Determination of phenylenediamine isomers in hair dyes by coal cinders micro-column extraction and MEKC

A new micellar electrokinetic chromatography (MEKC) method using beta-cyclodextrins (β-CDs) and 1-butyl-3-methylimidazolium hexafluorophosphates (ionic liquids) as additives was successfully developed for determination of para-, meta-, and ortho-phenylenediamines isomers (p-P, m-P, and o-P) in hair dyes. To improve the sensitivity of the MEKC-UV, a simple and cheap flow injection (FI) technique using a micro-column packed with coal cinders (the by-products from combustion in a boiler) as solid-phase extractant was also investigated. In the presence of 20 mmol L(-1) phosphates at pH 5.5, addition of 12 mmol L(-1) ionic liquids and 8 mmol L(-1) β-CDs greatly improved the separation efficiency. The three analytes could be quantitatively adsorbed by coal cinders, and desorbed readily with 0.15 mL of 0.01 mol L(-1) NaOH. Under the optimum conditions, an enrichment factor (EF) of 33.3 was obtained, and determination limits of p-P, m-P, and o-P were 1.97?×?10(-7), 0.99?×?10(-7), and 0.61?×?10(-7) mol L(-1), respectively. The adsorption capacities of the coal cinders micro-column for p-P, m-P, and o-P were all 1.20 mg g(-1). The presented procedure was successfully applied to the determination of p-P, m-P, and o-P in hair dyes with satisfactory results.     

Characterize the interaction between naringenin and bovine serum albumin using spectroscopic approach

Naringenin, a flavanone compound highly enriched in grapefruits, has been identified as a possible inhibitor of cell proliferation; and thus has the potential to act as an antitumorigenic agent. In this study, the binding of naringenin to bovine serum albumin (BSA) was studied at the physiological conditions (pH=7.40) by fluorescence and UV-vis spectroscopy. Naringenin strongly quenches the intrinsic fluorescence of BSA, and a decrease in the fluorescence quenching constant was observed together with an increase in temperature, which indicates that the fluorescence quenching of BSA by naringenin is a result of the formation of naringenin-BSA complex. Binding parameters calculating from Stern-Volmer method and Scatchard method showed that naringenin bind to BSA with the binding affinities of the order 10⁴ L mol⁻¹. Thermodynamic parameters such as ΔG, ΔH and ΔS, were calculated at different temperatures, showing that electrostatic interactions were mostly responsible for the binding of naringenin to BSA. Site marker competitive displacement experiments demonstrating that naringenin bind with high affinity to site I (subdomain IIA) of BSA. Furthermore, the effect of metal ions to naringenin-BSA system was studied, and the specific binding distance r (3.30 nm) between donor (Trp-212) and acceptor (naringenin) was obtained according to fluorescence resonance energy transfer (FRET).     

A facile fabrication of MOF for selective removal of chromium (III) from aqueous solution

A simple method for fabricating a metal organic framework (MOF: HKUST-1) as sorbent for selective removal of chromium (III) from aqueous solution is discussed. The structure and morphology of HKUST-1 was identified by fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), the powder X-ray diffraction (XRD) and N₂ adsorption-desorption (BET) analysis. Its removal process of chromium (III) and chromium (VI) on HKUST-1 was assessed systematically under various conditions such as pH value, shaking time and initial concentration of chromium (III). At pH 6.0–8.0, HKUST-1 were selective towards chromium (III) but hardly chromium (VI). Kinetic parameters fitted well with pseudo-second-order model and adsorption progress was described by Langmuir isotherm equations and spontaneous and endothermic according to the results of thermodynamics studies (?G?<?0, ?H?>?0, ?S?>?0).     

Bi2WO6/UiO-66复合材料的制备及其光催化性能

通过水热法制备了一种复合光催化剂Bi_2WO_6/UiO-66,探究了模板剂乙酸(CH_3COOH)对Ui O-66形貌的影响和2种中心元素Bi与Zr的不同物质的量之比对光催化性能的影响。通过XRD、SEM、N_2吸附-脱附、UV-Vis DRS、XPS等对催化剂的物相、形貌、比表面积、光吸收性能、元素组成等进行表征。实验结果表明,当n_(Bi)∶n_(Zr)=2∶1时,Bi_2WO_6/UiO-66对罗丹明B(RhB)的光催化活性最高,可见光照射50 min后,RhB的相对浓度降低98.5%。经过5次循环利用实验,催化剂的光催化活性没有明显下降,说明复合光催化剂的稳定性高。根据自由基捕获实验证明了空穴(h~+)为光催化中起决定性作用的活性物质,结合电化学测试以及UV-Vis DRS表征提出了可能的光催化降解机理。     

Synthesis and photophysical properties of europium pentafluorinated β-diketonate complexes

Research on Chemical Intermediates - Two pentafluorinated β-diketone ligands, 4,4,5,5,5-pentafluoro-1-(4-methoxyphenyl)pentane-1,3-dione (PFMP) and 4,4,5,5,5-pentafluoro-1-(4-dimethyl...     

Synthesis,characterization, and photoluminescence properties of difluoroboron complexes with bis-β-diketone ligands

Some novel difluoroboron bis-β-diketonates containing a pyridyl moiety were synthesized from diethyl 2,6-pyridinedicarboxylate via Claisen condensation with the corresponding aryl methyl ketones and followed by complexation with boron trifluoride etherate. Their spectroscopic behaviors were studied by FTIR, ¹H NMR, UV–Vis, and fluorescence spectroscopic techniques. The results indicated that difluoroboron bis-β-diketonates exhibited violet or blue fluorescence emission at 428–454 nm under UV illumination in DMSO and possessed high extinction coefficients. It was found that the nature of the substituents at benzene ring in bis-β-diketone ligands had a significant impact on the photoluminescence behaviors of difluoroboron complexes. The complex 5b exhibited the strongest photoluminescence intensity and highest quantum yield (Φ _u = 0.93), due to two strong electron-donating methoxyl moieties in molecule and the compound 4b displayed the lowest photoluminescence intensity and quantum yield, assigned to the heavy atom effect of the chlorine atom in its molecule. The photoluminescence intensity and quantum yield of these difluoroboron complexes decreased in the sequence, 5b > 2b > 1b > 3b > 4b.     

Electrochemical Signal Tracing by Glucose Oxidase and Ferrocene Dually Functionalized Gold Nanoprobe for Ultrasensitive Immunoassay

A glucose oxidase (GOD) and ferrocene (Fc) dually functionalized gold nanoprobe was simply prepared for electrochemical immunoassay. By combination with sandwich immunoreaction at a carbon nanotube (CNT)‐based immunosensor and signal tracing of the nanoprobe through the Fc‐mediated GOD‐catalytic reaction, a new electrochemical immunoassay method was successfully developed. Both the multi‐enzyme signal amplification of the nanoprobe and the electron transfer promotion of the CNTs modified on the immunosensor greatly enhanced the signal response. Thus this method showed excellent analytical performance including ultrahigh sensitivity, wide linear range as well as good specificity, reproducibility, stability and reliability for human IgG measurement.     

Syntheses and Crystal Structures of Two Chloro‐Bridged Coordination Polymers [Cd(BIM)Cl2]n and [Pb(BIM)Cl2]n

Two novel coordination polymers, [Cd(BIM)Cl₂]_n ( 1 ) and [Pb(BIM)Cl₂]_n ( 2 ) [wherein BIM = bis(imidazol‐1‐yl)methane], were synthesized by the reactions of the BIM ligand with CdCl₂ and PbCl₂, respectively. They were characterized by elemental analyses, IR, TGA and X‐ray single‐crystal diffraction techniques. Single‐crystal X‐ray structure analyses showed there is a pseudooctahedral arrangement around the cadmium atom in the complex 1 . It has a three‐dimensional network which contains one‐dimensional inorganic‐organic hybrid chains and μ₂‐bridging chloride ligands. A rare pentacoordinate square‐pyramidal arrangement was adopted for the lead(II) atom in the complex 2 , which has an unusual two‐dimensional layer structure of macrometallacycles crosslinked with the bridging Pb₂Cl₂ units. The metal atoms in both complexes were coordinated with two BIM ligands in cis arrangement and bridged by μ₂‐bridging chloride ligands.     

Micellar electrokinetic chromatography assay for the simultaneous quantification of urinary transferrin and albumin

A micellar electrokinetic chromatography (MEKC) method for simultaneous determination of urinary transferrin and albumin has been developed. The performance of the assay was evaluated. Under the optimum conditions, the linearity of transferrin and albumin is in the range of 10~1000 mg L^?1. The detection limits are 1.3 mg L^?1 for transferrin and 1.1 mg L^?1 for albumin, with relative standard deviations of less than 5.4%. The within-run and between-run coefficients of variation were <5.5% for transferrin and <8.2% for albumin, respectively. The recoveries of transferrin and albumin are 97.7~106.1%. The performance of the MEKC assay was compared with radioimmunoassay, and correlated well with this.     

Synthesis,Characterization and Biological Activities ofN-Acyl-3-(3-pyridyl)-5-aryl-pyrazoles

Ten novel N-acyl-3-(3-pyridyl)-5-aryl-pyrazoles were synthesized by Claisen condensation of the aryl methyl ketones with ethyl nicotinate, the cyclization with hydrazine hydrate and the N-acylation with acyl chloride in turn. The structures of all the compounds synthesized were confirmed by means of Fourier transform infrared(FTIR), ¹H NMR, mass spectroscopy and elemental analysis. The biological activities of the title compounds were examined by disc diffusion method against Escherichia coli, Staphylococcus aureus, Pyricularia oryzae and Rhizoctnia solani. All the N-acyl-3-(3-pyridyl)-5-aryl-pyrazoles exhibited a certain degree of antibacterial and antifungal activities. Comparatively, compounds 3c and 3d exhibited much significant antibacterial and antifungal activities than the other pyrazole derivatives.