Environmental water monitoring by capillary electrophoresis and result comparison with solvent chemistry techniques

The aim of this work was to determine inorganic ions from natural waters by capillary electrophoresis (CE) and to compare the results obtained with those measured with conventional solvent chemistry techniques. The project was part of a larger CE study, during which we measured inorganic ions from some lake and river systems and groundwaters in Southern Finland. Results obtained from contaminated Finnish waters were compared with samples from the River Rhine in the Düsseldorf area. Two CE methods were used for analysis: one for determination of chloride, sulfate, nitrite and nitrate at pH 7.7 and the other for ammonium, potassium, calcium, sodium and magnesium at pH 3.6, both methods using identification based on indirect UV detection. Two separation methods were used in order to prevent complex formation of metals with sulfate, hydroxide and decomposed organic matter present in the environmental samples. On the basis of the CE studies dilution was needed for those samples having more than 100 mg/l of sulfate, chloride, calcium and sodium. On average, the natural waters in the study contained ammonium, magnesium, sodium, potassium and calcium below 0.3, 20, 200, 20, and 200 mg/l, respectively. The concentrations of chloride, sulfate, nitrite and nitrate were below 20, 100, 10, and 10 mg/l, respectively. Correlation of the CE results with those acquired by titration, atomic absorption spectrometry, ion chromatography and flow injection analysis were obtained; R2 values for the comparison tests varied from 0.8816 to 0.9994 depending on the ion. The repeatabilities of the anion and cation CE methods were tested using laboratory-made reference sample mixtures with high and low salt concentration.     

New Sn(IV) and Ti(IV) bis(trimethylsilyl)amides in d,l-lactide polymerization, SEM characterization of polymers

Ring-opening polymerization of d,l-lactide initiated with new chlorotris(bis(trimethylsilyl) amido) tin(IV), tetrakis(bis(trimethylsilyl)amido) tin(IV) and titanium(IV) was investigated. New complexes reveal practically quantitative conversion degrees and produced polymers with higher molecular weight with respect to reference alkoxo-species.The X-ray crystal structure of chlorotris(bis(trimethylsilyl)amido) tin (IV) was investigated. Axial enantiomerism of [SnCl{N(SiMe₃)₂}₃] molecules in solution was studied by high-field dynamic NMR, the value of Gibbs activation energy ΔG^‡ = 59.5 kJ/mol.Field emission SEM investigation of bulk polymer samples and thin films on conductive Al foil revealed a stratified fibrous textures in the bulk polymers, as well as nanoscaled topographical features due to coils and entanglements of individual macromolecules in thin films.     

Syntheses and structure of bis(pentamethylcyclopentadienyl)-dithiophosphinato Complexes

Bis(pentamethylcyclopentadienyl)phosphane Cp*₂PH reacts with sulfur under basic conditions to give the corresponding dithiophosphinate salts M⁺ CP*₂PS−2 ( 5 M⁺ = HNEt+3, 6 M⁺ = Li⁺), which are formed via the intermediate CP*₂P(S)H ( 4 ). Both salts on treatment with cobalt(II) chloride give rise to the transition metal dithiophosphinate 7 . The structures of this new type of diorganodithiophosphinate complexes in the solid state have been investigated. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 521–525, 1997     

High-frequency hearing in phocid and otariid pinnipeds: an interpretation based on inertial and cochlear constraints (L)

Audiograms in air and underwater, determined by previous workers for four pinniped species, two eared seals (Otariidae) and two phocids (Phocidae), are supplemented here by measurements on their middle ear ossicular mass, enabling mechanistic interpretations of high-frequency hearing and audiogram differences. Otariid hearing is not largely affected by the medium (air/water). This indicates that cochlear constraints limit high-frequency hearing in otariids. Phocids, however, have massive middle ear ossicles, and underwater hearing has radically shifted towards higher frequencies. This suggests that the high-frequency hearing of phocids in air is constrained by ossicle inertia.     

The thermal decomposition,IR spectrum and crystal structure of ammonium manganese(II) tris(hydrogenselenite), NH4Mn(HSeO3)3

The compound NH₄Mn(HSeO₃)₃ has been prepared and its IR spectrum and thermal behaviour have been investigated. It crystallizes in the monoc     

Synthesis, characterization, reactivity and theoretical studies of ruthenium carbonyl complexes containing ortho-substituted triphenyl phosphanes

A series of ruthenium o-phosphane complexes was synthesized and characterized. The reactivity of the prepared complexes was studied by using them as catalysts for the hydroformylation of 1-hexene. The activities depended on the binding mode of the phosphane and on the strength of the ruthenium-phosphane interaction. Strongly coordinated chelating [2-(dimethylamino)phenyl]-(diphenyl) phosphane and [2-(methylthio)phenyl]-(diphenyl) phosphane showed poor activity, while weakly chelated [2-(methoxy)phenyl]-(diphenyl) phosphane and non-chelating phosphanes such as [2-(methyl)phenyl]-(diphenyl) phosphane or [2-(ethyl)phenyl]-(diphenyl) phosphane led to higher activities.     

Structures of bisphosphonate metal complexes: zinc and cadmium complexes of clodronate and its partial ester derivatives

Four new zinc and cadmium bisphosphonates [{NaZn(Cl2CP2O6H)(H2O)5}]n (1), [{Cd2(Cl2CP2O6)(H2O)4}.H2O]n (2), [{Zn(Cl2CP2O6Pri2)(H2O)3}.H2O]n (3), and [{Cd2(Cl2CP2O6Pri2)2(MeOH)2(H2O)2}.H2O]2 (4) have been prepared and their crystal structures determined by single-crystal X-ray diffractometry. Two bisphosphonate ligands were used: clodronate, (dichloromethylene)bis(phosphonate) and its symmetrical P,P'-diisopropyl ester derivative. The structure of the Zn complex 1 is three-dimensional, consisting of one-dimensional Zn-clodronate chains connected to the three-dimensional network by Na+ ions. The structure of Cd complex 2 consists of double layers, and a unique bond was found between the Cd2+ cation and a Cl atom of clodronate. Zn complex 3 consists of one-dimensional chains, but the binding of the bisphosphonate ligands is unique: in 3 the bisphosphonate ligand is only bidentate. Compound 4 is a tetramer, and hydrogen bonds hold the tetramers together, forming a layered structure.     

Preparation of copper–silicon dioxide nanoparticles with chemical vapor synthesis

Atmospheric pressure chemical vapor synthesis was used to produce copper nanoparticle composites in an amorphous silicon dioxide, i.e., either copper nanoparticles coated with amorphous silicon dioxide or copper nanoparticles embedded in amorphous silicon dioxide matrix. Synthesized metal–organic copper(I) complex was used as a precursor that provided well-defined ratio (1:2) of copper and silicon. The thermal decomposition of the Cu(I) complex molecule leads to homogenous nucleation and formation of copper nanoparticles which are subsequently coated with Si/SiO₂ in the gas phase. The decomposition was greatly enhanced when reductive atmosphere, i.e., H₂/N₂ 10 v% were used instead of pure nitrogen. A narrow size distribution with the geometric mean diameter of the particle agglomerates around 30 nm was observed while the primary size of the copper core particles was around 5 nm.