Spectroelectrochemistry and investigation of charge transport mechanisms of iron poly(pyridyl) redox polymers

In this work, we describe the characterization of the complex [Fe(tpy-NH₂)₂](PF₆)₂ (tpy-NH₂ = bis[4′-(3-aminophenyl)-2, 2′:6′,2″-terpyridine]. The complex was oxidatively electropolymerized on glassy-carbon electrodes in CH₃CN/0.1 M tetraethylammonium perchlorate (TEAP) to generate polymer films that exhibit reversible oxidative electrochemical behavior in a wide potential range (0.0–1.6 V), as well as high conductivity and stability/durability. In situ spectrocyclic voltammetry of this modified electrode was carried out on a photodiode array spectrophotometer attached to a potentiostat, which provided UV–Vis absorption spectra of the redox species during the potential sweep. We determined charge transport parameters as a function of time and thickness of the modified electrode, and the results showed that poly-[[Fe(tpy-NH₂)₂]²⁺]_n can be made to exhibit three regimes of charge transport behavior by manipulation of the film thickness and the experimental time-scale. Morphological characterization of the film was provided by atomic force microscopy.     

Crystal and molecular structure of 5-carbamyl-5H-dibenzo[b,f] azepine

The structure of the title compound has been determined by direct methods from diffractometer data, and refined by full-matrix least squares. Crystals are monoclinicP2₁/n,a=7.534(1),b=11.150(2),c=13.917(3) Å,=92.94(4)°,Z=4,D _x=1.34 (3) g cm^–3,R=0.084 for 1259 observed reflections. The azepine ring has a boat conformation. The fused benzene rings are planar. Molecules are packed as hydrogen-bonded dimers through the carboxamide groups. The atomic charge distribution over the fused ring system is approximately symmetrical.     

Spectra of regular polytopes

In this paper we compute the spectra with multiplicities of the adjancency graphs of all regular polytopes in ⁿ : it turns out that all such eigenvalues are algebraic intergers of degree no greater than 3.Both authors receive continuous support from FINEP and CNPq, Brazil.     

A three phase hollow fiber liquid‐phase microextraction for quantification of lamotrigine in plasma of epileptic patients by capillary electrophoresis

A three phase hollow fiber liquid‐phase microextraction technique combined with capillary electrophoresis was developed to quantify lamotrigine (LTG) in plasma samples. The analyte was extracted from 4.0 mL of a basic donor phase (composed of 0.5 mL of plasma and 3.5 mL of sodium phosphate solution pH 9.0) through a supported liquid membrane composed of 1‐octanol immobilized in the pores of the hollow fiber, and to an acidic acceptor phase (hydrochloric acid solution pH 4.0) placed in the lumen of the fiber. The extraction was carried out for 30 min at 500 rpm. The eletrophoretic analysis was carried out in 130 mmol/L MES buffer, pH 5.0 with a constant voltage of +15 kV and 20°C. Sample injections were performed for 10 s, at a pressure of 0.5 psi. The detection was performed at 214 nm for both LTG and the internal standard lidocaine. Under the optimized conditions, the method showed a limit of quantification of 1.0 μg/mL and was linear over the plasmatic concentration range of 1.0–20.0 μg/mL. Finally, the validated method was applied for the quantification of LTG in plasma samples of epileptic patients.     

An atlas for tridiagonal isospectral manifolds

Let be the compact manifold of real symmetric tridiagonal matrices conjugate to a given diagonal matrix Λ with simple spectrum. We introduce bidiagonal coordinates, charts defined on open dense domains forming an explicit atlas for . In contrast to the standard inverse variables, consisting of eigenvalues and norming constants, every matrix in now lies in the interior of some chart domain. We provide examples of the convenience of these new coordinates for the study of asymptotics of isospectral dynamics, both for continuous and discrete time.     

The design and synthesis of inhibitors of pantothenate synthetase

Pantothenate synthetase catalyses the ATP-dependent condensation of D-pantoate and beta-alanine to form pantothenate. Ten analogues of the reaction intermediate pantoyl adenylate, in which the phosphodiester is replaced by either an ester or sulfamoyl group, were designed as potential inhibitors of the enzyme. The esters were all modest competitive inhibitors, the sulfamoyls were more potent, consistent with their closer structural similarity to the pantoyl adenylate intermediate.