Ruthenium(II)/(III) complexes of bidentate acetyl hydrazide Schiff bases

A series of octahedral Ru^II/Ru^III complexes of the type [Ru(Y)(CO)(BAX)(PPh₃)₂] and [RuCl₂(BAX)(PPh₃)₂] (Y = H or Cl; BAX = benzaldehydeacetylhydrazone anion; X = H, Me, OMe, OH, Cl or NO₂) have been prepared and characterised by spectral, magnetic and cyclic voltammetric studies. The Ru^II complexes are low spin diamagnetic (S = 0) whereas the Ru^III complexes are low spin and paramagnetic (S = 1/2). These Ru^II and Ru^III complexes absorb in the visible region respectively at ca. 16,000 and 28,000 cm^–1 which bands are assigned to the MLCT. The correlation of the _max values of the Ru^III complexes with the ⁺ Hammett parameter, is linear, indicating the profound effect of substituents on the electron density of the central metal. I.r. spectral data reveals that the hydrazone is chelated to ruthenium through the hydrazinic nitrogen and the deprotonated enolic oxygen. The rhombic nature of the e.s.r. spectra of the Ru^III complexes indicates an asymmetry in the electronic environment around the Ru atom. Ru^II complexes in CH₂Cl₂ show an irreversible Ru^II/III redox couple at ca. 0.9–0.5 V, while the Ru^III complexes show two reversible redox couples in the –0.1–0.1 and 0.8–0.6 V range, indicating that the higher oxidation state of ruthenium is stabilised by hydrazones.     

Capture by stabilized continuum: Classical and quantum aspects

We review here the results of our investigations concerning chaotic atomic scattering in the presence of a laser field. Particular emphasis is put on the existence of classical stable resonance structures, induced by the intense laser field, which are embedded in the field-free continuum. We show that phase space structures in the vicinity of a resonance island play an important role in the chaotic scattering behavior and form the basis for a mechanism to enhance the lifetimes of the collisional partners. Quantum calculations, based on a wave packet propagation method, show that quantum solutions are strongly influenced by the classical phase space structures. More specifically, a wave packet is found to spread differently in the regular and chaotic regions; in the latter case it spreads exponentially with time until saturation occurs, defining the saturation time. We also investigate the dependence of the spreading rates in both the regular and chaotic regimes. Calculations with an ensemble of classical trajectories are also presented to further illustrate the smoothing effects of varying.     

Biomolecular docking,antimicrobial and cytotoxic studies on new bidentate schiff base ligand derived metal (II) complexes

Three new metal complexes [Cu(L)₂] (1), [Co(L)₂] (2) and [Zn(L)₂] (3) have been prepared by the reaction of hydrated salts of metal (II) acetate with new Schiff base ligand HL, [2‐((4‐(dimethylamino)phenylimino)methyl)‐4,6‐di‐t‐butylphenol] and characterized by different physico‐chemical analyses such as elemental analysis, single XRD, ¹H NMR, FTIR and UV–Vis spectroscopic techniques. Their biomolecular docking, antimicrobial and cytotoxicity studies have also been demonstrated. The proposed structure of Schiff base ligand HL and complex 2 are confirmed by Single crystal X‐ray crystallography study. This analysis revealed that metal (II) complexes remain in distorted tetrahedral coordination environments. The electronic properties such as HOMO and LUMO energies are carried out by gaseous phase DFT/B3LYP calculations using Gaussian 09 program. Complex 1 showed a good binding propensity to the DNA and HSA, during the assessment of docking studies. Schiff base ligand HL and its metal (II) complexes, 1–3 screened for their in vitro antimicrobial activities using the disc diffusion method against selected microbes. Complex 1 shows higher antimicrobial activity than complexes 2, 3 and Schiff base ligand HL. According to the results obtained from the cytotoxic studies, Schiff base ligand HL and its metal (II) complexes 1–3 have better cytotoxicity against MCF‐7 cell lines with potency higher than the currently used chemotherapeutic agent cyclophosphamide.     

Influence Of Zro2 on The Physicochemical Properties of Phosphate-Based Glasses and Glass Ceramics

Abstract

Phosphate-based bioactive glasses and their glass ceramics for 47P₂O₅– (30.5)CaO–(22.5 ? x)Na₂O–xZrO₂ for different ZrO₂ contents (x = 0, 1.5, 3.0, 4.5, and 6.0 mol%) were prepared through melt quenching and controlled heat treatment procedures. The amorphous nature of glasses and the presence of crystalline phases in glass ceramics were studied by means of X-ray diffraction (XRD) studies. The density, molar volume, ultrasonic velocities, attenuation, elastic constants, and microhardness of glass and glass ceramics were used to study the structural changes. The formation of hydroxyapatite layer on the surface of glasses and glass ceramics after immersion in simulated body fluid (SBF) was explored through XRD, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) analyses. The results indicate that the added ZrO₂ increases the crosslink density of glasses, resulting in network stability, and also induces the formation of an apatite layer on the surface of glasses.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Identification of a Prenyl Chalcone as a Competitive Lipoxygenase Inhibitor: Screening,Biochemical Evaluation and Molecular Modeling Studies

Cyclooxygenase (COX) and lipoxygenase (LOX) are key targets for the development of new anti-inflammatory agents. LOX, which is involved in the biosynthesis of mediators in inflammation and allergic reactions, was selected for a biochemical screening campaign to identify LOX inhibitors by employing the main natural product library of Brazilian biodiversity. Two prenyl chalcones were identified as potent inhibitors of LOX-1 in the screening. The most active compound, (E)-2-O-farnesyl chalcone, decreased the rate of oxygen consumption to an extent similar to that of the positive control, nordihydroguaiaretic acid. Additionally, studies on the mechanism of the action indicated that (E)-2-O-farnesyl chalcone is a competitive LOX-1 inhibitor. Molecular modeling studies indicated the importance of the prenyl moieties for the binding of the inhibitors to the LOX binding site, which is related to their pharmacological properties.     

Phthalocyanine-based Langmuir-Blodgett films as chemical sensors

Phthalocyanines are macrocycles with an appealing diversification of characteristics of fundamental interest in contemporary advanced technologies. On the other side, the Langmuir-Blodgett method permits to deposit films with a substantial control over thickness and molecular organisation. As a natural consequence, this review deals with an actual subject of attention in up-to-date research, the employment of Langmuir-Blodgett films of phthalocyanines in chemical sensors for the revelation of analytes in both gas and liquid phases. Experimental data on the structure, morphology and surface properties of the multilayers are connected with the most relevant characteristics of sensors, in order to discover the intimate relationships between the sensor performances and the peculiarities and molecular organisation induced by the deposition technique. The integration of the unconventional electrical and optical properties of phthalocyanines with the potentialities of the Langmuir-Blodgett thin films has generated not only promising expectations, but has given also certainties about the realisation of functional sensing devices.     

Size control of charge-orbital order in half-doped manganite La0.5Ca0.5MnO3

Motivated by recent experimental results, we study the effect of size reduction on half-doped manganite, La(0.5)Ca(0.5)MnO(3), using the combination of density-functional theory (DFT) and dynamical mean-field theory (DMFT). We find that upon size reduction the charge-ordered antiferromagnetic phase, observed in bulk, is destabilized, giving rise to the stability of a ferromagnetic metallic state. Our theoretical results, carried out on a defect-free nanocluster in isolation, establish the structural changes that follow upon size reduction to be responsible for this. Our study further points out the effect of size reduction to be distinctively different from application of hydrostatic pressure. Interestingly, our DFT+DMFT study additionally reports the correlation-driven stability of the charge-orbitally ordered state in bulk La(0.5) Ca(0.5) MnO(3), even in the absence of long-range magnetic order.     

Multi-band phase shifter design using modified slotline configuration

In this paper, an analog multiband phase shifter using slotline configuration is proposed. To implement the design, a pair of modified Split Ring Resonator (SRR) is employed. The periodic property of SRR provides multiband characteristics, whether the coupling slot gives the phase variations over the bands. The operation is well explained with an equivalent circuit model and its characteristics have been studied both in simulation and measurement. The prototype operates in 1.77–2.16, 3.5–3.97, 5.08–5.33, 6.43–6.93, and 8.01–8.59 GHz frequency bands which can be utilized for GSM, GPS, WLAN, C-band, and X-band applications, respectively.     

Asymmetric cyanosilylation of ketones catalyzed by recyclable polymer-supported copper(II) salen complexes

Various ketones have undergone asymmetric trimethylsilylcyanation at room temperature with (CH₃)₃SiCN (TMSCN) in the presence of a chiral-supported Cu(salen) complex and Ph₃PO as the catalyst. Aromatic, aliphatic, and heterocyclic ketones have been converted into the corresponding cyanohydrin trimethylsilyl ethers in 83?96% yields with 52?84% ee. Several factors concerning the reactivity and enantioselectivity have been discussed. A double activation where Cu(salen) plays the role of Lewis acid and Ph₃PO acts as a Lewis base is reported. Poly(ethylene glycol) monomethyl ether (MeO-PEG) has been used as a soluble support while JandaJel (JJ) and Merrifield (MF) resins served as insoluble supports. Each polymer is linked to the salen catalyst through a glutarate spacer. The soluble catalysts were recovered by precipitation with a suitable solvent while the insoluble catalysts were simply filtered from the reaction mixture. The JandaJel-attached Cu(salen) catalyst could be used for five cycles with the retention of efficiency and the Merrifield-bound Cu(salen) catalyst was found to loose activity with each use.