Driving forces for the adsorption of cyclopentene on InP(001)

In this work the interaction of cyclopentene with a set of InP(001) surfaces is investigated by means of the density functional theory. We propose a simple approach for evaluating the surface strain and based on it we have found a linear relation between bond and strain energies and the adsorption energy. Our results also indicate that the higher the bond energy, the more disperse the charge distribution is around the adsorption site associated to the high occupied state, a key feature that characterizes the adsorption process. Different adsorption coverages are used to evaluate the proposed equation. Our results suggest that the proposed approach might be extended to other systems where the interaction of the semiconductor surface and the molecule is restricted to first neighbor sites. (C) 2011 Elsevier B.V. All rights reserved.

TOWARD UNDERSTANDING THE B[e] PHENOMENON. III. PROPERTIES OF THE OPTICAL COUNTERPART OF IRAS 00470+6429

FS CMa type stars are a group of Galactic objects with the B[e] phenomenon. They exhibit strong emission-line spectra and infrared excesses, which are most likely due to recently formed circumstellar dust. The group content and identification criteria were described in the first two papers of the series. In this paper we report our spectroscopic and photometric observations of the optical counterpart of IRAS 00470+6429 obtained in 2003-2008. The optical spectrum is dominated by emission lines, most of which have P Cyg type profiles. We detected significant brightness variations, which may include a regular component, and variable spectral line profiles in both shape and position. The presence of a weak Li I 6708 angstrom line in the spectrum suggests that the object is most likely a binary system with a B2-B3 spectral-type primary companion of a luminosity log L/L(circle dot) = 3.9 +/- 0.3 and a late-type secondary companion. We estimate a distance toward the object to be 2.0 +/- 0.3 kpc from the Sun.

Revisiting cangitoxin, a sea anemone peptide: Purification and characterization of cangitoxins II and III from the venom of Bunodosoma cangicum

Sodium channel toxins from sea anemones are employed as tools for dissecting the biophysical properties of inactivation in voltage-gated sodium channels. Cangitoxin (CGTX) is a peptide containing 48 amino acid residues and was formerly purified from Bunodosoma cangicum. Nevertheless, previous works reporting, the isolation procedures for such peptide from B. cangicum secretions are controversial and may lead to incorrect information. In this paper, we report a simple and rapid procedure, consisting of two chromatographic steps, in order to obtain a CGTX analog directly from sea anemone venom. We also report a substitution of N16D in this peptide sample and the co-elution of an inseparable minor isoform presenting the R14H substitution. Peptides are named as CGTX-II and CGTX-III, and their effects over Nav1.1 channels in patch clamp experiments are demonstrated. (c) 2008 Elsevier Ltd. All rights reserved.

Diruthenium(II, III) complexes of ibuprofen, aspirin, naproxen and indomethacin non-steroidal anti-inflammatory drugs: Synthesis, characterization and their effects on tumor-cell proliferation

[Ru-2(dNSAID)(4)Cl] and novel [Ru-2(dNSAID)(4)(H2O)(2)]PF6 complexes, where dNSAID = deprotonated carboxylate from the non-steroidal anti-inflammatory drugs (NSIDs), respectively: ibuprofen, Hibp (1) and aspirin, Hasp (2); naproxen, Hnpx (3) and indomethacin, Hind (4), have been prepared and characterized by optical spectroscopic methods. All of the compounds exhibit mixed valent Ru-2(II, III) cores where metal-metal bonds are stabilized by four drug-carboxylate bridging ligands in paddlewheel type structures. The diruthenium complexes and their parent NSAIDs showed no significant effects for Hep2 human larynx or T24/83 human bladder tumor. In contrast, the coordination of Ru-2(II,III) core led to synergistic effects that increased significantly the inhibition of C6 rat glioma proliferation in relation to the organic NSAIDs naproxen and ibuprofen, The possibility that the complexes Ru-2-ibp and Ru-2-npx may exert effects (anti-angiogenic and anti-matrix metalloprotease) that are similar to those exhibited by NAMI-A opens new horizons for in vivo C6 glioma model studies. (C) 2007 Elsevier Ltd. All rights reserved.

Dynamics in dumbbell domains III. Continuity of attractors

In this paper we conclude the analysis started in [J.M. Arrieta, AN Carvalho, G. Lozada-Cruz, Dynamics in dumbbell domains I. Continuity of the set of equilibria, J. Differential Equations 231 (2006) 551-597] and continued in [J.M. Arrieta, AN Carvalho, G. Lozada-Cruz, Dynamics in dumbbell domains II. The limiting problem, J. Differential Equations 247 (1) (2009) 174-202 (this issue)] concerning the behavior of the asymptotic dynamics of a dissipative reaction-diffusion equation in a dumbbell domain as the channel shrinks to a line segment. In [J.M. Arrieta, AN Carvalho. G. Lozada-Cruz, Dynamics in dumbbell domains I. Continuity of the set of equilibria, J. Differential Equations 231 (2006) 551-597], we have established an appropriate functional analytic framework to address this problem and we have shown the continuity of the set of equilibria. In [J.M. Arrieta, AN Carvalho, G. Lozada-Cruz. Dynamics in dumbbell domains II. The limiting problem, J. Differential Equations 247 (1) (2009) 174-202 (this issue)], we have analyzed the behavior of the limiting problem. In this paper we show that the attractors are Upper semicontinuous and, moreover, if all equilibria of the limiting problem are hyperbolic, then they are lower semicontinuous and therefore, continuous. The continuity is obtained in L(p) and H(1) norms. (C) 2008 Elsevier Inc. All rights reserved.

CONSTRUCTING QUANTUM OBSERVABLES AND SELF-ADJOINT EXTENSIONS OF SYMMETRIC OPERATORS. III. SELF-ADJOINT BOUNDARY CONDITIONS

This paper completes the review of the theory of self-adjoint extensions of symmetric operators for physicists as a basis for constructing quantum-mechanical observables. It contains a comparative presentation of the well-known methods and a newly proposed method for constructing ordinary self-adjoint differential operators associated with self-adjoint differential expressions in terms of self-adjoint boundary conditions. The new method has the advantage that it does not require explicitly evaluating deficient subspaces and deficiency indices (these latter are determined in passing) and that boundary conditions are of explicit character irrespective of the singularity of a differential expression. General assertions and constructions are illustrated by examples of well-known quantum-mechanical operators like momentum and Hamiltonian.

On an Electrode Modified by a Supramolecular Ruthenium Mixed Valence (Ru(II)/Ru(III)) Diphosphine-Porphyrin Assembly

Three novel polymetallic ruthenium (III) meso-tetra(4-pyridyl)porphyrins containing peripheral ""RuCl(3)(dppb)"" moieties have been prepared and characterized. The X-ray structure of the tetraruthenated {NiTPyP[RuCl(3)(dppb)](4)} porphyrin complex crystallizes in the triclinic space group FT. This structure is discussed and compared with the crystal data for the mer-[RuCl(3)(dppb)(py)]. The {TPyP[RuCl(3)(dppb)](4)} and {CoTPyP[RuCl(3)(dppb)](4)} porphyrins were used to obtain electrogenerated films on ITO and glass carbon electrode surfaces, respectively. Such tetraruthenated porphyrins form films of a mixed-valence species {TPyP[Ru(dppb)](4)(mu Cl(3))(2)}(2)(4n2+) and {CoTPyP[Ru(dppb)](4)(mu Cl(3))(2)}(2n)(4n2+) on the electrode surface. The modified electrode with {CoTPyP[RuCl(3)(dppb)](4)} is very stable and can be used to detect organic substrates such as catechol.

Analyzing Ru(III)-dmso and Ru(III)-dms motifs in compounds used in the synthesis of the antimetastatic agents

The chemistry of Ru(III) complexes containing dmso as a ligand has become an interesting area in the cancer treatment field. Because of this, structural knowledge and chemistry of the moiety Ru(III)-dmso have become important to cancer research. The crystal structures of the compounds mer-[RuCl(3)(dms)(3)] (1) and mer-[RuCl(3)(dms)(2)(dmso)]:mer-[RuCl(3)(dms)(3)] (2) were determined by X-ray crystallography and a speciation of the presence of intramolecular hydrogen bond in these structures has been studied. Compound (1) crystallizes in the orthorhombic space group, Pna2(1); a = 16.591(8) angstrom, b = 8.724(2) angstrom. c = 10.547(3) angstrom; Z = 12 and (2) crystallizes in the space group, P2(1)/C: a = 11.9930(2) angstrom, b = 7.9390(2) angstrom, c = 15.8700(3) angstrom, beta = 93.266(1)degrees, Z = 2. From the X-ray structures solved in this work, were possible to suggest an interpretation for the broad lines observed in the EPR spectra of the Ru(III) compounds explored here. Also, the exchange interactions detected by EPR spectroscopy in solid state and in solution, confirm the presence of van der Waals interactions such as C-H center dot center dot center dot Cl in the compounds (1), (2) and (3). The use of techniques such as IR, UV-vis, (1)H NMR and EPR Spectroscopy and Cyclic Voltammetry were applied in this work to analyze the behavior of these metallocompounds. (c) 2008 Elsevier B.V. All rights reserved.

Dimethylthallium(III) complexes with picolinic acid and its hydroxyl derivatives

The reaction of dimethylthallium(III) hydroxide with picolinic acid (Hpic), 3-hydroxypicolinic acid (H(2)3hpic) and 6-hydroxypicolinic acid (H(2)6hpic) in an aqueous/methanol mixture afforded the complexes [TlMe(2)(pic)] (1), [TlMe(2)(H3hpic)] (2) and [TlMe(2)(H6hpic)] (3), respectively. Complex 3`, [NaTlMe(2)(6hpic)(2)](n), was obtained as a minor product from a methanolic solution of 3. Compounds 1-3 were characterized by IR and Raman spectroscopy and, in the cases of 1, 2 and Y, by single-crystal X-ray diffraction. Complex 3` is the first example of an H6hpic(-) heterobimetallic compound to be isolated. The (1)H and (13)C NMR spectra of 1 and 2 are also discussed. (c) 2008 Elsevier Ltd. All rights reserved.

Novel manganese (III) porphyrin containing peripheral [RuCl(dppb)(X-bipy)](+) cations [dppb=1,4-bis(diphenylphosphino) butane and X = -CH3, -OMe, -Cl]. X-ray structure of the cis-[RuCl(dppb)(bipy)(4-Mepy)]PF6 complex

New tetraruthenated manganese (III) porphyrins were synthesized and characterized (P-31 NMR, cyclic voltammetry, UV-Vis). This new system presents four units of cationic ``[RuCl(dppb)(X-bipy)](+)``. The electrochemical and catalytic properties of the central manganese (III) show dependence on the characteristics of the peripheral ruthenium complexes as evidenced by the Mn-(III)/Mn-(II) reduction potential. The catalytic oxidation reactions of olefins, cyclohexene and cyclohexane, were carried out in the presence of tetrapyridyl manganese (III) porphyrins containing cationic ruthenium complex and using iodosylbenzene as oxygen donor. The performance of these new tetraruthenated porphyrins systems were evaluated and compared with the manganese porphyrin. (C) 2007 Elsevier Ltd. All rights reserved.

Electronic Structure and Spectro-Structural Correlations of Fe(III)Zn(II) Biomimetics for Purple Acid Phosphatases: Relevance to DNA Cleavage and Cytotoxic Activity

Purple acid phosphatases (PAPs) are a group of metallohydrolases that contain a dinuclear Fe(II)M(II) center (M(II) = Fe, Mn, Zn) in the active site and are able to catalyze the hydrolysis of a variety of phosphoric acid esters. The dinuclear complex [(H(2)O)Fe(III)(mu-OH)Zn(II)(L-H)](CIO(4))(2) (2) with the ligand 2-[N-bis(2-pyridylmethyl)aminomethyl]-4-methyl-6-[N-(2-pyridylmethyl)(2-hydroxybenzyl) aminomethyl]phenol (H(2)L-H) has recently been prepared and is found to closely mimic the coordination environment of the Fe(III)Zn(II) active site found in red kidney bean PAP (Neves et al. J. Am. Chem. Soc. 2007, 129, 7486). The biomimetic shows significant catalytic activity in hydrolytic reactions. By using a variety of structural, spectroscopic, and computational techniques the electronic structure of the Fe(III) center of this biomimetic complex was determined. In the solid state the electronic ground state reflects the rhombically distorted Fe(III)N(2)O(4) octahedron with a dominant tetragonal compression align ad along the mu-OH-Fe-O(phenolate) direction. To probe the role of the Fe-O(phenolate) bond, the phenolate moiety was modified to contain electron-donating or -withdrawing groups (-CH(3), -H, -Br, -NO(2)) in the 5-position. Tie effects of the substituents on the electronic properties of the biomimetic complexes were studied with a range of experimental and computational techniques. This study establishes benchmarks against accurate crystallographic struck ral information using spectroscopic techniques that are not restricted to single crystals. Kinetic studies on the hydrolysis reaction revealed that the phosphodiesterase activity increases in the order -NO(2)<- Br <- H <- CH(3) when 2,4-bis(dinitrophenyl)phosphate (2,4-bdnpp) was used as substrate, and a linear free energy relationship is found when log(k(cat)/k(0)) is plotted against the Hammett parameter a. However, nuclease activity measurements in the cleavage of double stranded DNA showed that the complexes containing the electron-withdrawing -NO(2) and electron-donating CH3 groups are the most active while the cytotoxic activity of the biomimetics on leukemia and lung tumoral cells is highest for complexes with electron-donating groups.

Heterodinuclear Fe(III)Zn(II)-Bioinspired Complex Supported on 3-Aminopropyl Silica. Efficient Hydrolysis of Phosphate Diester Bonds

Presented herein is the synthesis and characterization of a new Fe(III)Zn(II) complex containing a Fe(III)-bound phenolate with a carbonyl functional group, which was anchored to 3-aminopropylfunctionalized silica as the solid support. The catalytic efficiency of the immobilized catalyst in the hydrolysis of 2,4-bis (dinitrophenyl) phosphate is comparable to the homogeneous reaction, and the supported catalyst can be reused for subsequent diester hydrolysis reactions.

Spectroscopic investigation of the interactions between emeraldine base polyaniline and Eu(III) ions

The interactions of emeraldine base form of polyaniline (EB-PANI) and Eu(III) ions in 1-methyl-2-pyrrolidinone (NMP) solution and in films have been investigated by UV-vis-NIR, resonance Raman. luminescence and electron paramagnetic resonance (EPR) spectroscopies. These spectroscopic techniques allowed to characterize quinone and semiquinone segments in the polymeric chains. and the oxidation state of europium ions in Eu-PANI samples. For high values of Eu(III)/N molar ratio (24/1) the presence of a weak polaronic absorption band at 980 nm in UV-vis-NIR spectrum and the observation of bands at 1330 and 1378 (nu(center dot)(C-N+)) cm(-1) due to emeraldine salt in the Raman spectrum at 1064 nm indicate a low doping degree. Oxidation of EB-PANI to pernigraniline base (PB-PANI) occurs in diluted solutions. The experimental data showed that the solvent plays an important role on the nature of formed species. The narrow EPR signal at g = 2.006 (line width 8G) confirms the presence of PANI radical cations in Eu-PANI film. The absence of broad signal characteristic of Eu(II) in EPR spectrum suggested that europium ions are primarily at Eu(III) oxidation state. The luminescence spectra of Eu-PANI film presented emission bands at 405 and 418 nm assigned to PANI moieties and bands at 594,615 and 701 nm assigned to (5)D(0) -> (7)F(J) (J = 1, 2 and 4, respectively) transitions of Eu(III). EPR and photoluminescence data confirm that europium ions are mainly in Eu(III) oxidation state in Eu(III)/PANI films. (C) 2008 Elsevier B.V. All rights reserved.

Synthesis, characterization and adsorption properties of porous mixed valent diruthenium(II,III)-terephthalate and diruthenium(II,III)-adipate polymers

Two porous mixed valent diruthenium(II,III)-dicarboxylate compounds have been prepared and characterized by spectroscopic methods, X-ray diffraction and thermogravimetry. Crystalline solids of [Ru(2)(tere)(2)Cl] center dot 3.5H(2)O (tere=terephthalate) and [Ru(2)(adip)(2)Cl] center dot 1.5H(2)O (adip=adipate) consist of extended chains in which polymeric layers of multiply metal-metal bonded [Ru(2)](5+) cores are bridged by dicarboxylate ligands in paddlewheel type geometries. Units of [Ru(2)(dicarboxylate)(2)](n)(+) are linked by axial bridging chloride ions generating three-dimensional networks. The polymers loose non-bonded water molecules at low temperatures but do not undergo thermal decomposition below 280-300 degrees C. Both of compounds exhibit high BET surface areas, [Ru(2)(tere)(2)Cl]: 235 m(2) g(-1) and [Ru(2)(adip)(2)Cl]: 281 m(2) g(-1), and occlude similar numbers of mol of N(2) per mol of metal. The terephthalate ligand generated an organized structure with supermicropores (total pore size of 0.24 cm(3) g(-1)) while the adipate ligand led to a mesoporous structure (total pore sizes of 0.47 cm(3) g(-1)) for the corresponding diruthenium(II,III)-dicarboxylate polymers. (c) 2008 Elsevier B.V. All rights reserved.

SYNTHESIS, CHARACTERIZATION AND THERMAL ANALYSIS OF 1:1 AND 2:3 LANTHANIDE(III) CITRATES

The synthesis and characterization of lanthanide(III) citrates with stoichiometries 1:1 and 2:3; [LnL center dot xH(2)O] and [Ln(2)(LH)(3)center dot 2H(2)O], Ln=La, Ce, Pr, Nd, Sm and Eu are reported. L stands for (C6O7H5)(3-) and LH for (C6O7H6)(2-). Infrared absorption spectra of both series evidence coordination of carboxylate groups through symmetric bridges or chelation. X-ray powder patterns show the amorphous character of [LnL center dot xH(2)O]. The compounds [Ln(2)LH(3)center dot 2H(2)O] are crystalline and isomorphous. Emission spectra of Eu compounds suggest C-2v symmetry for the coordination polyhedron of [LnL center dot xH(2)O] and C-4v for [Ln(2)(LH)(3)center dot 2H(2)O]. Thermal analyses (TG-DTG-DTA) were carried out for both series. The thermal analysis patterns of the two series are quite different and both fit in a 4-step model of thermal decomposition, with lanthanide oxides as final products.