One pot synthesis of structurally different mono and dimeric Ni(II) thiosemicarbazone complexes and N-arylation on a coordinated ligand: a comparative biological study

One pot synthesis of three structurally different Ni(II) thiosemicarbazone complexes 1, 2 and 3 were obtained from the reaction between [NiCl(2)(PPh(3))(2)], 1,2-bis(diphenylphosphino)ethane, and [H(2)-(Sal-tsc)]. The obtained products were characterized by various spectral and analytical techniques. From the X-ray crystallographic analysis, an unexpected N-arylation on the coordinated salicylaldehydethiosemicarbazone was found in complex 2. The comparative biological evolutions such as DNA/protein binding, antioxidant, cytotoxicity (MTT, LDH, and NO) and cellular uptake studies have been examined for [Ni(Sal-tsc)(PPh(3))] (1) and [(Ni(Sal-tsc))(2)(μ-dppe)] (3). When comparing the cytotoxicity of the complexes, 1 exhibited higher activity than 2 and 3 and by comparing with standard cis-platin, both of them were found to exhibit better activity under identical conditions.     

P-type nitrogen-doped ZnO nanoparticles stable under ambient conditions

Zinc oxide is considered as a very promising material for optoelectronics. However, to date, the difficulty in producing stable p-type ZnO is a bottleneck, which hinders the advent of ZnO-based devices. In that context, nitrogen-doped zinc oxide receives much attention. However, numerous reviews report the controversial character of p-type conductivity in N-doped ZnO, and recent theoretical contributions explain that N-doping alone cannot lead to p-typeness in Zn-rich ZnO. We report here that the ammonolysis at low temperature of ZnO(2) yields pure wurtzite-type N-doped ZnO nanoparticles with an extraordinarily large amount of Zn vacancies (up to 20%). Electrochemical and transient spectroscopy studies demonstrate that these Zn-poor nanoparticles exhibit a p-type conductivity that is stable over more than 2 years under ambient conditions.     

Electrochemiluminescence Mechanisms Investigated with Smartphone-Based Sensor Data Modeling,Parameter Estimation and Sensitivity Analysis

The present study introduces a unified framework combining a mechanistic model with a genetic algorithm (GA) for the parameter estimation of electrochemiluminescence (ECL) kinetics of the Ru(bpy)₃²⁺/TPrA system occurring in a smartphone-based sensor. The framework allows a straightforward solution for simultaneous estimation of multiple parameters which can be, otherwise, time-consuming and lead to non-convergence. Model parameters are estimated by achieving a high correlation between the model prediction and the measured ECL intensity from the ECL sensor. The developed model is used to perform a sensitivity analysis (SA), which provides quantitative effects of the model parameters on the concentrations of chemical species involved in the system. The results demonstrate that the GA-based parameter estimation and the SA approaches are effective in analyzing the kinetics of the ECL mechanism. Therefore, these approaches can be incorporated as analysis tools in the ECL kinetics study with practical application in the calibration of mechanistic models for any required sensing condition.     

Correlation between extrinsic magnetoresistance and electroresistance in La0.6Pb0.4MnO3 thin films as revealed from current-voltage and ferromagnetic resonance studies

We have investigated magnetoresistance (MR) and electroresistance (ER) of well characterized La_0.6Pb_0.4MnO₃ (LPMO) films having two different crystallinity (i) (00l) oriented single-crystalline, SC, i.e. without any grain boundaries, and (ii) nanocrystalline, NC, with an average grain size of 17 nm. Both MR and ER were remarkably different for the two films, that is, (i) NC films exhibited a highest MR of ∼100% near the metal-insulator transition temperature; while for SC films the MR was in the range of 40-60%, (ii) NC films exhibited a finite ER, which increased monotonically with decreasing temperature; while in SC films ER was completely absent. Using current-voltage characteristic and ferromagnetic resonance studies we demonstrate that both enhanced MR and ER in NC films are extrinsic in nature and originate due to the presence of spin glassy grain boundaries.     

Microwave induced selective enolization of steroidal ketones and efficient acetylation of sterols in semisolid state

Under microwave irradiation steroidal enones, more specifically, position three carbonyls were efficiently and selectively converted to the corresponding enol acetates in the presence of additional enolizable carbonyl functions at other positions, using acetic anhydride and a catalytic amount of toluene-p-sulfonic acid. Acetylation of hydroxyl groups of the sterols, including those at the hindered positions, was near quantitative. Strictly anhydrous conditions were not a pre-requisite for acetylation and the reaction system easily tolerated up to 10% (v/v) moisture.     

Study of the reactions of pyridinium poly(hydrogen fluoride) with some ternary oxides

The products of the reaction of pyridinium poly(hydrogen fluoride), PPHF, with KIO₃, Na₂SnO₃, NaBiO₃, K₂CrO₄, Na₂MoO₄ and Na₂WO₄ were KIO₂F₂; Na₂SnF₆; NaHF₂, BiF₃; K₃CrF₆, KHF₂, (PyH)₃CrF₆; NaHF₂, (PyH)₂MoO₂F₄·2NaHF₂; and (PyH)₂WO₂F₄·2NaHF₂, respectively, while KClO₃, KBrO₃ and KIO₄ react with complete decomposition to form KHF₂ as the fluorinated product. This differential reactivity and mode of reaction has been discussed in terms of the oxidation state of the central atom, the nature and strength of the bonds and the complex behaviour of the formed intermediate or fluorinated products that undergo complexation or solvation with pyridine and/or hydrogen fluoride.     

Reaction of sulphuryl chlorofluoride with a few metals and metal oxides

Sulphuryl chlorofluoride has no observable reaction with metals and metal oxides at room temperature. Metals like copper, silver, iron, and zinc react with the chlorofluoride in the temperature range 200–400°C. Metal chlorides, metal fluorides and sulphur dioxide are the main products of these reactions. With the corresponding metal oxides, on the other hand, the respective metal sulphates are formed in addition to the metal chlorides and fluorides. In the case of lead and lead oxide, lead chlorofluoride is formed instead of lead chloride and lead fluoride. Sulphuryl fluoride is formed in small quantities in all these reactions by the decomposition of the chlorofluoride. Glass is not attacked by sulphuryl chlorofluoride below 500°C.During the course of our investigations on the reactivity of sulphuryl chlorofluoride, it is observed that sulphuryl chlorofluoride does not react with glass up to 500° C. However, it reacts with metals and metal oxides between 200° to 400° C. The reaction products with metals are the corresponding metal chlorides, metal fluorides and sulphur dioxide. With the oxides, in addition to the metal chlorides and metal fluorides, metal sulphates are formed. The results of these investigations are presented in this communication.     

Aqueous polymerization of acrylonitrile initiated by the Mn3+/citric acid redox system

Kinetics of polymerization of acrylonitrile initiated by the redox system Mn³⁺/citric acid were investigated in aqueous sulphuric acid in the range of 20–25°; initial rates of polymerization and Mn³⁺ disappearance etc. were measured. The effects of certain water miscible organic solvents and certain cationic and anionic detergents on the rate of polymerization have been examined. A mechanism has been suggested involving formation of a complex between Mn³⁺ and citric acid, decomposition of which yields the initiating free radical and with polymerization being terminated by mutual interaction of growing radicals.