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Journal of the American Chemical Society

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https://www.readbyqxmd.com/read/28437104/redox-active-macrocycles-for-organic-rechargeable-batteries
#1
Dong Jun Kim, Keith R Hermann, Aleksandrs Prokofjevs, Michael T Otley, Cristian Pezzato, Magdalena Owczarek, J Fraser Stoddart
Organic rechargeable batteries, composed of redox-active molecules, are emerging as candidates for the next generation of energy storage materials because of their large specific capacities, cost effectiveness, and the abundance of organic precursors, when compared with conventional lithium-ion batteries. Although redox-active molecules often display multiple redox states, precise control of a molecule's redox potential, leading to a single output voltage in a battery, remains a fundamental challenge in this popular field of research...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28437103/ion-pair-oligomerization-of-chromogenic-triangulenium-cations-with-cyanostar-modified-anions-that-controls-emission-in-hierarchical-materials
#2
Bo Qiao, Brandon E Hirsch, Semin Lee, Maren Pink, Chun-Hsing Chen, Bo W Laursen, Amar H Flood
The hierarchical assembly of colored cationic molecules with receptor-modified counteranions can be used to control optical properties in materials. However, our knowledge of when the optical properties emerge in the hierarchical organization and the variety of cation-anion salts that are available to create these materials is limited. In this work, we extend the salts from small halides to large inorganic anions and determine how the structure coevolves with the emission properties using solution assemblies...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28437093/a-pathogen-specific-cargo-delivery-platform-based-on-mesoporous-silica-nanoparticles
#3
Bastian Ruehle, Daniel L Clemens, Bai-Yu Lee, Marcus A Horwitz, Jeffrey I Zink
We present a synthetic approach to a highly pathogen-selective detection and delivery platform based on the in-teraction of an antibody nanovalve with a tetrasaccharide from the O-Antigen of the lipopolysaccharide of Francisella tularensis bacteria, a Tier 1 Select Agent of bioterrorism. Different design considerations are explored, and proof-of-concept for highly pathogen-specific cargo release from mesoporous silica nanoparticles is demonstrated by comparisons of the release of a signal transducer and model drug by LPS from Francisella tularensis vs...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28437075/fluorescent-photoswitchable-diarylethenes-for-biolabeling-and-single-molecule-localization-microscopies-with-optical-superresolution
#4
Benoit Roubinet, Michael Weber, Heydar Shojaei, Mark Bates, Mariano L Bossi, Vladimir N Belov, Masahiro Irie, Stefan W Hell
A modular assembly of water soluble diarylethenes (DAEs), applicable as bio-markers for optical nanoscopy, is reported. Reversibly photoswitchable 1,2-bis(2-alkyl-6-phenyl-1-benzothiophene-1,1-dioxide-3-yl)perfluorocyclopentenes possessing a fluorescent "closed" form were decorated with one or two methoxy group(s) attached to the para-position(s) of phenyl ring(s) and two, four or eight carboxylic acid groups. Antibody conjugates of these DAEs feature low aggregation, efficient photoswitching in aqueous buffers, specific staining of cellular structures and photophysical properties (high emission efficiencies and low cycloreversion quantum yields) enabling their application in superresolution microscopy...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28437070/large-scale-synthesis-of-carbon-shell-coated-fep-nanoparticles-for-robust-hydrogen-evolution-reaction-electrocatalyst
#5
Dong Young Chung, Samuel Woojoo Jun, Gabin Yoon, Hyunjoong Kim, Ji Mun Yoo, Kug-Seung Lee, Taehyun Kim, Heejong Shin, Arun Kumar Sinha, Soon Gu Kwon, Kisuk Kang, Taeghwan Hyeon, Yung-Eun Sung
Highly active and stable non-Pt electrocatalyst for hydrogen production has been pursed for a long time as alternative of expensive Pt catalyst. Herein we report a simple and effective approach to prepare highly stable iron phosphide (FeP) nanoparticle electrocatalyst using iron oxide nanoparticles as the precursor. A single step heating procedure of polydopamine-coated iron oxide nanoparticles leads to carbonization of dopamine coating to carbon shell and phosphidation of iron oxide to FeP, simultaneously...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28436654/crystal-phase-transitions-and-photocatalysis-in-supramolecular-scaffolds
#6
Roman V Kazantsev, Adam J Dannenhoffer, Adam S Weingarten, Brian T Phelan, Boris Harutyunyan, Taner Aytun, Ashwin Narayanan, Daniel J Fairfield, Job Boekhoven, Hiroaki Sai, Andrew Senesi, Pascual I O'Dogherty, Liam C Palmer, Michael J Bedzyk, Michael R Wasielewski, Samuel I Stupp
The energy landscape of a supramolecular material can include different molecular packing configurations that differ in stability and function. We report here on a thermally driven crystalline order transition in the landscape of supramolecular nanostructures formed by charged chromophore amphiphiles in salt-containing aqueous solutions. An irreversible transition was observed from a metastable to a stable crystal phase within the nanostructures. In the stable crystalline phase, the molecules end up organized in a short scroll morphology at high ionic strengths and as long helical ribbons at lower salt content...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28436649/multi-arm-junctions-for-dynamic-dna-nanotechnology
#7
Shohei Kotani, William L Hughes
Non-enzymatic catalytic substrates have been engineered using toehold-mediated DNA strand displacement, and their programmable applications range from medical diagnosis to molecular computation. However, the complexity, stability, scalability, and sensitivity of those systems are plagued by network leakage. A novel way to suppress leakage is to increase its energy barrier through four-way branch migration. Presented here, we designed multi-arm junction substrates that simultaneously exploit four-way branch migration, with a high-energy barrier to minimize leakage, and three-way branch migration, with a low energy barrier to maximize catalysis...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28436228/an-accelerated-intermolecular-rauhut-currier-reaction-enables-the-total-synthesis-of-flueggenine-c
#8
Sangbin Jeon, Sunkyu Han
The first total synthesis of dimeric securinega alkaloid (-)-flueggenine C is completed via an accelerated intermolecular Rauhut-Currier (RC) reaction. Despite the numerous reports on the total synthesis of monomeric securinegas, the synthesis of dimeric securinegas whose monomeric units are connected by a putative enzymatic RC reaction has not been reported to date. We have found that an installation of a nucleophilic functional group at the γ-position of an enone greatly accelerates the rate of the diastereoselective intermolecular RC reaction...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28436226/unleashing-the-power-and-energy-of-lifepo4-based-redox-flow-lithium-battery-with-a-bi-functional-redox-mediator
#9
Yun Guang Zhu, Yonghua Du, Chuankun Jia, Mingyue Zhou, Li Fan, Xingzhu Wang, Qing Wang
Redox flow batteries, despite great operation flexibility and scalability for large-scale energy storage, suffer from low energy density and relatively high cost as compared to the state-of-the-art Li-ion batteries. Here we report a redox flow lithium battery, which operates via the redox targeting reactions of LiFePO4 with a bi-functional redox mediator, 2,3,5,6-tetramethyl-p-phenylenediamine, and presents superb energy density as the Li-ion battery and system flexibility as the redox flow battery. The battery has achieved a tank energy density as high as 1023 Wh/L, power density of 61 mW/cm2, and voltage efficiency of 91%...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28423893/the-least-stable-isomer-of-bn-naphthalene-toward-predictive-trends-for-the-optoelectronic-properties-of-bn-acenes
#10
Zhiqiang Liu, Jacob S A Ishibashi, Clovis Darrigan, Alain Dargelos, Anna Chrostowska, Bo Li, Monica Vasiliu, David A Dixon, Shih-Yuan Liu
The least stable isomer of the parental BN naphthalene series has been synthesized in a simple four-step sequence. Its experimental electronic structure characterization via UV-PES, cyclic voltammetry, and UV-vis spectroscopy in direct comparison with three other known BN naphthalene isomers has established two guiding principles for predicting the electronic structures of BN acene compounds: (1) Orientational BN isomers have similar HOMO-LUMO gaps. (2) For each pair of orientational BN isomers, the more thermodynamically stable compound has the lower HOMO energy...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28420237/intrinsic-instability-of-cs2in-i-m-iii-x6-m-bi-sb-x-halogen-double-perovskites-a-combined-density-functional-theory-and-experimental-study
#11
Zewen Xiao, Ke-Zhao Du, Weiwei Meng, Jianbo Wang, David B Mitzi, Yanfa Yan
Recently, there has been substantial interest in developing double-B-cation halide perovskites, which hold the potential to overcome the toxicity and instability issues inherent within emerging lead halide-based solar absorber materials. Among all double perovskites investigated, In(I)-based Cs2InBiCl6 and Cs2InSbCl6 have been proposed as promising thin-film photovoltaic absorber candidates, with computational examination predicting suitable materials properties, including direct bandgap and small effective masses for both electrons and holes...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28398730/self-assembly-can-direct-dynamic-covalent-bond-formation-toward-diversity-or-specificity
#12
Dávid Komáromy, Marc C A Stuart, Guillermo Monreal Santiago, Meniz Tezcan, Victor V Krasnikov, Sijbren Otto
With the advent of reversible covalent chemistry the study of the interplay between covalent bond formation and noncovalent interactions has become increasingly relevant. Here we report that the interplay between reversible disulfide chemistry and self-assembly can give rise either to molecular diversity, i.e., the emergence of a unprecedentedly large range of macrocycles or to molecular specificity, i.e., the autocatalytic emergence of a single species. The two phenomena are the result of two different modes of self-assembly, demonstrating that control over self-assembly pathways can enable control over covalent bond formation...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28434220/effects-of-the-backbone-and-chemical-linker-on-the-molecular-conductance-of-nucleic-acid-duplexes
#13
Edward Beall, Selma Ulku, Chaoren Liu, Emil Wierzbinski, Y Zhang, Yookyung Bae, Peng Zhang, Catalina Achim, David N Beratan, David H Waldeck
Scanning tunneling microscope-break junction measurements are used to examine how the molecular conductance of nucleic acids depends on the composition of their backbone and the linker group to the electrodes. Molecular conductances of 10-base pair long homoduplexes of DNA, aeg-PNA, γ-PNA, and a heteroduplex of DNA/aeg-PNA with identical nucleobase sequence were measured. The molecular conductance was found to vary by 12 to 13 times with the change in backbone. Computational studies show that the molecular conductance differences between nucleic acids of different backbones correlate with differences in backbone structural flexibility...
April 23, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28431206/phase-transfer-ligand-exchange-of-lead-chalcogenide-quantum-dots-for-direct-deposition-of-thick-highly-conductive-films
#14
Qianglu Lin, Hyeong Jin Yun, Wenyong Liu, Hyung-Jun Song, Nikolay S Makarov, Oleksandr Isaienko, Tom Nakotte, Gen Chen, Hongmei Luo, Victor I Klimov, Jeffrey M Pietryga
The use of semiconductor nanocrystal quantum dots (QDs) in optoelectronic devices typically requires post-synthetic chemical surface treatments to enhance electronic coupling between QDs and allow for efficient charge transport in QD films. Despite their importance to solar cells, and infrared (IR) light-emitting diodes and photodetectors, advances in these chemical treatments for lead chalcogenide (PbE, E = S, Se, Te) QDs have lagged behind those of, for instance, II-VI semiconductor QDs. Here, we introduce a method for fast and effective ligand exchange for PbE QDs in solution, resulting in QDs completely passivated by a wide range of small anionic ligands...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28430435/cu-in-halide-perovskite-cihp-solar-absorbers
#15
Xin-Gang Zhao, Dongwen Yang, Yuanhui Sun, Tianshu Li, Lijun Zhang, Liping Yu, Alex Zunger
The long-term chemical instability and the presence of toxic Pb in otherwise stellar solar absorber APbX3 made of organic molecules on the A site and halogens for X have hindered their large-scale commercialization. Previously explored ways to achieve Pb-free halide perovskites involved replacing Pb(2+) with other similar M(2+) cations in ns(2) electron configuration, e.g., Sn(2+) or by Bi(3+) (plus Ag(+)), but unfortunately this showed either poor stability (M = Sn) or weakly absorbing oversized indirect gaps (M = Bi), prompting concerns that perhaps stability and good optoelectronic properties might be contraindicated...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28430424/elucidation-of-the-stereospecificity-of-c-methyltransferases-from-trans-at-polyketide-synthases
#16
Xinqiang Xie, Chaitan Khosla, David E Cane
S-Adenosyl methionine (SAM)-dependent C-methyltransferases are responsible for the C2-methylation of 3-ketoacyl-acyl carrier protein (ACP) intermediates to give the corresponding 2-methy-3-ketoacyl-ACP products during bacterial polyketide biosynthesis mediated by trans-AT polyketide synthases that lack integrated acyl transferase (AT) domains. A coupled ketoreductase (KR) assay was used to assign the stereochemistry of the C-methyltransferase-catalyzed reaction. Samples of chemoenzymatically-generated 3-ketopentanoyl-ACP (9) were incubated with SAM and BonMT2 from module 2 of the bongkrekic acid polyke-tide synthase...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28430420/a-thorium-chalcogenolate-series-generated-by-atom-insertion-into-thorium-carbon-bonds
#17
Nicholas S Settineri, Mary E Garner, John Arnold
A new thorium monoalkyl complex, Th(CH2SiMe3)(L3) (L = MeC(N(i)Pr)2) (2), undergoes insertion of chalcogen atoms resulting in a series of thorium chalcogenolate complexes, Th(ECH2SiMe3)(L3) (E = S, SS, Se, Te; 5-8). Complex 6 represents the first alkyl disulfide thorium species and illustrates the ability of 2 to undergo controllable, stoichiometric atom insertion. All complexes have been characterized by (1)H and (13)C NMR spectroscopy, FTIR, EA, and melting point, and in the case of 1, 2, and 4-8, X-ray crystallography...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28429936/electron-decoupling-with-dynamic-nuclear-polarization-in-rotating-solids
#18
Edward P Saliba, Erika L Sesti, Faith J Scott, Brice J Albert, Eric J Choi, Nicholas Alaniva, Chukun Gao, Alexander B Barnes
Dynamic nuclear polarization (DNP) can enhance NMR sensitivity by orders of magnitude by transferring spin polarization from electron paramagnetic resonance (EPR) to NMR. However, paramagnetic DNP polarizing agents can have deleterious effects on NMR signals. Electron spin decoupling can mitigate these paramagnetic relaxation effects. We demonstrate electron decoupling experiments in conjunction with DNP and magic angle spinning (MAS) NMR spectroscopy. Following a DNP and spin diffusion period, the microwave irradiation frequency is quickly tuned on-resonance with electrons on the DNP polarizing agent...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28422494/genetically-encoded-2-aryl-5-carboxytetrazoles-for-site-selective-protein-photo-cross-linking
#19
Yulin Tian, Marco Paolo Jacinto, Yu Zeng, Zhipeng Yu, Jun Qu, Wenshe R Liu, Qing Lin
The genetically encoded photo-cross-linkers promise to offer a temporally controlled tool to map transient and dynamic protein-protein interaction complexes in living cells. Here we report the synthesis of a panel of 2-aryl-5-carboxytetrazole-lysine analogs (ACTKs) and their site-specific incorporation into proteins via amber codon suppression in Escherichia coli and mammalian cells. Among five ACTKs investigated, N-methylpyrroletetrazole-lysine (mPyTK) was found to give robust and site-selective photo-cross-linking reactivity in E...
April 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28418250/identifying-the-active-surfaces-of-electrochemically-tuned-licoo2-for-oxygen-evolution-reaction
#20
Zhiyi Lu, Guangxu Chen, Yanbin Li, Haotian Wang, Jin Xie, Lei Liao, Chong Liu, Yayuan Liu, Tong Wu, Yuzhang Li, Alan C Luntz, Michal Bajdich, Yi Cui
Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (112̅0) and polar (011̅2) surfaces are predicted to be highly active and dependent on (de)lithiation...
April 21, 2017: Journal of the American Chemical Society
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