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Aggoun Djouhra, Ourari Ali, Ruiz-Rosas Ramiro, Morallon Emilia
A new colorimetric receptor HL, acting as a bidentate Schiff base ligand, has been synthesized by condensation of 2-methoxybenzylamine on 2,3-dihydroxybenzaldehyde in a methanolic solution. Interestingly, this chelating agent can selectively detect Cu(2+), Co(2+), Fe(2+) and Fe(3+) ions with a simple and an easy-to-make, well defined naked-eye visible color changes in two different solvents like acetonitrile and methanol. This bidentate ligand coordinates three metal ions of Co(II), Cu(II) and Fe(II) via nitrogen and oxygen atoms...
May 10, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Jagdish Rai
Natural heme proteins may have heme bound to poly-peptide chain as a cofactor via non-covalent forces or heme as a prosthetic group may be covalently bound to the proteins. Nature has used porphyrins in diverse functions like electron transfer, oxidation, reduction, ligand binding, photosynthesis, signaling, etc. by modulating its properties through diverse protein matrices. Synthetic chemists have tried to utilize these molecules in equally diverse industrial and medical applications due to their versatile electro-chemical and optical properties...
May 15, 2017: Current Protein & Peptide Science
Mojtaba Alipour, Soheila Mohseni
There is a surge in the literature on the development of exchange-correlation density functionals for a wide variety of physical and chemical properties. As a recent endeavor toward the systematic and nonempirical design of density functional approximations, optimally tuned range-separated hybrid (OT-RSH) models have been introduced. In this work, we propose novel OT-RSH density functionals for predicting the oxidation potentials of organic compounds from different categories. In this regard, detailed analysis of the role of nonempirical optimization of the range separation parameter and importance of short- and long-range exact-like exchange in OT-RSH calculations of the oxidation potential has also been done...
May 17, 2017: Journal of Physical Chemistry. A
Xu Liang, Yingjie Niu, Qianchong Zhang, John Mack, Xiaoyi Yi, Zweli Hlatshwayo, Tebello Nyokong, Minzhi Li, Weihua Zhu
The synthesis of four low symmetry A2B type Cu(iii)triarylcorroles with meso-aryl substituents that provide electron donating (push) and withdrawing (pull) properties is reported, along with their structural characterization by NMR spectroscopy and X-ray crystallography. An analysis of the structure-property relationships in the optical and redox properties has been carried out by comparing their optical spectroscopy, electrochemistry, and spectroelectrochemistry to trends predicted in DFT and TD-DFT calculations...
May 15, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Johannes Klein, Alexandra Stuckmann, Sebastian Sobottka, Lisa Suntrup, Margarethe van der Meer, Paul Hommes, Hans-Ulrich Reissig, Biprajit Sarkar
The combination of 2,2':6',2″-terpyridines (tpy) and RuII is known to deliver molecular and supramolecular assemblies with remarkable properties. We present here new RuII complexes with modified tpy ligands substituted with varying numbers of dimethlyamino groups. Electrochemistry shows that the incorporation of the strongly electron-donating groups on the tpy ligands leads to a negative shift of the RuII oxidation potential by close to 1 V. The reductive electrochemical responses are strongly dependent on the nature of the working electrode, with glassy carbon and gold working electrodes showing the best results...
May 15, 2017: Chemistry: a European Journal
Fataneh Jafari, Setareh Samadi, Amin Nowroozi, Komail Sadrjavadi, Sajad Moradi, Mohammad Reza Ashrafi-Kooshk, Mohsen Shahlaei
In the present research, the binding properties of Diazinon (DZN), as an organophosphorus herbicide, to human serum albumin (HSA) were investigated using combination of spectroscopic, electrochemistry and molecular modeling techniques. Changes in the UV-Vis and FT-IR spectra were observed upon ligand binding along with a significant degree of tryptophan fluorescence quenching on complex formation. The obtained results from spectroscopic and electrochemistry experiments along with the computational studies suggest that DZN binds to residues located in subdomains IIA of HSA with binding constant about 1410...
May 15, 2017: Journal of Biomolecular Structure & Dynamics
Lucy E Wilson, Christopher Hassenrück, Rainer F Winter, Andrew J P White, Tim Albrecht, Nicholas J Long
Cyclic multiredox centered systems are currently of great interest, with new compounds being reported and developments made in understanding their behavior. Efficient, elegant, and high-yielding (for macrocyclic species) synthetic routes to two novel alkynyl-conjugated multiple ferrocene- and biferrocene-containing cyclic compounds are presented. The electronic interactions between the individual ferrocene units have been investigated through electrochemistry, spectroelectrochemistry, density functional theory (DFT), and crystallography to understand the effect of cyclization on the electronic properties and structure...
May 12, 2017: Angewandte Chemie
Chen Wang, Xing-Guo Nie, Yi Shi, Yue Zhou, Jing-Juan Xu, Xing-Hua Xia, Hong-Yuan Chen
Direct photocatalysis making use of plasmonic metals has attracted significant attention due to the unique light harnessing capabilities of these materials associated with localized surface plasmon resonance (LSPR) features. Thus far, most reported work has been limited to plasmon-induced chemical transformations. Herein, we demonstrate that electrochemical reactions can also be accelerated by plasmonic nanoparticles upon LSPR excitation. Using glucose electrocatalysis as a model reaction system, the direct plasmon-accelerated electrochemical reaction (PAER) on gold nanoparticles (AuNPs) is observed...
May 11, 2017: ACS Nano
Hyeokjun Park, Hee-Dae Lim, Hyung-Kyu Lim, Won Mo Seong, Sehwan Moon, Youngmin Ko, Byungju Lee, Youngjoon Bae, Hyungjun Kim, Kisuk Kang
Shedding new light on conventional batteries sometimes inspires a chemistry adoptable for rechargeable batteries. Recently, the primary lithium-sulfur dioxide battery, which offers a high energy density and long shelf-life, is successfully renewed as a promising rechargeable system exhibiting small polarization and good reversibility. Here, we demonstrate for the first time that reversible operation of the lithium-sulfur dioxide battery is also possible by exploiting conventional carbonate-based electrolytes...
May 11, 2017: Nature Communications
Ashley Page, David Perry, Patrick R Unwin
Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has traditionally been used to image topography or to deliver species to an interface, particularly in a biological setting. This article highlights the recent blossoming of SICM into a technique with a much greater diversity of applications and capability that can be used either standalone, with advanced control (potential-time) functions, or in tandem with other methods. SICM can be used to elucidate functional information about interfaces, such as surface charge density or electrochemical activity (ion fluxes)...
April 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
Saithip Pakapongpan, Rungtiva P Poo-Arporn
A novel approach of the immobilization of a highly selective and stable glucose biosensor based on direct electrochemistry was fabricated by a self-assembly of glucose oxidase (GOD) on reduced graphene oxide (RGO) covalently conjugated to magnetic nanoparticles (Fe3O4 NPs) modified on a magnetic screen-printed electrode (MSPE). The RGO-Fe3O4 nanocomposite has remarkable enhancement in large surface areas, is favorable environment for enzyme immobilization, facilitates electron transfer between enzymes and electrode surfaces and possesses superparamagnetism property...
July 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Zhenguo Wang, Weijiu Huang, Yan Li, Haoran He, Yongtao Zhou, Ziqing Zheng
The tribocorrosion behaviour of biomaterial Ti-25Nb-3Mo-3Zr-2Sn alloy in Ringer's solution was evaluated by micro-abrasion experiments, electrochemical tests and scanning electron microscope (SEM) observations. Potentiodynamic polarization results suggested that the effect of particle concentration on the electrochemistry characteristic is greater than the applied load. When the particle concentration and applied load were 0.05g·cm(-3) and 0.25N, respectively, the Ecorr reached the maximum as -0.381V. The micro-abrasion-corrosion results showed that the wear rates of the Ti-25Nb-3Mo-3Zr-2Sn alloy increased with increasing particle concentration and decreased as applied load increased...
July 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
M Bartošík, D Bartáková
BACKGROUND: Since DNA methylation results in gene silencing, it plays an important role in cell proliferation and differentiation. Abnormal DNA methylation is often associated with carcinogenesis, and therefore its analysis could be an interesting option in early diagnostics of cancer, determination of tumour invasiveness, progression or metastatic potential. One of the methods for DNA analysis could be also electrochemistry, which offers inexpensive instrumentation, short measurement times and parallel detection of samples...
2017: Klinická Onkologie: Casopis Ceské a Slovenské Onkologické Spolecnosti
Kai S Exner, Herbert Over
Multielectron processes in electrochemistry require the stabilization of reaction intermediates (RI) at the electrode surface after every elementary reaction step. Accordingly, the bond strengths of these intermediates are important for assessing the catalytic performance of an electrode material. Current understanding of microscopic processes in modern electrocatalysis research is largely driven by theory, mostly based on ab initio thermodynamics considerations, where stable reaction intermediates at the electrode surface are identified, while the actual free energy barriers (or activation barriers) are ignored...
May 2, 2017: Accounts of Chemical Research
Zhangxun Xia, Ruili Sun, Suli Wang, Luhua Jiang, Hai Sun, Gongquan Sun
Ion migration and electron transfer are crucial phenomena in electrochemistry and interfacial sciences, which require effective coupling and integration of the separated charge pathways within the medium materials. Here in this work, we fabricate an ordered nanowire material based on hybrid polymers of polypyrrole with electronic conductance and PFSA ionomer with ionic conductance via a facile one-step electrochemical route. Because of the nano-confined effects for the different charge transfer channels within the nanowire polymer matrix, the electronic and ionic conductivity of the hybrid polymer is surprisingly enhanced as 26...
May 2, 2017: ACS Applied Materials & Interfaces
Shunchao Ma, William C McKee, Jiawei Wang, Limin Guo, Martin Jansen, Ye Xu, Zhangquan Peng
Research interest in aprotic sodium-air (Na-O2) batteries is growing because of their considerably high theoretical specific energy and potentially better reversibility than lithium-air (Li-O2) batteries. While Li2O2 has been unequivocally identified as the major discharge product in Li-O2 batteries containing relatively stable electrolytes, a multitude of discharge products, including NaO2, Na2O2 and Na2O2·2H2O, have been reported for Na-O2 batteries and the corresponding cathodic electrochemistry remains incompletely understood...
May 21, 2017: Physical Chemistry Chemical Physics: PCCP
Garrison M Crouch, Donghoon Han, Susan K Fullerton-Shirey, David B Go, Paul W Bohn
Nanoscale conductive filaments, usually associated with resistive memory or memristor technology, may also be used for chemical sensing and nanophotonic applications; however, realistic implementation of the technology requires precise knowledge of the conditions that control the formation and dissolution of filaments. Here we describe and characterize an addressable direct-write nanoelectrochemical approach to achieve repeatable formation/dissolution of Ag filaments across a ∼100 nm poly(ethylene oxide) (PEO) film containing either Ag(+) alone or Ag(+) together with 50 nm Ag-nanoparticles acting as bipolar electrodes...
May 4, 2017: ACS Nano
Fahimeh Charbgoo, Mohammad Ramezani, Majid Darroudi
Cerium oxide nanoparticles (CNPs) contain several properties such as catalytic activity, fluorescent quencher and electrochemical, high surface area, and oxygen transfer ability, which have attracted considerable attention in developing high-sensitive biosensors. CNPs can be used as a whole sensor or a part of recognition or transducer element. However, reports have shown that applying these nanoparticles in sensor design could remarkably enhance detection sensitivity. CNP's outstanding properties in biosensors which go from high catalytic activity and surface area to oxygen transfer and fluorescent quenching capabilities are also highlighted...
April 26, 2017: Biosensors & Bioelectronics
Annkatrin Lennert, Michelle Sternberg, Karsten Meyer, Rubén D Costa, Dirk M Guldi
In the current work, novel symmetrically alkyl-substituted imidazolium-based ionic liquids have been synthesized featuring either iodide (I(-)) or selenocyanate (SeCN(-)) as counteranions. Physicochemical assays based on spectroscopy and electrochemistry techniques have been performed to identify the best ionic liquid for application as electrolytes in quasi-solid-state dye-sensitized solar cells (qssDSSC). The latter were mixed with additives such as 4-tert-butylpyridine (4tbpy) and guanidinium thiocyanate (GuSCN) to optimize electrode surface coverage, ionic diffusion, and dye regeneration...
April 27, 2017: ACS Applied Materials & Interfaces
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