scholarly journals Stepwise synthesis of a Ru4Cd4 coordination cage using inert and labile subcomponents: introduction of redox activity at specific sites

2014 ◽  
Vol 50 (48) ◽  
pp. 6330-6332 ◽  
Author(s):  
Alexander J. Metherell ◽  
Michael D. Ward
Keyword(s):  
Binding Sites ◽  
Redox Activity ◽  
Stepwise Synthesis ◽  
Redox Active

Combination of four [RuL3]2+ units, each with three pendant binding sites, and four Cd2+ ions affords the redox-active, heteronuclear, cubic cage [Ru4Cd4L12]16+.

scholarly journals Redox-Active Monolayers Self-Assembled on Gold Electrodes—Effect of Their Structures on Electrochemical Parameters and DNA Sensing Ability

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 607 ◽  
Author(s):  
Kamila Malecka ◽  
Shalini Menon ◽  
Gopal Palla ◽  
Krishnapillai Girish Kumar ◽  
Mathias Daniels ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Redox Activity ◽  
Gold Electrodes ◽  
Complex Structures ◽  
Transfer Coefficients ◽  
Sensing Properties ◽  
Redox Active ◽  
Electrochemical Parameters ◽  
Self Assembled

The background: The monolayers self-assembled on the gold electrode incorporated transition metal complexes can act both as receptor (“host” molecules) immobilization sites, as well as transducer for interface recognitions of “guest” molecules present in the aqueous solutions. Their electrochemical parameters influencing the sensing properties strongly depend on the transition metal complex structures. The objectives: The electrochemical characterization of the symmetric terpyridine–M2+–terpyridine and asymmetric dipyrromethene–M2+–terpyridine complexes modified with ssDNA probe covalently attached to the gold electrodes and exploring their ssDNA sensing ability were the main aims of the research presented. The methods: Two transition metal cations have been selected: Cu2+ and Co2+ for creation of redox-active monolayers. The electron transfer coefficients indicating the reversibility and electron transfer rate constant measuring kinetic of redox reactions have been determined for all SAMs studied using: Cyclic Voltammetry, Osteryoung Square-Wave Voltammetry, and Differential Pulse Voltammetry. All redox-active platforms have been applied for immobilization of ssDNA probe. Next, their sensing properties towards complementary DNA target have been explored electrochemically. The results: All SAMs studied were stable displaying quasi-reversible redox activity. The linear relationships between cathodic and anodic current vs. san rate were obtained for both symmetric and asymmetric SAMs incorporating Co2+ and Cu2+, indicating that oxidized and reduced redox sites are adsorbed on the electrode surface. The ssDNA sensing ability were observed in the fM concentration range. The low responses towards non-complementary ssDNA sequences provided evidences for sensors good selectivity. The conclusions: All redox-active SAMs modified with a ssDNA probe were suitable for sensing of ssDNA target, with very good sensitivity in fM range and very good selectivity. The detection limits obtained for SAMs incorporating Cu2+, both symmetric and asymmetric, were better in comparison to SAMs incorporating Co2+. Thus, selection of the right transition metal cation has stronger influence on ssDNA sensing ability, than complex structures.

scholarly journals Selenium Anticancer Properties and Impact on Cellular Redox Status

Antioxidants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 80 ◽  
Author(s):  
Lolita Kuršvietienė ◽  
Aušra Mongirdienė ◽  
Jurga Bernatonienė ◽  
Jurgita Šulinskienė ◽  
Inga Stanevičienė
Keyword(s):  
Anticancer Activity ◽  
Antioxidant Activities ◽  
Chemotherapeutic Agents ◽  
Redox Activity ◽  
Biological Functions ◽  
Cellular Redox ◽  
Selenium Compounds ◽  
Anticancer Properties ◽  
Redox Active ◽  
The Impact

(1) Background: In this review, we provide information published in recent years on the chemical forms, main biological functions and especially on antioxidant and prooxidant activities of selenium. The main focus is put on the impact of selenoproteins on maintaining cellular redox balance and anticancerogenic function. Moreover, we summarize data on chemotherapeutic application of redox active selenium compounds. (2) Methods: In the first section, main aspects of metabolism and redox activity of selenium compounds is reviewed. The second outlines multiple biological functions, asserted when selenium is incorporated into the structure of selenoproteins. The final section focuses on anticancer activity of selenium and chemotherapeutic application of redox active selenium compounds as well. (3) Results: optimal dietary level of selenium ensures its proper antioxidant and anticancer activity. We pay special attention to antioxidant activities of selenium compounds, especially selenoproteins, and their importance in antioxidant defence. It is worth noting, that data on selenium anticancer properties is still contraversive. Moreover, selenium compounds as chemotherapeutic agents usually are used at supranutritional doses. (4) Conclusions: Selenium play a vital role for many organism systems due to its incorporation into selenoproteins structure. Selenium possesses antioxidant activity at optimal doses, while at supranutritional doses, it displays prooxidant activity. Redox active selenium compounds can be used for cancer treatment; recently special attention is put to selenium containing nanoparticles.

scholarly journals Redox Polymers Incorporating Pendant 6-Oxoverdazyl and Nitronyl Nitroxide Radicals

2019 ◽  
Author(s):  
Michael Anghel ◽  
Francois Magnan ◽  
Sara D. Catingan ◽  
Matthew A. McCready ◽  
Elaheh Aawani ◽  
...  
Keyword(s):  
Thin Films ◽  
Polymerization Reaction ◽  
Redox Activity ◽  
Nitronyl Nitroxide ◽  
Nitroxide Radicals ◽  
Redox Active ◽  
Current Voltage ◽  
Radical Content ◽  
Memory Applications ◽  
Semiconducting Thin Films

Polymers comprised of redox-active organic radicals have emerged as promising materials for use in a variety of organic electronics, including fast-charging batteries. Despite these advances, relatively little attention has been focused on the diversification of the families of radicals that are commonly incorporated into polymer frameworks, with most radical polymers being comprised of nitroxide radicals. Here, we report two new examples prepared via ring-opening methathesis polymerization containing 6-oxoverdazyl and nitronyl nitroxide radicals appended to their backbones. The polymerization reaction and optoelectronic properties were explored in detail, revealing high radical content and redox activity that may be advantageous for their use as semiconducting thin films. Initial studies revealed that current-voltage curves obtained from thin films of the title polymers exhibited memory effects making them excellent candidates for use in resistive memory applications.

scholarly journals Mussel-Inspired Redox-Active and Hydrophilic Conductive Polymer Nanoparticles for Adhesive Hydrogel Bioelectronics

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Donglin Gan ◽  
Tao Shuai ◽  
Xiao Wang ◽  
Ziqiang Huang ◽  
Fuzeng Ren ◽  
...  
Keyword(s):  
Uniform Distribution ◽  
Tissue Regeneration ◽  
Conductive Polymer ◽  
Redox Balance ◽  
Polymer Nanoparticles ◽  
Redox Activity ◽  
Redox Active ◽  
Hydrogel Network ◽  
Conductive Hydrogels

AbstractConductive polymers (CPs) are generally insoluble, and developing hydrophilic CPs is significant to broaden the applications of CPs. In this work, a mussel-inspired strategy was proposed to construct hydrophilic CP nanoparticles (CP NPs), while endowing the CP NPs with redox activity and biocompatibility. This is a universal strategy applicable for a series of CPs, including polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene). The catechol/quinone contained sulfonated lignin (LS) was doped into various CPs to form CP/LS NPs with hydrophilicity, conductivity, and redox activity. These CP/LS NPs were used as versatile nanofillers to prepare the conductive hydrogels with long-term adhesiveness. The CP/LS NPs-incorporated hydrogels have a good conductivity because of the uniform distribution of the hydrophilic NPs in the hydrogel network, forming a well-connected electric path. The hydrogel exhibits long-term adhesiveness, which is attributed to the mussel-inspired dynamic redox balance of catechol/quinone groups on the CP/LS NPs. This conductive and adhesive hydrogel shows good electroactivity and biocompatibility and therefore has broad applications in electrostimulation of tissue regeneration and implantable bioelectronics.

scholarly journals Redox activity of a dissymmetric ligand bridging divalent ytter-bium and reactive nickel fragments

2021 ◽  
Author(s):  
Ding Wang ◽  
Maxime Tricoire ◽  
Valeriu Cemortan ◽  
Jules Moutet ◽  
Grégory Nocton
Keyword(s):  
Nickel Complex ◽  
Bond Formation ◽  
Lanthanide Complex ◽  
Redox Activity ◽  
Trimeric Complex ◽  
Redox Active ◽  
Divalent Lanthanide

The reaction of a nickel complex bearing a redox-active dissymmetric ligand (Kbimpm) with a divalent lanthanide complex, Cp*2Yb(OEt2) affords an unprecedented, trimeric complex with C(sp3)–C(sp3) bond formation between two ligands in an exo position.

scholarly journals Naphthalene SOA: redox activity and naphthoquinone gas–particle partitioning

2013 ◽  
Vol 13 (19) ◽  
pp. 9731-9744 ◽  
Author(s):  
R. D. McWhinney ◽  
S. Zhou ◽  
J. P. D. Abbatt
Keyword(s):  
Average Rate ◽  
Organic Aerosol ◽  
Redox Cycling ◽  
Oxidation Products ◽  
Redox Activity ◽  
Particle Phase ◽  
Ambient Particles ◽  
Redox Active ◽  
Potential Impact ◽  
Measured Particle

Abstract. Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox-active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. These results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10−4 m3 μg−1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. Also, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.

Redox activity of lignite and its accelerating effects on the chemical reduction of azo dye by sulfide

RSC Advances ◽  
2016 ◽  
Vol 6 (71) ◽  
pp. 66930-66937 ◽  
Author(s):  
Juanjuan Li ◽  
Guangfei Liu ◽  
Jiti Zhou ◽  
Aijie Wang ◽  
Jing Wang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Azo Dye ◽  
Chemical Reduction ◽  
Dye Decolorization ◽  
Redox Activity ◽  
Redox Active ◽  
Azo Dye Decolorization

Redox active lignite can act as a mediator to accelerate azo dye decolorization through enhancing electron transfer from sulfide to the azo dye.

scholarly journals Labile plasma iron in iron overload: redox activity and susceptibility to chelation

Blood ◽  
2003 ◽  
Vol 102 (7) ◽  
pp. 2670-2677 ◽  
Author(s):  
Breno P. Esposito ◽  
William Breuer ◽  
Pornpan Sirankapracha ◽  
Pensri Pootrakul ◽  
Chaim Hershko ◽  
...  
Keyword(s):  
Iron Overload ◽  
Oral Treatment ◽  
Oxidation Products ◽  
Redox Activity ◽  
Iron Chelators ◽  
Plasma Iron ◽  
Redox Active ◽  
Reactive Radicals

Abstract Plasma non-transferrin-bound-iron (NTBI) is believed to be responsible for catalyzing the formation of reactive radicals in the circulation of iron overloaded subjects, resulting in accumulation of oxidation products. We assessed the redox active component of NTBI in the plasma of healthy and β-thalassemic patients. The labile plasma iron (LPI) was determined with the fluorogenic dihydrorhodamine 123 by monitoring the generation of reactive radicals prompted by ascorbate but blocked by iron chelators. The assay was LPI specific since it was generated by physiologic concentrations of ascorbate, involved no sample manipulation, and was blocked by iron chelators that bind iron selectively. LPI, essentially absent from sera of healthy individuals, was present in those of β-thalassemia patients at levels (1-16 μM) that correlated significantly with those of NTBI measured as mobilizer-dependent chelatable iron or desferrioxamine chelatable iron. Oral treatment of patients with deferiprone (L1) raised plasma NTBI due to iron mobilization but did not lead to LPI appearance, indicating that L1-chelated iron in plasma was not redox active. Moreover, oral L1 treatment eliminated LPI in patients. The approach enabled the assessment of LPI susceptibility to in vivo or in vitro chelation and the potential of LPI to cause tissue damage, as found in iron overload conditions. (Blood. 2003;102:2670-2677)

scholarly journals Interplay of hemilability and redox activity in models of hydrogenase active sites

2017 ◽  
Vol 114 (46) ◽  
pp. E9775-E9782 ◽  
Author(s):  
Shengda Ding ◽  
Pokhraj Ghosh ◽  
Marcetta Y. Darensbourg ◽  
Michael B. Hall
Keyword(s):  
Lewis Acid ◽  
Hydrogen Evolution Reaction ◽  
Resting State ◽  
Active Sites ◽  
Reductive Elimination ◽  
Lewis Base ◽  
Redox Activity ◽  
Production Mechanism ◽  
Acid Base ◽  
Redox Active

The hydrogen evolution reaction, as catalyzed by two electrocatalysts [M(N2S2)·Fe(NO)2]+, [Fe-Fe]+ (M = Fe(NO)) and [Ni-Fe]+ (M = Ni) was investigated by computational chemistry. As nominal models of hydrogenase active sites, these bimetallics feature two kinds of actor ligands: Hemilabile, MN2S2 ligands and redox-active, nitrosyl ligands, whose interplay guides the H2 production mechanism. The requisite base and metal open site are masked in the resting state but revealed within the catalytic cycle by cleavage of the MS–Fe(NO)2 bond from the hemilabile metallodithiolate ligand. Introducing two electrons and two protons to [Ni-Fe]+ produces H2 from coupling a hydride temporarily stored on Fe(NO)2 (Lewis acid) and a proton accommodated on the exposed sulfur of the MN2S2 thiolate (Lewis base). This Lewis acid–base pair is initiated and preserved by disrupting the dative donation through protonation on the thiolate or reduction on the thiolate-bound metal. Either manipulation modulates the electron density of the pair to prevent it from reestablishing the dative bond. The electron-buffering nitrosyl’s role is subtler as a bifunctional electron reservoir. With more nitrosyls as in [Fe-Fe]+, accumulated electronic space in the nitrosyls’ π*-orbitals makes reductions easier, but redirects the protonation and reduction to sites that postpone the actuation of the hemilability. Additionally, two electrons donated from two nitrosyl-buffered irons, along with two external electrons, reduce two protons into two hydrides, from which reductive elimination generates H2.

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