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Ryan M Clarke, Tiffany Jeen, Serena Rigo, John R Thompson, Loren G Kaake, Fabrice Thomas, Tim Storr
We detail the rational design of a series of bimetallic bis-ligand radical Ni salen complexes in which the relative orientation of the ligand radical chromophores provides a mechanism to tune the energy of intense intervalence charge transfer (IVCT) bands in the near infrared (NIR) region. Through a suite of experimental (electrochemistry, electron paramagnetic resonance spectroscopy, UV-vis-NIR spectroscopy) and theoretical (density functional theory) techniques, we demonstrate that bimetallic Ni salen complexes form bis-ligand radicals upon two-electron oxidation, whose NIR absorption energies depend on the geometry imposed in the bis-ligand radical complex...
February 14, 2018: Chemical Science
Johannes Kasnatscheew, Ralf Wagner, Martin Winter, Isidora Cekic-Laskovic
Energy storage is considered a key technology for successful realization of renewable energies and electrification of the powertrain. This review discusses the lithium ion battery as the leading electrochemical storage technology, focusing on its main components, namely electrode(s) as active and electrolyte as inactive materials. State-of-the-art (SOTA) cathode and anode materials are reviewed, emphasizing viable approaches towards advancement of the overall performance and reliability of lithium ion batteries; however, existing challenges are not neglected...
April 18, 2018: Topics in Current Chemistry (Journal)
Bendix Petersen, Rafael Roa, Joachim Dzubiella, Matej Kanduč
Metal nanoparticles are receiving increased scientific attention owing to their unique physical and chemical properties that make them suitable for a wide range of applications in diverse fields, such as electrochemistry, biochemistry, and nanomedicine. Their high metallic polarizability is a crucial determinant that defines their electrostatic character in various electrolyte solutions. Here, we introduce a continuum-based model of a metal nanoparticle with explicit polarizability in the presence of different kinds of electrolytes...
April 19, 2018: Soft Matter
Ming-Xing Zhang, Jing Zhang, Jun Yin, František Hartl, Sheng Hua Liu
Two related three-membered series of nonlinear aminophenylferrocene and diphenylaminoferrocene complexes were prepared and characterized by 1H and 13C NMR spectroscopy. The first series consists of 4-(diphenylamino)phenylferrocene (TPA-Fc, 1a), its dimethoxy-substituted tetraphenylphenylenediamine derivative (M2TPPD-Fc, 1c), and the triphenylamine-bridged bis(ferrocenyl) complex (Fc-TPA-Fc, 1b). The second series involves bis(4-methoxyphenyl)aminoferrocene (M2DPA-Fc, 1d), 4-methoxyphenylaminoferrocene (MPA-Fc) with N-phenyl-appended terminal TPA (1e), and the corresponding bis(MPA-Fc) complex with bridging TPA (1f)...
April 17, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Hasan Raboui, Alan J Lough, Anjuli M Szawiola, Timothy P Bender
Tetrabenzotriazacorroles (Tbcs) are a family of molecules related to phthalocyanines but have the unique ability to intensely absorb both blue and red light. Here, we report the synthesis of four novel silicon tetrabenzotriazacorrole derivatives (SiTbcs) with varying sized axial ligands. SiTbcs are formed starting from bis(hydroxy) silicon phthalocyanine ((OH)2 -SiPc) via a simple in situ axial functionalization and reductive chemical process using magnesium metal and the respective chlorosilane in pyridine...
April 17, 2018: Inorganic Chemistry
Feipeng Duan, Wenjuan Xu, Jie Liu, Zhixin Jia, Kuikui Chen, Yijun Chen, Mingxia Wang, Kaiyue Ma, Jiaojiao Dong, Lianming Chen, Hongbin Xiao
The key in vivo metabolites of a drug play an important role in its efficacy and toxicity. However, due to the low content and instability of these metabolites, they are hard to obtain through in vivo methods. Electrochemical reactions can be an efficient alternative to biotransformation in vivo for the preparation of metabolites. Accordingly, in this study, the metabolism of Z-ligustilide was investigated in vitro by electrochemistry coupled online to mass spectrometry. This work showed that five oxidation products of the electrochemical reaction were detected and that two of the oxidation products (senkyunolide I and senkyunolide H) were identified from liver microsomal incubation as well...
April 16, 2018: Journal of Separation Science
Shadi Fatayer, Bruno Schuler, Wolfram Steurer, Ivan Scivetti, Jascha Repp, Leo Gross, Mats Persson, Gerhard Meyer
Intermolecular single-electron transfer on electrically insulating films is a key process in molecular electronics1-4 and an important example of a redox reaction5,6 . Electron-transfer rates in molecular systems depend on a few fundamental parameters, such as interadsorbate distance, temperature and, in particular, the Marcus reorganization energy 7 . This crucial parameter is the energy gain that results from the distortion of the equilibrium nuclear geometry in the molecule and its environment on charging8,9 ...
April 16, 2018: Nature Nanotechnology
Christopher M Lemon, Seung Jun Hwang, Andrew G Maher, David C Powers, Daniel G Nocera
Main-group p-block metals are ideally suited for mediating two-electron reactions because they cycle between M n and M n+2 redox states, as the one-electron state is thermodynamically unstable. Here, we report the synthesis and structure of an SbIII corrole and its SbV X2 (X = Cl, Br) congeners. SbIII sits above the corrole ring, whereas SbV resides in the corrole centroid. Electrochemistry suggests interconversion between the SbIII and SbV X2 species. TD-DFT calculations indicate a HOMO → LUMO+2 parentage for excited states in the Soret spectral region that have significant antibonding character with respect to the Sb-X fragment...
April 16, 2018: Inorganic Chemistry
Ravishankar Sundararaman, Kendra Letchworth-Weaver, Kathleen A Schwarz
Reliable first-principles calculations of electrochemical processes require accurate prediction of the interfacial capacitance, a challenge for current computationally efficient continuum solvation methodologies. We develop a model for the double layer of a metallic electrode that reproduces the features of the experimental capacitance of Ag(100) in a non-adsorbing, aqueous electrolyte, including a broad hump in the capacitance near the potential of zero charge and a dip in the capacitance under conditions of low ionic strength...
April 14, 2018: Journal of Chemical Physics
Weiwei Mao, Haiping He, Pengcheng Sun, Zhizhen Ye, Jingyun Huang
A facile and scalable in situ micro-electrolysis nanofabrication technique is developed for preparing crosslinked Ni(OH)2 nanosheets on a novel 3D porous nickel template (Ni(OH)2@3DPN). For the constructed template, the porogen of NaCl particles not only induce a self-limiting surficial hot corrosion to claim the "start engine stop" mechanism, but also serve as the primary battery electrolyte to greatly accelerate the growth of Ni(OH)2. As far as we know, the micro-electrolysis nanofabrication is superior to the other reported Ni(OH)2 synthesis methods due to the mild condition (60 ℃, 6 h, NaCl solution, ambient environment) and without any post treatment...
April 13, 2018: ACS Applied Materials & Interfaces
Xiuting Li, Christopher Batchelor-McAuley, Javor K Novev, Richard G Compton
An optimised thermostated electrochemical cell is designed and implemented. This is informed by experimental and computational studies characterizing the extent to which the thermostating of an electrochemical cell via a heated bath can be realised, both with the cell closed and open to the environment. The heat transfer in the system is simulated and probed experimentally; special emphasis is put on heat loss due to radiation and evaporation. Experiments and simulations demonstrate that these two mechanisms of heat transfer lead to a steady temperature in the cell that differs from that of the thermostat by ∼0...
April 13, 2018: Physical Chemistry Chemical Physics: PCCP
Long Le-Quang, Rajaa Ghassan Farran, Youssef Lattach, Hugues Bonnet, Helene Jamet, Liliane Guerente, Emmanuel Maisonhaute, Jérôme Chauvin
We propose in this work a stepwise approach to construct photoelectrodes. This takes advantage of the self-assembly interactions between thiol with a gold surface and terpyridine ligands with first row transition metals. Here, a [Ru(bpy)3]2+ photosensitive center bearing a free terpyridine group has been used to construct two linear dyads on gold (Au/[ZnII-RuII]4+ and Au/[CoIII-RuII]5+). The stepwise construction was characterized by electrochemistry, quartz crystal microbalance and AFM imaging. The results show that the dyads behave as rigid layers and are inhomogeneously distributed on the surface...
April 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Amy Fisher
As a professor of chemistry at the University of Pennsylvania, Robert Hare actively shaped early American science. He participated in a large network of scholars, including Joseph Henry, François Arago, and Jacob Berzelius, and experimented with and wrote extensively about electricity and its associated chemical and thermal phenomena. In the early nineteenth century, prominent chemists such as Berzelius and Humphry Davy proclaimed that a revolution had occurred in chemistry through electrical research. Examining Robert Hare's contributions to this discourse, this paper analyzes how Hare's study of electricity and the caloric theory of heat led him to propose a new theory of galvanism...
April 9, 2018: Ambix
L M Frensemeier, J Mayr, G Koellensperger, B K Keppler, C R Kowol, U Karst
Pt(iv) prodrugs are a class of promising anticancer agents, which are activated by reduction to the active Pt(ii) species. Consequently, the reduction process is a crucial parameter. Herein, a new approach using electrochemistry (EC) coupled to liquid chromatography (LC) and electrospray ionization-mass spectrometry (ESI-MS) or inductively coupled plasma (ICP)-MS was applied. This enabled getting insights into the differences in the reduction and ligand release of platinum(iv) complexes with varying equatorial core structures...
April 9, 2018: Analyst
Lifu Chen, Eden E L Tanner, Chuhong Lin, Richard G Compton
Graphene nanoplatelets are shown to electrocatalyse the oxidation of dopamine. Single entity measurements ('nano-impacts') coupled with microdisc voltammetry and UV-visible spectroscopy reveal that adsorption of dopamine and its oxidised product on the graphene nanoplatelets is the key factor causing the observed catalysis. Genetic implications are drawn both for the study of catalysts in general and for graphene nanoplatelets in particular.
January 7, 2018: Chemical Science
Luana S Pedroza, Pedro Brandimarte, Alexandre Reily Rocha, M-V Fernández-Serra
Understanding the local structure of water at the interfaces of metallic electrodes is a key issue in aqueous-based electrochemistry. Nevertheless a realistic simulation of such a setup is challenging, particularly when the electrodes are maintained at different potentials. To correctly compute the effect of an external bias potential applied to truly semi-infinite surfaces, we combine Density Functional Theory (DFT) and Non-Equilibrium Green's Function (NEGF) methods. This framework allows for the out-of-equilibrium calculation of forces and dynamics, and directly correlates to the chemical potential of the electrodes, which is introduced experimentally...
January 7, 2018: Chemical Science
Xiaohan Wu, Claire Villevieille, Petr Novák, Mario El Kazzi
Understanding the degradation of the solid electrolyte-electrodes interface during cycling is currently one of the most challenging obstacles in the development of all-solid-state batteries. Here, we introduce operando X-ray photoelectron spectroscopy (XPS) as a combined approach for real-time monitoring of the (i) (electro-) chemical interfacial reactions between different components of the composites electrode and (ii) surface electronic properties. The dedicated electrochemical cell, capable of maintaining high mechanical pressure, offers reliable electrochemistry and versatility in terms of materials application...
April 6, 2018: Physical Chemistry Chemical Physics: PCCP
Almagul Zhanaidarova, Curtis E Moore, Milan Gembicky, Clifford P Kubiak
Surface modification of glassy carbon electrodes (GCEs) with molecular electrocatalysts is an important step towards developing more efficient heterogeneous CO2 reduction materials. Here, we report direct anodic electrografting of [Ni(alkynyl-cyclam)]2+ catalysts to the surface of GCEs in one simple step using inexpensive earth-abundant chemicals. When modified, these electrodes show reversible electrochemistry in organic solvents with zero peak-to-peak separations (ΔE = 0) and non-diffusive I (V) profiles that are typical for heterogeneous redox materials...
April 5, 2018: Chemical Communications: Chem Comm
Rudra N Samajdar, Dhivya Manogaran, S Yashonath, Aninda J Bhattacharyya
Quasi reversibility in electrochemical cycling between different oxidation states of iron is an often seen characteristic of iron containing heme proteins that bind dioxygen. Surprisingly, the system becomes fully reversible in the bare iron-porphyrin complex: hemin. This leads to the speculation that the polypeptide bulk (globin) around the iron-porphyrin active site in these heme proteins is probably responsible for the electrochemical quasi reversibility. To understand the effect of such polypeptide bulk on iron-porphyrin, we study the interaction of specific amino acids with the hemin center in solution...
April 5, 2018: Physical Chemistry Chemical Physics: PCCP
Yating Zhao, Wujiong Xia
The employment of nitrogen sources with free N-H bonds for amination is considered to be most straightforward and desirable, especially when the C-N bonds are prepared from N-H bonds and non-functionalized carbon sources, such as C-H bonds and C-C double/triple bonds, since this obviates the needs for the pre-installation of reactive groups in the starting materials and leads to a high atom and step economy. Recently, radical chemistry has been resuscitated owing to its great value in organic synthesis, and notable advances have been made in the direct use of N-H bonds for radical-based C-N bond formation with photo-/electrotechniques...
April 5, 2018: Chemical Society Reviews
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