Synthesis and X-ray crystal structure of a novel organometallic (μ3-oxido)(μ3-imido) trinuclear iridium complex

Reaction of the organometallic aqua ion [Cp*Ir(H(2)O)(3)](2+) with tert-butyl(trimethylsilyl)amine in acetone yielded a novel trinuclear (μ(3)-oxido)(μ(3)-imido)pentamethylcyclopentadienyliridium(III) complex, [(Cp*Ir)(3)(O)(N(t)Bu)](2+). Single crystal structure analyses show the complex can be isolated both in the double salt ((t)BuNH(3))[(Cp*Ir)(3)(O)(N(t)Bu)](CF(3)SO(3))(3) (1) and in the simple triflate [(Cp*Ir)(3)(O)(N(t)Bu)](CF(3)SO(3))(2) (2). The double salt is stabilized by hydrogen bonding between the tert-butylammonium ion and the three triflate anions. It is the first time that a trinuclear (μ(3)-oxido)(μ(3)-imido) transition metal complex has been structurally characterized.     

Evaluation of Chromatographic Methods for the Determination of Isocyanates in Air

Abstract

Chromatographic methods for the determination of toluene diisocyanates (TDI) in air, at concentrations of 20–40μg/m³, were evaluated. Test atmospheres were generated by a gas-phase permeation principle. The GC method was based on sampling in impingers containing an acidic aqueous solution (0.4 M HC1), where the isocyanates are hydrolysed into the corresponding amines. The pentafiuoropropionic acid derivatives of the amines were analysed using glass capillary GC with thermionic detection. The HPLC methods were based on reaction with the amine reagents 9-(N-methylaminomethyl)-anthracene (1 × 10^?4M in toluene) and 1-(2-methoxyphenyl)-piperazine (2 × 10^?4M in toluene). The urea derivatives were determined using UV detection. The sampling efficiency for gaseous TDI with toluene as absorbing solution was 97%. Sampling efficiencies in various acidic aqueous solutions were 83–88%. The relative standard deviation for the various methods was ca. 6%. No sampling losses for TDI, due to influences of interfering substances (diethylamine, dimethylethylamine, N-methylmorpholine, DABCO, aniline, ethanol, phenol) using acidic aqueous 0.4 M HC1 were obtained. Diethylamine, N-methylmorpholine and DABCO affected the analytical results when toluene solutions of the amine reagents MAMA and MPP were used.     

A method for measurements of the efficiency of immunogold labelling of epoxy-embedded proteins subjected to different retrieval techniques

The purpose of this study was to compare the level of immunogold labelling of both osmicated and non-osmicated epoxy sections when subjected to different antigen retrieval, etching and incubation temperature for the antibodies. Pure IgG protein gels were produced by glutaraldehyde fixation, eventually postfixed with 1% osmium tetroxide, and embedded in epoxy resin. Ultrathin sections were antigen retrieved in citrate solution at 95 or 144 degrees C and eventually etched with NaIO4. Immunogold labelling with anti-IgG was performed at 4 degrees C overnight or at 60 degrees C for 1 h. The level of labelling for osmicated gels was 140% higher when heated at 144 degrees C and incubated with primary antibodies at 60 degrees C than when heated at 95 degrees C, etched with NaIO4 and incubated with primary antibodies at 4 degrees C. Osmium-fixed IgG-gels antigen retrieved at 144 degrees C and incubated with anti-IgG at 60 degrees C showed more labelling than sections of non-osmicated gels heated at 95 degrees C. Non-osmicated gels gained significant intensity of immunolabelling when the antibody incubation occurred at 60 degrees C for 1 h than at 4 degrees C overnight. Resin embedding of pure protein gels was a useful tool for comparing different protocols for immunoelectron microscopy.     

Rhenium(IV) sulfide nanotubes

Rhenium(IV) sulfide, ReS(2), has been prepared with nanotubular morphology by carbon nanotube templating. A multiwall carbon nanotube material was impregnated with solutions of NH(4)ReO(4) or ReCl(5), followed by drying and sulfidation with H(2)S at 1000 degrees C. The composite material synthesized was characterized by high-resolution transmission electron microscopy and X-ray powder diffraction. Like previously described MS(2) nanotube compounds, ReS(2) has a layered structure consisting of S-M-S layers. Re atoms in ordinary ReS(2) are octahedrally coordinated with S, and tetranuclear metal clusters are present as a consequence of metal-metal bonds.     

Methylcyclopentadienyl-substituted tungsten(IV) sulfido cluster [(eta5-Cp')3W3S4]+ and its heterobimetallic derivative [(eta5-Cp')3W3S4Ni(PPh3)]+

The aqueous cluster salt [(H2O)9W3S4][pts]4.9H2O (pts = p-toluenesulfonate) was converted to the methylcyclopentadienyl (Cp') substituted cluster [(eta5-Cp')3W3S4][pts] ([1][pts]) from which the cubane-like cluster [(eta5-Cp')3W3S4Ni(PPh3)][pts] ([2][pts]) was obtained by reaction with Ni(cod)2 and PPh3. [2][pts] was characterized by X-ray crystal structure analysis.     

Increased yield of immunogold labeling of epoxy sections by adding para-phenylendiamine in the tissue processing

The purpose of this study was to examine if the presence of para-phenylendiamine (PPD) in the tissue processing could increase the yield of immunogold labeling of the epoxy sections. Renal swine tissue with glomerular immune complex deposits with reactivity against IgG was embedded in epoxy resin. PPD was added (1) at the beginning of the dehydration, (2) in the first step with propylene oxide, (3) in the beginning of the dehydration and in all steps with propylene oxide included the infiltration step where propylene oxide and epoxy resin are mixed, or (4) PPD was totally avoided. The tissue was embedded with two different combinations of accelerator. Immunogold labeling with anti-IgG was performed on both non-heated and heated ultrathin sections. The immunogold labeling on the heated sections which were based on processing with PPD in all steps (3) was about 55–65% higher than the corresponding labeling for epoxy sections processed in total absence of PPD (4). The immunolabeling was not significantly increased when the tissue was processed with PPD only in the start of the dehydration (1) or in the first step with propylene oxide (2). We believe that tissue processing with sufficient PPD contributes to reduce the co-polymerization between the antigens and the epoxy polymer in the same way as excess of accelerator does (Brorson and Skjørten, 1996a). The practical significance of this study provides better opportunities for increasing the immunogold labeling of epoxy sections by adding PPD in the tissue processing, and our result may inspire other researchers to develop even more efficient methods for controlling the copolymerization between antigens and epoxy resin.