Abstract Two cobalt(II) complexes of the Schiff base with morpholino or aza‐crown ether pendants, CoL 1 and CoL 2 , as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester (PNPP). The analysis of specific absorption spectra of the hydrolytic reaction systems indicates that key intermediates, made up of PNPP and Co(II) complexes, have been formed in reaction processes of the PNPP catalytic hydrolysis. The mechanism of PNPP catalytic hydrolysis has been proposed based on the analytic result of specific absorption spectrum. A kinetic mathematical model, applied to the calculation of the kinetic parameter of PNPP catalytic hydrolysis, has been established based on the mechanism proposed. The acid effect of buffer solution, structural effect of the complexes, and effect of temperature on the rate of PNPP hydrolysis catalyzed by the complexes have been also discussed.
The surfactant ligand 2,2′,2″-(dodecylammonio)triacetate (L) was synthesised and characterised. The kinetics of hydrolysis of bis(4-nitrophenyl) phosphate (BNPP) in the catalytic system containing the surfactant ligand and cobalt(II) were investigated. The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that key intermediates made up of BNPP and the Co(II) complex are formed. Here, the proposed mechanism of BNPP catalytic hydrolysis is based on the analytical result of the specific absorption spectrum and the corresponding kinetic constants are calculated. The results show that the Co(II) complex as a hydrolase mimic exhibits good catalytic activity and similar catalytic character to the natural enzyme.
Herein, we reported a well-controlled hydrothermal synthesis of Co3O4 nanowires using CoSO4 as a cobalt precursor and glycerol as a morphological directing agent. Scanning electron microscopy was employed to observe the growth of nanowires. As an important synthetic parameter, reaction time is spanned from 4 to 24 h, which played an important role in the morphology and properties of materials. When the reaction time was 4 h, the resulting Co3O4 nanoparticles assembled into some short nanorods. While increasing the reaction time, the nanorods grew into long nanowires with large aspect ratio, and then attached into bundles when the reaction time was extended up to 24 h. Electrochemical characterization shows that Co3O4 nanowires prepared by hydrothermal reaction for 12 h exhibited the highest catalytic activity for oxygen evolution reaction (OER) among all synthesized nanowires and nanoparticles using the similar method. The enhanced OER activity of the 12 h-prepared Co3O4 nanowires should be attributed to the increased electroactive surface area because observed from the cyclic voltammogram, the 12 h-prepared Co3O4 nanowires possessed the highest surface area among all tested samples. It was also illustrated that there existed a close correlation of the OER catalytic activity with the transition of oxidation state and the density of activity sites of the catalyst exposing to the electrolyte solution during the electrolysis. Though both Co3O4 nanowires and nanoparticles exhibited a considerable loss in OER activity during the stability testing, after polarization for 4 h at 1.7 V (versus a reversible hydrogen electrode), the Co3O4 nanowires still produced the higher catalytic current than that of the Co3O4 nanoparticles showing a slightly higher stability than the particles because of the nanowire structure.
MTT assay is adopted to study of proliferation inhibiting effect of four kinds of alkyl trimethyl ammonium chlorides and three kinds of alkyl dimethyl benzyl ammonium chlorides on HeLa cells and CHO cells,and to discuss cyto-toxicity of two kinds of cationic surfactants which are structurally related.The results indicated that the proliferation inhibiting effect of alkyl trimethyl ammonium chlorides and alkyl dimethyl benzyl ammonium chlorides on both HeLa cells and CHO cells gradually increased with concentration increasing;and as for the same concentration,proliferation inhibiting effect of both two kinds increased with the number of carbons increasing.Cytotoxicity of alkyls dimethyl benzyl ammonium chloride is stronger than that alkyls trimethyl ammonium chloride.
One novel dodecyliminodiacetate nickel (II) complex were synthesized and characterized, and these complexes were used as mimic hydrolytic in catalytic hydrolysis of bis (p-nitrophenyl) phosphate (BNPP). The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by BNPP with nickel (II) complexes. The kinetic parameter of BNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 95.26kJ·mol -1 .
The hydrophobic ionic liquids/water two-phase system was developed to prepare CuO nano particles. The catalytic activity of the synthesized CuO was investigated by photodegradation of 4-nitrophenol (4-NP) in the presence of H2O2 under visible light irradiation. The optical properties of the synthesized CuO were characterized by ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS). Experimental results indicated that the band gap energy (Eg), conduction band edge potential (ECB) and valence band edge potential (EVB) of the synthesized CuO were 1.37 eV, 0.625 eV and 1.995 eV, respectively. A degradation efficiency of 4-NP (4.8 mmol L−1) as high as 95.3% could be achieved under the conditions of pH 6.0, 0.48 g L−1 of CuO dosage, 1.4% of H2O2 dosage and 90 min of degradation time. The synthesized CuO exhibited poor catalytic activity under alkaline conditions due to the disassociation of 4-NP, which elevated the repulsion between CuO and the 4-NP anions. The synthesized CuO nano particles exhibited higher catalytic activity compared with the catalysts reported in literature. Furthermore, the synthesized CuO nano particles could be reused at least six times without decreasing their catalytic activity. Compared with the traditional hydrothermal method, mild operating conditions and time saving are the advantages of the developed method for the preparation of CuO.
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