Organoplatinum(IV) tris-chelate complexes, each having a cyclic metallacarbonate ring: synthesis, characterization and kinetic studies of the formation

The complexes [Pt[(CH2)4](NN)], 1a (NN = 2,2'-bipyridine) and 1b (NN = 1,10-phenanthroline) react with 2,3-epoxypropylphenyl ether in the presence of CO2 to give tris-chelate platina(IV)cyclopentane complexes characterized by 1H and 13C NMR spectroscopy as [Pt[(CH2)4](CH2CHCH2OPhOCO2)(NN)], 2. The reactions proceed by the SN2 mechanism and the rates were independent of concentration of CO2. It is demonstrated that for 1a, the reaction proceeds 2.32 times faster than the similar reaction in which the dimethyl analog, [PtMe2(2,2'-bipyridine)], is used. The analog tris-chelate complex [Pt[(CH2)4](CH2CHPhOCO2)(phen)], 3a, was similarly synthesized.     

Sonochemical synthesis of silver vanadium oxide micro/nanorods: Solvent and surfactant effects

In this investigation, a facile sonochemical route has been developed for the preparation of silver vanadium oxide (SVO) micro/nanorods by using silver salicylate and ammonium metavanadate as silver and vanadate precursor, respectively. Here, silver salicylate, [Ag(HSal)], is introduced as a new silver precursor to fabricate AgVO₃ nanorods. The effect of numerous solvents and surfactants on the morphology and sonochemical formation mechanism of AgVO₃ nanorods was studied. AgVO₃ nanorods were characterized by SEM and TEM images, XRD patterns, FT-IR, XPS, and EDS spectroscopy. SEM, TEM, and XRD results showed that AgO nanoparticles were formed onto AgVO₃ nanorods in the presence of ethanol, cyclohexanol, dimethylsulfoxide (DMSO), and acetone. By using polyethylene glycol (PEG-6000) and N,N-dimethylformamide (DMF) as organic additives, the thickness of AgVO₃ nanorods decreased.     

Comparison of graphs associated to a commutative Artinian ring

Let R be a commutative ring with \(1\ne 0\) and the additive group \(R^+\). Several graphs on R have been introduced by many authors, among zero-divisor graph \(\Gamma _1(R)\), co-maximal graph \(\Gamma _2(R)\), annihilator graph AG(R), total graph \( T(\Gamma (R))\), cozero-divisors graph \(\Gamma _\mathrm{c}(R)\), equivalence classes graph \(\Gamma _\mathrm{E}(R)\) and the Cayley graph \(\mathrm{Cay}(R^+ ,Z^*(R))\). Shekarriz et al. (J. Commun. Algebra, 40 (2012) 2798–2807) gave some conditions under which total graph is isomorphic to \(\mathrm{Cay}(R^+ ,Z^*(R))\). Badawi (J. Commun. Algebra, 42 (2014) 108–121) showed that when R is a reduced ring, the annihilator graph is identical to the zero-divisor graph if and only if R has exactly two minimal prime ideals. The purpose of this paper is comparison of graphs associated to a commutative Artinian ring. Among the results, we prove that for a commutative finite ring R with \(|\mathrm{Max}(R)|=n \ge 3\), \( \Gamma _1(R) \simeq \Gamma _2(R)\) if and only if \(R\simeq \mathbb {Z}^n_2\); if and only if \(\Gamma _1(R) \simeq \Gamma _\mathrm{E}(R)\). Also the annihilator graph is identical to the cozero-divisor graph if and only if R is a Frobenius ring.     

Synthesis and characterization of some nickel(II) Schiff bases complexes

Summary The reaction of nickel(II) salts with 2-picolyl- and 2,6-lutidyl-phenylketone benzoylhydrazone and theirp-nitro- andp-methoxy-derivatives were carried out and the compounds characterized on the basis of analytical and spectral data.     

Highly selective thiocyanate poly(vinyl chloride) membrane electrode based on a cadmium–Schiff’s base complex

A PVC membrane electrode based on a cadmium–salen (N,N′-bis-salicylidene-1,2ethylenediamine) complex as an anion carrier is described. The electrode has an anti-Hofmeister selectivity sequence with a preference for thiocyanate at pH 1.5–11.0. It has a linear response to thiocyanate from 1.0 × 10^–6 to 1.0 × 10^–1 mol L^–1 with a slope of 59.1 ± 0.2 mV per decade, and a detection limit of 7 × 10^–7 mol L^–1. This electrode has high selectivity for thiocyanate relative to many common organic and inorganic anions. The proposed sensor has a fast response time of approximately 15 s. It was applied to the determination of thiocyanate in a milk sample. Received: 1 December 2000 / Revised: 19 April 2001 / Accepted: 30 April 2001     

A model of nanofluids effective thermal conductivity based on dimensionless groups

Thermal conductivity is an important parameter in the field of nanofluid heat transfer. This article presents a novel model for the prediction of the effective thermal conductivity of nanofluids based on dimensionless groups. The model expresses the thermal conductivity of a nanofluid as a function of the thermal conductivity of the solid and liquid, their volume fractions, particle size and interfacial shell properties. According to this model, thermal conductivity changes nonlinearly with nanoparticle loading. The results are in good agreement with the experimental data of alumina-water and alumina-ethylene glycol based nanofluids.     

Synthesis, characterization and catalytic oxyfunctionalization of cyclohexene with tert-butylhydroperoxide over a manganese(II) complex covalently anchored to multi-wall carbon nanotubes (MWNTs)

The chemical modification of multi-wall carbon nanotubes (MWNTs) is an emerging area in material science. In the present study, an hydroxyl functionalized manganese(II) Schiff-base has been covalently anchored on modified MWNTs. The new modified MWNTs have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), thermal analysis, UV–Vis, diffuse reflectance (DRS), FT-IR spectroscopy and elemental analysis. The results suggest that the symmetrical Schiff-base; N,N-bis(4-hydroxysalicylidene)-ethylene-1,2-diamine; H₂[(OH)₂-salen]; is a bivalent anion with tetradentate N₂O₂ donors derived from the phenolic oxygens and azomethine nitrogens. The formulae was found to be [Mn((OH)₂-salen)] for the 1:1 non-electrolytic complex. The multi-wall carbon nanotubes covalently anchored manganese(II) complex ([Mn((OH)₂-salen)]@MWNTs) catalyze the oxidation of cyclohexene with TBHP. Oxidation of cyclohexene catalyzed by this complex gave 2-cyclohexene-1-ol, 2-cyclohexene-1-one and 1-(tert-butylperoxy)-2-cyclohexene as the major products. The manganese(II) complex covalently anchored on MWNTs shows significantly higher catalytic activity than [Mn((OH)₂-salen)]. The activity of the immobilized catalyst remains nearly the same after three cycles, suggesting the true heterogeneous nature of the catalyst. This catalyst is more selective towards 2-cyclohexene-1-one.     

Thermal properties of mercury(II) and palladium(II) purine and pyrimidine complexes

Six solid Pd(II) and Hg(II) complexes of some purines and pyrimidines have been prepared and characterized by elemental analyses, IR, UV–Vis spectra, magnetic measurements, and thermal analyses. The data suggest tetrahedral and square planar geometries for mercury and palladium complexes, respectively. The thermal behavior of the complexes has been studied applying TG, DTA, and DSC techniques, and the thermodynamic parameters and mechanisms of the decompositions were evaluated. The ?S* values of the decomposition steps of the metal complexes indicated that the activated fragments have more ordered structure than the undecomposed complexes, and/or the decomposition reactions are slow. The thermal processes proceeded in complicated mechanisms where the bond between the central metal ion and the ligands dissociates after losing small molecules such as H₂O, HCl or C=O. The palladium adenine complex is ended with the metal as a final product. However, the thermal reactions of the other five palladium and mercury pyrimidines complexes are ended with metal bonded to O, N, or S of the pyrimidine ring.