding nanoparticles in a responsive polymer matrix is a formidable way to fabricate hybrid materials with predesigned properties and prospective applications in actuators, mechanically tunable optical elements or electroclinic films. However, achieving chemical compatibility between nanoparticles and organic matter is not trivial and often results in disordered structures. Herein we show that using nanoparticles as exclusive cross-linkers in the preparation of liquid-crystalline polymers can yield long-range ordered liquid-crystalline elastomers with high loading of well dispersed nanoparticles, as confirmed with small angle XRD measurements...
April 26, 2017: Chemistry: a European Journal
Filiberto Ricciardella, Sten Vollebregt, Tiziana Polichetti, Mario Miscuglio, Brigida Alfano, Maria L Miglietta, Ettore Massera, Girolamo Di Francia, Pasqualina M Sarro
The crystal structure of graphene flakes is expected to significantly affect their sensing properties. Here we report an experimental investigation on the crystalline structure of graphene aimed at exploring the effects on the gas sensing properties. The morphology of graphene, prepared via Chemical Vapor Deposition (CVD), Liquid Phase Exfoliation (LPE) and Mechanical Exfoliation (ME), is inspected through Raman spectroscopy, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). CVD and LPE-graphene structures are found to be more defective with respect to ME-graphene...
April 26, 2017: Nanoscale
M Spivak, V Arcisauskaite, X López, J E McGrady, C de Graaf
Density functional theory, Complete Active Space Self-Consistent Field (CASSCF) and perturbation theory (CASPT2) methodologies have been used to explore the electronic structure of a series of trichromium Extended Metal Atom Chains (EMACS) with different capping ligands. The study is motivated by the very different structural properties of these systems observed in X-ray experiments: the CN(-)-capped example has a symmetric Cr3 unit while for the NO3(-)-capped analogue the same unit has two very different Cr-Cr bond lengths...
April 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
E Varathan, V Subramanian
In this study a series of dibenzothiophene (DBT) derivatives having different valence states of sulfur atoms have been reported as host materials for blue phosphorescent organic light-emitting diodes. Their electronic properties have also been thoroughly investigated to develop structure-property relationships which include the consideration of the effect of various oxidation states of the sulfur atom in the core moiety and linking (C-N linkage) of subunits with the core at different positions. The results obtained from the electronic structure calculations highlight that the triplet energy (ET), singlet-triplet energy difference (ΔEST), reorganization energy for the hole and the injection barrier for the electron decrease with an increase in the oxidation state of the sulfur atom in DBT...
April 26, 2017: Physical Chemistry Chemical Physics: PCCP
Pip C J Clark, Hanna Radtke, Atip Pengpad, Andrew I Williamson, Ben F Spencer, Samantha J O Hardman, Marina A Leontiadou, Darren C J Neo, Simon M Fairclough, Andrew A R Watt, Igor Pis, Silvia Nappini, Federica Bondino, Elena Magnano, Karsten Handrup, Karina Schulte, Mathieu G Silly, Fausto Sirotti, Wendy R Flavell
Achieving control of the surface chemistry of colloidal quantum dots (CQDs) is essential to fully exploit their properties in solar cells, but direct measurement of the chemistry and electronic structure in the outermost atomic layers is challenging. Here we probe the surface oxidation and passivation of cation-exchanged PbS/CdS core/shell CQDs with sub nm-scale precision using synchrotron-radiation-excited depth-profiling photoemission. We investigate the surface composition of the topmost 1-2.5 nm of the CQDs as a function of depth, for CQDs of varying CdS shell thickness, and examine how the surface changes after prolonged air exposure...
April 26, 2017: Nanoscale
S Zhao, J H Li, S M An, S N Li, B X Liu
A realistic interatomic potential was first constructed for the Ca-Mg-Ni system and then applied to Monte Carlo simulations to predict the favored composition for metallic glass formation in the ternary system. The simulations not only predict a hexagonal composition region, within which the Ca-Mg-Ni metallic glass formation is energetically favored, but also pinpoint an optimized sub-region within which the amorphization driving force, i.e. the energy difference between the solid solution and disordered phase, is larger than that outside...
April 26, 2017: Physical Chemistry Chemical Physics: PCCP
Ying-Rui Lu, Tzung-Zing Wu, Han-Wei Chang, Jeng-Lung Chen, Chi-Liang Chen, Da-Hau Wei, Jin-Ming Chen, Wu-Ching Chou, Chung-Li Dong
Smart windows, which change color in response to external stimuli, are extensively studied owing to their potential technological applications in sensors and their ability to reduce the energy consumed by buildings. Most related studies focus on the optical properties of smart color switching films that can control the transmission of light and that of heat independently. This study examines the vanadium pentoxide thin film as a model system of a color switchable window. A gasochromic thin film of V2O5 is fabricated using sol-gel spin coating...
April 26, 2017: Physical Chemistry Chemical Physics: PCCP
Alain C Tagne Kuate, Roger A Lalancette, F Jäkle
The synthesis of ferrocenylphosphine-borane adducts 1,2-fc(E)(PPh2·BH3) (E = SnR2R', HgX; 1,2-fc = 1,2-ferrocenediyl) that are substituted with organotin or organomercury Lewis acid moieties in ortho-position is presented. Several compounds that feature two ferrocenylphosphine-borane moieties bridged by Sn or Hg are also introduced. The products are fully characterized by multinuclear NMR spectroscopy, high-resolution MALDI-TOF mass spectrometry and elemental analysis. The attachment of the Lewis acid substituent to the same Cp ring of the ferrocene results in planar-chirality and the close proximity between the boron hydride group and the Lewis acid is expected to allow for agostic-type B-HE (E = Sn, Hg) interactions...
April 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Da-Hai Li, Hua Zheng, Zi-Yi Wang, Rong-Jun Zhang, Hao Zhang, Yu-Xiang Zheng, Song-You Wang, David Wei Zhang, Liang-Yao Chen
Centimeter-scale WS2 ultrathin films were synthesized on sapphire substrates, and they showed highly oriented crystallographic growth along the c axis. Afterwards, the as-grown samples were systematically characterized using various detection methods. Reliable values of the roughness layer thickness and the film thickness were extracted using both atomic force microscopy (AFM) and spectroscopic ellipsometry (SE), and identified using Raman spectroscopy as well. The expansion and tensile strain along the [001] direction were discovered using X-ray diffraction (XRD) measurements...
April 26, 2017: Physical Chemistry Chemical Physics: PCCP
Rebecca L Gieseking, Mark A Ratner, George C Schatz
Nanoelectrochemical experiments using detection based on tip enhanced Raman spectroscopy (TERS) show a broad distribution of single-molecule formal potentials E°' for large π-conjugated molecules; theoretical studies are needed to understand the origins of this distribution. In this paper, we present a theoretical approach to determine E°' for electrochemical reactions involving a single molecule interacting with an electrode represented as a metal nanocluster and apply this method to the Ag20-pyridine system...
April 26, 2017: Faraday Discussions
Naresh K Jena, Rafael B Araujo, Vivekanand Shukla, Rajeev Ahuja
Borophene, single atomic-layer sheet of boron (Science, 2015, 350, 1513), is a rather new entrant into the burgeoning class of 2D materials. Borophene exhibits anisotropic metallic properties whereas its hydrogenated counterpart borophane is reported to be a gapless Dirac material lying on the same bench with the celebrated graphene. Interestingly, this transition of borophane also rendered stability to it considering the fact that borophene was synthesized under ultra-high vacuum conditions on a metallic (Ag) substrate...
April 26, 2017: ACS Applied Materials & Interfaces
Junga Ryou, Jinwoo Park, Gunn Kim, Suklyun Hong
Using density functional theory calculations, we have studied the edge-functionalization of armchair graphene nanoribbons (AGNRs) with pentagonal-hexagonal edge structures. While the AGNRs with pentagonal-hexagonal edge structures (labeled (5,6)-AGNRs) are metallic, the edge-functionalized (5,6)-AGNRs with substitutional atoms (i.e., nitrogen, oxygen, sulfur, and selenium) opens a band gap, similarly to the defect-free AGNRs. Furthermore, we find that electronic band structures and charge densities vary, depending on the wave vector: The band structures of edge-functionalized (5,6)-N-AGNRs by substitution resemble those of defect-free (N-1)-AGNR at the Γ point, while those at the X point show the original ones of the defect-free N-AGNR...
April 26, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Burcu Butun, Gulacti Topcu, Turan Ozturk
Flavonoids are naturally occurring phenolic compounds named as 2-phenyl-1-benzopyran-4-one and classified into several subclasses according to their basic chemical structures such as flavones, flavonols, flavanones, flavanonols, and flavanols. Among them, flavonols (3-hydroxyflavone), containing a 3-hydroxyl group in association with its 4-keto group and double bond between 2- and 3- carbon atoms, have the best electron conjugated skeleton in flavonoid family, providing several resonance structures and chelating ability, through which various pharmacological activities such as antiviral, antitumor, anti-inflammatory, anticholinesterase, cytotoxicity, and particularly high antioxidant activity are demonstrated...
April 24, 2017: Mini Reviews in Medicinal Chemistry
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