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Physical Chemistry Chemical Physics: PCCP

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https://www.readbyqxmd.com/read/30010680/study-of-light-induced-formation-of-photodimers-in-the-i-motif-nucleic-acid-structure-by-rapid-scan-ftir-difference-spectroscopy-and-hybrid-hard-and-soft-modelling
#1
Sanae Benabou, Cyril Ruckebusch, Michel Sliwa, Anna Aviñó, Ramon Eritja, Raimundo Gargallo, Anna de Juan
The i-motif is a DNA structure formed by cytosine-rich sequences, very relevant from a biochemical point of view and potentially useful in nanotechnology as pH-sensitive nanodevices or nanomotors. To provide a different view on the structural changes and dynamics of direct excitation processes involving i-motif structures, the use of rapid-scan FTIR spectroscopy is proposed. Hybrid hard- and soft-modelling based on the Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) algorithm has been used for the resolution of rapid-scan FTIR spectra and the interpretation of the photochemically induced time-dependent conformational changes of i-motif structures...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30010166/pinpointing-the-active-species-of-the-cu-dat-catalyzed-oxygen-reduction-reaction
#2
Bas van Dijk, Jan P Hofmann, Dennis G H Hetterscheid
Dinuclear CuII complexes bearing two 3,5-diamino-1,2,4-triazole (DAT) ligands have gained considerable attention as a potential model system for laccase due to their low overpotential for the oxygen reduction reaction (ORR). In this study, the active species for the ORR was investigated. The water soluble dinuclear copper complex (Cu(DAT)) was obtained by mixing a 1 : 1 ratio of Cu(OTf)2 and DAT in water. The electron paramagnetic resonance (EPR) spectrum of Cu(DAT) showed a broad axial signal with a g factor of 2...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009313/binding-indirect-greenhouse-gases-ocs-and-cs-2-by-nitrogen-heterocyclic-carbenes-nhcs
#3
M Merced Montero-Campillo, Ibon Alkorta, José Elguero
Carbon disulfide (CS2) and carbonyl sulfide (OCS) are indirect greenhouse gases that can be effectively trapped by classical, abnormal and remote nitrogen heterocyclic carbenes (NHCs), according to high level ab initio calculations. The process is described through a reaction profile involving two minima, a non-covalent complex and a covalently bound product, connected by a single transition state. Both CS2 and OCS react towards NHCs in a similar way, forming a new C-C bond and leading to very stable products with feasible barriers in many cases, although they vary significantly depending on the NHC structure...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009307/principal-component-analysis-for-automatic-extraction-of-solid-state-kinetics-from-combined-in-situ-experiments
#4
Pietro Guccione, Luca Palin, Benny Danilo Belviso, Marco Milanesio, Rocco Caliandro
Solid-state reactivity is often studied by in situ experiments with a multi-technique approach, where complementarity of different probes is exploited. In situ data are usually analysed using a complex protocol: first the reaction model most suited to describe the specific solid-state reaction is chosen, second the reaction coordinate is obtained from the data, the order of reaction is then calculated by applying a specific kinetic equation, and finally kinetic parameters are obtained with an Arrhenius plot...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009306/role-of-transition-metals-in-a-charge-transfer-mechanism-and-oxygen-removal-in-li-1-17-ni-0-17-mn-0-5-co-0-17-o-2-experimental-and-first-principles-analysis
#5
Tanmay Sarkar, Kunkanadu R Prakasha, Mridula Dixit Bharadwaj, Annigere S Prakash
Oxygen removal from high capacity Li-rich layered oxide Li1.17Ni0.17Mn0.5Co0.17O2 affects the charge transfer process during cycling. During de-lithiation, oxygen removal takes place with the reduction in oxygen binding energy. Co substitution affects oxygen removal by shifting the O-p orbital closer to the Fermi energy. A convex hull plot is used to analyse single-phase and two-phase reactions during de-lithiation in Li1.17Ni0.17Mn0.5Co0.17O2 and Li2MnO3. Experimentally, the single-phase and two-phase reactions are identified based on the characteristics of the charge curve...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009300/molecular-structure-of-octadecylphosphonic-acids-during-their-self-assembly-on-%C3%AE-al-2-o-3-0001
#6
Christian Meltzer, Hui Yu, Wolfgang Peukert, Björn Braunschweig
The formation of octadecylphosphonic acid (ODPA) self-assembled monolayers (SAMs) from 2-propanol solutions on hydroxylated α-Al2O3(0001) surfaces was studied in situ and in real time at the solid/liquid interface. Time-resolved vibrational spectra from sum-frequency generation (SFG) of C-H stretching modes revealed contributions from ODPA's alkyl backbone and the terminal methyl group as well as vibrational bands that originated from the presence of 2-propanol molecules at the α-Al2O3 surface. 2-Propanol signatures in SFG spectra decreased during SAM formation...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009296/in-situ-infrared-study-of-photo-generated-electrons-and-adsorbed-species-on-nitrogen-doped-tio-2-in-dye-sensitized-solar-cells
#7
Jiawei Liu, Piyapong Winwarid, Thomas C K Yang, Steven S C Chuang
Charge transfer between adsorbed dyes and the TiO2 surface plays a key role in controlling the efficiency of dye-sensitized solar cells (DSSCs). The lack of understanding of charge transfer steps has hindered further development of DSSCs and many solar energy conversion devices/processes. In this study, we used in situ infrared spectroscopy to investigate electron transfer and photo-electric energy conversion processes at the interface, i.e., surface hydroxyls, adsorbed species, as well as the dynamics of photo-generated electrons in TiO2 and N-TiO2 in DSSCs...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009293/collision-induced-dissociation-of-sodiated-glucose-galactose-and-mannose-and-the-identification-of-anomeric-configurations
#8
Hai Thi Huynh, Huu Trong Phan, Po-Jen Hsu, Jien-Lian Chen, Hock Seng Nguan, Shang-Ting Tsai, Thantip Roongcharoen, Chia Yen Liew, Chi-Kung Ni, Jer-Lai Kuo
Collision-induced dissociation of sodiated α-glucose, β-glucose, α-galactose, β-galactose, α-mannose, and β-mannose was studied using electronic structure calculations and resonance excitation in a low-pressure linear ion trap. We made an extensive search of conformers and transition states in calculations to ensure the transition state with the lowest barrier height for each dissociation channel could be located. The major dissociation channels, in addition to desodiation, are cross-ring dissociation and dehydration...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009291/mxene-nanoribbons-as-electrocatalysts-for-the-hydrogen-evolution-reaction-with-fast-kinetics
#9
Xiaowei Yang, Nan Gao, Si Zhou, Jijun Zhao
MXenes, a new class of two-dimensional materials, arouse great interest due to their diverse chemistries, superior electrical conductivity and stability. Recently, the nanostructures of MXenes such as nanoribbons and nanodots have been synthesized in experiments, which show peculiar properties and expand the application spectrum of MXenes. Here we exploited MXene nanoribbons as potential electrocatalysts for the hydrogen evolution reaction (HER) by considering 12 kinds of MXene systems. Our first-principles calculations showed that the edges of the MXene nanoribbons can adsorb hydrogen species and serve as the reaction sites for hydrogen evolution...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009290/simulated-and-experimental-force-spectroscopy-of-lysozyme-on-silica
#10
Nils Hildebrand, Gang Wei, Susan Köppen, Lucio Colombi Ciacchi
The force spectra of proteins detaching from oxide surfaces measured by atomic force microscopy (AFM) often present complex patterns of peaks, which are difficult to correlate with individual bond-breaking events at the atomic scale. In this work we rationalize experimental AFM force spectra of hen-egg-white lysozyme detaching from silica by means of all-atom steered molecular dynamics (SMD) simulations. In particular, we demonstrate that the native tertiary structure of lysozyme is preserved if, and only if, its four intramolecular disulfide bridges are intact...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30009286/macromolecular-crowding-and-the-importance-of-proper-hydration-for-the-structure-and-dynamics-of-protein-solutions
#11
Philipp Honegger, Michael Schmollngruber, Othmar Steinhauser
Recent experiments by Weingärtner et al. have given a first hint that dielectric spectroscopy is able to yield a quantitative measure of inter-protein mutual orientation. Therefore, in this computational study, we investigate crowded multi-protein solutions with a special focus on this mutual orientation and its context with dielectric spectroscopy. To the end, existing standard force fields had to be improved by re-scaling the dispersion interaction between protein and water. We find that proper hydration has a strong influence on inter-protein correlations as an enhancement of protein hydration by 10% has a great impact on orientational intermolecular structure...
July 16, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30004096/potential-dependent-changes-in-the-structural-and-dynamical-properties-of-1-butyl-3-methylimidazolium-bis-trifluoromethanesulfonyl-imide-on-graphite-electrodes-revealed-by-molecular-dynamics-simulations
#12
Hiroo Miyamoto, Yasuyuki Yokota, Akihito Imanishi, Kouji Inagaki, Yoshitada Morikawa, Ken-Ichi Fukui
An understanding of the characteristics of ionic liquid/graphite interfaces is highly important for electrochemical devices such as batteries and capacitors. In this paper, we report microscopic studies of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM-TFSI) on charged graphite electrodes using molecular dynamics simulations to reveal the two-dimensional arrangement of the ions and their dynamics at the interfaces. Analyses of surface distribution and mobility of ions revealed that the ion arrangement changes from a bilayer type to a checkerboard type with increasing applied potential...
July 13, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30004095/strong-light-matter-interaction-in-tungsten-disulfide-nanotubes
#13
Lena Yadgarov, Bojana Višić, Tsafrir Abir, Ron Tenne, Alexander Yu Polyakov, Roi Levi, Tatyana V Dolgova, Varvara V Zubyuk, Andrey A Fedyanin, Eugene A Goodilin, Tal Ellenbogen, Reshef Tenne, Dan Oron
Transition metal dichalcogenide materials have recently been shown to exhibit a variety of intriguing optical and electronic phenomena. Focusing on the optical properties of semiconducting WS2 nanotubes, we show here that these nanostructures exhibit strong light-matter interaction and form exciton-polaritons. Namely, these nanotubes act as quasi 1-D polaritonic nano-systems and sustain both excitonic features and cavity modes in the visible-near infrared range. This ability to confine light to subwavelength dimensions under ambient conditions is induced by the high refractive index of tungsten disulfide...
July 13, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30003208/bismuth-oxysulfide-film-electrodes-with-giant-incident-photon-to-current-conversion-efficiency-the-dynamics-of-properties-with-deposition-time
#14
Evgeny A Bondarenko, Eugene A Streltsov, Alexander V Mazanik, Anatoly I Kulak, Vytautas Grivickas, Patrik Ščajev, Ekaterina V Skorb
It was demonstrated in our previous work that the photoelectrochemical (PEC) reduction processes occur with a giant incident photon-to-current conversion efficiency (IPCE ≫ 100%) at bismuth oxysulfide (BOS) semiconductor films in aqueous solutions containing acceptors of photoelectrons ([Fe(CN)6]3-). The anomalously high IPCE was related to the photoconductivity of the semiconductor. In this work, we analyze the dynamics of the chemical and phase composition of BOS films with variation of their deposition time, as well as the dependence of photocurrent on the film thickness and wavelength of the incident light...
July 13, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/30003203/infrared-photodissociation-spectroscopy-of-cold-cationic-trimethylamine-complexes
#15
Xin Lei, Xiangtao Kong, Zhi Zhao, Bingbing Zhang, Dongxu Dai, Xueming Yang, Ling Jiang
Cryogenic ion-trap infrared photodissociation spectroscopy combined with a dielectric barrier discharge source was constructed to establish the general trends in the stepwise growth motif of trimethylamine (TMA)n+ complexes. The results showed a strong preference for the formation of a stable charge-shared NN type (TMA)2+ ion core over the proton-transferred CHN type ion core, evidencing that the source condition has a remarkable effect on the kinetic stability of isomers. A maximum of four TMA molecules are located perpendicularly to the NN axis of the charge-shared (TMA)2+ ion core...
July 13, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29999072/effect-of-transition-metal-ion-dopants-on-the-oxygen-evolution-reaction-on-niooh-0001
#16
Alexander J Tkalych, John Mark P Martirez, Emily A Carter
Iron-doped nickel oxyhydroxide has been identified as one of the most active alkaline oxygen evolution reaction (OER) catalysts, exhibiting an overpotential lower than values observed for state-of-the-art precious metal catalysts. Several computational investigations have found widely varying effects of doping on the theoretical overpotential of the OER on NiOx. Comparisons of these results are made difficult by the numerous differences in the structural and computational parameters used in these studies. In this work, within a consistent framework, we calculate the theoretical overpotentials for reactions occurring on the most stable, basal plane of undoped and doped β-NiOOH...
July 12, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29999071/new-insights-into-the-sensing-mechanism-of-a-phosphonate-pyrene-chemosensor-for-tnt
#17
Meiheng Lu, Panwang Zhou, Zhongwei Li, Jianyong Liu, Yanqiang Yang, Keli Han
As security needs have increased, mechanism investigation has become of high importance in the development of new sensitive and selective chemosensors for chemical explosives. This study details a theoretical investigation of the sensing mechanism of a new phosphonate pyrene chemosensor for trinitrotoluene (TNT), suggesting a different interaction mode between the probe and TNT from the one previously reported. The invalidity of the mechanism of binding TNT through intermolecular hydrogen bonds was proved using the Gibbs free energy profile and 1H NMR analysis...
July 12, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29999070/sub-molecular-spectroscopy-and-temporary-molecular-charging-of-ni-phthalocyanine-on-graphene-with-stm
#18
Mali Zhao, Faisal Almarzouqi, Eric Duverger, Philippe Sonnet, Gérald Dujardin, Andrew J Mayne
In this study, the self-assembled molecular network and electronic properties of Ni-phthalocyanine (NiPc) molecules on monolayer graphene (MLG)/6H-SiC(0001) were studied by room temperature Scanning Tunnelling Microscopy (STM) and Density Functional Theory (DFT) calculations. In this study, a very weak electronic coupling between the graphene and the NiPc molecules is found. This is due to the very small charge transfer of only 0.035e- per molecule. The weak molecule-graphene interaction has two observable consequences: sub-molecular resolution was obtained in the STM spectroscopy at room-temperature with the molecules adsorbed directly on the graphene, and the occupied and unoccupied molecular resonance peaks were observed to shift their position in energy as a function of the tip-surface distance...
July 12, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29999069/enhancement-of-co-2-adsorption-on-oxygen-functionalized-epitaxial-graphene-surface-under-near-ambient-conditions
#19
Susumu Yamamoto, Kaori Takeuchi, Yuji Hamamoto, Ro-Ya Liu, Yuichiro Shiozawa, Takanori Koitaya, Takashi Someya, Keiichiro Tashima, Hirokazu Fukidome, Kozo Mukai, Shinya Yoshimoto, Maki Suemitsu, Yoshitada Morikawa, Jun Yoshinobu, Iwao Matsuda
The functionalization of graphene is important in practical applications of graphene, such as in catalysts. However, the experimental study of the interactions of adsorbed molecules with functionalized graphene is difficult under ambient conditions at which catalysts are operated. Here, the adsorption of CO2 on an oxygen-functionalized epitaxial graphene surface was studied under near-ambient conditions using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). The oxygen-functionalization of graphene is achieved in situ by the photo-induced dissociation of CO2 with X-rays on graphene in a CO2 gas atmosphere...
July 12, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29999060/direct-kinetics-study-of-ch-2-oo-methyl-vinyl-ketone-and-ch-2-oo-methacrolein-reactions-and-an-upper-limit-determination-for-ch-2-oo-co-reaction
#20
Arkke J Eskola, Malte Döntgen, Brandon Rotavera, Rebecca L Caravan, Oliver Welz, John D Savee, David L Osborn, Dudley E Shallcross, Carl J Percival, Craig A Taatjes
Methyl vinyl ketone (MVK) and methacrolein (MACR) are important intermediate products in atmospheric degradation of volatile organic compounds, especially of isoprene. This work investigates the reactions of the smallest Criegee intermediate, CH2OO, with its co-products from isoprene ozonolysis, MVK and MACR, using multiplexed photoionization mass spectrometry (MPIMS), with either tunable synchrotron radiation from the Advanced Light Source or Lyman-α (10.2 eV) radiation for photoionization. CH2OO was produced via pulsed laser photolysis of CH2I2 in the presence of excess O2...
July 12, 2018: Physical Chemistry Chemical Physics: PCCP
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