Crystal and molecular structures of dichloro((Z)-2-chloro-2-phenylvinyl)(organo)tellurium(IV) for organo = n-butyl and phenyl

In each of the title compounds, R[Ph(Cl)C=(H)C]TeCl(2), R = nBu (1) and Ph (2), the primary geometry about the Te(IV) atom is a pseudo-trigonal-bipyramidal arrangement, with two Cl atoms in apical positions, and the lone pair of electrons and C atoms in the equatorial plane. As the Te(IV) is involved in two, an intra- and an inter-molecular, Te center dot center dot center dot Cl interactions the coordination geometry might be considered as a Psi-pentagonal bipyramid in each case. In addition, in (2) there is a hint of a Te center dot center dot center dot pi interaction (Te center dot center dot center dot C = 3.911(3) A). The key feature in the crystal structure of both compounds is the formation of supramolecular chains mediated by Te center dot center dot center dot Cl contacts. (1): C(12)H(15)Cl(3)Te, triclinic, P (1) over bar, a = 5.9471 (11), b = 10.7826(22), c = 11.7983(19) angstrom, alpha = 75.416(12), beta = 78.868(13), gamma = 80.902(14)degrees, V = 713.6(2) angstrom(3), Z = 2, R(1) = 0.021; (2): C14HIIC13Te, orthorhombic, Pcab, a=7.7189(10), b=17.415(2), c=21.568(3)angstrom, V = 2899.3(6) angstrom(3), Z = 8, R(1) = 0.027.

Direct Zincation of Functionalized Aromatics and Heterocycles by Using a Magnesium Base in the Presence of ZnCl(2)

A wide range of polyfunctional aryl and heteroaryl zinc reagents were efficiently prepared in THF by using (TMP)(2)Mg center dot 2LiCl (TMP = 2,2,6,6-tetramethylpiperamidyl) in the presence of ZnCl(2). The possible pathways of this metalation procedure as well as possible reactive intermediates are discussed. This experimental protocol expands the tolerance of functional groups and allows an efficient zincation of sensitive heterocycles such as quinoxaline or pyrazine. The zincated arenes and heteroarenes react with various electrophiles providing the expected products in 60-95 % yield.

Enantiomeric resolution of (+/-)-licarin A by high-performance liquid-chromatography using a chiral stationary phase

(+/-)-Licarin A (1), a neolignan obtained by the oxidative coupling reaction of isoeugenol, had in this study its enantiomers resolved. A novel, quick and efficient enantiomeric resolution of 1 was directly performed by chiral high-performance liquid chromatography (HPLC-PDA) protocol (CHIRALPACK (R) AD column; 9:1 (v/v) n-hexane:2-propanol; 1.0 mL/min). This method provided a chromatogram profile with a well-resolved peak separation. After isolation of each enantiomer with ee >99.9%, they were analysed in a polarimeter. Compound 2, which showed a retention time (t(r)) of 12.13 min, was the (+)-enantiomer and compound 3 (t(r) =18.90 min) was the (-)-enantiomer. (C) 2011 Elsevier B.V. All rights reserved.

Thermal and hydrolytic degradation of electrospun fish gelatin membranes

The thermal and hydrolytic degradation of electrospun gelatin membranes cross-linked with glutaraldehyde in vapor phase has been studied. In vitro degradation of gelatin membranes was evaluated in phosphate buffer saline solution at 37 ºC. After 15 days under these conditions, a weight loss of 68 % was observed, attributed to solvation and depolymerization of the main polymeric chains. Thermal degradation kinetics of the gelatin raw material and as-spun electrospun membranes showed that the electrospinning processing conditions do not influence polymer degradation. However, for cross-linked samples a decrease in the activation energy was observed, associated with the effect of glutaraldehyde cross-linking reaction in the inter- and intra-molecular hydrogen bonds of the protein. It is also shown that the electrospinning process does not affect the formation of the helical structure of gelatin chains.

Matrix Converter-Based Unified Power-Flow Controllers: Advanced Direct Power Control Method

This paper presents a direct power control (DPC) for three-phase matrix converters operating as unified power flow controllers (UPFCs). Matrix converters (MCs) allow the direct ac/ac power conversion without dc energy storage links; therefore, the MC-based UPFC (MC-UPFC) has reduced volume and cost, reduced capacitor power losses, together with higher reliability. Theoretical principles of direct power control (DPC) based on sliding mode control techniques are established for an MC-UPFC dynamic model including the input filter. As a result, line active and reactive power, together with ac supply reactive power, can be directly controlled by selecting an appropriate matrix converter switching state guaranteeing good steady-state and dynamic responses. Experimental results of DPC controllers for MC-UPFC show decoupled active and reactive power control, zero steady-state tracking error, and fast response times. Compared to an MC-UPFC using active and reactive power linear controllers based on a modified Venturini high-frequency PWM modulator, the experimental results of the advanced DPC-MC guarantee faster responses without overshoot and no steady-state error, presenting no cross-coupling in dynamic and steady-state responses.

Endothelialization of chitosan porous conduits via immobilization of a recombinant fibronectin fragment (rhFNIII7–10)

The present study aimed to develop a pre-endothelialized chitosan (CH) porous hollowed scaffold for application in spinal cord regenerative therapies. CH conduits with different degrees of acetylation (DA; 4% and 15%) were prepared, characterized (microstructure, porosity and water uptake) and functionalized with a recombinant fragment of human fibronectin (rhFNIII7–10). Immobilized rhFNIII7–10 was characterized in terms of amount (125I-radiolabelling), exposure of cell-binding domains (immunofluorescence) and ability to mediate endothelial cell (EC) adhesion and cytoskeletal rearrangement. Functionalized conduits revealed a linear increase in immobilized rhFNIII7–10 with rhFNIII7–10 concentration, and, for the same concentration, higher amounts of rhFNIII7–10 on DA 4% compared with DA 15%. Moreover, rhFNIII7–10 concentrations as low as 5 and 20 lgml 1 in the coupling reaction were shown to provide DA 4% and 15% scaffolds, respectively, with levels of exposed cell-binding domains exceeding those observed on the control (DA 4% scaffolds incubated in a 20 lgml 1 human fibronectin solution). These grafting conditions proved to be effective in mediating EC adhesion/cytoskeletal organization on CH with DA 4% and 15%, without affecting the endothelial angiogenic potential. rhFNIII7–10 grafting to CH could be a strategy of particular interest in tissue engineering applications requiring the use of endothelialized porous matrices with tunable degradation rates.

Linear and sliding-mode control design for matrix converter-based unified power flow controllers

This paper presents the design and compares the performance of linear, decoupled and direct power controllers (DPC) for three-phase matrix converters operating as unified power flow controllers (UPFC). A simplified steady-state model of the matrix converter-based UPFC fitted with a modified Venturini high-frequency pulse width modulator is first used to design the linear controllers for the transmission line active (P) and reactive (Q) powers. In order to minimize the resulting cross coupling between P and Q power controllers, decoupled linear controllers (DLC) are synthesized using inverse dynamics linearization. DPC are then developed using sliding-mode control techniques, in order to guarantee both robustness and decoupled control. The designed P and Q power controllers are compared using simulations and experimental results. Linear controllers show acceptable steady-state behaviour but still exhibit coupling between P and Q powers in transient operation. DLC are free from cross coupling but are parameter sensitive. Results obtained by DPC show decoupled power control with zero error tracking and faster responses with no overshoot and no steady-state error. All the designed controllers were implemented using the same digital signal processing hardware.

Matrix converter as unified power flow controller: design and implementation of decoupled direct power controllers

This paper presents the design and implementation of direct power controllers for three-phase matrix converters (MC) operating as Unified Power Flow Controllers (UPFC). Theoretical principles of the decoupled linear power controllers of the MC-UPFC to minimize the cross-coupling between active and reactive power control are established. From the matrix converter based UPFC model with a modified Venturini high frequency PWM modulator, decoupled controllers for the transmission line active (P) and reactive (Q) power direct control are synthesized. Simulation results, obtained from Matlab/Simulink, are presented in order to confirm the proposed approach. Results obtained show decoupled power control, zero error tracking, and fast responses with no overshoot and no steady-state error.

Enzymatic treatments to improve mechanical properties and surface hydrophobicity of jute fiber membranes

Fiber membranes prepared from jute fragments can be valuable, low cost, and renewable. They have broad application prospects in packing bags, geotextiles, filters, and composite reinforcements. Traditionally, chemical adhesives have been used to improve the properties of jute fiber membranes. A series of new laccase, laccase/mediator systems, and multi-enzyme synergisms were attempted. After the laccase treatment of jute fragments, the mechanical properties and surface hydrophobicity of the produced fiber membranes increased because of the cross-coupling of lignins with ether bonds mediated by laccase. The optimum conditions were a buffer pH of 4.5 and an incubation temperature of 60 °C with 0.92 U/mL laccase for 3 h. Laccase/guaiacol and laccase/alkali lignin treatments resulted in remarkable increases in the mechanical properties; in contrast, the laccase/2,2-azino-bis-(3-ethylthiazoline-6-sulfonate) (ABTS) and laccase/2,6-dimethoxyphenol treatments led to a decrease. The laccase/ guaiacol system was favorable to the surface hydrophobicity of jute fiber membranes. However, the laccase/alkali lignin system had the opposite effect. Xylanase/laccase and cellulase/laccase combined treatments were able to enhance both the mechanical properties and the surface hydrophobicity of jute fiber membranes. Among these, cellulase/laccase treatment performed better; compared to mechanical properties, the surface hydrophobicity of the jute fiber membranes showed only a slight increase after the enzymatic multi-step processes.

Bioconjugated lanthanide luminescent helicates as multilabels for lab-on-a-chip detection of cancer biomarkers.

The lanthanide binuclear helicate [Eu(2)(L(C2(CO(2)H)))(3)] is coupled to avidin to yield a luminescent bioconjugate EuB1 (Q = 9.3%, tau((5)D(0)) = 2.17 ms). MALDI/TOF mass spectrometry confirms the covalent binding of the Eu chelate and UV-visible spectroscopy allows one to determine a luminophore/protein ratio equal to 3.2. Bio-affinity assays involving the recognition of a mucin-like protein expressed on human breast cancer MCF-7 cells by a biotinylated monoclonal antibody 5D10 to which EuB1 is attached via avidin-biotin coupling demonstrate that (i) avidin activity is little affected by the coupling reaction and (ii) detection limits obtained by time-resolved (TR) luminescence with EuB1 and a commercial Eu-avidin conjugate are one order of magnitude lower than those of an organic conjugate (FITC-streptavidin). In the second part of the paper, conditions for growing MCF-7 cells in 100-200 microm wide microchannels engraved in PDMS are established; we demonstrate that EuB1 can be applied as effectively on this lab-on-a-chip device for the detection of tumour-associated antigens as on MCF-7 cells grown in normal culture vials. In order to exploit the versatility of the ligand used for self-assembling [Ln(2)(L(C2(CO(2)H)))(3)] helicates, which sensitizes the luminescence of both Eu(III) and Tb(III) ions, a dual on-chip assay is proposed in which estrogen receptors (ERs) and human epidermal growth factor receptors (Her2/neu) can be simultaneously detected on human breast cancer tissue sections. The Ln helicates are coupled to two secondary antibodies: ERs are visualized by red-emitting EuB4 using goat anti-mouse IgG and Her2/neu receptors by green-emitting TbB5 using goat anti-rabbit IgG. The fact that the assay is more than 6 times faster and requires 5 times less reactants than conventional immunohistochemical assays provides essential advantages over conventional immunohistochemistry for future clinical biomarker detection.

Métodos sintéticos para preparação de 2,2'-bipiridinas substituídas

The 2,2'-bipyridine has been entitled as the most widely used ligand. Nowadays there is a large variety of known molecules comprising at least two 2,2'-bipyridine units and the number of applications in many areas such as catalysis, new materials, optoeletronics and electrochemistry have increased very much in the past decades. Nevertheless, there is no article that gives an overview of the main synthetic methods for obtaining the substituted 2,2'-bipyridines, generally non available. This article presents a synthetic discussion about the three different methods (coupling reaction, ciclo-functionalization and functionalization of the heteroaromatic rings of 2,2'-bipyridine) for preparing these heterocyclic compounds and also provides a practical and fundamental guide, for obtaining more than eighty different symmetric and unsymmetrical substituted 2,2'-bipyridines, shown in a table with the corresponding references.

Miniprojeto para ensino de Química Orgânica Experimental baseado no acoplamento catalítico N-C promovido por micro-ondas

This paper describes a three-week mini-project for an Experimental Organic Chemistry course. The activities include N-C cross-coupling synthesis of N-(4-methoxyphenyl) benzamide in an adapted microwave oven by a copper catalyst (CuI). Abilities and concepts normally present in practical organic chemistry courses are covered: use of balances, volumetric glassware, separation of mixtures (liquid-liquid extraction and filtration), chromatographic techniques, melting point determination and stoichiometric calculations.

Cycle modulation of insulin-like growth factor-binding protein 1 in human endometrium

Endometrium is one of the fastest growing human tissues. Sex hormones, estrogen and progesterone, in interaction with several growth factors, control its growth and differentiation. Insulin-like growth factor 1 (IGF-1) interacts with cell surface receptors and also with specific soluble binding proteins. IGF-binding proteins (IGF-BP) have been shown to modulate IGF-1 action. Of six known isoforms, IGF-BP-1 has been characterized as a marker produced by endometrial stromal cells in the late secretory phase and in the decidua. In the current study, IGF-1-BP concentration and affinity in the proliferative and secretory phase of the menstrual cycle were measured. Endometrial samples were from patients of reproductive age with regular menstrual cycles and taking no steroid hormones. Cytosolic fractions were prepared and binding of 125I-labeled IGF-1 performed. Cross-linking reaction products were analyzed by SDS-polyacrylamide gel electrophoresis (7.5%) followed by autoradiography. 125I-IGF-1 affinity to cytosolic proteins was not statistically different between the proliferative and secretory endometrium. An approximately 35-kDa binding protein was identified when 125I-IGF-1 was cross-linked to cytosol proteins. Secretory endometrium had significantly more IGF-1-BP when compared to proliferative endometrium. The specificity of the cross-linking process was evaluated by the addition of 100 nM unlabeled IGF-1 or insulin. Unlabeled IGF-1 totally abolished the radioactivity from the band, indicating specific binding. Insulin had no apparent effect on the intensity of the labeled band. These results suggest that IGF-BP could modulate the action of IGF-1 throughout the menstrual cycle. It would be interesting to study this binding protein in other pathologic conditions of the endometrium such as adenocarcinomas and hyperplasia.

An analysis of the methyl rotation dynamics in the So (x' A) and T (a A) states of thioacetaldehyde from Pyrolysis jet spectra /

Jet-cooled, laser-induced phosphorescence excitation spectra (LIP) of thioacetaldehyde CH3CHS, CH3CDS, CD3CHS and CD3CDS have been observed over the region 15800 - 17300 cm"^ in a continuous pyrolysis jet. The vibronic band structure of the singlet-triplet n -* n* transition were attributed to the strong coupling of the methyl torsion and aldehydic hydrogen wagging modes . The vibronic peaks have been assigned in terms of two upper electronic state (T^) vibrations; the methyl torsion mode v^g, and the aldehydic hydrogen wagging mode v^^. The electronic origin O^a^ is unequivocally assigned as follows: CH3CHS (16294.9 cm"'' ), CH3CDS (16360.9 cm"'' ), CD3CHS (16299.7 cm"^ ), and CD3CDS (16367.2 cm"'' ). To obtain structural and dynamical information about the two electronic states, potential surfaces V(e,a) for the 6 (methyl torsion) and a (hydrogen wagging) motions were generated by ab initio quantum mechanical calculations with a 6-3 IG* basis in which the structural parameters were fully relaxed. The kinetic energy coefficients BQ(a,e) , B^(a,G) , and the cross coupling term B^(a,e) , were accurately represented as functions of the two active coordinates, a and 9. The calculations reveal that the molecule adopts an eclipsed conformation for the lower Sq electronic state (a=0°,e=0"') with a barrier height to internal rotation of 541.5 cm"^ which is to be compared to 549.8 cm"^ obtained from the microwave experiment. The conformation of the upper T^ electronic state was found to be staggered (a=24 . 68° ,e=-45. 66° ) . The saddle point in the path traced out by the aldehyde wagging motion was calculated to be 175 cm"^ above the equilibrium configuration. The corresponding maxima in the path taken by methyl torsion was found to be 322 cm'\ The small amplitude normal vibrational modes were also calculated to aid in the assignment of the spectra. Torsional-wagging energy manifolds for the two states were derived from the Hamiltonian H(a,e) which was solved variationally using an extended two dimensional Fourier expansion as a basis set. A torsionalinversion band spectrum was derived from the calculated energy levels and Franck-Condon factors, and was compared with the experimental supersonic-jet spectra. Most of the anomalies which were associated with the interpretation of the observed spectrum could be accounted for by the band profiles derived from ab initio SCF calculations. A model describing the jet spectra was derived by scaling the ab initio potential functions. The global least squares fitting generates a triplet state potential which has a minimum at (a=22.38° ,e=-41.08°) . The flatter potential in the scaled model yielded excellent agreement between the observed and calculated frequency intervals.

Studies in the mass spectra of perfluoroaromatic derivatives of phosphorus and some selected transition metals

The mass spectra and fragmentation of a variety of fluoroaromatic compounds of Group V and some selected transition elements are discussed in some detail, aided by data from metastable defocussed experiments. Results of ,studies on the coupling reaction using unstable organotitanium chloride intermediate species are reported. The preparation of some 5-substituted octafluorodibenzophospho1es is also discussed. Rearrangements under electron bombardment resulting in the loss of heteroatom-fluoride fragments are discussed in the light of presently accepted mechanisms for these processes as are rearrangements observed in compounds involving thionophosphoryl bonds ( p=s ).