Electrochemical Redox Behavior Research Articles

Effect of chirality on the anticancer activity of Pt(II) and Pt(IV) complexes containing 1R,2R and 1S,2S enantiomers of the trans-1,2-diamino-4-cyclohexene ligand (DACHEX), an analogue of diaminocyclohexane used in oxaliplatin.

Six enantiomerically pure, oxaliplatin-like, platinum compounds (two platinum(II) and four platinum(IV)), all containing unsaturated cyclic diamine trans-1,2-diamino-4-cyclohexene (DACHEX) as a substitute for the trans-1,2-diaminocyclohexane used in oxaliplatin, were investigated. The complexes were characterized by elemental analyses, ESI-MS, and 1H-NMR spectroscopy. For the four Pt(IV) complexes the electrochemical redox behaviour, investigated by cyclic voltammetry, showed that all complexes possess reduction potentials suitable for activation in vivo. The antiproliferative activity was assessed in vitro on human cancer cell lines, also selected for resistance to platinum-based drugs or belonging to the MultiDrug-Resistant (MDR) phenotype. All complexes exhibited antiproliferative activity superior to that of cisplatin and almost equivalent to or better than that of oxaliplatin; moreover, most complexes were also capable of overcoming both the cisplatin- and the oxaliplatin-resistance. By comparing the effectiveness of the enantiomerically pure compounds with the racemic one, the R,R enantiomer emerged as the most effective in the case of Pt(II) complexes whereas the S,S enantiomer was the most effective in the case of the Pt(IV) derivatives. From the results obtained also against 3D spheroid tumor models, cis,trans,cis-[Pt(OXA)(OBz)2(1S,2S-DACHEX)] (OBz = benzoate) emerged as the most promising candidate for further preclinical investigation.

Engineering carbon-nanochain concatenated hollow Sn4P3 nanospheres architectures as ultrastable and high-rate anode materials for sodium ion batteries

Tin phosphide (Sn4P3) that identified as a potential anode for sodium ion batteries (SIBs) based on its high theoretical specific capacity mostly confronts with the huge challenges in rapid capacity decay, severe volume evolution and weak diffusion kinetics upon cycling. It is of great theoretical and practical significance to develop the multilevel structured metal phosphide anode in high performance SIBs systems. Herein, we construct a nanochain-like architecture built from hollow yolk-shell Sn4P3@C nanospheres (Sn4P3@CNF) by electrospinning method and phosphorization treatment, in which all hollow Sn4P3 nanospheres are uniformly chained to one dimensional (1D) carbon nanofibers, forming a necklace-like hybrid conductive construction. The synergistic effect between hollow Sn4P3 nanospheres and nanochain architecture not only offers unblocked transfer channels for Na+ and accelerates the long-distance electronic transmission, but also guarantees excellent electrode kinetics and accommodates volume expansion. The Sn4P3@CNF electrode delivers a highly reversible discharge capacity of 297.6 mAh g−1 at 1 A g−1 after 1750 cycles, 250.6 mAh g−1 at 2 A g−1 after 4700 cycles, as well as ultrastable cycling durability up to 14000 cycles with a capacity of 157.8 mAh g−1 even at a high rate of 5 A g−1. These results demonstrate the greatest cyclability reported so far on Sn4P3-based anodes for SIBs. Meanwhile, the consecutive CV measurement further confirms a capacitive electrochemical redox behavior of Sn4P3@CNF upon cycling. More interestingly, the Sn4P3@CNF electrode displays the superior cycling stability and rate capability in sodium ion full cells as combined with a high-voltage Na3V2(PO4)3 cathode, where the full cell delivers an initial discharge capacity of 286.4 mAh g−1 and maintains a 67.2% capacity retention after 160 cycles at 1 A g−1, making it a great potential for practical application in SIBs systems.

Energy Storage Applications of Cobalt and Manganese Metal–Organic Frameworks

This work highlights the electrochemical properties of as-synthesized cobalt and manganese metal–organic frameworks. The electrochemical redox behavior of Co-MOF and Mn-MOF electrode was investigated in 0.1 M KOH solution by cyclic voltammetry. The rectangular CV curve obtained by the Mn-MOF electrode implies the pseudocapacitor act from the surface redox reaction of Mn. Well separated oxidation and reduction peaks achieved by the Co-MOF electrode implied the battery like behavior. For battery, the charge is represented as the capacity and the calculated capacity for the Co-MOF was 1064.3 mhAg−1 at 0.1 Ag−1. For pseudocapacitor, capacitance should be used, and achieved capacitance by Mn-MOF electrode was 483 Fg−1 at constant current density 1 Ag−1. With this delineation in mind, it should be clear that Co-MOF is suitable for battery purpose and Mn-MOF is suitable for pseudocapacitor application.

EQCM study on the electrochemical redox behavior of gallium in alkaline solution

The electrochemical redox behavior of gallium (Ga) in alkaline solution was investigated using the combination of electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry (CV). The electrodeposition morphology and elemental composition were observed using the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results indicate that during the reduction process, the reduction of gallium anion (GaO2−) begins at high negative values of the potential (−1.42 V, vs. Hg/HgO), and the reduction product (Ga2O) is transformed into Ga2O3 and Ga via the disproportionation reaction; the electrodeposition potential of Ga is −1.76 V (vs. Hg/HgO). The oxidation process of Ga can be divided into four stages with the increasing of potential: (i) the oxidation of Ga to form Ga2O, (ii) the electrodissolution of Ga to form GaO2−, (iii) the formation of passivation films (GaO(OH)) on the Ga surface, and (iv) the destruction of passivation films and the continuous dissolution of Ga.

Electrochemical redox behavior of organic quinone compounds in aqueous metal ion electrolytes

Organic quinone compounds are promising electrode materials for aqueous rocking-chair batteries due to chemical inert toward aqueous solutions and wide feasibility of various charge carriers. However, in aqueous electrolytes, the ion-pairing effect of different charge carriers on the electrochemical properties of organic quinone compounds remains unclear. Herein, we selecte a small molecule 9,10-anthraquinone as a study model and propose that the proton assisted metathesis reaction between anthrahydroquinone and M n+ results in stabilizing electrode reaction. Meantime, the possibility of anthraquinone as anode for aqueous multivalent metal-ion (Al 3+ , Mg 2+ , Zn 2+ ) batteries is illustrated. Typically for aluminum-ion battery, a reversible capacity of 211.4 mA h g -1 at 800 mA g -1 after 500 full cycles with a capacity retention of 94.5% can be obtained. This work may provide guidance to design and explore more organic quinone compounds for aqueous batteries. Here, two redox mechanisms of AQ in different aqueous metal ion electrolytes were proposed. In 1 M LiCl, NaCl, KCl, CaCl 2 and BaCl 2 , AQ molecule obtains an electron and becomes a radical anion [AQ] - , then a metal ion pairs with radical anion to form red [AQ-M n+ ] (n-1)+ ; In 1 M AlCl 3 , MgCl 2 and ZnCl 2 , AQ molecules undergoes one step two-electron redox process assisted by protons in electrolyte. Then metathesis reactions between AQ-H2 and metal-ions occur and induce morphology evolution in electrode. • Different electrochemical redox behaviors of AQ in different aqueous electrolytes were observed. • The spin density distribution of red species result in poor redox stability of AQ in 1M LiCl, NaCl, KCl, CaCl 2 and BaCl 2 . • Metathesis reactions assisted by protons induce the reversible redox reaction of AQ in 1 M AlCl 3 , MgCl 2 and ZnCl 2 . • The possibility of AQ as anode for aqueous multivalent metal-ion (Al 3+ , Mg 2+ , Zn 2+ ) batteries was demonstrated.

Platinum(IV) Complexes of trans-1,2-diamino-4-cyclohexene: Prodrugs Affording an Oxaliplatin Analogue that Overcomes Cancer Resistance.

Six platinum(IV) compounds derived from an oxaliplatin analogue containing the unsaturated cyclic diamine trans-1,2-diamino-4-cyclohexene (DACHEX), in place of the 1,2-diaminocyclohexane, and a range of axial ligands, were synthesized and characterized. The derivatives with at least one axial chlorido ligand demonstrated solvent-assisted photoreduction. The electrochemical redox behavior was investigated by cyclic voltammetry; all compounds showed reduction potentials suitable for activation in vivo. X-ray photoelectron spectroscopy (XPS) data indicated an X-ray-induced surface reduction of the Pt(IV) substrates, which correlates with the reduction potentials measured by cyclic voltammetry. The cytotoxic activity was assessed in vitro on a panel of human cancer cell lines, also including oxaliplatin-resistant cancer cells, and compared with that of the reference compounds cisplatin and oxaliplatin; all IC50 values were remarkably lower than those elicited by cisplatin and somewhat lower than those of oxaliplatin. Compared to the other Pt(IV) compounds of the series, the bis-benzoate derivative was by far (5–8 times) the most cytotoxic showing that low reduction potential and high lipophilicity are essential for good cytotoxicity. Interestingly, all the complexes proved to be more active than cisplatin and oxaliplatin even in three-dimensional spheroids of A431 human cervical cancer cells.

Development, validation and enzyme kinetic evaluation of multi walled carbon nano tubes mediated tyrosinase based electrochemical biosensing platform for the voltammetric monitoring of epinephrine

Epinephrine (EP) is one of the key neurotransmitter, which plays a vital role in the central nervous system. Current research report designates the development of biosensor based on the modification of glassy carbon electrode (GCE) with multi walled carbon nano tubes (MWCNTs) followed by drop casting of Tyrosinase (Ty) enzyme (Ty/MWCNTs/GCE) towards the sensitive monitoring of EP. The electrochemical behavior of EP at Ty/MWCNTs/GCE biosensor was examined and the redox mechanism was proposed. The developed Ty/MWCNTs/GCE was characterized by electrochemical techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and tafel plot studies. The influence of pH of phosphate buffer solution (PBS) on the electrochemical redox behavior of EP was observed and pH-7.0 was identified as optimal pH value. The electrochemical kinetic parameters such as heterogeneous rate constant, diffusion coefficient and charge transfer coefficient values were evaluated. The limit of detection and limit of quantification values were evaluated. The low apparent Michaelis – Menten constant (Kmapp) was determined as 0.159 mM, demonstrating the immense catalytic activity of Ty enzyme. Repeatable, reproducible and stable nature of the fabricated Ty/MWCNTs/GCE was successfully examined. Finally, the developed biosensor was tested for the practical application in quantification of EP in human serum samples.

Chelated Zn–Metal–Organic Frameworks: Synthesis, Crystal Structure and Electrochemical Energy Storage

We have successfully synthesized the chelated Zn-EDTA metal–organic framework (Zn–MOF) by an eco-friendly hydrothermal route at 160 °C. The product obtained was confirmed by techniques such as ATRIR, SEM, SXRD, TGA, and BET. High stability, homogeneous topology, and significant surface area are the notable properties, which have been studied. The electrochemical redox behavior property of the as-prepared Zn–MOF electrode was investigated in 0.005 M K4Fe(CN)6 solution by Cyclic voltammetry. The CV nature obtained by the Zn–MOF electrode implies the typical battery act from the surface redox reaction. The chelated Zn–MOF electrode has been subjected to charge–discharge study to find out the specific capacity of the Zn–MOF electrode in KOH solution different temperatures and also in mixed electrolyte separately. Higher specific capacity of the Zn–MOF electrode about 243.2 mA hg−1 was found at room temperature in 0.1 M KOH at 1 Ag−1. Also, excellent capacity about 589.28 mA hg−1 was observed in mixed electrolytes. The Zn–MOF to be a promising candidate for energy (gas) storage application.

NbO2 as a Noble Zero-Strain Material for Li-Ion Batteries: Electrochemical Redox Behavior in a Nonaqueous Solution

Lithium-ion batteries are widely available commercially and attempts to extend the lifetime of these batteries remain necessary. The energy storage characteristics of NbO2 with a rutile structure as a material for the negative electrode of lithium-ion batteries were investigated. When negative potential was applied to the NbO2 electrode during application of a constant current in a nonaqueous solution containing lithium ions, these ions were inserted into the NbO2. Conversely, upon application of positive potential, the inserted lithium ions were extracted from the NbO2. In situ X-ray diffraction results revealed that the variation in the volume of NbO2 accompanying the insertion and extraction of lithium was 0.14%, suggesting that NbO2 is a zero-strain (usually defined by a volume change ratio of 1% or less) active material for lithium-ion batteries. Moreover, the highly stable structure of NbO2 allows the corresponding electrode to exhibit excellent cycling performance and coulombic efficiency.

Electroactive six arm star poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate): Synthesis and application as cathode material for rechargeable Li-ion batteries

In this report, we described organic radical batteries (ORBs) based on a newly synthesized star polymer. Six arm star polymer in which the polymer chains radiating from an electroactive triphenylamine core and the chains containing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) pendant groups was designed and synthesized via core first method using ATRP technique. The molecular weight (Mn) and polydispersity index of the star poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) (star PTMA) obtained was 6.8 × 104 g mol−1 and 1.08 respectively. The cathode composite materials comprised of star PTMA with SP carbon were prepared and successfully used in rechargeable batteries against lithium metal anode. The cyclic voltammetry results of star PTMA exhibited reversible redox peak pair distinctly at 3.61 V and 2.88 V (vs. Li/Li+) attributed to the electrochemical redox behavior of the nitroxide radicals and triphenylamine moieties respectively. The batteries fabricated with 40% and 20% star PTMA (active material) showed initial specific energy capacity of 115.2 mWh/g and 72.6 mWh/g respectively and the batteries retained 95% of its energy capacity after 10th charge/discharge cycle. The initial charge/discharge capacities of the cell containing 40% active material were found high compared to that containing 20% active material; however, both the cells exhibited similar discharge capacity.

Effect of cation (Li+, Na+, K+, Rb+, Cs+) in aqueous electrolyte on the electrochemical redox of Prussian blue analogue (PBA) cathodes

Abstract Prussian blue analogue (PBA) material is a promising cathode for applications in Na-ion and K-ion batteries which can support high c-rates for charge and discharge. In this study, the material of composition [K2CuIIFeII(CN)6] was synthesized and its structural and electrochemical redox behavior was investigated with 5 different alkali insertion cations (Li+, Na+, K+, Rb+, Cs+). Galvanostatic measurements indicate that the redox potential strongly depends on the ionic radius of the inserted cation. The redox potential varies by ∼400 mV between using Li+ (0.79 A) or Cs+ (1.73 A) in the electrolyte. The underlying modification of the Fe2+/Fe3+ redox potential in PBA is proposed to be due to the weakening of the Fe–C bond in the material. This hypothesis is supported by XRD measurements which reveal that the lattice parameter of the de-intercalated host structure follows the same trend of monotonic increase with the cation size. The relatively minor volume changes accompanying the redox (1.2%–2.4%) allow the PBA to accommodate differently sized cations, although the structural hindrances are quite pronounced at high c-rates for the larger ones (Rb+ and Cs+). Cycle aging studies indicate that the minimum capacity fade rate is observed in case of K+ and Rb+ containing electrolyte. The peak intensity corresponding to the [220] crystallographic plane varies depending on the state of charge of PBA, since this plane contains the insertion cations. Owing to the sensitivity of the redox potential to the insertion cation coupled with the observed fast ion-exchange ability, the PBA material may find additional analytical applications such as ion sensing or filtration devices.

Klonopin assay using modified electrode with multiwalled carbon nanotubes and poly melamine nanocomposite

Developing of cheap, sensitive and stable sensors plays a significant role in pharmaceutical and clinical applications. Considering the effective role of Klonopin (KNP) in the treatment of epilepsy, KNP quantification in its production process for dose adjustments and checking the purity and also after its usage by patents for bioavailability testing and effectiveness assay is vital. In present work, an efficient electrochemical sensor based on poly melamine and multiwalled carbon nanotubes nanocomposite (PMela/CNTs) was constructed which displayed effective electrochemical response toward KNP. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square-wave voltammetry (SWV) experiments were applied for performance evaluation of the PMela/CNTs modified electrode and electrochemical redox behavior of KNP. Distinguish synergetic effect was observed between CNTs and poly melamine in response to KNP electrochemical redox reaction. A linear detection range of 0.05 to 10 μM with the detection limits of 63 nM was achieved for KNP analysis. The practical application of the PMela/CNTs modified electrode revealed satisfactory results for quantification of KNP in biological fluids.

Evidence of proton-coupled mixed-valency by electrochemical behavior on transition metal complex dimers bridged by two Ag+ ions.

H-Bonded metal complex dimers with reversible redox behaviour, which are connected by a low-barrier hydrogen bond (LBHB) with a very low energy barrier for proton transfer, can provide a unique mixed-valency state stabilized by the proton-coupled electron transfer (PCET) phenomenon. Using cyclic voltammetry measurements, newly prepared [ReIIICl2(PnPr3)2(Hbim)]2 (2) and [OsIIICl2(PnPr3)2(Hbim)]2 (3) existing as H-bonded dimers in a CH2Cl2 solution showed a four-step and four-electron transfer containing two mixed-valency states of ReIIReIII and ReIIIReIV, and OsIIOsIII and OsIIIOsVI, respectively. Furthermore, [ReIIICl2(PnPr3)2(Agbim)]2 (4) and [OsIIICl2(PnPr3)2(Agbim)]2 (5), bridged by two Ag+ ions instead of two H-bonding protons, were prepared, and their electrochemical behaviours changed to a two-step and four-electron transfer. It is clear that the H-bonded complex dimers 2 and 3, connected by an LBHB, can be electrochemically stabilized into unique pairs of mixed-valency states by PCET, and the H-bonding proton transfer also controls the electrochemical redox behaviour.

Facile synthesis of cellulose microfibers supported palladium nanospindles on graphene oxide for selective detection of dopamine in pharmaceutical and biological samples

The cost-effective synthesis of novel functional nanomaterials has received significant attention in the physical and chemical sciences due to their improved surface area, high catalytic activity along with unique morphological features. This paper reports a facile and eco-friendly synthesis of spindle-like palladium nanostructures (PdSPs) on graphene oxide-cellulose microfiber (GO-CMF) composite for the first time. The GO-CMF/PdSPs composite was synthesized by an electrochemical method without the use of additional surfactants and capping agents. The synthesized materials were characterized and confirmed by using transmission electron microscopy, high-resolution scanning electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy and Fourier-transform infrared spectroscopy. As-synthesized GO-CMF/PdSPs composite modified electrode was used as a selective electrocatalyst for the oxidation of dopamine (DA). The electrochemical redox behaviors of DA were investigated using cyclic voltammetry (CV). The CV results revealed that the GO-CMF/PdSPs composite modified electrode has 10 folds enhanced oxidation current response to DA than GO, PdSPs and GO-CMF modified GCEs. Under optimized conditions, the GO-CMF/PdSPs composite sensor exhibits a linear response to DA in the concentration range from 0.3 to 196.3 μM with the lower detection limit of 23 nM. The nanocomposite electrode also shows promising features towards the reliable and selective detection of DA, which includes high stability, reproducibility and high selectivity towards the commonly interfering species such as ascorbic acid, uric acid, and dihydroxybenzene isomers. The sensor was successfully tested for the real-time detection of DA in the commercial DA injections and human serum samples.

Benzothiadiazole, hexylthiophen and alkoxy benzene based solution processable copolymer: Effect of the electron withdrawing substituents (fluorine atoms) on electrochemical, optical and electrochromic properties

Abstract 4,7-Bis(4-hexyl-5-(trimethylstannane) -2-thienyl) −2,1,3-benzothiadiazole (HTBT) coupled with 2,5-bis (decyloxy)-1,4-dibromobenzene to afford the donor-π-bridge-donor-acceptor conjugated poly (4,7-bis (4-hexyl-2-thienyl) −2,1,3-benzothiadiazole-co-p-didecyloxybenzene) (PTBTB). Further, copolymerization of fluorine-functionalized HTBT moiety with alkoxyl benzene π-bridge using Stille crossing-coupling reaction yield PTBTB-F. The optical, electrochemical, fluorescent, spectroelectrochemical and electrochromic switching properties of two polymers with different acceptors are studied in detail. Both polymers exhibit excellent solubility in conventional organic solvents, high thermal stability and favorable fluorescence properties. The combination of a strong electron withdrawing pendant group (fluorine atoms) with benzothiadiazole (BT) backbone significantly influences the electrochemical redox, optical and electrochromic behaviors of conducting polymers. The introduction of fluorine atoms to BT lead to a higher oxidation onset potential, but an improved electrochemical n-doping process. The optical band gaps (Eg) of PTBTB and PTBTB-F films are calculated to be 2.02 eV and 1.91 eV, respectively. PTBTB and PTBTB-F films exhibited obvious and reversible color switching between their neutral and oxidized states with high optical contrasts as well as favorable response times, making the polymers unique candidates for flexible organic electrochromic device applications.

Determination of Vitamin-B6 by Vanadium (III) Schiff base complex modified GCE

Vitamin B6 (pyridoxine) is an important vitamin for both mental and physical health processes. Vitamin B6 (V-B6) is much essential for the formation of red blood cells. It takes up wide variety of functions in human body in maintaining good health. The conversion of tryptophan amino acid to niacin vitamin needs the V-B6. V-B6 is an important vitamin for the nervous and immune system functions. V-B6 is an essential vitamin for the better health condition of human body. The deficiency of V-B6 can causes anaemia that is similar to iron deficiency anaemia. Due to these health factors, it is necessary to develop a simple, selective and sensitive method for the analysis of V-B6. There are several analytical methods available for the quantification of V-B6, such as flow HPLC, electrophoresis, spectrophotometric method, fluorimetric method and electrocatalytic detection. The electrocatalytic method gives good accuracy, faster response, simple procedure and cost effective, so the electrocatalytic sensing was chosen for the determination of V-B6. In the present work, we have used voltammetric method for the determination of V-B6 using modified GCE. For the GCE active surface modification we have utilized vanadium(III) Schiff base complex. Vanadium has received considerable interest biologically and chemically, due to its various stable oxidation states +3, +4, +5. Due to different oxidation states, vanadium complexes show good electrochemical redox behaviour. The vanadium Schiff base complex was electrochemically polymerized using the GCE as working electrode. The polymer vanadium complex was deposited on the GCE surface. The modified GCE exhibits the oxidation peak for V-B6 at 1.212 V and the anodic peak current 9.21 μA. The bare GCE shows the anodic peak at 1.236 V with the peak current is 8.49 μA. These results clearly indicate that the vanadium Schiff base complex modified GCE has better electrocatalytic sensing ability for the determination of vitamin B6.© 2017 Elsevier Ltd. All rights reserved.Selection and/or Peer-review under responsibility of International Conference On Recent Advances In Material Chemistry.

Raman and Electrochemical Study of Zirconium in LiCl-KCl-LiF-ZrCl4

In this work, Raman measurements were performed with quenched LiCl-KCl-LiF-ZrCl4/ZrF4/K2ZrF6 salt mixtures for deciphering the coordination chemistry of zirconium(IV) in the presence of fluoride ion in the melt. The occurrence of ZrCl62−, ZrCl4F22−, ZrF62−, ZrF73− and ZrF84− in melt at different F/Zr molar ratios was confirmed by Raman spectra. The electrochemical redox behaviors of zirconium in LiCl-KCl-LiF-ZrCl4 were also examined at 773 K. Transient methods such as cyclic voltammetry and square wave voltammetry were used. In LiCl-KCl-LiF-ZrCl4 with LiF concentration less than 1.27 wt% (molar ratio F/Zr < 9.1), the reduction behavior was found to be largely dependent on the formed Zr(I) species; In LiCl-KCl-8.0 wt% LiF (F/Zr > 101), the reduction of Zr(IV) followed a two-step mechanism of Zr(IV)/Zr(III) and Zr(III)/Zr(0) at the potentials of about −0.85 and −1.40 V versus Pt, respectively.

Fabrication of carbon-based nanomaterial composite electrochemical sensor for the monitoring of terbutaline in pharmaceutical formulations

The present investigation is focused on the development of a chemical sensor made by the modification of glassy carbon electrode (GCE) with graphene followed by multi walled carbon nanotubes (MWCNTs) towards the quantitative monitoring of Terbutaline (TB). The developed sensor was characterized with cyclic voltammetry, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) studies. The detailed electrochemical redox behavior of TB was examined and possible redox mechanism was proposed. We have studied the effect of pH of phosphate buffer solution (PBS) on the redox behavior of TB and the results suggest that the pH-4.5 was an optimum pH. From the effect of scan rate results, it was concluded that the redox process was controlled by diffusion process and the kinetic parameters were calculated. The effect of concentration of TB was studied and calibration plot was constructed to study the limit of detection and limit of quantification and it was found to be as 6.527×10−7M and 2.175×10−6M respectively. The repeatability, reproducibility and stability of MWCNTs/graphene/GCE, suggest that the developed sensor was superior in condition. The developed sensor was used for the estimation of TB in pharmaceutical formulations and the results were found to be in satisfactory range.

The synthesis and electrochemical behaviour of carbazole-substituted phthalocyanines

The syntheses of new cobalt and zinc phthalocyanine complexes containing carbazole (Cz) substituents at the peripheral positions are reported (CzCoPc and CzZnPc). The reaction of Cz with 4-iodophthalonitrile in the presence of a catalytic amount of copper(I) oxide and potassium carbonate led to the formation of 4-(9H-carbazol-9-yl) phthalonitrile. Furthermore, by heating the dinitrile and anhydrous metal salts (CoCl2, Zn(CH3COO)2) at 160 °C in n-hexanol in the presence of DBU, the phthalocyanines were obtained. They were characterised by 1H NMR, FT-IR, UV-Vis and MS spectroscopic data. Aggregation behaviours of Pcs were investigated in THF. Electrochemical redox behaviour of CzCoPc was investigated by cyclic voltammetry depending on the potential range, and the oxidation and reduction products were followed by UV-Visible absorption measurements. Polymerisation of CzCoPc was carried out by potentiodynamic methods on glassy carbon electrode, and the catalytic activity of resulting polymer (P[CzCoPc]) was tested comparatively with polycarbazole (PCz)-coated electrode for dopamine and better response was obtained for P[CzCoPc] modified electrode.

Electric cars fuel separator market growth

Polyoxometalates (POMs) are alternative anode materials of lithium ion batteries (LIBs) for their reversible electrochemical redox behaviors and electron storage functions. To overcome the low conductivity and poor stability of the POMs, embedment of POMs into metal–organic hybrid complexes is a promising synthetic strategy. Here, we designed a family of copper-containing POM-resorcin[4]arene-based complexes supported by a resorcin[4]arene ligand (TPTR4A), copper cations and Keggin-type POMs, namely, [Cu4(TPTR4A)2][PMo12O40](OH)·2DMA·H2O (1a), [Cu4(TPTR4A)2][SiW12O40]·2.5DMA (1b) and [Cu4(TPTR4A)2][PW12O40](OH)·0.5DMA·5H2O (1c) (DMA = N,N’-dimethylacetamide). To improve the conductivity of the complexes, composites [email protected]-[email protected] were obtained through mechanical grinding of the complexes and graphene oxide (GO). Strikingly, they show high initial specific capacity and stability for LIBs. This work offered a strategy for application of the POM-based complexes as LIBs via combining POM-based complexes and RGO.