Presented herein is the synthesis and characterization of a new Fe(III)Zn(II) complex containing a Fe(III)-bound phenolate with a carbonyl functional group, which was anchored to 3-aminopropyl-functionalized silica as the solid support. The catalytic efficiency of the immobilized catalyst in the hydrolysis of 2,4-bis(dinitrophenyl)phosphate is comparable to the homogeneous reaction, and the supported catalyst can be reused for subsequent diester hydrolysis reactions.
Gold nanoparticles dispersed in an ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (Au-BMI.PF(6)) and a binuclear nickel(II) complex ([Ni(2)(HBPPAMFF)mu-(OAc)(2)(H(2)O)]BPh(4)) immobilized on functionalized silica were successfully applied in the construction of a novel sensor for the determination of fisetin by square-wave voltammetry. Under optimized conditions, the analytical curve showed two linear ranges for fisetin concentrations from 0.28 to 1.39 microM and 2.77 to 19.50 microM with a detection limit of 0.05 microM. This sensor demonstrated suitable stability (ca. 150 days; at least 500 determinations) and good repeatability and reproducibility, with relative standard deviations of 2.91 and 5.11%, respectively. The recovery study of fisetin in apple juice samples gave values from 96.4 to 106.4%. The efficient analytical performance of the proposed sensor can be attributed to the effective immobilization of the Ni(ii)Ni(ii) complex on silica and the Au-BMI.PF(6) contribution to the electrode response.
Presented herein is the design of a dinuclear Ni(II) synthetic hydrolase [Ni(2)(HBPPAMFF)(μ-OAc)(2)(H(2)O)]BPh(4) (1) (H(2)BPPAMFF = 2-[(N-benzyl-N-2-pyridylmethylamine)]-4-methyl-6-[N-(2-pyridylmethyl)aminomethyl)])-4-methyl-6-formylphenol) to be covalently attached to silica surfaces, while maintaining its catalytic activity. An aldehyde-containing ligand (H(2)BPPAMFF) provides a reactive functional group that can serve as a cross-linking group to bind the complex to an organoalkoxysilane and later to the silica surfaces or directly to amino-modified surfaces. The dinuclear Ni(II) complex covalently attached to the silica surfaces was fully characterized by different techniques. The catalytic turnover number (k(cat)) of the immobilized Ni(II)Ni(II) catalyst in the hydrolysis of 2,4-bis(dinitrophenyl)phosphate is comparable to the homogeneous reaction; however, the catalyst interaction with the support enhanced the substrate to complex association constant, and consequently, the catalytic efficiency (E = k(cat)/K(M)) and the supported catalyst can be reused for subsequent diester hydrolysis reactions.
The Michaelis-Menten equation is used in many biochemical and bioinorganic kinetic studies involving homogeneous catalysis. Otherwise, it is known that determination of Michaelis-Menten parameters K M , V max , and k cat by the well-known Lineweaver-Burk double reciprocal linear equation does not produce the best values for these parameters. In this paper we present a discussion on different linear equations which can be used to calculate these parameters and we compare their results with the values obtained by the more reliable nonlinear least-square fit.
Recebido em 10/8/07; aceito em 14/11/07; publicado na web em 8/7/08 Sulfonamides obtained by reaction of 8-aminoquinoline with 4-nitrobenzenesulfonylchloride and 2,4,6-triisopropylbenzenesulfonyl chloride were used to synthesize coordination compounds with Cu II and Zn II with a ML 2 composition. Determination of the crystal structures of the resulting zinc and copper complexes by X-ray diffraction show a distorted tetrahedral environment for the [Cu(qnbsa) 2 ], [Cu(qibsa) 2 ] and [Zn(qibsa) 2 ] complexes in which the sulfonamide group acts as a bidentate ligand through the nitrogen atoms from the sulfonamidate and quinoline groups. The complex [Zn(qnbsa) 2 ] crystallizes with a water molecule from the solvent and the Zn is five-coordinated and shows a bipyramidal-trigonal geometry. The electrochemical and electronic spectroscopy properties of the copper complexes are also discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.