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Journal of Physical Chemistry Letters

Yan Xu, Yanjing Gao, Yingying Su, Lele Sun, FeiFei Xing, Chunhai Fan, Di Li
Unraveling the conformational changes of enzymes together with inhibition kinetics during an enzymatic reaction has great potential in screening therapeutic candidates, however, remains challenging due to the transient nature of each intermediate step. We report our study on the non-competitive inhibition of horseradish peroxidase with single turnover resolution using single molecule fluorescence microscopy. By introducing DNA origami as an addressable nanoreactor, we observe the coexistence of nascent-formed fluorescent product on both catalytic and docking sites...
November 9, 2018: Journal of Physical Chemistry Letters
Marlius Castillo, Christine Pho, Anton V Naumov, Sergei V Dzyuba
The chirality-selective near-infrared emission of surfactant-stabilized single-wall carbon nanotubes could be controlled by simply varying the anion of the commonly used 1-butyl-3-methylimidazolium ionic liquids. This result advances the notion of the designer solvent ability of ionic liquids and provides opportunities for modulating the properties of nanomaterials.
November 9, 2018: Journal of Physical Chemistry Letters
Sanghamitra Sengupta, Daniel Roger Moberg, Francesco Paesani, Eric Claude Tyrode
Whether the surface of neat water is "acidic" or "basic" remains an active and controversial field of research. Most of the experimental evidence supporting the preferential adsorption of H3O+ ions stems from non-linear optical spectroscopy methods typically carried out at extreme pH conditions (pH < 1). Here, we use vibrational sum frequency spectroscopy (VSFS) to target the "proton continuum", an unexplored frequency range characteristic of hydrated protons and hydroxide ions...
November 8, 2018: Journal of Physical Chemistry Letters
Zhizhong Chen, Yiping Wang, Xin Sun, Yu Xiang, Yang Hu, Jie Jiang, Jing Feng, Yi-Yang Sun, Xi Wang, Gwo-Ching Wang, Toh-Ming Lu, Hanwei Gao, Esther A Wertz, Jian Shi
Despite their weak nature, van der Waals (vdW) interactions have been shown to effectively control the optoelectronic and vibrational properties of layered materials. However, how vdW effects exist in Ruddlesden-Popper layered halide perovskites remains unclear. Here we reveal the role of interlayer vdW force in Ruddlesden-Popper perovskite in regulating phase-transition kinetics and carrier dynamics based on high-quality epitaxial single-crystalline (C4 H9 NH3 )2 PbI4 flakes with controlled dimensions. Both substrate-perovskite epitaxial interaction and interlayer vdW interaction play significant roles in suppressing the structural phase transition...
November 8, 2018: Journal of Physical Chemistry Letters
Nicolas Dubouis, Alessandra Serva, Elodie Salager, Michael Deschamps, Mathieu Salanne, Alexis Grimaud
The water reduction that produces hydrogen is one key reaction for electrochemical energy storage. While it has been widely studied in traditional aqueous electrolytes for water splitting (electrolyzers), it also plays an important role for batteries. Indeed, the reduction of water at relatively high potential prevents the practical realization of high-voltage aqueous batteries, while water contamination is detrimental for organic battery electrolytes. Nevertheless, recent studies pointed toward the positive effect of traces of water for Li-air batteries as well as for the formation of solid-electrolyte interphase...
November 8, 2018: Journal of Physical Chemistry Letters
Yan Wan, Gary P Wiederrecht, Richard D Schaller, Justin C Johnson, Libai Huang
Singlet fission provides a promising route for overcoming the Shockley-Queisser limit in solar cells using organic materials. Despite singlet fission dynamics have been extensively investigated, the transport of the various intermediates in relation to the singlet and triplet states is largely unknown. Here we employ temperature-dependent ultrafast transient absorption microscopy to image the transport of singlet fission intermediates in single crystals of tetracene. These measurements suggest a mobile singlet fission intermediate state at low temperatures, with a diffusion constant of 36 cm2s-1 at 5 K, approaching that for the free singlet excitons, which we attribute to the spin-entangled correlated triplet pair state 1[TT]...
November 7, 2018: Journal of Physical Chemistry Letters
Hang Liu, Jia-Tao Sun, Miao Liu, Sheng Meng
To date only a few two-dimensional (2D) magnetic crystals were experimentally confirmed, such as CrI3 and CrGeTe3, all with very low Curie temperatures (TC). High-throughput first-principles screening over a large set of materials yields 89 magnetic monolayers including 56 ferromagnetic (FM) and 33 antiferromagnetic compounds. Among them, 24 FM monolayers are promising candidates possessing TC higher than that of CrI3. High TC monolayers with fascinating electronic phases are identified: (i) quantum anomalous and valley Hall effects coexist in a single material RuCl3 or VCl3, leading to a valley-polarized quantum anomalous Hall state; (ii) TiBr3, Co2NiO6 and V2H3O5 are revealed to be half-metals...
November 7, 2018: Journal of Physical Chemistry Letters
Taegon Lee, Hanju Rhee, Minhaeng Cho
Vibrationally-resonant optically-active (VOA) sum-frequency generation (SFG) is a second-order nonlinear process sensitive to stereo-specific vibrational structure of chiral molecule. We demonstrate that a femtosecond VOA SFG signal can be measured in the isotropic bulk of a chiral liquid. The chiral, achiral, and VOA SFG spectra of R-, S-limonene and their racemic mixture in the C-H stretching frequency region are characterized. In particular, it is shown that the observed circular intensity difference (CID) signal, which can provide distinguishable stereochemical vibrational information between enantiomers, arises from interference of the electric-dipole allowed anti-symmetric Raman tensor-induced and Raman optical activity (ROA) tensor-induced SFG fields...
November 7, 2018: Journal of Physical Chemistry Letters
Wen-Kai Chen, Xiang-Yang Liu, Weihai Fang, Pavlo O Dral, Ganglong Cui
In this work we show that deep learning (DL) can be used for exploring complex and highly nonlinear multi-state potential energy surfaces of polyatomic molecules and related nonadiabatic dynamics. Our DL is based on deep neural networks (DNNs), which are used as accurate representations of the CASSCF ground- and excited-state potential energy surfaces (PESs) of CH2 NH. After including geometries near conical intersection in the training set, the DNN models accurately reproduce excited-state topological structures, photoisomerization paths, and, importantly, conical intersections...
November 7, 2018: Journal of Physical Chemistry Letters
Alessandro Greco, Alexander Hinderhofer, M Ibrahim Dar, Neha Arora, Jan Hagenlocher, Andrei Chumakov, Michael Grätzel, Frank Schreiber
The exchange of ions in hybrid organic-inorganic perovskites with the general formula APbX3 (A = MA, FA; X = I, Cl, Br) is studied in five different systems using in situ real-time grazing incident X-ray diffraction (GIXD). In systems where the organic cation is exchanged, we find a continuous shift of the lattice parameter. The relative shift compared to the pure materials is used to quantify the exchange. Whether or not a conversion is possible, as well as the amount of exchanged cations, depends on the halide used...
November 7, 2018: Journal of Physical Chemistry Letters
Zhiyuan Cui, Shaofeng Ye, Lu Wang, Haoqing Guo, Ablikim Obolda, Shengzhi Dong, Yingxin Chen, Xin Ai, Alim Abdurahman, Ming Zhang, Lei Wang, Feng Li
A new luminescent radical, tris-2,4,6-trichlorophenylmethyl-1,5-diazarcarbazole (TTM-DACz), was synthesized and characterized. The photoluminescence quantum yield of TTM-DACz in solid 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene matrix film (5 wt %) is as high as 57.0%. Organic light-emitting diodes (OLEDs) employing TTM-DACz as the emitter were fabricated. By rational design of the device structure and host-guest doping system, external quantum efficiency (EQE) of up to 10.6% of the optimized device with a red CIE chromaticity of (0...
November 7, 2018: Journal of Physical Chemistry Letters
Veronica R Policht, Andrew Niedringhaus, Jennifer P Ogilvie
Bacteriochlorophyll a (BChla) is the most abundant pigment found in the Bacterial Reaction Center (BRC) and light-harvesting proteins of photosynthetic purple and green bacteria. Recent two-dimensional electronic spectroscopy (2DES) studies of photosynthetic pigment-protein complexes including the BRC and the Fenna-Matthews-Olson (FMO) complex have shown oscillatory signals, or coherences, whose physical origin has been hotly debated. To better understand the observations of coherence in larger photosynthetic systems, it is important to carefully characterize the spectroscopic signatures of the monomeric pigments...
November 7, 2018: Journal of Physical Chemistry Letters
Ryuma Sato, Hirotaka Kitoh-Nishioka, Kenji Kamada, Toshiko Mizokuro, Kenji Kobayashi, Yasuteru Shigeta
In condensed solids, triplet exciton migration and succeeding triplet-triplet annihilation (TTA) are major bottleneck processes for efficient photon upconversion (UC) using sunlight excitation. We theoretically investigated the reaction times of TTA and the triplet-triplet energy transfer (TTET) as the elementary processes of triplet exciton migration in organic crystals of two molecular species: 9,10-diphenylanthracene (DPA) and its double-strapped alkyl  derivative (C7-sDPA) as the models of a recently reported crystalline system of TTA-UC by Kamada et al...
November 7, 2018: Journal of Physical Chemistry Letters
Soya Hatazaki, Dharmendar Kumar Sharma, Shuzo Hirata, Keiji Nose, Tomokazu Iyoda, Adrian Kölsch, Heiko Lokstein, Martin Vacha
A peculiarity of cyanobacterial Photosystem I (PSI) is the presence of so-called red chlorophylls absorbing at wavelengths longer than the reaction center P700. The origin and function of these chlorophylls have been debated in literature, but so far no consensus has been reached on either question. Here, we use plasmon-enhanced single particle fluorescence spectroscopy to elucidate the origin of both short and long-wavelength emitting species in monomeric PSI from Thermosynechococcus elongatus at room temperature...
November 6, 2018: Journal of Physical Chemistry Letters
Chanaka Kumara, M Mozammel Hoque, Xiaobing Zuo, David A Cullen, Robert L Whetten, Amala Dass
Disclosed hereby is a method to obtain the ~ 300- kDa gold-hexanethiolate compound, extracted from the Faradaurate series of smaller (3) and larger (1) homologs, permitting thereby the first measurement of its distinctive properties by methods including mass spectrometry, optical spectroscopy, solution phase small-angle X-ray scattering, X-ray diffraction, synchrotron-based atomic pair distribution function analysis, and aberration-corrected scanning transmission electron microscopy. The results suggest a mono-crystalline metallic core (free of twinning planes) of ~3...
November 6, 2018: Journal of Physical Chemistry Letters
Chenqiang Hua, Feng Sheng, Qifeng Hu, Zhuan Xu, Yunhao Lu, Yi Steve Zheng
The discovery of archetypal two-dimensional (2D) materials provides enormous opportunities in both fundamental breakthroughs and device applications, as evident by the research booming in graphene, transition-metal chalcogenides, and black phosphorous. Here, we report a new, large family of semiconducting dialkali-metal monochalcogenides (DMMCs) with an inherent A2 X monolayer (ML) structure, in which two alkali sub-MLs form hexagonal close packing and sandwich the triangular chalcogen atomic plane. Such unique lattice leads to extraordinary physical properties, such as good dynamical and thermal stability, visible to near-infrared energy gap, and high electron mobility...
November 6, 2018: Journal of Physical Chemistry Letters
Anirban Dutta, Rakesh Kumar Behera, Sumit Kumar Dutta, Samrat Das Adhikari, Narayan Pradhan
Annealing perovskite nanocrystals at high reaction temperature changes their crystal phase, shape, and optical properties. Carrying out reactions between 180 and 250 °C, the impact of thermal annealing for CsPbCl3 and CsPbBr3 nanocrystals in a reaction flask was investigated here. At higher temperature, a phase change was observed instantly, which could not be trapped even with ice-bath cooling. Interestingly, using a calculated amount of preformed alkylammonium halides as dual passivating agents, the nanocrystals of both CsPbCl3 and CsPbBr3 could even be stabilized for hours of annealing at 250 °C...
November 6, 2018: Journal of Physical Chemistry Letters
Zhengfei Chen, Yuto Tonouchi, Kazuhiko Matsumoto, Masayuki Saimura, Rob Atkin, Takashi Nagata, Masato Katahira, Rika Hagiwara
Truly naked fluoride only exists in the gas phase. Fluoride can be stabilized by a complexing agent and an organic cation, resulting in anhydrous or dehydrated fluoride which is "partially naked." This partially naked fluoride enables fluorination reactions at much lower temperatures than hydrated fluorides. Here we show a simple method for preparing fluoride based solvate ionic liquids (SILs) by mixing 1-alkyl-3-methylimidazolium (1-ethyl-3-methylimidazolium or 1-butyl-3-methylimidazolium) bromide, silver fluoride (AgF), and EG (1:1:1 in molar ratio) in dry methanol...
November 6, 2018: Journal of Physical Chemistry Letters
Halil I Okur, Chad Isaac Drexler, Eric Claude Tyrode, Paul S Cremer, Sylvie Roke
Pure aqueous electrolyte solutions display a minimum in surface tension at concentrations of ~ 2 mM. This effect has been a source of controversy since first reported by Jones and Ray in the 1930s. The Jones-Ray effect has frequently been dismissed as an artifact linked to the presence of surface-active impurities. Herein we systematically consider the effect of surface-active impurities by purposely adding nanomolar concentrations of surfactants to dilute electrolyte solutions. Trace amounts of surfactant are indeed found to decrease the surface tension and influence the surface chemistry...
November 6, 2018: Journal of Physical Chemistry Letters
Qiaogang Song, Tong Lin, Zisheng Su, Bei Chu, Huishan Yang, Wenlian Li, Chun-Sing Lee
Comparing to traditional near infrared (NIR) imaging devices, NIR-to-visible upconversion display which integrated a NIR photodetector with a visible light-emitting diode have merits of simple device structure, low cost, high resolution, and a simple pixelless structure. However, photon-to-photon upconversion efficiencies of these devices are typically much lower than unity. Here we report an all-organic NIR-to-visible upconversion display with a photon-to-photon upconversion efficiency higher than 100% by integrating a photomultiplying organic NIR photodetector with a high-efficiency thermally activated delayed fluorescent organic light-emitting-diode...
November 6, 2018: Journal of Physical Chemistry Letters
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