Spectrophotometric determination of silver with cadion 2B and triton X-100

A highly sensitive and selective procedure for spectrophotometric determination of silver has been developed. At pH 9.2, in the presence of Triton X-100, silver forms a dark red-violet complex with cadion 2B which has an absorption maximum at 565 nm. The molar absorptivity is 1.0 x 10(5) l.mole(-1).cm(-1). Beer's law is obeyed for silver in the range 0.02-0.8 mug ml . The colour reaction, if EDTA is used as a masking agent, is free from interference by the 20 cations and 19 anions investigated. Only Cl(-), Br(-), I(-), S(2-) and CN(-) interfere and must be absent. This method has been used to determine silver in waste-water.     

IR-Spektren der Caesium-bis-sulfato-metallate(III)

Compounds of the type CsLn(SO₄)₂, (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were prepared at 300°C. IR spectra were recorded in the range 4,000-250cm^–1 and tentatively assigned. The number of observed bands exceeds the predicted number by site symmetry selection rules. Streching bands show bathochromic shifts whereas the deformations exibit hypsochromic shifts on going to heavier lanthanides. At the same time there is an increased splitting of these bands in the same direction. All these facts indicate an increased coupling in the layer structure which is in accordance with the lanthanide contraction.

N. Bukovec, P. Bukovec undJ. iftar, Vest. Slov. Kem. Drus.26, 103 (1979).     

Packing capilllary electrochromatography columns using vacuum--a preliminary study

This paper introducesa novel method for packing Capillary Electrochromatography Columns (CEC). Using vacuum packing methodology, silica particles as small as 1 microm were successfully packed into the capillary columns with 75 microm inner diameter. The columns are verystable and show no noticeable loss in efficiency after 200 sample injections. The performance of these vacuum packed capillary columns was evaluated with a mixture of aromatic and non-aromatic compounds. A 24 cm long capillary column can produce peak efficiencies of around 45,000 plates for benzene.     

Synthesis, Crystal Structure, UV-vis and EPR Studies of（ NH3CH2CH2NH2 ） 2.5 [ Mo0.5^（V）W0.5^（VI）O2 （ OC6H4O ） 2]

Cis-dioxo-metal complex ( NH3CH2CH2NH2 ) 2.5 [ Mo0.5^(V)W0.5^(VI)O2 ( OC6H4O ) 2] 1 was obtained by the reaction of tetra-butyl ammonium hexamolybdotungstate with 1, 2-dihydroxybenzene in the mixed solvent of CH3OH, CH3CN and ethylenediamine,and characterized by X-ray diffraction, UV-vis and EPR analysis. Compared with its analogous complexes (NH3CH2CH2NH2)3[Mo^(V)O2(OC6H40)2] 2 and (NH3CH2CH2NH2)2[W^(VI)O2(OC6H4O)2] 3, the results show that tungsten(VI) is less active in redox than molybdenum (VI) and that the change of the valence induced by substitution of W(VI) for Mo(V) in EMO2(OC6H40)2]n- does not influence the coordination geometry of the complex anion in which the metal center exhibits distorted octahedral coordination with cis-dioxo catechol. The responses to EPR of complexes 1 and 2 are active but complex 3 is silent,and the UV-vis spectra exhibited by the three complexes are obvious different because of the different electronic configuration between the central Mo(V) and W(VI) ions in the complexes.It is noteworthy that complexes 1 and 2 have the similar EPR signal to flavoenzyme, suggesting that the three complexes have the same coordination geometry feature with the co-factor of flavoenzyme.     

动力学涂层毛细管电泳分离双链脱氧核糖核酸片段

以异丙醇为聚合反应链转移试剂，水相法合成了短链聚N，N－二甲基丙烯酰胺（PDMA），研究表明，该聚合物能在毛细管内壁形成稳定的动力学涂层，从而有效地抑制电渗流和毛细管内壁与DNA的作用。这种介质被成功地应用于DNA片段的高效分离。     

Acidichromism in the Mixed Langmuir—Blodgett Films of Stearic Acid with a Carbazole—containing Schiff Base

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｖｅｒｓｉｂｌｅｃｏｌｏｒｃｈａｎｇｅｓｕｐｏｎｅｘｔｅｒｎａｌｏｒｉｎｔｅｒｎａｌｓｔｉｍｕｌａｔｉｏｎｓｈａｖｅｂｅｅｎａｔｔｒａｃｔｉｎｇｍｕｃｈａｔｔｅｎｔｉｏｎｄｕｅｔｏｔｈｅｉｒｕｔｉｌｉｔｙａｓｆｕｎｃｔｉｏｎａｌｍａｔｅｒｉａｌｓ .Ｆｏｒｅｘａｍｐｌｅ ,ｐｈｏ ｔｏｃｈｒｏｍｉｓｍｄｅｓｃｒｉｂｅｓｔｈｅｃｏｌｏｒｃｈａｎｇｅｓｉｎｄｕｃｅｄｂｙｐｈｏ ｔｏｉｒｒａｄｉａｔｉｏｎａｎｄｃａｎｂｅｕｓｅｄａｓｐｈｏｔｏ ｒｅｃｏｒｄｉｎｇｍａｔｅｒｉ ａｌｓ…     

An electrochemical DNA hybridization detection assay based on a silver nanoparticle label

A novel, sensitive electrochemical DNA hybridization detection assay, using silver nanoparticles as the oligonucleotide labeling tag, is described. The assay relies on the hybridization of the target DNA with the silver nanoparticle-oligonucleotide DNA probe, followed by the release of the silver metal atoms anchored on the hybrids by oxidative metal dissolution and the indirect determination of the solubilized Ag(I) ions by anodic stripping voltammetry (ASV) at a carbon fiber ultramicroelectrode. The influence of the relevant experimental variables, including the surface coverage of the target oligonucleotide, the duration of the silver dissolution steps and the parameters of the electrochemical stripping measurement of the silver(I) ions, is examined and optimized. The combination of the remarkable sensitivity of the stripping metal analysis at the microelectrode with the large number of silver(I) ions released from each DNA hybrid allows detection at levels as low as 0.5 pmol L(-1) of the target oligonucleotides.     

Pentanuclear Ba(II) complex of a macrocyclic ligand

We report here the first pentanuclear Ba(II) complex of a new tri-aza, tri-oxa macrocycle with two carboxymethyl "arms" pending from two N atoms, H2L2. The crystal structure corresponds to the formula [Ba5(H0.375L2)4(ClO4)(CH3CH2OH)(H2O)2](ClO4)2.5 x 9.5H2O and reveals the presence of four molecules of the ligand surrounding five Ba(II) ions, giving rise to an unusual structure with the metal ions inside a spherical organic cavity.     

Syntheses and properties of mixed dinuclear copper(II) complexes with heterocyclic dithiocarbamates and a cyclic octadentate tertiary amine

Five new Cu^II complexes of general formula [Cu₂(Rdtc)tpmc](ClO₄)₃, (1)–(5), where tpmc and Rdtc ^– refer to N,N,N,N-tetrakis(2-pyridylmethyl)-1,4,8,11-teraazacyclotetradecane and piperidine- (Pipdtc), 4-morpholine- (Morphdtc), 4-thiomorpholine- (Timdtc), piperazine- (Pzdtc) or N-methylpiperazine- (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. Elemental analyses, conductometric and magnetic measurements, u.v./vis, i.r., e.p.r. and mass spectroscopy have been employed to characterize them. The complexes adopt an exo coordination of Cu^II ions and tpmc. The dithiocarbamate ion joins both the sulphur and the copper atoms acting as a bridging ligand The presence of different heteroatoms in the piperidine ring influences the (C=N) and (C=S) vibrations which decrease in the order of the complexes: Pipdtc>N-Mepipdtc>Pzdtc>Morphdtc>Timdtc ligands. Attention has been paid to the detailed mechanism of the mass spectral fragmentation of the complexes. The g _eff factors of the complexes have been also estimated by e.p.r. spectra. Finally, the complexes obtained demonstrate microbiologycal activity against some bacteria.     

Novel composite polymer electrolytes based on poly(ether-urethane) network polymer and fumed silicas

Novel composite solid polymer electrolytes (CSPEs) and composite gel polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) network polymer (PUN), fumed silicas and LiClO₄. The ionic conductivity of CSPEs can be enhanced nearly 20 times in comparison with the plain system without the addition of fumed silicas and can be above 1×10⁻⁵ S/cm at room temperature. The effects of both kinds of fumed silicas, viz. uSiO₂ with hydrophilic groups at the surface and mSiO₂ with hydrophobic groups at the surface on ionic conductivity were investigated. CGPE comprising of the CSPE and LiClO₄–PC solution with good mechanical strength exhibits ionic conductivity in the order of 10⁻³ S/cm at room temperature and above 3×10⁻⁴ S/cm at low temperature −40 °C.