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Journal of Physical Chemistry Letters

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https://www.readbyqxmd.com/read/28085291/solvation-shell-structure-of-small-molecules-and-proteins-by-ir-mcr-spectroscopy
#1
Yuchen Sun, Poul Bering Petersen
The flexibility of the hydrogen-bonded network of water is the basis for its excellent solvation properties. Accordingly, it is valuable to understand the properties of water in the solvation shell surrounding small molecules and biomolecules. Recent high-quality Raman spectra analyzed with Self-Modeling Curve Resolution (SMCR) have provided the Raman spectra of small molecule solvation shells. Here we apply SMCR to the complementary technique of Fourier transform infrared (FTIR) spectroscopy in the attenuated total reflection (ATR) configuration to extract the IR spectra of solvation shells...
January 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28085290/magnetical-control-of-the-charge-separated-state-lifetime-realized-by-covalent-attachment-of-a-platinum-complex
#2
Tomoaki Miura, Dai Fujiwara, Kimio Akiyama, Takafumi Horikoshi, Shuichi Suzuki, Masatoshi Kozaki, Keiji Okada, Tadaaki Ikoma
Dynamics of the photo-generated charge separated (CS) state is studied for a newly synthesized molecular triad, in which the donor (D) dimethoxytriphenylamine, 1,3-bis(2-pyridylimino)isoindolate platinum (BPIPt) and the acceptor (A) naphthaldiimide are linked with triethynylbenzene unit (BPIPt-DA). Photoexcitation of BPIPt gives rise to generation of a long-lived (~4 μs) CS state BPIPt-D(+)A(-), of which the lifetime is considerably increased by an applied magnetic field of 270 mT. The positive magnetic field effect (MFE) is in contrast to the negative MFE for the reference DA molecule, which indicates successful switching of the initial spin state of the CS state from singlet to triplet...
January 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28084740/black-phosphorus-quantum-dots-for-holes-extraction-of-typical-planar-hybrid-perovskite-solar-cells
#3
Wei Chen, Kaiwen Li, Yao Wang, Xiyuan Feng, Zhenwu Liao, Qicong Su, Xinnan Lin, Zhubing He
Black phosphorus, famous as two-dimensional (2D) materials, shows such excellent properties for opto-electronic devices as tunable direct band-gap, extremely high hole mobility (300-1000cm2/(Vs)) and etc. In this paper, facile processed black phosphorus quantum dots (BPQDs) were successfully applied to enhance holes extraction at the anode side of the typical p-i-n planar hybrid perovskite solar cells, which remarkably improved the performance of devices with photon conversion efficiency ramping up from 14...
January 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28080058/fabrication-of-pedot-nanocone-arrays-with-electrochemically-modulated-broadband-antireflective-properties
#4
Seulgi So, Han Wai Millie Fung, Kellen Kartub, Adam M Maley, Robert M Corn
Ordered nanocone arrays of the electroactive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) were fabricated by the simultaneous oxygen plasma etching of an electrodeposited PEDOT thin film coated with a hexagonally closed packed polystyrene bead monolayer. PEDOT nanocone arrays with an intercone spacing of 200 nm and an average nanocone height of 350 nm exhibited a low broadband reflectivity of <1.5% from 550 to 800 nm. Electrochemical modulation of the oxidation state of the PEDOT nanocone array film was used to change both its ex situ absorption spectrum (electrochromism) and reflection spectrum (electroreflectivity)...
January 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28080055/morphological-transformation-of-surface-femtodroplets-upon-dissolution
#5
Shuhua Peng, Bat-El Shani Pinchasik, Hao Hao, Helmuth Möhwald, Xuehua Zhang
Constructing controllable liquid patterns with high resolution and accuracy is of great importance in droplet depositions for a range of applications, such as 3D printing of optical and electronic devices, bio-microarrays, and highly efficient chemical conversion in compartment. Simple surface chemical micropatterns are popularly used to regulate the shape of liquid droplets and the final structure of deposited materials from droplet evaporation. Understanding the morphological transition of liquid at a very small amount on a substrate is essential for the design and control of droplet deposition processes...
January 12, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28076952/compactness-of-lithium-peroxide-thin-film-formed-in-li-o2-batteries-and-its-link-to-charge-transport-mechanism-insights-from-stochastic-simulations
#6
Yinghui Yin, Ruijie Zhao, Yue Deng, Alejandro A Franco
Nano-catalysts are added into Li-O2 batteries to overcome the issues of limited discharge capacity and high charge potential, which may be resulted from the formation of the insulating Li2O2 film during discharge process. We simulated the growth of Li2O2 thin film with a mesoscale novel kinetic Monte Carlo model to investigate the impacts of catalysts. The simulation results show that the ordering of the Li2O2 thin film is determined by the interplay between diffusion kinetics and reaction kinetics. Due to faster reaction kinetics, the Li2O2 formed with the presence of catalyst (cat-CNF) shows a low degree of ordering and is more likely to be amorphous...
January 12, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28076951/a-multiscale-study-of-plasmonic-scattering-and-light-trapping-effect-in-silicon-nanowire-array-solar-cells
#7
Lingyi Meng, Yu Zhang, ChiYung Yam
Nanometallic structures that support surface plasmons provide new ways to confine light at deep-subwavelength scales. In this paper, the effect of light scattering in nanowire array solar cells is studied by a multiscale approach combining classical electromagnetics (EM) and quantum mechanical (QM) simulations. A photovoltaic device is constructed by integrating a silicon nanowire array with a plasmonic silver nanosphere. The light scatterings by plasmonic element and nanowire array are obtained via classical EM simulations while current-voltage characteristics and optical properties of the nanowire cells are evaluated quantum mechanically...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28075601/nitrogen-doped-mesoporous-carbons-as-counter-electrodes-in-quantum-dot-sensitized-solar-cells-with-a-conversion-efficiency-exceeding-12
#8
Shuang Jiao, Jun Du, Zhonglin Du, Donghui Long, Wuyou Jiang, Zhenxiao Pan, Yan Li, Xinhua Zhong
The exploration of catalyst materials for counter electrode (CE) in quantum dot sensitized solar cells (QDSCs) that have both high electrocatalytic activity and low charge transfer resistance is always significant yet challenging. In this work, we report the incorporation of nitrogen heteroatoms into carbon lattices leading to nitrogen doped mesoporous carbon (N-MC) materials with superior catalytic activity when used as CE in Zn-Cu-In-Se QDSCs. A series of N-MC materials with different nitrogen contents were synthesized by colloidal silica nanocasting method...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28075599/enhancing-cation-diffusion-and-suppressing-anion-diffusion-via-lewis-acidic-polymer-electrolytes
#9
Brett M Savoie, Michael A Webb, Thomas F Miller
Solid polymer electrolytes (SPE) have the potential to increase both the energy density and stability of lithium-based batteries, but low Li+ conductivity remains a barrier to technological viability. SPEs are designed to maximize Li+ diffusivity relative to the anion, while maintaining sufficient salt solubility. It is thus remarkable that polyethylene oxide (PEO), the most widely used SPE, exhibits Li+ diffusivity that is an order of magnitude smaller than that of typical counter-ions at moderate salt concentrations...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28072545/ultrafast-photoinduced-deactivation-dynamics-of-proteorhodopsin
#10
C Elias Eckert, Jagdeep Kaur, Clemens Glaubitz, Josef Wachtveitl
We report femtosecond time-resolved absorption change measurements of the photoinduced deactivation dynamics of a microbial rhodopsin in the ultraviolet-visible and mid-infrared range. The blue light quenching process is recorded in green proteorhodopsin's (GPR) primary proton donor mutant E108Q from the deprotonated 13-cis photointermediate. The return of GPR to the dark state occurs in two steps, starting with the photoinduced 13-cis to all-trans reisomerization of the retinal. The subsequent Schiff base reprotonation via the primary proton acceptor (D97) occurs on a nanosecond time scale...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28071909/current-status-and-bioinspired-perspective-of-electrochemical-conversion-of-co2-to-a-long-chain-hydrocarbon
#11
Ki Dong Yang, Chan Woo Lee, Kyoungsuk Jin, Sang Won Im, Ki Tae Nam
Electrocatalytic conversion of CO2 into a long-chain hydrocarbon represents an important research direction in adding value to CO2-based chemicals and realizing its practical application. Long-chain hydrocarbons may change the current fossil fuel-based industry in that those chemicals have a similar energy density as gasoline, high compatibility with the current infrastructure, and low hydroscopicity for pipeline distribution. However, most of the electrocatalysts produce C1, C2, and C3 chemicals, and methods for producing long-chain hydrocarbons are not available thus far...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28067530/infrared-absorption-and-hot-electron-production-in-low-electron-density-nanospheres-a-look-at-real-systems
#12
R Carmina Monreal, S Peter Apell, Tomasz J Antosiewicz
Doped semiconductor quantum dots are a new class of plasmonic systems exhibiting infrared resonances. At ultralow concentrations of charge carriers that can be achieved by controlled doping, only few carriers occupy each quantum dot; therefore, a spectrum with well-defined atomic-like peaks is expected. Here we investigate theoretically how surface imperfections and inhomogeneities in shape and morphology (surface "roughness") always present in these nanocrystals, randomize their energy levels, and blur the atomic-like features...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28067529/in-situ-evidence-of-the-redox-state-dependence-of-photoluminescence-in-graphene-quantum-dots
#13
Joaquin Barrera, David Ibañez, Aranzazu Heras, Virginia Ruiz, Alvaro Colina
Changes in the optical properties of graphene quantum dots (GQD) during electrochemical reduction and oxidation were investigated by photoluminescence (PL) spectroelectrochemistry, which provided direct in situ evidence of the dependence of GQD luminescence on their redox state. We demonstrated that GQD PL intensity was enhanced upon reduction (quantum yield increased from 0.44 to 0.55) and substantially bleached during oxidation (quantum yield ∼0.12). Moreover, PL emission blue/red-shifted upon GQD reduction/oxidation, rendering information about electronic transitions involved in the redox processes, namely, the π → π* and the n → π* transitions between energy levels of the aromatic sp(2) domains and the functional groups, respectively...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28067523/increased-binding-of-calcium-ions-at-positively-curved-phospholipid-membranes
#14
Aniket Magarkar, Piotr Jurkiewicz, Christoph Allolio, Martin Hof, Pavel Jungwirth
Calcium ion is the ubiquitous messenger in cells and plays a key role in neuronal signaling and fusion of synaptic vesicles. These vesicles are typically ∼20-50 nm in diameter, and thus their interaction with calcium ions cannot be modeled faithfully with a conventional flat membrane bilayer setup. Within our newly developed molecular dynamics simulations setup, we characterize here interactions of the calcium ion with curved membrane interfaces with atomistic detail. The present molecular dynamics simulations together with time-dependent fluorescence shift experiments suggest that the mode and strength of interaction of calcium ion with a phospholipid bilayer depends on its curvature...
January 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28071915/variational-flooding-study-of-a-sn2-reaction
#15
GiovanniMaria Piccini, James McCarty, Omar Valsson, Michele Parrinello
We have studied the reaction dynamics of a prototypical organic reaction using a variationally optimized truncated bias to accelerate transitions between educts and products reactant states. The asymmetric SN2nucleophilic substitution reaction of fluoromethane and chloromethane CH3F + Cl- <=> CH3Cl + F- is considered and many independent biased molecular dynamics simulations have been performed at 600, 900, and 1200 K collecting several hundred transitions at each temperature. The transition times and relative rate constants have been obtained for both reaction directions...
January 10, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28071911/high-defect-tolerance-in-lead-halide-perovskite-cspbbr3
#16
Jun Kang, Lin-Wang Wang
The formation energies and charge transition levels of intrinsic point defects in lead halide perovskite CsPbBr3 are studied from first-principles calculations. It is shown that the formation energy of dominant defect under Br-rich growth condition is much lower than that under moderate or Br-poor conditions. Thus avoiding the Br-rich condition can help to reduce the defect concentration. Interestingly, CsPbBr3 is found to be highly defect tolerant in terms of its electronic structure. Most of the intrinsic defects induce shallow transition levels...
January 10, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28071054/high-pressure-study-of-perovskite-like-organometal-halide-band-gap-narrowing-and-structural-evolution-of-nh3-ch2-4-nh3-cucl4
#17
Qian Li, Shourui Li, Kai Wang, Zewei Quan, Yue Meng, Bo Zou
Searching for nontoxic and stable perovskite-like alternatives to lead-based halide perovskites for photovoltaic application is one urgent issue in photoelectricity science. Such exploration inevitably requires an effective method to accurately control both the crystalline and electronic structures. This work applies high pressure to narrow the band gap of perovskite-like organometal halide, [NH3-(CH2)4-NH3]CuCl4 (DABCuCl4), through the crystalline-structure tuning. The band gap keeps decreasing below ~12 GPa, involving with the shrinkage and distortion of CuCl42-...
January 10, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28071046/quantifying-single-carbon-nanotube-electrode-contact-via-the-nanoimpact-method
#18
Xiuting Li, Christopher Batchelor-McAuley, Lidong Shao, Stanislav V Sokolov, Neil P Young, Richard G Compton
A new methodology is developed to enable the measurement of the resistance across individual carbon nanotube-electrode contacts. Carbon nanotubes (CNTs) are suspended in the solution phase and occasionally contact the electrified interface, some of which bridge a micron sized gap between two microbands of an interdigitated gold electrode. A potential difference is applied between the contacts and the magnitude of the current increase after the arrival of the CNT gives a measure of the resistance associated with the single CNT-gold contact...
January 10, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28067527/probing-the-acid-induced-packing-structure-changes-of-the-molten-globule-domains-of-a-protein-near-equilibrium-unfolding
#19
Yi-Qi Yeh, Kuei-Fen Liao, Orion Shih, Ying-Jen Shiu, Wei-Ru Wu, Chun-Jen Su, Po-Chang Lin, U-Ser Jeng
Using simultaneously scanning small-angle X-ray scattering (SAXS) and UV-vis absorption with integrated online size exclusion chromatography, supplemental with molecular dynamics simulations, we unveil the long-postulated global structure evolution of a model multidomain protein bovine serum albumin (BSA) during acid-induced unfolding. Our results differentiate three global packing structures of the three molten globule domains of BSA, forming three intermediates I1, I2, and E along the unfolding pathway. The I1-I2 transition, overlooked in all previous studies, involves mainly coordinated reorientations across interconnected molten globule subdomains, and the transition activates a critical pivot domain opening of the protein for entering into the E form, with an unexpectedly large unfolding free energy change of -9...
January 9, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28067526/extraction-of-thermodynamic-parameters-of-protein-unfolding-using-parallelized-differential-scanning-fluorimetry
#20
Thaiesha A Wright, Jamie M Stewart, Richard Christopher Page, Dominik Konkolewicz
Thermodynamic properties of protein unfolding have been extensively studied; however, the methods used have typically required significant preparation time and high protein concentrations. Here, we present a facile, simple, and parallelized differential scanning fluorimetry (DSF) method that enables thermodynamic parameters of protein unfolding to be extracted. This method assumes a two-state, reversible protein unfolding mechanism and provides the capacity to quickly analyze the biophysical mechanisms of changes in protein stability and to more thoroughly characterize the effect of mutations, additives, inhibitors, or pH...
January 9, 2017: Journal of Physical Chemistry Letters
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