scholarly journals Cobalt(II) complexes with aromatic carboxylates and N-functionalized cyclam bearing 2-pyridylmethyl pendant arms

2005 ◽  
Vol 70 (8-9) ◽  
pp. 1121-1129 ◽  
Author(s):  
Gordana Vuckovic ◽  
V. Stanic ◽  
Sofija Sovilj ◽  
M. Antonijevic-Nikolic ◽  
J. Mrozynski
Keyword(s):  
Cyclic Voltammetry ◽  
Ir Spectroscopy ◽  
Chair Conformation ◽  
Trans Position ◽  
Cyclic Voltammetric ◽  
Aromatic Carboxylates ◽  
Elemental Analyses ◽  
Electrical Conductivities ◽  
Pendant Arms ◽  
Voltammetric Measurements

Novel binuclear Co(II) complexeswithN-functionalized cyclam N,N?,N",N???-tetrakis( 2-pyridylmethyl)tetraazacyclotetradecane (tpmc) and one of the aromatic monoor dicarboxylato ligands (benzoate, phthalate or isophthalate ions) were prepared. They were analyzed and studied by elemental analyses (C, H, N), electrical conductivities, VIS and IR spectroscopy andmagnetic as well as cyclic voltammetric measurements. In [Co2(C6H5COO)2tpmc]ClO4)2.3H2O, the benzoate ligands are most probably coordinated as chelates in the trans-position to each Co(II) and the macrocycle adopts a chair conformation. In the complexes [Co2(Y)tpmc]ClO4)2.zH2O, (Y = phthalate or i-phthalate dianizon, z = 2; 4) it is proposed that the isomeric dicarboxylates are bonded combined as bridges and chelates. The composition and the assumed geometries of the complexes are compared with the, earlier reported, corresponding Cu(II) complexes. Cyclic voltammetry measurements showed that the compounds are electrochemically stable.

scholarly journals High-spin binuclear Co(II) complexes with a pendant octaazamaclocycle and carboxylates

2007 ◽  
Vol 72 (12) ◽  
pp. 1295-1308 ◽  
Author(s):  
G. Vuckovic ◽  
S.B. Tanaskovic ◽  
Z.M. Miodragovic ◽  
V. Stanic
Keyword(s):  
Antibacterial Activity ◽  
Terephthalic Acid ◽  
Chair Conformation ◽  
Molar Conductivity ◽  
Mixed Ligand ◽  
Boat Conformation ◽  
Trans Position ◽  
Oxidation Of Co ◽  
Elemental Analyses ◽  
Cv Measurements

Three new binuclear Co(II) mixed-ligand complexes with N,N?,N??,N???-tetrakis( 2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and mono- or dicarboxylate ligands were prepared and some of their physical properties were determined. The general formulas: [Co2(HCOO)2tpmc](ClO4)2?4H2O, [Co2(CH3COO)2tpmc](ClO4)2 and [Co2(tpht)tpmc](ClO4)2?4H2O (tphtH2 = terephthalic acid) were proposed on the basis of elemental analyses (C,H,N) and molar conductivity. UV/Vis absorption and IR spectra, magnetic and CV measurements were used to study their geometries and properties. For the monocarboxylate complexes, an exo coordination of Co(II) with four nitrogens from tpmc and bis-bidentate bonded HCOO-/CH3COO- in the trans position is assumed. Tpmc adopts the chair conformation. For the dicarboxylate complex, it is supposed that a terephthalate dianion, as well as methylene chains from cyclam bridge two Co(II) atoms, while tpmc is in the boat conformation. The complexes were stable against chemical and electrochemical oxidation of Co(II) to Co(III). The data are compared with those for the previously published Cu(II) complexes containing the corresponding ligands and mutual similarities or differences were considered. Finally, some antibacterial activity of the complexes was found.

A cyclic voltammetric study of some 4-substituted Benzene-1,2-diols

1983 ◽  
Vol 36 (5) ◽  
pp. 885 ◽  
Author(s):  
GM Proudfoot ◽  
IM Ritchie
Keyword(s):  
Cyclic Voltammetry ◽  
Linear Sweep Voltammetry ◽  
Molecular Size ◽  
Disc Electrode ◽  
Rotating Disc ◽  
Cyclic Voltammetric ◽  
Cyclic Voltammetric Study ◽  
Voltammetric Study ◽  
Stationary Electrode ◽  
Voltammetric Measurements

A voltammetric study of several 4-substituted benzene-1,2-diols in aqueous solutions as a function of pH has been carried out. From slow linear sweep voltammetry at a rotating disc electrode, diffusion coefficients were obtained which could be correlated, in the main, with molecular size. From cyclic voltammetry at a stationary electrode, it was established that the rate of the redox reaction decreases with increasing pH. The cyclic voltammetric measurements were also used to estimate E1/2 as a function of pH. All systems studied showed regions in which plots of E1/2 against pH were linear with a slope of close to -59 mV per pH unit. Such plots were used to estimate values of E1/2 at pH 0, which were then correlated with the Hammett function. The cyclic voltammetry also showed that the reactivity of the quinone formed by oxidation of the benzene-1,2 diols increased with pH. With the most reactive quinones (e.g. that formed from 3,4-dihydroxyacetophenone), a second pair of cyclic voltammetric peaks could be observed, which were ascribed to the oxidation and reduction of a dimer formed by quinone coupling.

Synthesis, characterisation and activity in catalytic epoxidation of olefins of new dinuclear nickel(ll) complexes

2009 ◽  
Vol 2009 (8) ◽  
pp. 527-532
Author(s):  
Manindranath Bera
Keyword(s):  
Visible Region ◽  
Chemical Oxidation ◽  
Cyclic Voltammetric ◽  
Catalytic Epoxidation ◽  
Redox Couples ◽  
Square Planar ◽  
Catalytically Active ◽  
Mecn Solution ◽  
Voltammetric Measurements ◽  
Epoxidation Of Olefins

Two new dinuclear nickel(ll) compounds of formula [Nill2(μ-L1)2](CIO4)2·MeCN (1·MeCN) and [NiII2(μ-L2)2](CIO4)2 (2) where HL1 and HL2 stand for 3-(2-(dimethylamino)ethylimino)butan-2-one oxime and 1-(2-(dimethylamino)ethyl-imino)-1-phenylpropan-2-one oxime respectively, have been synthesised. Single crystal X-ray analyses of the complexes reveal that the nickel(ll) ions are in square-planar N3O environments and form six-membered (NiNO)2 metallacycles. Cyclic voltammetric measurements of 1·MeCN and 2 in MeCN solution show quasirreversible one-electron oxidations at E1/2 = 0.566 V and 0.603 V ( vs Fc+/Fc), respectively, attributed to NiIIINiII/NiII2 redox couples. Additional reversible NiIII2/NiIIINiII redox responses were observed at relatively higher potential near E1/2 = 0.832 V and 0.850 V ( vs Fc+/Fc), respectively, for 1·MeCN and 2. Complexes 1·MeCN and 2 display intense charge-transfer bands at ∼390 and ∼345 nm in the visible region. Chemical oxidation of complex 1·MeCN by sodium hexachloroiridate(IV) hexahydrate generates red Ni2III species with characteristic new bands at ∼520 and 427 nm in the visible region as well as the characteristic EPR signals at 77 K with g⊥ > gII. Similar phenomena were observed for complex 2 upon chemical oxidation. The dinickel(ll) complexes are catalytically active for epoxidation of olefins using iodosylbenzene as the terminal oxidant.

Electrochemically Synthesis and Characterization of Copolymers Based on 1, 4-Diethoxybenzene and 3, 4-Ethylenedioxythiophene

2011 ◽  
Vol 335-336 ◽  
pp. 989-993
Author(s):  
Mi Ouyang ◽  
Zhen Wei Yu ◽  
Yi Xu ◽  
Yu Jian Zhang ◽  
Cheng Zhang
Keyword(s):  
Cyclic Voltammetry ◽  
Ir Spectroscopy ◽  
Feed Ratio ◽  
Synthesis And Characterization ◽  
Monomer Mixture ◽  
Long Wavelength ◽  
H Nmr ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Copolymers based on 1, 4-diethoxybenzene (DEB) and 3, 4-ethylenedioxythiophene (EDOT) were electrochemically synthesized and characterized. The structures of the copolymers were established by 1H NMR and FT-IR spectroscopy. The results indicated the final product was a copolymer instead of a blend or a composite. The physical properties were systematically investigated by cyclic voltammetry, UV-vis absorption and fluorescence. The PL maximum of copolymers presented obviously red-shift to long wavelength as the feed ratio of EDOT in monomer mixture increased.

The origin of the hysteresis in cyclic voltammetric response of alkaline methanol electrooxidation

2020 ◽  
Vol 22 (29) ◽  
pp. 16648-16654
Author(s):  
Theresa Haisch ◽  
Fabian Kubannek ◽  
Lialia Nikitina ◽  
Igor Nikitin ◽  
Sabine Pott ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Methanol Electrooxidation ◽  
Electrochemical Measurements ◽  
Cyclic Voltammetric ◽  
Platinum Oxides

The origin of the hysteresis is investigated by electrochemical measurements, in situ IR spectroscopy and simulations. It is concluded that the formation of platinum oxides rather than the formation of blocking intermediates causes the hysteresis.

Assessment of Antimicrobial Features of Selenium Nanoparticles (SeNPs) Using Cyclic Voltammetric Strategy

2019 ◽  
Vol 19 (11) ◽  
pp. 7363-7368 ◽  
Author(s):  
Madiha Saeed ◽  
M. Tayyab Ansari ◽  
Imdad Kaleem ◽  
Sadia Zafar Bajwa ◽  
Asma Rehman ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Biomedical Applications ◽  
Selenium Nanoparticles ◽  
Size Distributions ◽  
Cyclic Voltammetric ◽  
Microwave Assisted ◽  
Straightforward Method ◽  
Microwave Assisted Method ◽  
Controllable Size ◽  
Cyclic Voltammetry Data

The emerging biomedical applications of selenium nanoparticles (SeNPs) require facile and efficient strategy to assess its interactions with cell membrane. In this study, an efficient and reproducible microwave assisted method was used to synthesize SeNPs with controllable size distributions. The physical properties of the emergent structures, such as morphology, structure, and size were studied. The antimicrobial applications of SeNPs were assessed by electrochemical analyses that entailed the systematic acquisition of cyclic voltammetry data. Our results demonstrate a straightforward method to predict the integrity of bacterial cell membranes following the administration of SeNP treatments.

scholarly journals Ferrocene-Based Bioactive Bimetallic Thiourea Complexes: Synthesis and Spectroscopic Studies

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Shafqat Ali ◽  
Ghulam Yasin ◽  
Zareen Zuhra ◽  
Zhanpeng Wu ◽  
Ian S. Butler ◽  
...  
Keyword(s):  
Double Helix ◽  
Spectroscopic Studies ◽  
Cyclic Voltammetric ◽  
Binding Model ◽  
Elemental Analyses ◽  
Ft Ir ◽  
Relative Potential ◽  
Double Helix Structure ◽  
Enzyme Alkaline Phosphatase ◽  
C Nmr

Bioactive 1,1′-(4,4′-di-ferrocenyl)di-phenyl thiourea and various metal complexes of this ligand have been successfully synthesized and characterized by using physicoanalytical techniques such as FT-IR and multinuclear (1H and13C) NMR spectroscopy along with melting point and elemental analyses. The interaction of the synthesized compounds with DNA has been investigated by using cyclic voltammetric and viscometric measurements. The intercalation of the complexes into the double helix structure of DNA is presumably occurring. Viscosity measurements of the complexes have shown that there is a change in length and this is regarded as the least ambiguous and the most critical test of the binding model in solution. The relative potential of the complexes as anti-bacterial, antifungal, and inhibition agents against the enzyme, alkaline phosphatase EC 3.1.3.1, has also been assessed and the complexes were found to be active inhibitors.

Electrochemical and Adsorption Properties of Novel Phthalocyanines with Four 16-Membered Diazadithia Macrocycles

1998 ◽  
Vol 02 (06) ◽  
pp. 483-492 ◽  
Author(s):  
A. R. ÖZKAYA ◽  
İ YILMAZ ◽  
Ö. BEKAROǦLU
Keyword(s):  
Aqueous Medium ◽  
Copper Ions ◽  
Mixed Valence ◽  
Adsorption Properties ◽  
Oxidation Peak ◽  
Cyclic Voltammetric ◽  
Working Electrode ◽  
Strong Adsorption ◽  
Voltammetric Measurements

Cyclic voltammetric measurements of Cu (II) and Ni (II) phthalocyanines with four 16-membered diazadithia macrocycles (1 and 2) and pentanuclear Ni (II) phthalocyanine bearing four Cu (II) ions in diazadithia macrocycles at the peripheral positions (3) have been carried out on platinum in DMSO and in aqueous medium 3 showed strong adsorption properties in DMSO and especially in aqueous medium, possibly as a result of the interaction between the copper ions in the four macrocycles and the platinum working electrode. Interestingly, the oxidation peak of 3 was split into two waves in aqueous medium. This behaviour is discussed in terms of disaggregation of the mixed valence species produced by the oxidation of aggregated species. A mechanism for both the oxidation of the complex and the splitting of the oxidation peak into two waves is suggested.

scholarly journals Tuning the interactions between electron spins in fullerene-based triad systems

2014 ◽  
Vol 10 ◽  
pp. 332-343 ◽  
Author(s):  
Maria A Lebedeva ◽  
Thomas W Chamberlain ◽  
E Stephen Davies ◽  
Bradley E Thomas ◽  
Martin Schröder ◽  
...  
Keyword(s):  
Spin Coupling ◽  
Fullerene Cage ◽  
Potential Range ◽  
Cyclic Voltammetric ◽  
Electronic Interactions ◽  
Precise Control ◽  
Good Solubility ◽  
The Individual ◽  
Spin Spin Coupling ◽  
Voltammetric Measurements

A series of six fullerene–linker–fullerene triads have been prepared by the stepwise addition of the fullerene cages to bridging moieties thus allowing the systematic variation of fullerene cage (C60 or C70) and linker (oxalate, acetate or terephthalate) and enabling precise control over the inter-fullerene separation. The fullerene triads exhibit good solubility in common organic solvents, have linear geometries and are diastereomerically pure. Cyclic voltammetric measurements demonstrate the excellent electron accepting capacity of all triads, with up to 6 electrons taken up per molecule in the potential range between −2.3 and 0.2 V (vs Fc+/Fc). No significant electronic interactions between fullerene cages are observed in the ground state indicating that the individual properties of each C60 or C70 cage are retained within the triads. The electron–electron interactions in the electrochemically generated dianions of these triads, with one electron per fullerene cage were studied by EPR spectroscopy. The nature of electron–electron coupling observed at 77 K can be described as an equilibrium between doublet and triplet state biradicals which depends on the inter-fullerene spacing. The shorter oxalate-bridged triads exhibit stronger spin–spin coupling with triplet character, while in the longer terephthalate-bridged triads the intramolecular spin–spin coupling is significantly reduced.

scholarly journals Interaction of Cu(II) with Cytosine in Britton-Robinson Buffer Solution - A Cyclic Voltammetric Study

2015 ◽  
Vol 63 (1) ◽  
pp. 31-36
Author(s):  
AA Shaikh ◽  
Jannatul Firdaws ◽  
S Islam ◽  
PK Bakshi
Keyword(s):  
Cyclic Voltammetry ◽  
Suitable Condition ◽  
Anodic Peak ◽  
Molar Ratio ◽  
Cathodic Peak ◽  
Buffer Solution ◽  
Cyclic Voltammetric ◽  
Cyclic Voltammetric Study ◽  
Voltammetric Study ◽  
Electrochemical Redox

Electrochemical redox behavior of Cu(II) at different pH in Britton-Robinson (BR) buffer solution has been investigated using cyclic voltammetry at glassy carbon electrode (GCE). Cu(II) shows a cathodic peak and a hump-like peak, and an intense anodic peak at pH, 0.59, 1.59, 3.01 and 4.08. Although at lower pH (0.59 and 1.59) a cathodic peak, a hump and an anodic peak are observed, at higher pH (3.01 and 4.08) the hump-like cathodic peak disappeared. Cyclic voltammetry has also been used to observe the interaction of Cu(II) with cytosine in BR buffer solution at various pH. A reasonably strong interaction between Cu(II) and cytosine at different Cu(II)/cytosine molar ratio is observed at all the studied pH. However, maximum interaction occurs at 1:4 molar ratio at pH 4.08, this is perhaps the most suitable condition for Cu(II)-cytosine interaction. DOI: http://dx.doi.org/10.3329/dujs.v63i1.21765 Dhaka Univ. J. Sci. 63(1): 31-36, 2015 (January)

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