Ba3MIIITiMVO9 (MIII = Fe,Ga, Y,Lu; MV = Nb,Ta, Sb) perovskite oxides: Synthesis,structure and dielectric properties

We describe the synthesis, structures and dielectric properties of new perovskite oxides of the formula, Ba₃M^IIITiM^VO₉, for M^III = Fe, Ga, Y, Lu and M^V = Nb, Ta, Sb. While M^V = Nb and Ta oxides adopt disordered/partially ordered 3C perovskite structures where M^III/Ti/M^V metal-oxygen octahedra are corner-connected, the M^V = Sb oxides show a distinct preference for the 6H structure, where Sb^V/Ti^IV metal-oxygen octahedra share a common face forming (Sb,Ti)O₉ dimers that are corner-connected to the M^IIIO₆ octahedra. The preference of antimony oxides (Sb^V:4d¹⁰) for the 6H structure – which arises from a special Sb^V–O chemical bonding that tends to avoid linear Sb–O–Sb linkages unlike Nb^V/Ta^V:d⁰ atoms which prefer ～180° Nb/Ta–O–Nb/Ta linkages – is consistent with the crystal chemistry of M^V–O oxides in general. The dielectric properties reveal a significant difference among M^III members. All the oxides with the 3C structure excepting those with M^III = Fe show a normal low loss dielectric behaviour with ε = 20–60 in the temperature range 50–400 °C; the M^III = Fe members with this structure (M^V = Nb, Ta) display a relaxor-like ferroelectric behaviour with large ε values at frequencies ≤1 MHz (50–500 °C).     

Dihydrogen phosphate mediated supramolecular frameworks in 2‐ and 4‐chloroanilinium dihydrogen phosphate salts

The title compounds, 2‐chloroanilinium dihydrogen phosphate (2CADHP) and 4‐chloroanilinium dihydrogen phosphate (4CADHP), both C₆H₇NCl⁺·H₂PO₄⁻, form two‐dimensional supramolecular organic–inorganic hybrid frameworks. In 2CADHP, the dihydrogen phosphate anions form a double‐stranded anionic chain generated parallel to the [010] direction through O—H...O hydrogen bonds, whereas in 4CADHP they form a two‐dimensional supramolecular net extending parallel to the crystallographic (001) plane into which the cations are linked through strong N—H...O hydrogen bonds.     

An Amperometric Biological Toxic Hydrazine Sensor Based on Multiwalled Carbon Nanotubes and Iron Tetrasulfonated Phthalocyanine Composite Modified Electrode

Hydrazines are well‐known for their diverse biological properties but especially for their toxicity. An amperometric hydrazine sensor was developed at multi‐walled carbon nanotubes (MWCNT) and iron tetrasulfonated phthalocyanine (FeTsPc) composite modified electrode for the first time. The TEM and UV‐Vis spectroscopy results revealed the successful formation of MWCNT/FeTsPc composite. Compared with the response of MWCNT and FeTsPc modified electrodes, the MWCNT/FeTsPc composite showed enhanced oxidation current response with lower overpotential for hydrazine. Under optimum conditions, the amperometric i–t response of hydrazine was linear in the concentration range from 100 nM L^?1 to 3 μM L^?1 with the detection limit of 7.6 nM L^?1. The response time of hydrazine was found as 6 s with a high sensitivity of 7.615 μA/μM L^?1 cm^?2.     

Simultaneous and Selective Detection of Environment Hazardous Metals in Water Samples by Using Flower and Christmas Tree Like Cerium Hexacyanoferrate Modified Electrodes

We report facile, template‐free, surfactant‐less flower and Christmas tree‐like cerium hexacyanoferrate (CeHCF) modified electrodes for simultaneous measurement of environmentally hazardous metals. The hierarchical growth of CeHCF on electrode surface was controlled by electrodeposition time at constant potential. This CeHCF modified electrode exhibits a prominent electrocatalytic activity towards detection of heavy metal ions such as cadmium (Cd), copper (Cu), lead (Pb) and mercury (Hg). The peaks are separated well at CeHCF modified electrode. Well separated peaks for the detection of these heavy metals in lake and tap water samples indicating CeHCF modified electrode as successful electrode for the reported sensor.     

A metal-organic framework sustained by a nanosized Ag12 cuboctahedral node for solid-phase extraction of ultra traces of lead(II) ions

We show that a metal-organic framework (MOF) sustained by a nanosized Ag12 cuboctahedral node can be applied to selectively extract traces of lead(II) ion from environmental water samples. The MOF was characterized by thermogravimetric and differential thermal analysis, scanning electron microscopy, FTIR, and X-ray diffraction. The effects of pH value, flow rates, of type, concentration and volume of the eluent, of break-through volume and potentially interfering ions on the separation and determination of lead were evaluated. Following desorption with EDTA, Pb(II) was quantified by FAAS. The use of the MOF results in excellent analytical figures of merit including an analytical range from 2 to 180 μg L^?1 of Pb(II) (R²?>?0.99); a limit of detection of 500 ng L^?1; an adsorption capacity of 120 mg g^?1; an extraction efficiency of >95 %, and a relative standard deviation of <4 % (for eight separate column experiments).

Synthesis and characterization of low-spin and cation radical complexes of ruthenium(III) of a tridentate pyridine bis-amide ligand

Using a tridentate bis-amide ligand 2,6-bis(N-phenylcarbamoyl)pyridine (H(2)L), in its deprotonated form, a new mononuclear ruthenium(III) complex [Et(4)N][RuL(2)] x H(2)O (1) has been synthesized. Structural analysis reveals that the RuN(6) coordination comprises four deprotonated amide-N species in the equatorial plane and two pyridine-N donors in the axial positions, imparting a tetragonally compressed octahedron around Ru. To the best of our knowledge, this is the first time that a ruthenium(III) complex coordinated solely by two tridentate deprotonated peptide ligands has been synthesized and structurally characterized. When examined by cyclic voltammetry, complex 1 displays in MeCN/CH(2)Cl(2) solution three chemically/electrochemically reversible redox processes: a metal-centered reductive Ru(III)-Ru(II) couple (E(1/2) = -0.84/-0.89 V vs SCE) and two ligand-centered oxidative responses (E(1/2) = 0.59/0.60 and 1.05/1.05 V vs SCE). Isolation of a dark blue one-electron oxidized counterpart of 1, [RuL(2)] x H(2)O (2), has also been readily achieved. The complexes have been characterized by analytical, solution electrical conductivity, IR, electronic absorption and EPR spectroscopy, and temperature-dependent magnetic susceptibility measurements. For complex 1, a weak and broad transition within the t(2g) level has been identified at approximately 1400 nm and supported by EPR spectral analysis (S = (1)/(2)). Temperature-dependent magnetic susceptibility data provide unambiguous evidence that in 2 strong antiferromagnetic coupling of the S = (1)/(2) ruthenium atom with the S = (1)/(2) ligand pi-cation radical leads to an effectively S = 0 ground state ((1)H NMR spectra in CDCl(3) solution).     

Cleavage of benzyl ethers by triphenylphosphine hydrobromide

Triphenylphosphine hydrobromide was found to cleave the benzyl ethers derived from 1°, 2° alkyl, and aryl alcohols to the corresponding alcohols and benzyltriphenylphosphonium bromide in good yields. Alkene and allyl phosphonium salts were produced from the benzyl ethers with 3° alkyl and allyl groups, respectively. These results indicate that the formation of the product is determined by the relative stability of the carbocationic intermediate. The anhydrous, stoichiometric amount of PPh₃·HBr offers a new and effective method for the deprotection of benzyl ethers.     

Thermosensitive Micelles Based on Folate‐Conjugated Poly(N‐vinylcaprolactam)‐block‐Poly(ethylene glycol) for Tumor‐Targeted Drug Delivery

Thermosensitive PNVCL‐b‐PEG block copolymer coupled with folic acid was prepared as an anti‐cancer drug carrier. This polymer self‐assembled into stable micelles in aqueous solutions at above 33 °C. At 37 °C, the release profile of PNVCL‐b‐PEG‐FA micelles showed a slower and more controlled release of the entrapped 5‐FU than that at 25 °C. The blank and 5‐FU‐loaded PNVCL‐b‐PEG‐FA micelles did not induce remarkable cytotoxicity against the EA.hy 926 human endothelial cell line; however, 5‐FU‐loaded PNVCL‐b‐PEG‐FA micelles showed a cytotoxicity effect against 4T1 mouse mammary carcinoma cells due to the availability of loaded anti‐cancer drugs delivered to the inside of the cancer cells by the folate‐receptor‐mediated endocytosis process.

     

Preparation and Characterization of Mixed‐Valent Osmium Hexacyanoferrate/Silicomolybdate Hybrid Films and Their Electrocatalytic Properties

A polynuclear mixed‐valent osmium hexacyanoferrate/silicomolybdate film electrode has been prepared using repetitive cyclic voltammetry. The cyclic voltammograms have been recorded for the deposition of a mixed‐valent osmium hexacyanoferrate/silicomolybdate hybrid film directly from the mixture of Os³⁺, Fe(CN₆)^3?, and SiMo₁₂O₄₀^4? ions from the acidic aqueous solutions. The polynuclear mixed‐valent osmium hexacyanoferrate/silicomolybdate film exhibited four redox couples. The electrocatalytic properties of the osmium hexacyanoferrate/silicomolybdate film electrode have been studied. The modified electrode has shown good electrocatalytic properties towards the oxidation of dopamine, ascorbic acid, epinephrine, norepinephrine, and reduction of IO₃^?, Fe³⁺.     

Mononuclear, helical binuclear palladium and lithium complexes bearing a new pyrrole-based NNN-pincer ligand: fluxional property

A new pyrrole based NNN-pincer ligand, 2,5-bis(3,5-dimethylpyrazolylmethyl)pyrrole 2, was readily synthesized in two steps from pyrrole in 56% yield. The lithiation of the pincer ligand 2 using n-BuLi led to isolation of the dimeric lithium complex, [Li{μ-C(4)H(2)N-2,5-(CH(2)Me(2)pz)(2)-N,N,N}](2) 4, in 23% crystalline yield. The transmetalation reaction of 4 with [Pd(PhCN)(2)Cl(2)] afforded the mononuclear Pd(II) complex, [PdCl{C(4)H(2)N-2,5-(CH(2)Me(2)pz)(2)-N,N,N}] 5, containing one chloride ion in 45% yield. Alternatively 5 was obtained in an excellent yield of 87% by the reaction 2 of with [Pd(COD)Cl(2)] in the presence of triethylamine. On the contrary, a 20-membered macrometalacyclic molecule, [Pd(2)Cl(4){μ-C(4)H(3)N-2,5-(CH(2)Me(2)pz)(2)-N,N}(2)] 6, in which two PdCl(2) units are bridged by two molecules of 2 to give a helical structure, was synthesized by the reaction of 2 with [Pd(COD)Cl(2)] in the absence of base. The acetate analogue of complex 5, [Pd(OAc){C(4)H(2)N-2,5-(CH(2)Me(2)pz)(2)-N,N,N}] 3, was obtained by the treatment of 2 with [Pd(OAc)(2)]. The pyrrole twist angle of 5 is higher than that of 3. Complexes 3 and 5 show an AB pattern for their methylene protons at room temperature in CDCl(3) as well as in DMSO-d(6). The variable temperature NMR studies showed that the acetate and chloride complexes exhibit slightly different coalescence temperatures, which is a solvent dependent phenomenon, and twist angles.