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Journal of Physical Chemistry Letters

Yiyao Tian, Anna M Plonka, Amani M Ebrahim, Robert M Palomino, Sanjaya D Senanayake, Alex Balboa, Wesley O Gordon, Diego Troya, Djamaladdin G Musaev, John R Morris, Mark B Mitchell, Daniel L Collins-Wildman, Craig L Hill, Anatoly I Frenkel
Development of technologies for protection against chemical warfare agents (CWAs) is critically important. Recently, polyoxometalates have attracted attention as potential catalysts for nerve-agent decomposition. The improvement of their effectiveness in real operating conditions requires an atomic-level understanding of CWA decomposition at the gas-solid interface. We investigated decomposition of the nerve agent Sarin and its simulant, dimethyl chlorophosphate (DMCP), by a zirconium polytungstate. Using a multimodal approach, we showed that, upon DMCP and Sarin exposure, the dimeric tungstate undergoes monomerization, making coordinatively unsaturated Zr(IV)-centers available, which activate nucleophilic hydrolysis...
April 19, 2019: Journal of Physical Chemistry Letters
Ji-Hyun Cha, Kyungkyou Noh, Wenping Yin, Yongju Lee, Yongmin Park, Tae Kyu Ahn, Alvaro Mayoral, Jaheon Kim, Duk-Young Jung, Osamu Terasaki
Improving the stability and tuning the optical properties of semiconducting perovskites are vital for their applications in advanced optoelectronic devices. We present a facile synthetic method for hybrid composites of perovskites and metal-organic frameworks (MOFs). A simple two-step solution-based method without organic surfactants was employed to make all-inorganic halide perovskites (CsPbX3 ; X = Cl, Br, I, or mixed halide compositions) form directly in the pores of MIL-101 MOF. That is, a polar organic solution of lead halide (PbX2 ) was impregnated into the MOF pores to give PbX2 @MIL-101, which was then subjected to a perovskite-formation reaction with cesium halide (CsX) dissolved in methanol...
April 19, 2019: Journal of Physical Chemistry Letters
Lingyun He, Wu Zhou, Liu Hong, Daixing Wei, Guangxu Wang, Xiaobo Shi, Shaohua Shen
The interfaces with multi-functions for the promoted solid/solid interfacial charge transfer dynamics and the accelerated solid/electrolyte interfacial water redox reaction kinetics are determinative to the photoelectrodes achieving high performances for photoelectrochemical (PEC) water splitting. In this work, the well-designed cascading interfaces are introduced in the n-Si photoanode, which is effectively protected by an atomic layer deposited CoOx thin layer for stabilizing the n-Si photoanode and then coated with an earth-abundant NiCuOx layer for catalyzing water oxidation reaction...
April 19, 2019: Journal of Physical Chemistry Letters
Bethany Jochim, Ben Berry, Travis Severt, Peyman Feizollah, Mo Zohrabi, Kanaka Raju Pandiri, Eric Wells, Kevin D Carnes, Itzik Ben-Itzhak
We have investigated the femtosecond laser-induced fragmentation of C$_2$H$_2^{q}$ ion beam targets in various initial configurations, including acetylene (linear HCCH), vinylidene (H$_2$CC), and \emph{cis}/\emph{trans}. The initial configuration is shown to have tremendous impact on the branching ratio of acetylene-like (CH$^{q_1}$~+~CH$^{q_2}$) and vinylidene-like (C$^{q_1'}$~+~CH$_2^{q_2'}$) dissociation of a specific C$_2$H$_2^{q}$ molecular ion. In particular, whereas C$_2$H$_2^+$ generated from C$_2$H$_2$, a linear HCCH target, exhibits comparable levels of acetylene-like and vinylidene-like fragmentation, vinylidene or \emph{cis}/\emph{trans} configuration ion beams preferably undergo vinylidene-like fragmentation, with an acetylene branching ratio ranging from 13...
April 19, 2019: Journal of Physical Chemistry Letters
Tianlun Huang, David Kirk Lewis, Sahar Sharifzadeh
We present a first-principles many-body perturbation theory study of the role of inter-molecular coupling on the optoelectronic properties of a one-dimensional -stacked nanowire composed of perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) molecules on a DNA-like backbone. We determine that strong inter-molecular electronic coupling results in large bandwidths and low carrier effective masses, suggesting a high electron mobility material. Additionally, by including the role of finite temperature phonons on optical absorption via a newly presented approach, we predict that the optical absorption spectrum at room temperature is significantly altered from room temperature due to allowed indirect transitions, while the exciton delocalization and binding energy, a measure of inter-molecular electronic interactions, remains constant...
April 19, 2019: Journal of Physical Chemistry Letters
Sneha Menon, Neelanjana Sengupta
In contrast with the general behavior of folded proteins, cold thermal response of amyloid assemblies is difficult to elicit with simple models. We exploit exhaustive simulations to evaluate the thermal response of a barrel-shaped model amyloid oligomer, with a distinct hydrophobic core akin to that of folded proteins. Cumulative thermal data over 210 to 483 K indicate a sharp inflexion and rise in structural stability as the temperature is lowered below the melting temperature of the water model. This is not commensurate with the equilibrium free energy profile obtained with core packing as the order parameter...
April 19, 2019: Journal of Physical Chemistry Letters
Tufan Ghosh, Joanna Dehnel, Marcel Fabian, Efrat Lifshitz, Roi Baer, Sanford Ruhman
The conjecture that, as in bulk semiconductors, hot multi excitons in nanocrystals cool rapidly to the lowest available energy levels is tested here by recording the effects of a single cold "spectator" exciton on the relaxation dynamics of a subsequently deposited hot counterpart. Results in CdSe/CdS nanodots show that a preexisting cold "spectator exciton" allows only half of the photoexcited electrons to relax directly to the band-edge. The rest are blocked in an excited quantum state due to conflicts in spin orientation...
April 19, 2019: Journal of Physical Chemistry Letters
Nathan Andrew Seifert, Arsh Singh Hazrah, Wolfgang Jaeger
Using chirped-pulse Fourier transform microwave spectroscopy, we have experimentally identified the most abundant dimer of an alcohol analogue of naphthalene, 1-naphthol. The 1-naphthol dimer features a V-shaped, partially overlapping π-π stacked structure with no canonical hydrogen bonds between the subunits. This structural assignment is in contradiction to an earlier study of the 1-naphthol dimer using UV-IR dip double resonance spectroscopy in the O-H stretch region, which assigns a π-stacked but also canonically hydrogen bonded structure...
April 19, 2019: Journal of Physical Chemistry Letters
Achintya Kundu, Fabian Dahms, Benjamin P Fingerhut, Erik T J Nibbering, Ehud Pines, Thomas Elsaesser
The solvation structure of protons in aqueous media is highly relevant to electric properties and to proton transport in liquids and membranes. At ambient temperature, polar liquids display structural fluctuations on femto- to picosecond time scales with a direct impact on proton solvation. We apply two-dimensional infrared (2D-IR) spectroscopy for following proton dynamics in acetonitrile/water mixtures with the Zundel cation H5 O2 + prepared in neat acetonitrile as a benchmark. The 2D-IR spectra of the proton transfer mode of H5 O2 + demonstrate stochastic large-amplitude motions in the double-minimum proton potential, driven by fluctuating electric fields...
April 18, 2019: Journal of Physical Chemistry Letters
Nicola Molinari, Jonathan Pradana Mailoa, Boris Kozinsky
We show that strong cation-anion interactions in a wide range of lithium-salt/ionic liquid mixtures result in a negative lithium transference number, using molecular dynamics simulations and rigorous concentrated solution theory. This behavior fundamentally deviates from the one obtained using self-diffusion coefficient analysis, and explains well recent experimental electrophoretic NMR measurements, which account for ion correlations. We extend these findings to several ionic liquid compositions. We investigate the degree of spatial ionic coordination employing single-linkage cluster analysis, unveiling asymmetrical anion-cation clusters...
April 18, 2019: Journal of Physical Chemistry Letters
Marius Hervé, Richard Brédy, Gabriel Karras, Bruno Concina, Jeffery M Brown, Abdul-Rahman Allouche, Franck Lepine, Isabelle Compagnon
Understanding optical properties of molecular dyes is compulsory to drive progresses in molecular photonics. This requires a fundamental comprehension of the role of electronic structure, geometry and interactions with the environment in order to guide molecular engineering strategies. In this context, we studied charged cyanine dyes molecules in the gas phase with controlled micro-environment to unravel the origin of the spectral tuning of this class of molecules. This was performed using a new approach combining femtosecond multiple photon action spectroscopy of on-the-fly mass-selected molecular ions and high level quantum calculations...
April 18, 2019: Journal of Physical Chemistry Letters
Qige Qi, Chunfan Yang, Ye Xia, Shaoshi Guo, Di Song, Hongmei Su
Human telomeric RNA (TERRA) containing thousands of G-rich repeats has the propensity to form parallel-stranded G-quadruplexes. The emerging crucial roles of TERRA G-quadruplexes in RNA biology fuel increasing attention for studying anticancer ligand binding with such structures, which, however, remains scarce. Here we utilized multiple steady-state and time-resolved spectroscopy analyses in conjunction with NMR methods and investigated thoroughly the binding behavior of TMPyP4 to a TERRA G-quadruplex dimer formed by the 10-nucleotide sequence r(GGGUUAGGGU)...
April 17, 2019: Journal of Physical Chemistry Letters
Yingcheng Wang, Yuanhao Jin, Tianfu Zhang, Zhongzheng Huang, Haitao Yang, Jiaping Wang, Kaili Jiang, Shoushan Fan, Qunqing Li
A high-performance exciton-localized surface plasmon (LSP) coupling system consisting of well-designed plasmonic nanostructures and CdSe/ZnS quantum dots (QDs) was fabricated by first introducing a Ta2 O5 layer as both an adhesive coating and coupling medium. It is shown that a larger emission enhancement factor of 6 from CdSe/ZnS QDs can be obtained from the strong coupling effect between QDs and triprism Au nanoarrays and the high scattering efficiency of LSPs without damping. This can be attributed to the matching conditions and a low extinction coefficient with little damping absorption of the Ta2 O5 layer in the system...
April 17, 2019: Journal of Physical Chemistry Letters
Huiyan Li, Xiangtao Kong, Ling Jiang, Zhifeng Liu
With a pKa of 2.0, HSO4- is not a strong acid, as its dissociation percentage is only ~10% in a solution of 1 M. However, our ab initio molecular dynamics and density functional theory calculations show that acid dissociation in the hydrate clusters, HSO4-(H2O)n, is quite facile at moderate sizes. It starts at around n = 12 and it is completed by n = 16 when the energetics becomes very favorable. The dissociation explains the significant broadening at n=16 in the S=O stretching region of the previously reported infrared photodissociation spectra for HSO4-(H2O)n, as the solvation shell is tightened around the sulfate dianion and the proton...
April 16, 2019: Journal of Physical Chemistry Letters
Shenkai Wang, Natcha Wattanatorn, Naihao Chiang, Yuxi Zhao, Moonhee Kim, Hong Ma, Alex K-Y Jen, Paul S Weiss
We measured photo-induced charge separation in isolated individual C60 tethered 2,5 dithienylpyrrole triad (C60 triad) molecules with submolecular resolution using a custom built laser assisted scanning tunneling microscope. Laser illumination was introduced evanescently into the tunneling junction through total internal reflection and the changes in tunneling current and electronic spectra caused by photoexcitation were measured and spatially resolved. Photo-induced charge separation was not detected for all C60 triad molecules, indicating that the conformations of the molecules may affect the excitation probability, lifetime, and/or charge distribution...
April 16, 2019: Journal of Physical Chemistry Letters
Gül H Zerze, Wenwei Zheng, Robert B Best, Jeetain Mittal
Experimental studies on intrinsically disordered and unfolded proteins have shown that in isolation they typically have low populations of secondary structure, and exhibit distance scalings suggesting they are at near theta-solvent conditions. Until recently, however, all-atom force fields failed to reproduce these fundamental properties of intrinsically disordered proteins (IDPs). Recent improvements by refining against ensemble- averaged experimental observables for polypeptides in aqueous solution have addressed deficiencies including secondary structure bias, global conformational properties, and thermodynamic parameters of biophysical reactions such as folding and collapse...
April 16, 2019: Journal of Physical Chemistry Letters
Samrat Das Adhikari, Amit K Guria, Narayan Pradhan
Doping Mn2+ in semiconductor nanocrystals is widely known for the long lifetime Mn d-d orange emission. While this has been extensively studied for chalcogenide nanostructures, recently this was also extended to perovskite nanocrystals. Being CsPbCl3 has wide bandgap, the exciton energy transfer was found more efficient; but the dopant induced photoluminescence was also obtained for layered perovskites and quantum confined CsPbBr3 nanocrystals. Significant advances have been achieved in understanding the physical insights of doping following various approaches and optimizing the conditions for obtaining intense dopant emission...
April 16, 2019: Journal of Physical Chemistry Letters
Katiuscia Pagano, Marco Paolino, Stefania Fusi, Vinicio Zanirato, Claudio Trapella, Germano Giuliani, Andrea Cappelli, Serena Zanzoni, Henriette Molinari, Laura Ragona, Massimo Olivucci
Rhodopsins are photoreceptive proteins using light to drive a plethora of biological functions such as vision, proton and ion pumping, cation and anion channeling, gene and enzyme regulation. Here we combine organic synthesis, NMR structural studies and photochemical characterization to show that it is possible to prepare a fully synthetic mimic of rhodopsin photoreceptors. More specifically, we conjugate a bile acid binding protein with a synthetic mimic of the rhodopsin protonated Schiff base chromophore, to achieve a covalent complex featuring an unnatural protein host, photoswitch and photoswitch-protein linkage with a reverse orientation...
April 15, 2019: Journal of Physical Chemistry Letters
Hendrik H Heenen, Christoph Scheurer, Karsten Reuter, Johannes Voss, Alan C Luntz
Antiperovskite glasses such as Li3OCl and doped analogs have been proposed as excellent electrolytes for all solid-state Li ion batteries (ASSB). Incorporating these electrolytes in ASSBs results in puzzling properties. This paper describes a theoretical Li3OCl glass created by conventional melt-quench procedures. The ion conductivities are calculated using molecular dynamics based on a polarizable force field that is fitted to an extensive set of density functional theory based energies, forces, and stresses for a wide range of non-equilibrium structures encompassing crystal, glass, and melt...
April 15, 2019: Journal of Physical Chemistry Letters
Matthew M Brister, Carlos E Crespo-Hernández
Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, however, investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5'-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a long-lived 1 nπ* state, and a receiver triplet state within 200 fs...
April 15, 2019: Journal of Physical Chemistry Letters
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