In situ AFM study of electrochemical synthesis of polypyrrole/Au nanocomposite

In this work, in situ AFM measurements with simultaneously electrochemical characterization were developed to study the mechanisms of both polypyrrole (PPy) and PPy/Au composite deposition. The nanoscale information derived from the in situ AFM images associated with theoretical simulation from the measured current–time transient (i–t) reveals that Au nanoparticles with negatively charged carboxylic groups can be the nuclei by both adsorption on the electrode surface and doping on PPy for the polymerization, and thus has faster nucleation and growth rate than Py alone at the early polymerization stage. The PPy/Au deposition shows parallel nucleation processes of Au nanoparticle and Py, and an instantaneous 3D nucleation mode. The work not only provides fundamental insights for PPy/Au nanocomposite deposition process, but also optimization approaches to fabricate a superior PPy/Au film with favorable features for greater potential applications.     

利用原子力显微镜探测人正常与慢性淋巴白血病外周血B淋巴细胞

采用Ficoll密度梯度离心法得到人外周血单个核细胞(PBMC),并结合磁珠分选的方法进一步纯化得到正常B淋巴细胞,探索了正常和肿瘤B淋巴细胞之间的差异。通过应用具有高分辨率的原子力显微镜(AFM)对正常人和慢性淋巴白血病人外周血B淋巴细胞进行成像,并对这两种B淋巴细胞的高度、直径、体积及膜表面的颗粒平均高度、平均粗糙度和颗粒分布进行测量,对比观察两组细胞膜表面宏观和纳米结构的变化。结果表明,慢性淋巴白血病B淋巴细胞比正常的B淋巴细胞高大,细胞膜表面颗粒更大且细胞膜粗糙。此外,对这两组淋巴细胞进行了机械性质方面的测量和统计,结果发现慢性淋巴白血病B淋巴细胞粘附力(524.1±160.0)pN比正常B淋巴细胞粘附力(1091±260)pN约小1倍,且癌变的B淋巴细胞硬度明显比正常的小。当正常细胞癌变时,细胞的形貌、超微结构及骨架会发生一定的改变。实验证明应用AFM可在形态学和机械性质上明显区别正常和慢性淋巴白血病B淋巴细胞,为临床诊断慢性淋巴白血病提供新的技术手段。     

Addition of tetrachloromethane to oct-1-ene initiated by amino alcohols

The kinetics and mechanism of an addition of CCl₄ to oct-1-ene initiated by amines, aromatic alcohols, and amino alcohols (structural analogs of ephedrin) were studied. The radical mechanism of the reaction was established by ESR using the technique of spin traps. Aromatic amino alcohols as initiators are more active than amines and aromatic alcohols of similar structure. They are more selective compared to the amines and aromatic alcohols and react with CCl₄ already at room temperature to form predominantly benzaldehyde. The scheme of initiation by aromatic amino alcohols of the addition of CCl₄ to olefins was proposed on the basis of the experimental data. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1565–1571, September, 2006.     

溶液法剥离的氮化碳在各种衬底上分散的AFM研究

石墨相氮化碳(g-C_3N_4)因为其特殊的层状结构及电子性质在催化和光催化领域里受到广泛关注和研究。本文以异丙醇及异丙醇-水混合溶液为介质对g-C_3N_4粉末进行超声液相剥离,并利用原子力显微镜详细表征了剥离后的溶液分散至云母、高定向热解石墨(HOPG)、Au(111)等不同衬底表面的结果。发现溶液经10h超声后,g-C_3N_4被剥离成尺寸约100nm左右的扁平颗粒,但无法形成完美的超薄层结构。这可能是由于经热聚合法合成的g-C_3N_4本身晶化程度较低所致。     

Oxidation of secondary alcohols byN-methylmorpholine-N-oxide (NMO) catalyzed by atrans-dioxo ruthenium(VI) complex or perruthenate complex: A kinetic study

Thetrans-dioxo ruthenium (VI) complex, [P(C₆H₅)₃C₆H₅CH₂]⁺[Ru(O)₂OAcCl₂] or tetrapropylammonium perruthenate catalyzes the oxidation of secondary alcohols to ketones byN-methylmorpholine-N-oxide (NMO). Kinetic studies showed the formation of a complex between catalyst and substrate (alcohol) as the first step in the mechanism.     

Pyrazoles as molecular probes to study the properties of co-crystals by solid state NMR spectroscopy

Equimolar mixtures of 3,5-dimethylpyrazole (1) with four NH-imidazoles (2–5) have been studied by¹³C and ¹⁵N CPMAS NMR and by DSC. In three cases, the solid mixture behaves as the sum of the individual components [imidazole (2), 2-methylimidazole (3) and 2,4(5)-dimethylimidazole (5)]. In one case [4,5-dimethylimidazole (4)], the mixture corresponds to a new species in which the dynamic behavior of1 no longer exists.     

Potentiometric studies on the complex formation of lanthanides with proline and hydroxyproline

The formation of the lanthanide (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) complexes with proline and hydroxyproline has been investigated by potentiometric methods as well as by a turbidimetric one which has provided some additional conclusions. It has been found that 11 and a slight amount of 21 complexes are formed. The deviation from the typical course of the formation function is discussed. It is suggested that the perturbations of complex formation in the systems are caused by hydrolysis. The stability constants of the complexes are reported.

---

Potentiometrische Untersuchungen an Lanthanid-Komplexen von Prolin und Hydroxyprolin

Zusammenfassung Die Bildung von Lanthanid-Komplexen (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) mit Prolin und Hydroxyprolin wurde potentiometrisch und mit Hilfe von Trübungsmessungen untersucht. Es wurde festgestellt, daß sich Komplexe der Zusammensetzung 11 und in kleiner Menge auch 21 bilden. Die Abweichung von typischem Verlauf der Bildungskurven wurde untersucht. Es wurde dabei festgestellt, daß für die Störungen in der Komplexbildung die Hydrolyse verantwortlich ist. Die Stabilitätskonstanten wurden bestimmt.

     

Mechanistic investigations of oxidation of isatins by sodium N-chlorobenzenesulfonamide in alkaline medium: A kinetic study

Oxidation of isatins (isatin, 5-methylisatin, 5-bromoisatin and 5-nitroisatin) to their anthranilic acids was performed efficiently with sodium N-chlorobenzenesulfonamide or chloramine-B (CAB) in alkaline medium at 35±0.1°C. The reactions follow identical kinetics for all the isatins, being first-order dependence each in [CAB] _o and [Isatin] _o and inverse fractional-order on [NaOH]. Addition of halide ions and benzenesulfonamide, reduction product of CAB, do not significantly affect the rate. Variation of ionic strength of the medium had no effect on the rate, while the dielectric effect is negative. The solvent isotope effect was studied using D₂O. Activation parameters for the overall reaction have been computed. The rates satisfactorily correlate with the Hammett σ relationship and the reaction constant ρ is −0.31 signifies that electron releasing groups accelerate the reaction while the electron withdrawing groups retard the rate. Values of ΔH^≠ and ΔS^≠ are linearly related and an isokinetic relationship is observed with β=376 K, indicating the reaction is controlled by enthalpy. The stoichiometry of the title reaction is found to be 1∶1. Oxidation products of isatins were identified as their corresponding anthranilic acids and the yields were found to be around 90 %. The observed results have been explained by a plausible mechanism and the related rate law deduced. This method offers several advantages including high yield of the products, short reaction times, easier isolation of products, and stable, cost effective and relatively non-toxic reagents, which make the reaction process simple and smooth.     

Anionic graft polymerization of vinyl monomers initiated by metallized aromatic rings of graphite powder

Anionic graft polymerizations of methyl methacrylate (MMA) and styrene from graphite powder initiated by metallized aromatic rings on the surface were investigated. Metalation of the surface was achieved by the reaction of polycondensed aromatic rings of graphite withn-butyllithium (BuLi) in N,N,N,N-tetramethylethylenediamine (TMEDA) or hexamethylphosphorous triamide (HMPT) at 0 °C., Anionic polymerizations of MMA and styrene were initiated by metallized graphite, and these polymers were grafted onto the surface. The conversion and percentage of grafting increased by increasing the amount of BuLi used for metalation. When 0.20 g of graphite was treated with 0.4–0.5 mmol of BuLi in TMEDA, the percentage of grafting of PMMA and polystyrene reached the maximum value: PMMA 52.8% (PMMA/graphite =0.528 g/1.0 g) and polystyrene 37.2% (polystyrene/graphite=0.372 g/1.0 g). Grafting of polymers was also confirmed by infrared spectra. Although no metalation of graphite proceeded in toluene, graphite could be metallized even in toluene by the addition of crown ether as a complexing cation agent. The stability of graphite powder in organic solvent dispersion was found to be improved remarkably by grafting of polymer onto the surface.     

Time and temperature-based study for the production of high T C phase by sol-gel technique in Pb-bscco system

The high T_C superconducting phase Bi₂Sr₂Ca₂Cu₃Ox (2223) in the Pb-BSCCO system has been produced by EDTA-gel processing using nitrate solutions. The precursor has heated in two stages, at 300 and 800°C each for 2 h, to avoid the burning of the important species involved in the final product. The effects of time (6 to 48 h) and temperature (845 and 855°C) on the formation of the 2223 phase have been studied by sintering the samples in air. Thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vibrating sample magnetometer (VSM) have been employed to investigate the powder produced at different stages of decomposition, oxidation and formation of sintered materials from the powders. The volume-fraction of the 2223 phase at 845°C increases with time, the maximum value of the 2223 phase was obtained at 120 h. It has been observed that the formation of the high T_C phase is remarkably enhanced at the temperature of the endothermic peak of the DTA curve. The best result has been obtained in the sample sintered for 24 h at the temperature 855°C (endothermic peak). This also indicated that at 855°C, the large volume-fraction of 2223 phase with T_C 113 K grew in short time and as the sintering time increased, it decomposed into the Bi₂Sr₂CaCu₂Ox (2212) phase and other phases.     

A study of sample mineralization methods for arsenic analysis of blood and urine by hydride generation and graphite furnace atomic absorption spectrometry

Mineralization procedures for blood and urine suitable for the determination of arsenic by Hydride Generation Atomic Absorption Spectrometry (HGAAS) are studied on model samples, and the results are utilized in biological monitoring investigations. The objective of this work is to obtain good total As recoveries for both matrices regardless of added As species (As(III), As(V), DMA, MMA, AsB, or AsC). Prior to the HGAAS analyses, preparation procedures were controlled under optimised conditions by graphite furnace atomic absorption spectrometry (GFAAS). Two preparation procedures for urine give As recoveries close to 100% by HGAAS: a) dry ashing at 420°C with Mg(NO₃)₂ on a hot plate, and b) microwave oven decomposition with (NH₄)₂S₂O₈. For blood samples, As recoveries by HGAAS range between 95 and 108% for all species when using dry ashing after a pretreatment of samples with HNO₃ and H₂O₂ in a microwave oven. Wet digestion with (NH₄)₂S₂O₈ in a microwave oven gives recoveries very near 100% for As _inorg. and MMA. For other As species in spiked blood samples, recoveries of less than 20% As are found. Precision and detection limits obtained by both techniques are evaluated as well. For arsenic concentrations of 20 μg dm⁻³ or more in blood and urine, a chemical modifier is recommended for GFAAS analysis; it may or may not be proceeded by a mineralization step. For low As levels encountered in the unexposed population, the HGAAS technique provides reliable results only if a very complete mineralization procedure is used.     

Investigation of Calcium Carbonate Scaling Inhibition and Scale Morphology by AFM

The calcium carbonate scale inhibition by two inhibitors, polyacrylic acid (PAA) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), has been studied in two heat transfer systems: recirculating cooling water and pool boiling systems. It is found that PBTCA has a better inhibition effect than PAA under identical conditions. The inhibition effect increases with increasing fluid velocity for the cooling water system, whereas in the presence of inhibitors, the fluid velocity has less effect on the scaling behavior. When the initial surface temperature increases, the inhibition efficiency decreases. In the presence of inhibitors, the scaling behavior is insensitive to the change of surface temperature. The relationship between the inhibition effect and the fractal dimension has also been investigated. The results show that the fractal dimension is higher in the presence of inhibitors. The better the inhibition effect, the higher the fractal dimension. XRD and FTIR analyses demonstrate that for the CaCO₃ formed in the pool boiling system, the content of vaterite increases with the increase of inhibition effects. The metastable crystal forms of vaterite and aragonite are stabilized kinetically in the presence of inhibitors. The step morphology has been observed by atomic force microscopy. It is shown that the step space on the CaCO₃ surface increases in the presence of inhibitors. Moreover, with the increase in inhibition effect, both the step space and the fractal dimension increase. Step bunching is also found and discussed in this paper.     

Etherates and pyridinium compounds of mixed complex iodoacids of gallium(III)

The preparationof etherates and pyridinium compounds of mixed complex iodoacids of Ga(III) is reported together with some physical and chemical properties, as well as conductometric measurements and the ultraviolet and infrared spectra of the new compounds. From the analytical, conductometric, stability and spectral data, some information is gained about the probable structure of the complexes.

---

Etherate und Pyridin-Verbindungen von gemischtkomplexen Jodosäuren von Gallium(III)

Zusammenfassung Es wird über die Darstellung von Ether- und Pyridiniumverbindungen gemischter komplexer Jodosäuren von Ga(III), sowie über einige physikalische und chemische Eigenschaften, konduktometrische Daten und die UV- und IR-Spektren dieser neuen Verbindungen berichtet. Auf Grund von analytischen, konduktometrischen, spektroskopischen und Stabilitätsbefunden wurden Informationen über die wahrscheinliche Struktur dieser Komplexe gewonnen.

     

Ni(II)/N,N-dimethylglycine complex equilibrium study

The complex formation of Ni(II) withN,N-dimethyl-glycine in water and in water-methanol has been studied by computer analysis of potentiometric data.

---

Gleichgewichtsuntersuchungen der Komplexbildung von Ni(II) mitN,N-Dimethylglycin (Kurze Mitteilung)

Zusammenfassung Anhand der Computer-Analyse von potentiometrischen Daten wurden die Bildungsgleichgewichte von Nickel(II)-Komplexen mitN,N-Dimethylglycin in Wasser und Wasser — Methanol untersucht.

     

Crystal structure and spectra of the Ni(II) complex of pyridine-2,6-dithio-carbomethylamide

The crystal structure of the paramagnetic bis(pyridine-2,6-dithiocarbomethylamide) nickel(II) nitrate (NiPDTA) is described: C₁₈H₂₂N₆S₄·(NO₃)₂·(H₂O)_1,5, monoclinic, C2/c,Z=4,a=14.705 (3) Å,b=23.254 (8) Å,c=8.383 (3) A, =98.18 (2)°,d _x=1.55 gcm^–3,d _m=1.53 gcm^–3. The structure was solved withPatterson and differenceFourier techniques and refined to a residual ofR=0.053. The nickel is surrounded by a square bipyramidal coordination of four thioamide sulfur atoms and two pyridine nitrogen atoms. Vibrational and electronic band positions for this compound are discussed.

---

Kristallstruktur und Spektren des Pyridin-2,6-dithiocarbomethylamid Nickel(II)-Komplexes

Zusammenfassung Die Kristallstruktur des paramagnetischen bis(Pyridin-2,6-dithiocarbomethylamid) Nickel(II)-nitrats (NiPDTA) wurde bestimmt. C₁₈H₂₂N₆S₄Ni·(NO₃)₂·(H₂O)_1,5, monoklin, C2/c,Z=4,a=14,705 (3) Å,b=23,254 (8) Å,c=8,383 (3) A, =98,18 (2)°,d _x=1,55gcm^–3,d _m=1,53gcm^–3. Das Phasenproblem wurde mittelsPatterson-und Differenz-Fourier-Synthese bestimmt und die Struktur bis zu einem kristallographischenR-Faktor vonR=0.053 verfeinert. Das Nickel-Atom ist von vier Thioamid-Schwefelatomen und zwei Pyridin-Stickstoffatomen in quadratisch-bipyramidaler Anordnung umgeben. Schwingungsspektren und Anregungsspektren des Komplexes werden diskutiert.

     

AFM study of conducting polymer polypyrrole nanoparticles formed by redox enzyme - glucose oxidase - initiated polymerisation

Redox enzyme – glucose oxidase E.C. 1.1.3.4 from Penecillum vitale (GOx) – initiated polypyrrole (Ppy) synthesis was applied for the formation of polypyrrole based nanoparticles. The increase in optical absorbance at λ = 460 nm was exploited for the monitoring of polypyrrole polymerisation process. The shape and size of the formed Ppy nanoparticles was also monitored by means of contact mode AFM. The highest increase in the diameter of the formed Ppy nanoparticles was detected during 15-day period. AFM imaging was performed in contact mode to investigate the shape and flexibility of particles deposited on the SiO₂ and Pt surfaces. Contact mode AFM investigations allowed us to conclude that after drying at 50 °C the formed Ppy particles are more flexibly deposited on the Pt electrode if compared to those deposited on the SiO₂ substrate. The application of well-shaped Ppy nanoparticles in biomedicine, chromatography and bioanalysis may be predicted.     

Combined polymerization catalysis of nickel complex and zirconocene for branched polyethylene

The polymerization behavior of 2-(2′-pyridyl) quinoxaline nickel dibromide/Cp₂ZrCl₂/MAO system was investigated in three ways: the Ni catalyst was added first, followed by addition of Zr catalyst (method I); the Ni and Zr catalysts were added simultaneously (method II); and the Zr catalyst was added first, followed by addition of Ni catalyst (method III). Results of GC-MS, GPC,¹³C NMR and DSC investigations indicated that the properties of resulting polyethylene were greatly varied by changing feeding orders of the two catalysts. Decreasing Ni/Zr molar ratio or increasing polymerization temperature gave corresponding polyethylenes with less branches and higher melting point. Compared to the procedure using Cp₂ZrCl₂ catalyst only, the activity of Zr catalyst in those combined system decreased because of the competition of ethylene between the [Ni−C] and [Zr−C] active centers. In addition, other zirconocenes were also employed as copolymerization catalysts in the combined system with nickel complex. compared to Cp₂ZrCl₂ case, the ethyl-bridged Zr catalyst performed better for polymerization of ethylene while the Si-bridged Zr catalyst showed better copolymerization ability.     

Stability of bivalent metal complex with L-hydroxyproline

Potentiometric titration of L-hydroxyproline with NaOH solution at 30° ±0.1°C in a medium of constant ionic strenth, =0.1M (KNO₃) gave the stepwise formation constants of the complexes formed between Mn(II), Co(II) and Zn(II) ions. The values were logK ₁=3.45; logK ₁=4.58, logK ₂=4.03; logK ₁=5.08, logK ₂=4.66; for Mn(II), Co(II) and Zn(II) complexes. The order of stability constant is in accordance with theIrving-Williams series.

---

Die Stabilität bivalenter metall-komplexe mit L-hydroxyprolin

Zusammenfassung Potentiometrische Titration von L-Hydroxyprolin in NaOH-Lösung bei 30±0,1°C und einer konstanten Ionenstärke von =0,1M-KNO₃ ergab stufenweise die Bildungskonstanten der entsprechenden Komplexe mit Mn(II), Co(II) und Zn(II). Die Werte sind logK ₁=3,45; logK ₁=4,58, logK ₂=4,03; logK ₁=5,08, logK ₂=4,66; für Mn(II); Co(II); Zn(II). Die Reihenfolge der Stabilität der Komplexe ist im Einklang mit derIrving-Williams-Reihung.

     

Studies on the complex formation of N,N-diethylglycine with copper(II) in acetonitrile

The formation of copper(II) complexes with N,N-diethylglycine in acetonitrile has been investigated by visible, infrared as well as NMR spectral techniques. It has been found that 11 and 12 complexes are formed. In both compounds nitrogen and carboxyl oxygen of ligand molecules are involved in coordination. The stability constants are reported.

---

Untersuchungen von Kupfer(II)-Komplexen mit N,N-Diethylglycin in Acetonitril

Zusammenfassung Die Bildung von Kupfer(II)-Komplexen mit N,N-Diethyglycin in Acetonitril wurde mit Hilfe von UV-VIS, IR- und NMR-Spektroskopie untersucht. Es wurde festgestellt, daß sich Komplexe der Zusammensetzung 11 und 12 bilden. In beiden Verbindungen koordinieren Stickstoff und Carboxylsauerstoff der Liganden. Die Stabilitätskonstanten wurden bestimmt.

     

Ring-opening polymerization of ε-caprolactone initiated by diphenylzinc

In the present work the polymerization of ε-caprolactone (ε-CL) using Ph₂Zn as initiator is reported. The effects of reaction temperature, molar ratio of monomer/initiator and reaction time on the yield and the molecular weight are investigated. The temperature is varied between 20 and 120 °C and the molar ratio of monomer to initiator between 200 and 800 mol/mol. The results indicate that the Ph₂Zn induces the polymerization of ε-CL to high conversion and produces polymer with high molecular weight at temperatures around 40-60 °C.