Cyclometalated platinum(II) complexes containing monodentate phosphines: antiproliferative study

Reaction of cyclometalated platinum(II) precursor [Pt(C^N)Cl(dmso)], 1, C^N = N(1), C(2′)-chelated deprotonated 2-phenylpyridine and dmso = dimethylsulfoxide, with 1 equivalent of triphenyl phosphine, PPh₃, or 1,3,5-triaza-7-phosphaadamantane, PTA, gave the complex [Pt(C^N)Cl(PPh₃)], 2, or [Pt(C^N)Cl(PTA)], 3, respectively. On the basis of careful multinuclear NMR spectroscopy, supported by a number of 2D NMR experiments, structures of the complexes 2 and 3 in solution were determined to be neutral four coordinate. The X-ray crystallography indicated that the solid-state structure of complex 3 comprised a common square-planar geometry around platinum(II). Cytotoxicity of the complexes 2 and 3 was studied in three human cancer cell lines derived from ovarian carcinoma (CH1), lung carcinoma (A549), and colon carcinoma (SW480).     

Exceedingly Facile PhX Activation (X=Cl,Br, I) with Ruthenium(II): Arresting Kinetics,Autocatalysis, and Mechanisms

[(Ph₃P)₃Ru(L)(H)₂] (where L=H₂ ( 1 ) in the presence of styrene, Ph₃P ( 3 ), and N₂ ( 4 )) cleave the Ph? X bond (X=Cl, Br, I) at RT to give [(Ph₃P)₃RuH(X)] ( 2 ) and PhH. A combined experimental and DFT study points to [(Ph₃P)₃Ru(H)₂] as the reactive species generated upon spontaneous loss of L from 3 and 4 . The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2 , originating from the initial PhI activation with 3 , is roughly as reactive toward PhI as 3 itself; and 2) the Ph? I bond cleavage with the just‐produced 2 gives rise to [(Ph₃P)₂RuI₂], which quickly comproportionates with the still‐present 3 to recover 2 . Both the initial and onward activation reactions involve PPh₃ dissociation, PhI coordination to Ru through I, rearrangement to a η²‐PhI intermediate, and Ph? I oxidative addition.     

Synthesis and antibacterial evaluations of new pyridazino[4,3‐e][1,3,4]oxadiazines

Several derivatives of the new pyridazino[4,3‐e][1,3,4]oxadiazine ring system were prepared, and their antibacterial evaluations were performed on four different Gram‐negative and Gram‐positive bacteria. J. Heterocyclic Chem., (2010).     

Multiple hydrogen bondings in a platinum complex

An unprecedented example of a platinum(II) complex with simultaneous formation of intermolecular NH···I-Pt and CH···I-Pt H-bondings (with neighboring platinum center) and an intramolecular CH···Pt hydrogen bonding in solid state is described. There are indications showing that the complex in solution probably forms a different kind of H-bonding type interaction.     

Brushless and controlled microphase separation of lamellar polystyrene‐b‐polyethylene oxide thin films for block copolymer nanolithography

Creating perpendicular alignment in lamellar block copolymer (BCP) systems has considerable industrial and commercial significance, most importantly for generating nanowire structures in electronic devices. In general, these lamellar systems require careful interface engineering to obtain vertical orientation of the blocks. To avoid the strong preferential adsorption of one block to either the substrate or the polymer/air interface, the surface must be “neutralized” by chemical brushes or external forces, for example, solvent fields. Reported here is a stepwise thermo/solvent annealing process allowing the formation of perpendicular domains of polystyrene‐b‐polyethylene oxide lamellar structures while avoiding brush or other surface modifications. This BCP has a relatively small minimum feature size and can be used to generate substrate patterns for use in fabrication of nanowire electronic device structures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

3D dynamic modeling of powder forming processes via a simple and efficient node-to-surface contact algorithm

In this paper, a simple and efficient contact algorithm is presented for the evaluation of density distribution in three-dimensional dynamic modeling of powder compaction processes. The contact node-to-surface algorithm is employed to impose the contact constraints in large deformation frictional contact, and the contact frictional slip is modified by the Coulomb friction law to simulate the frictional behavior between the rigid punch and the work-piece. The 3D nonlinear contact friction algorithm is employed together with a double-surface cap plasticity model within the framework of large finite element deformation in order to predict the non-uniform relative density distribution during the dynamic simulation of powder die-pressing. The accuracy and robustness of contact algorithm is verified by the impact analysis of two elastic rods, which is compared with the analytical solution. Finally, the performance of computational schemes is illustrated in dynamic modeling of a set of powder components.     

Development of multi‐response optimization and quadratic calibration curve for determination of ten pesticides in complex sample matrices using QuEChERS dispersive liquid–liquid microextraction followed by gas chromatography

In this study, QuEChERS combined with dispersive liquid‐liquid microextraction is developed for extraction of ten pesticides in complex sample matrices of water and milk. In this regard, effective factors of proposed extraction technique combined with gas chromatography with flame ionization detector were designed, modeled, and optimized using central composite design, multiple linear regression, and Nelder–Mead simplex optimization. Later, univariate calibration model for ten pesticides was developed in concentration range of 0.5–100 ng/mL. Surprisingly, quadratic calibration behavior was observed for some of the pesticides. In this regard, Mandel's test was used for evaluating linearity and types of calibration equation. Finally, four pesticides followed linear calibration curve with sensitivity (0.23–0.66 mL/ng), analytical sensitivity (0.20–0.32), regression coefficient (0.988–0.995), limit of detection (0.39–1.83 ng/mL), and limit of quantitation (1.30–6.10 ng/mL) and six of them followed quadratic calibration curve with sensitivity (0.18–0.93 mL/ng), analytical sensitivity (0.25–0.86), regression coefficient (0.944–0.999), limit of detection (0.59–1.92 ng/mL), and limit of quantitation (1.96–6.40 ng/mL). The calculated limits of detection were below the maximum residue limits according to European Union pesticides database of European Commission. Finally, the proposed analytical method was used for determination of ten pesticides in water and milk samples.     

Three dimensional solution of thick rectangular simply supported plates under a moving load

Dynamic behavior of continuous systems such as beams and plates, under a moving load is an important engineering subject. In this paper, 3D elasticity equations are solved by use of the displacement potential functions and the exact solution of a simply supported thick rectangular plate under moving load is presented. For this purpose, the governing equations in terms of displacements, Navier’s equations, are converted to two linear partial differential equations of forth and second order using displacement potential functions. Then the governing equations in terms of the potential functions are solved using the separation of variables and Laplace integral transform, satisfying exact initial and boundary conditions. In order to validate the present approach, the obtained results of this study are compared with the results of the classical theory of plates for thin and existing solutions for moderately thick plates. Also, it is observed that the speed of a moving load has an important effect on the dynamic response of plate.