Changes In Redox Properties Research Articles

On the driving forces behind the change of reduction potentials and the prediction of redox properties through analysis of EPR hyperfine couplings in VO(acac)2pyr and VO(acac)2 imidazole complexes. A DFT study

The use of vanadium complexes for potential applications in medicine largely depends on the structural properties of the complex itself, as well as on the electronic configuration of the metal and its oxidation state. When the vanadium complex binds to biomolecules or by binding solvent molecules to the complex, there is a change in the structure but also a change in the redox properties of the complex. Using theoretical methods, especially Density Functional theory (DFT), it is possible to determine which factors influence changes in the redox properties of the complex. Furthermore, by calculating the Electron Paramagnetic Resonance (EPR) constants of hyperfine coupling, it is possible to obtain not only data on the electronic configuration, but also to predict changes in redox properties upon changes in the structure of the complex. DFT results show that the binding of pyridine or imidazole to the VO(acac)2 complex leads to a lowering of the redox potential. The largest changes in the redox potential were observed in the case when the incoming ligand binds in a cis position relative to the VO bond.

Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat

Exposure to oxygen and aerobic biological activity during drought periods alters the availability of terminal electron acceptors (TEA) in the peat catotelm layer. We investigated the changes in the electrochemical and chemical characteristics of humic acids (HA) induced by subjecting air-dried sphagnum peat to biological oxidation or reduction during a 90-day incubation experiment. Structural modifications of HAs from anaerobically (HAred) and aerobically (HAox) incubated peat were investigated by ATR-FTIR, UV–vis, and EEM fluorescence spectroscopy. Number and strength of acid groups were characterized by titration, while changes in redox properties were characterized by cyclic voltammetry and quantified by coulometry with mediated electrochemical oxidation (MEO). Exposure to oxygen had small effects, but compared to anaerobic incubation, decreased by 20% the capacity of HA to reduce the radical ion of 2,2′-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS●−), passing from 2.77 ± 0.13 mmole- gHA−1 in HAred to 2.21 ± 0.10 mmole- gHA−1 in HAox. Pseudo-first-order electron transfer kinetic constants were 13.3 ± 1.2 s−1 for HAox and 16.7 ± 1.4 s−1 for HAred. Alterations in the hydrological status of the catotelm have minor effects on the actual in situ availability of organic TEA, but if coupled to intensified biological activity they may result in significant variations of greenhouse gases emissions.

Effect of NaCl, sucrose and pectin addition on the reductive properties of vegetable and fruit puree

Inclusion of minor components in the formulation of homogeneous food systems should inevitably result in some shift of redox equilibrium under conditions of interaction as "all with all." Chemical nature of components combined with properties of elements of medium chemical composition should determine direction and expression of such displacement. But due to the multicomponence of the medium itself and the small initial expression of redox properties for the added components, predicting the resulting properties of the formed food system becomes difficult. The aim of the work was to study the regularities of the influence of neutral minor components on the change of redox properties of homogeneous canned products from vegetable raw materials. Puree-shaped single-component natural canning products (puree) from fruit (apples, plum) and vegetable (pumpkin, carrots) raw materials are taken as research objects. Table salt (NaCl), sucrose and apple pectin were used as minor components. In the obtained canned product, active acidity (pH) and redox potential (Eh) were determined, and the reducing power index (RH) value was calculated. The studies showed that there was no statistically significant effect of NaCl on the redox properties of the food systems studied. There was a statistically significant effect of sucrose on the reducing power index of homogeneous canned puree from plums (in the range up to 18%) and carrots (in the range up to 10%). It has been found that inclusion of pectin in the composition of fruit and vegetable puree does not have a statistically significant effect on the reducing capacity of the product, except for stone fruit puree, for which there was statistically significant single step increase of RH within a weight fraction value of the minor component as 0.61-0.62%. In order to determine the mechanism of such a response, it is necessary to carry out an additional set of targeted studies.

Effect of Neodymium on the Physico‐chemical Properties and N2O Decomposition Activity of Co(Cu)−Al Mixed Oxides

AbstractCu−Al and Co−Al (M/Al=0.8/0.2, molar ratio; M=Cu or Co) mixed metal oxides showed a moderate activity in N2O decomposition (deN2O) with full conversion at about 500–550 °C. Addition of Nd modified the physico‐chemical and catalytic properties of both Cu−Al and Co−Al materials, though an optimal Nd loading was required. The addition of Nd in Cu0.8Al0.2 and Co0.8Al0.2 with Nd/Co(Cu)/Al = 0.5/0.8/0.2 molar ratio, improved significantly their catalytic activity. In particular, the temperatures needed for full N2O conversion were 100 °C lower than those of the bare materials. Furthermore, the most active Nd0.5Co0.8Al0.2 catalyst exhibited a stable 60 % N2O conversion at 450 °C for 50 h in presence of NO (200 ppm), O2 (20,000 ppm) and H2O (2500 ppm). The enhancement in the activity of both Cu‐ and Co‐containing materials was related to the formation of CuNd2O4 for Nd0.5Cu0.8Al0.2 and NdCoO3 for Nd0.5Co0.8Al0.2. The presence of CuNd2O4 or NdCoO3 accounted for changes in redox properties, e. g., easier reduction or faster release of oxygen, and in turn an increased catalyst activity in deN2O. The investigation of rare earth‐based catalysts for deN2O is limited in the scientific literature, while a comprehensive understanding of the involved active species may facilitate a knowledge‐based catalyst optimization.

Evolution of Photochemical Reaction Centres: More Twists?

One of the earliest events in the molecular evolution of photosynthesis is the structural and functional specialisation of type I (ferredoxin-reducing) and type II (quinone-reducing) reaction centres. In this opinion article we point out that the homodimeric type I reaction centre of heliobacteria has a calcium-binding site with striking structural similarities to the Mn4CaO5 cluster of photosystem II. These similarities indicate that most of the structural elements required to evolve water oxidation chemistry were present in the earliest reaction centres. We suggest that the divergence of type I and type II reaction centres was made possible by a drastic structural shift linked to a change in redox properties that coincided with or facilitated the origin of photosynthetic water oxidation.

Different thermal behavior of nanostructured CeO2-ZrO2 based oxides with varied Ce/Zr molar ratios

Redox property is an important feature common to all three-way catalysts to eliminate harmful vehicle exhaust. To understand the thermal behavior of redox ability for different ceria-zirconia based materials, five CeO2-ZrO2-Y2O3-La2O3 quaternary mixed oxides (CZ) with varied ratio of Ce/Zr were synthesized. We investigated the changes in redox properties and structures of the as-prepared CZ during thermal aging, together with their relationships. It is found that the Ce-rich CZ samples (Ce/Zr > 1) show a declined OSC after thermal aging, however, an increased OSC is observed in the Zr-rich CZ samples (Ce/Zr ≤ 1). Based on XRD, Raman and XPS analyses, we propose an atom rearrangement mechanism that Zr ions migrate into ceria lattices in the Zr-rich samples during thermal aging accompanied by sintering, accounting for the enhanced OSC, while only sintering occurs in the Ce-rich samples, resulting in deteriorated OSC.

C-terminal residues of ferredoxin-NAD(P)+ reductase from Chlorobaculum tepidum are responsible for reaction dynamics in the hydride transfer and redox equilibria with NADP+/NADPH.

Ferredoxin-NAD(P)+ reductase ([EC 1.18.1.2], [EC 1.18.1.3]) from Chlorobaculum tepidum (CtFNR) is structurally homologous to the bacterial NADPH-thioredoxin reductase (TrxR), but possesses a unique C-terminal extension relative to TrxR that interacts with the isoalloxazine ring moiety of the flavin adenine dinucleotide prosthetic group. In this study, we introduce truncations to the C-terminal residues to examine their role in the reactions of CtFNR with NADP+ and NADPH by spectroscopic and kinetic analyses. The truncation of the residues from Tyr326 to Glu360 (the whole C-terminal extension region), from Phe337 to Glu360 (omitting Phe337 on the re-face of the isoalloxazine ring) and from Ser338 to Glu360 (leaving Phe337 intact) resulted in a blue-shift of the flavin absorption bands. The truncations caused a slight increase in the dissociation constant toward NADP+ and a slight decrease in the Michaelis constant toward NADPH in steady-state assays. Pre-steady-state studies of the redox reaction with NADPH demonstrated that deletions of Tyr326-Glu360 decreased the hydride transfer rate, and the amount of reduced enzyme increased at equilibrium relative to wild-type CtFNR. In contrast, the deletions of Phe337-Glu360 and Ser338-Glu360 resulted in only slight changes in the reaction kinetics and redox equilibrium. These results suggest that the C-terminal region of CtFNR is responsible for the formation and stability of charge-transfer complexes, leading to changes in redox properties and reactivity toward NADP+/NADPH.

Encapsulation of Cu(II)[2-(2′-hydroxyphenyl)benzimidazole]2 within zeolite nano-cavity: Structural properties and its catalytic activity towards phenol and styrene oxidation

The Cu(opbmzl)2 [ohpbmzl=2-(2′-hydroxyphenyl)benzimidazole] was encapsulated within the super-cage of zeolite-Na-Y through a facile ligand approach and characterized by various analytical techniques such as elemental analysis, X-ray diffraction, inductively coupled plasma-atomic emission, FT-IR, UV–vis-DRS and EPR spectroscopy, thermogravimetric analysis (TGA), BET surface area measurements, pore volume by Horvath-Kawazoe (HK) method and cyclic voltammetry (CV). The shifting of the absorption bands and changes in redox properties of intra-zeolite complex compared to non-encapsulated complex implicated that the zeolite matrix remarkably influenced the structure-electronic properties. The peak potentials of Cu(opbmzl)2-Y in cyclic voltammogram were independent of scan rates, further corroborating the intrazeolite mechanism for electron-transfer-pathway in the zeolite-Y. The catalytic activity of Cu-Y, non-encapsulated and encapsulated complex was evaluated for phenol and styrene oxidation. As very low selectivity and formation of tarry products (for phenol oxidation) prevailed with t-butyl hydroperoxide (TBHP), H2O2 was reported to be the reasonable oxidant for the probe reactions. The influence of reaction parameters such as catalyst dosage, substrate concentration, substrate: H2O2 mole-ratio, temperature, time and solvent effects were investigated in detail. All the reaction parameters investigated were very crucial in tuning the product selectivity and conversion efficiency. The encapsulated complex exhibited better catalytic activity and selectivity than the non-encapsulated complex for the probe reactions, associated with exceptional structural stability during the recycling process. From the results, it was derived that the reactions proceeded without the involvement of free radicals and the probable mechanistic pathways based on the intermediate complexes associated with Cu-O species were proposed tentatively.

Redox-Controlled Selective Docking in a [2]Catenane Host

The docking by neutral and charged guests selectively in two geometrically different binding pockets in a dynamic [2]catenane host is demonstrated in the solid state by manipulating its redox chemistry. The change in redox properties, not only alters the affinity of the host toward neutral and charged guests, but it also induces a profound change in the geometry of the host to accommodate them. X-ray crystallography, performed on the two different 1:1 complexes, demonstrates unambiguously the fact that the [2]catenane host provides a uniquely different binding pocket wherein a methyl viologen dication is stabilized by interacting with a bipyridinium radical cation, despite the presence of Coulombic repulsions.

Experimental and Theoretical Evidence for Encapsulation and Tethering of 1,10-Phenanthroline Complexes of Fe, Cu, and Zn in Zeolite–Y

Tris(1,10-phenanthroline) complexes of iron(II), copper(II), and zinc(II) have been encapsulated within the supercage of zeolite–NaY by the reaction of exchanged metal ion and flexible ligand that diffuses into the cavities. The hybrid material obtained has been characterized by elemental analysis (EDX), SEM, powder XRD, FTIR, UV–vis/DRS, cyclic voltammetry, and EPR techniques. The Fe and Cu complexes show electrochemical behavior in the presence of 0.1 M TBAP, whereas Zn complex gives electrochemical response only in the presence of H+ ion. This difference in electrochemical behavior of the complexes indicates an intrazeolite electron transport in the case of Fe and Cu phenanthroline complexes and an extrazeolite electron transport in the case of Zn complex anchored on the surface of zeolite–Y. The red shifting of UV–vis spectra and changes in redox properties of intrazeolite complexes in comparison to those of the neat complexes suggest that the zeolite matrix influences the electronic properties. This ...

QCM sensing of a chemical nerve agent analog via electropolymerized molecularly imprinted polythiophene films

AbstractThe highly selective and sensitive detection of a chemical nerve agent analog pinacolyl methylphosphonate (PMP) was demonstrated using an electrochemically molecularly imprinted polymer (MIP) polythiophene film onto a quartz crystal microbalance (QCM) transducer surface. The fabrication and optimization of the sensor film was monitored by in situ electrochemistry‐QCM (EC‐QCM) measurements, which determined the change in mass and simultaneous change in redox properties of the polymer film. The film deposition, template loading, and template removal were evidenced by a combination of surface characterization techniques such as the attenuated total reflection infrared spectroscopy and high‐resolution X‐ray photoelectron spectroscopy. The fabricated MIP film demonstrated a limit of detection and a limit of quantification of ∼60 and ∼197 μM, respectively. The linear sensing range is between 125 and 250 μM concentration of PMP. Finally, theoretical modeling (AM1 semiempirical quantum calculations) studies revealed that a stable prepolymerization complex is formed in solution with the existence of H‐bonding interactions using the 2:1 monomer‐to‐template ratio. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Structural and Functional Studies Indicating Altered Redox Properties of Hemoglobin E: IMPLICATIONS FOR PRODUCTION OF BIOACTIVE NITRIC OXIDE

Hemoglobin (Hb) E (β-Glu26Lys) remains an enigma in terms of its contributions to red blood cell (RBC) pathophysiological mechanisms; for example, EE individuals exhibit a mild chronic anemia, and HbE/β-thalassemia individuals show a range of clinical manifestations, including high morbidity and death, often resulting from cardiac dysfunction. The purpose of this study was to determine and evaluate structural and functional consequences of the HbE mutation that might account for the pathophysiology. Functional studies indicate minimal allosteric consequence to both oxygen and carbon monoxide binding properties of the ferrous derivatives of HbE. In contrast, redox-sensitive reactions are clearly impacted as seen in the following: 1) the ∼2.5 times decrease in the rate at which HbE catalyzes nitrite reduction to nitric oxide (NO) relative to HbA, and 2) the accelerated rate of reduction of aquometHbE by L-cysteine (L-Cys). Sol-gel encapsulation studies imply a shift toward a higher redox potential for both the T and R HbE structures that can explain the origin of the reduced nitrite reductase activity of deoxyHbE and the accelerated rate of reduction of aquometHbE by cysteine. Deoxy- and CO HbE crystal structures (derived from crystals grown at or near physiological pH) show loss of hydrogen bonds in the microenvironment of βLys-26 and no significant tertiary conformational perturbations at the allosteric transition sites in the R and T states. Together, these data suggest a model in which the HbE mutation, as a consequence of a relative change in redox properties, decreases the overall rate of Hb-mediated production of bioactive NO.

A dihydroindolizine-porphyrin dyad as molecule-based all-photonic AND and NAND gates

A molecular dyad consisting of a photochromic dihydroindolizine unit covalently linked to a porphyrin performs, when illuminated through a third-harmonic-generating crystal, the functions of both an AND and a NAND Boolean logic gate with shared all-optical inputs. The NAND gate is of particular interest as it is a so-called universal gate, and hence all other digital systems can be implemented by combinations of NAND gates. The functions of the AND and the NAND gates rely on changes in absorption and emission of the dyad in the visible spectral region upon isomerization of the photochromic unit. The change in absorption which forms the basis for the AND gate function is ascribed to the colorization/decolorization of the photochrome itself in response to the optical inputs. The variation in emission intensity which constitutes the NAND gate function is a result of the changes in redox properties of the photochrome that follow upon isomerization, such that only one of the two isomers is competent to quench the porphyrin emission by electron transfer.

Aqueous Spectroscopy and Redox Properties of Carboxylate-Bound Titanium

The aqueous chemistry of Ti(III) and Ti(IV) in two different chemical environments is investigated given its relevance to environmental, materials, and biological chemistry. Complexes of titanium with the carboxylate ligands citrate and oxalate, found ubiquitously in Nature, were synthesized. The redox properties were studied by using cyclic voltammetry. All the titanium citrate redox couples are quasi-reversible. Electrospray mass spectrometry of the Ti(III) citrate solution shows the presence of a 1:2 Ti/cit complex in solution, in contrast to the predominant 1:3 Ti/cit complex with Ti(IV). The change in the coordination of the ligand to the metal on reduction may explain the quasi-reversible behavior of the electrochemistry. The redox potentials for Ti(IV) citrate in water vary with pH. At pH 7, the approximate E(1/2) is less than -800 mV. This stated change in redox properties is considered in light of the previously reported Ti(IV) citrate solution speciation. Analogous speciation behavior is suggested from the EPR spectroscopy of Ti(III) citrate aqueous solutions. The g tensors are deduced for several pH-dependent species from the simulated data. The X-ray crystal structure of a Ti(III)(2) oxalate dimer Ti(2)(mu-C(2)O(4))(C(2)O(4))(2)(H(2)O)(6).2H(2)O (3), which crystallizes from water below pH 2, is reported. Complex 3 crystallizes in a monoclinic P2(1)/c space group with a = 9.5088(19) Angstroms, b = 6.2382(12) Angstroms, c = 13.494(3) Angstroms, V = 797.8(3) Angstroms(3), and Z = 2. The infrared spectroscopy, EPR spectroscopy, and cyclic voltammetry on complex 3 are reported. The cyclic voltammetry shows an irreversible redox couple approximately -196 mV which likely corresponds to the Ti(IV)(2)/Ti(III)Ti(IV) couple. The EPR spectroscopy on solid complex 3 shows a typical S = 1 triplet-state spectrum. The solid follows non-Curie behavior, and the antiferromagnetic coupling between the two metal centers is determined to be -37.2 cm(-1). However, in solution the complex follows Curie behavior and supports a Ti(III)Ti(IV) oxidation state for the dimer.

Seasonal changes in redox properties of peat, nutrition and phenology of Menyanthes trifoliata L. in a floating peat mat in Mizorogaike Pond, central Japan

Seasonal changes in leaf population per area, nutrient absorption rate and elemental concentration of Menyanthes trifoliata L. were studied in a floating peat mat in Mizorogaike Pond, central Japan, with reference to the peat redox potential. Leaf population of M. trifoliata showed a rapid increase in May, reached the maximum in June, and then decreased to 12% of the maximum density in July. The foliage density of M. trifoliata again increased and reached its second maximum in September, and then it decreased to zero in December. The decrease of the foliage density from June to July corresponded to the minimum of redox potential (Eh) of the surface peat. Low Eh in the rhizosphere of M. trifoliata relates to the temporary disappearance of the foliage of the plant from June to July. Nutrient concentration (K, Mg, Ca, Fe) in M. trifoliata roots showed minimum in June to August. The nutrient absorption rate of M. trifoliata evaluated from the rubidium absorption rate of excised root of M. trifoliata showed a minimum value in June and July. Peat redox properties would affect the nutrient absorption activity of the roots and the consequent foliage phenology of M. trifoliata in Mizorogaike Pond.

An investigation about thin films of poly[2-methoxy-5-(2′-ethyl-hexyloxy) phenylene vinylene] (MEH-PPV) prepared by Langmuir-Schaefer technique

The Langmuir monolayer behaviour of poly[(2-methoxy-5-(2′-ethyl-hexyloxy) phenylene vinylene] (MEH-PPV) conducting polymer was investigated at air-water interface at different subphases containing anions. A uniform deposition of MEH-PPV monolayers was shown by UV-visible, electrochemical techniques, where the influence of anions on redox properties was investigated by cyclic voltammetric surveying. The nature of anions revealed significant changes in redox properties of the MEH-PPV LS films. The photoelectrochemical response of MEH-PPV LS conducting polymer was also investigated at length.

A Transient Exchange of the Photosystem II Reaction Center Protein D1:1 with D1:2 during Low Temperature Stress ofSynechococcus sp. PCC 7942 in the Light Lowers the Redox Potential of QB

Upon exposure to low temperature under constant light conditions, the cyanobacterium Synechococcus sp. PCC 7942 exchanges the photosystem II reaction center D1 protein form 1 (D1:1) with D1 protein form 2 (D1:2). This exchange is only transient, and after acclimation to low temperature the cells revert back to D1:1, which is the preferred form in acclimated cells (Campbell, D., Zhou, G., Gustafsson, P., Oquist, G., and Clarke, A. K. (1995) EMBO J. 14, 5457-5466). In the present work we use thermoluminescence to study charge recombination events between the acceptor and donor sides of photosystem II in relation to D1 replacement. The data indicate that in cold-stressed cells exhibiting D1:2, the redox potential of Q(B) becomes lower approaching that of Q(A). This was confirmed by examining the Synechococcus sp. PCC 7942 inactivation mutants R2S2C3 and R2K1, which possess only D1:1 or D1:2, respectively. In contrast, the recombination of Q(A)(-) with the S(2) and S(3) states did not show any change in their redox characteristics upon the shift from D1:1 to D1:2. We suggest that the change in redox properties of Q(B) results in altered charge equilibrium in favor of Q(A). This would significantly increase the probability of Q(A)(-) and P680(+) recombination. The resulting non-radiative energy dissipation within the reaction center of PSII may serve as a highly effective protective mechanism against photodamage upon excessive excitation. The proposed reaction center quenching is an important protective mechanism because antenna and zeaxanthin cycle-dependent quenching are not present in cyanobacteria. We suggest that lowering the redox potential of Q(B) by exchanging D1:1 for D1:2 imparts the increased resistance to high excitation pressure induced by exposure to either low temperature or high light.

Selective catalytic reduction of NO by NH3 on Cu-faujasite catalysts: an experimental and quantum chemical approach.

The selective catalytic reduction (SCR) of NO by NH3 in the presence of O2 on Cu-faujasite (Cu-FAU) has been studied. Substitution of some Cu2+ with H+ and Na+ cations, compensating for the negative charge of the zeolite framework, forms the various CuHNa-FAU studied. The amount of Cu was held constant and the proportion of H+ and Na+ varied in the sample. The substitution of Na+ for H+ increases sharply the SCR rate by lowering the temperature of reaction by about 150 K. It is proposed that the rate increase mainly comes from an unhindered migration of Cu from hidden to active sites and a modification of the redox properties of Cu species. The former was demonstrated by diffuse reflectance IR spectroscopy of adsorbed CO. The change in redox properties was demonstrated by a faster oxidation of Cu+ to Cu2+ (rate-determining step). Quantum chemical calculations on model clusters of CuHNa-FAU indicate that the faster rate of oxidation can be explained by a higher lability of protons in the absence of Na, which can be then removed from the catalyst more easily to yield H2O during the oxidation process.

Formation (and properties) of palladium derivatives of [Mo3Q4(H2O)9]4+: absence of similar derivatives of [W3Q4(H2O)9]4+ (Q = S, Se)

The reaction of Pd black with [Mo3Se4(H2O)9]4+ in 2 M HCl gives the single cube [Mo3(PdCl)Se4(H2O)9]3+, which on removal of Cl− forms the edge-linked double cube [{Mo3PdSe4(H2O)9}2]8+. No similar reactions of [W3S4(H2O)9]4+ and [W3Se4(H2O)9]4+ are observed, and in no case is Pt black incorporated into the trinuclear species. The crystal structure of [{Mo3PdSe4(H2O)9}2](pts)8·18H2O has been determined (pts− = p-toluenesulfonate), and is consistent with Mo–Mo and Mo–Pd bonding. Properties of the Pd derivatives of both [Mo3Q4(H2O)9]4+ (Q = S, Se) are considered. No heteroatom transfer is observed on mixing [Mo3(PdCl)Se4(H2O)9]3+ with [Mo3S4 (H2O)9]4+ as is the case of [Mo3SnSe4(H2O)12]6+ with [Mo3S4 (H2O)9]4+. The single cubes [Mo3(PdCl)Q4 (H2O)9]3+ (Q = S, Se), react 1 ∶ 1 with SnCl3− to give [Mo3(PdSnCl3)Q4(H2O)9]3+ with Pd–Sn bonding. Formation constants K (25 °C) are 1.15 × 103 M−1 (Q = S) and 9.5 × 103 M−1 (Q = Se). On mixing the heterometal cubes [Mo3PdS4(H2O)10]4+ and [Mo3SnS4(H2O)12]6+ in 2 M HCl no Pd–Sn bonding occurs. With [Pd(H2O)4]2+ and [Mo3SnS4(H2O)12]6+ in 2.0 M HClO4, reaction steps Mo3SnS46+ → Mo3S44+ + SnII, followed by SnII + PdII → SnIV + Pd0 are observed, and Pd0 is precipitated. Rate constants for the oxidation of [Mo3(PdCl)S4(H2O)9]4+ and [{Mo3PdS4(H2O)9}2]8+ with [Co(dipic)2]− (dipic = 2,6-pyridinedicarboxylate) are within a factor of 2, indicating no significant change in redox properties. This contrasts with the behaviour of single and corner-shared double cubes e.g. M′ = Sn.

Synthesis of 3-derivatized pyrroles precursors polymers for functionalization with biomolecules toward biosensor devices

In this report, we explore the synthesis and the characterization of some new pyrrole monomers bearing various active groups such as amine and alcohol activated esters. The functionalized monomers undergo facile electropolymerization to give electrode bound electroactive polymers. In the case where the pyrrole is bearing the amino group, the 3-(ω-aminopropyl) pyrrole, the amine must be protonated or protected in order to electropolymerize the monomer. The precursor polymers can be functionalized by various molecules via post polymerization chemistry. Biomolecules such as biotin were substituted onto precursor polymers and the biological recognition with avidin was determined by the change in redox properties of the backbone polymer.