New surface-modified zinc oxide nanoparticles with aminotriethylene oxide chains linked by 1,2,3-triazole ring: Preparation, and visible light-emitting and noncytotoxic properties

Novel surface-modified, visible light-emitting and noncytotoxic ZnO nanoparticles (NPs) (ZPAZ) having aminotriethylene oxide chains linked by 1,4- and/or 1,5-disubstituted 1,2,3-triazole rings were prepared from ZnO NPs (ZPA) with ethynyl groups on the surfaces and an azide derivative of triethylene oxide chain linking terminal amino group (ATA) via 1,3-dipolar azide/alkyne click reaction by heating without Cu(I) catalyst. FTIR spectroscopy, elemental analysis, XRD analysis and TEM observation suggested that the resulting ZPA and ZPAZ NPs have the particle sizes below 10 nm in diameters, triethylene oxide chains linking the terminal amino groups and wurtzite crystal structure. UV-vis absorption spectrum of the ZPAZ NPs in methanol showed maximum absorption band at 346.5 nm, supporting the TEM observation. PL spectra depicted that the ZPA and ZPAZ NPs display broad light green and lightly greenish yellow visible light emitting bands in methanol. Zeta potentials measured in distilled water suggested that the ZPAZ NPs have a low tendency to aggregate and possess better stability than the ZPA NPs. Cytotoxicity assay revealed that the ZPAZ NPs, having water-dispersion properties, are noncytotoxic at low concentrations and almost all RAW264.7 cells are alive after 24 h of treatment.     

Ion-pair extraction of some cinchona alkaloids with various chiral organic anions

Some cinchona alkaloids, the quinine/quinidine and cinchonine/cinchonidine pairs, are extracted by ion-pair formation with some chiral amino acids and d-camphorsulfonic acid. Their extraction behaviors are examined and the differences between the two isomers are compared. These alkaloids are extracted into chloroform in the pH range 4–7 as the 1:1 ion-pair with the organic acid. The relationship between the distribution ratio of the ion-pair and pH is discussed. In the pH range between the pK_a1 and pK_a2 values of these alkaloids, logarithmic plots of the distribution ratio are independent of pH. In this pH region, the extraction constants are determined and the differences caused by the ion-pair formation are discussed.     

Reactivity of a kinetically stabilized 1,3,6-triphosphafulvene toward some nucleophiles

A kinetically stabilized 1,3,6-triphosphafulvene displayed regioselective reactivity toward nucleophiles at the external phosphorus atom (position 6) to afford the corresponding phosphinodiphospholide anions, which gave phosphinodiphospholes after quenching with electrophiles, as well as being readily reduced by sodium naphthalenide suggesting properties similar to fulvenes.     

Mesomorphic phase transitions of tetraphenylporphyrins with four long aliphatic chains

Abstract

Studies of 5,10,15,20-tetrakis(4-n-alkylphenyl)porphyrins revealed that the homologues with longer alkyl chains than hexyl were mesomorphic, in contrast to the non-mesomorphic alkoxy derivatives. Metal complexes (Co, Ni, Cu, Zn, and Pd) of the dodecyl derivative were also shown to exhibit mesophases. These mesophases were assigned as discotic lamellar (D_L) phases by X-ray diffraction studies.     

Improved omnibus test statistic for normality

We propose a new omnibus test statistic for normality based on the Jarque–Bera test statistic. We give the exact first four moments of the null distribution for the statistic using a computer algebra system. Our proposed statistic is an improvement of Jarque–Bera test statistic. Then the cumulants of the standardized statistic satisfy the Cornish–Fisher assumption. We give a normalizing transformation of the statistic based on the Wilson–Hilferty transformation.     

Sequential perfluoroalkylation and asymmetric reduction of nitriles triggered with perfluoroalkyl titanates: catalytic asymmetric synthesis of perfluoroalkyl amines

Highly enantio-enriched perfluoroalkyl amines are shown to be synthesized by perfluoroalkylation and asymmetric reduction of nitriles. Perfluoroalkylation of nitriles can be attained by the Lewis acidic perfluoroalkyl titanate reagents to give acyclic ketimines. Catalytic asymmetric hydrogenation of the acyclic ketimines affords the perfluoroalkyl amine products in up to 93% ee.     

Reliable enzyme immunoassay detection for chlorothalonil: fundamental evaluation for residue analysis and validation with gas chromatography

This work describes the analytical performance of the enzyme-linked immunosorbent assay (ELISA) for the fungicide chlorothalonil to effectively exploit as a simple and rapid detection system for pesticide residue on the scenes of the agricultural production and distribution. This ELISA represents the satisfactory analytical characteristics (I50 value, 0.34 ng/g; limit of detection, 0.052 ng/g) to detect chlorothalonil at the regulatory values or thereabout in a sample. Noticeable cross-reactivities were shown with two fungicides, fthalide (58.8%) and pentachloronitrobenzene (quintozene) (20.0%), and some non-agrochemicals such as tetrachloroterephthalonitrile (96.8%) and tetrachlorophthalonitrile (68.3%). The influence of three organic solvents (methanol, acetone, and acetonitrile) used as extractants for chlorothalonil residue was evaluated, with the result that methanol was the most suitable solvent for the ELISA, and the final concentration in the well could be up to 5% (v/v) without any negative influence on the ELISA. It has been possible to directly analyze chlorothalonil residue only by giving dilution of each sample extract with water prior to the ELISA analysis. The average recovery values from the spiked samples by the ELISA were between 101.7 and 113.6% with the average coefficients of variation between 2.6 and 5.9%. Although the results obtained from the ELISA correlated well with those from the reference GC/MS methods for all agricultural samples (r>0.98), the linear function inclined to the ELISA results because of loss during complex sample preparations for GC/MS analysis. Nevertheless, the results demonstrated that the proposed ELISA is a reliable, cost-effective, and rapid quantitative method for chlorothalonil residue.     

Neutron and X-ray diffraction and spectroscopic investigations of intramolecular [C-H...F-C] contacts in post-metallocene polyolefin catalysts: modeling weak attractive polymer-ligand interactions

A family of Group 4 post-metallocene catalysts, supported by fluorine-functionalized tridentate ligands with the fluorine substituent in the locality of the metal center, is described. For the first time, the contentious C-H...F-C interaction has been characterized by a neutron diffraction study, which has allowed the position of the hydrogen atoms to be accurately determined. The nature of the weak intramolecular C-H...F-C contacts in these complexes in solution and the solid state was probed by using multinuclear NMR spectroscopy in tandem with neutron and X-ray crystallography. Evidence is presented to demonstrate that the spectroscopic C-H...F-C coupling occurs "through-space" rather than "through-bond" or by MF coordination. The titanium catalysts exhibit excellent activities and high co-monomer incorporation in olefin polymerization. The observed intramolecular C-H...F-C interactions are important with regards to potential applications in polyolefin catalysis because they substantiate the proposed ortho-F...H(beta) ligand-(polymer chain) contacts derived from DFT calculations for the remarkable fluorinated phenoxyimine Group 4 catalysts. Compared with agostic and co-catalyst...metal contacts, weak attractive noncovalent interactions between a polymer chain and a judiciously designed "active" ligand is a new concept in polyolefin catalysis.