Fluorometric Determination of Trace Amounts of Fluoride Ion Using an Expanded Porphyrin

A highly selective and sensitive method of fluorometry is described for determination of the fluoride ion at the parts per billion level via the ion-pair complex formation of the fluoride ion with an expanded prophyrin [2,23-diethyl-8,17-bis(2-ethoxycarbonylethyl)-3,7,12,13,18,22-hexamethylsapphyrin (H₃sap)]. The ion-pair complex gives out an enhanced fluorescence intensity at 680 nm on excitation at 450 nm. Since the present method is based on a direct reaction of the fluoride ion with the sappyrin, a 200-fold amount of the aluminum (III) ion [10⁻⁴M (M = mol dm⁻³)] and a 2000-fold amount of the iron(III) ion (10⁻³M) over the fluoride ion did not interfere with determination of the fluoride ion at concentrations as low as 5 × 10⁻⁷M in the presence of 1,2-diaminocyclohexane-N,N,N′,N′-teraacetic acid. The proposed method was applied to determination of the fluoride ion in various water samples (tap water, river water, rain water, underground water, and hot spring water) and satisfactory results were obtained.     

Rapid ruthenium-catalyzed synthesis of pyranopyrandiones by reconstructive carbonylation of cyclopropenones involving C[bond]C bond cleavage

Pyranopyrandiones were prepared by a novel ruthenium-catalyzed carbonylative dimerization of cyclopropenones via C-C bond cleavage. For example, treatment of dipropylcyclopropenone with a catalytic amount of Ru3(CO)12 and NEt3 in THF under 15 atm of carbon monoxide at 140 degrees C for 20 h gave a novel functional monomer, 3,4,7,8-tetrapropylpyrano[6,5-e]pyran-2,6-dione, in an isolated yield of 81%. Unsymmetrically substituted pyranopyrandiones were also obtained by ruthenium-catalyzed carbonylative coupling of cyclopropenones with alkynes under similar reaction conditions.     

Ammonia chemical ionization tandem mass spectrometry in structural determination of alkaloids. II. Tetraponerines from pseudomyrmecine ants

Chemical ionization tandem mass spectrometry (CI-MS/MS) of alkaloids with ammonia reagent gas and collision-activated dissociation as well as EI-MS/MS were applied to the tetraponerine alkaloids in extracts from six pseudomyrmecine ants of the genus Tetraponera. The MS/MS techniques along with gas chromatography Fourier transform infrared (GC/FTIR) spectra allowed identification in two extracts of seven of the eight known tetraponerines. The EI-MS/MS fragmentations proved diagnostic for the ring system and the CI-MS/MS patterns for the C-8 or C-9 substitution, while the Bohlmann bands in FTIR spectra were diagnostic for the C-8 or C-9 configurations. An Indian ant (T. allaborans) had T-2, T-4 and T-8, while a Chinese ant (T. binghami) had T-5, T-6, T-7 and T-8. Four other ants, T. rufonigra (India), T. penzigi (Africa), T. clypeata (Africa) and T. sp. cf. emeryi (Africa), had no tetraponerines.     

Basic evaluation of highly sensitive thyroid stimulating hormone immunoradiometric assay kits

Usefulness of three kinds of TSH kits by immunoradiometric assay (IRMA) was evaluated. They were able to measure low levels (less than 0.1 microIU/ml) in serum thyroid stimulating hormone (TSH) with incubation of short time (4 hours). In particular, RIABEAD II kit had a highly specific affinity for TSH and the normal range (+/- 2 S.D.) using it showed from 0.20 to 3.50 microIU/ml in 150 normal subjects. In patients with hyperthyroidism and in patients with hypothyroidism, the values of TSH were lower and higher than those of normal subjects, respectively. Another kits showed similar results. These results indicate that these TSH-IRMA kits are useful to evaluate serum TSH levels exactly.     

Electron spin resonance study on polymerization of alkyl acrylates with n-butyl titanate(IV)–triethylaluminum catalyst

n-Butyl titanate(IV)–triethylaluminum catalyst at Al/Ti molar ratios greater than 6 polymerizes methyl and n-butyl acrylates at ?78°C. The polymerization system which includes methyl acrylate at ?78°C, gives two ESR signals with g factors of 1.958 and 1.961 that overlap each other. The absorption intensity of the latter signal is approximately proportional to the polymer chain concentration calculated from polymer yield and the molecular weight. The polymerization system at Al/Ti ratios smaller than 3 has no catalytic activity on the polymerization and shows only the ESR signal with the g factor of 1.958. On the basis of these facts the ESR signal with the g factor of 1.961 is attributed to the active growing end of poly(methyl acrylate) with this catalyst. The character of this active growing end is discussed.     

Is recombinant human granulocyte colony-stimulating factor (G-CSF) orally available in rats?

Oral availability of recombinant human granulocyte colony-stimulating factor (G-CSF) was investigated in rats by measuring the blood total leucocyte (BTL) counts. Oral test G-CSF solution was prepared with 10% HCO-60 (polyoxyethylated, 60 mumol, castor oil derivative), 1% DK ester (sugar ester) or 10% MYS-40 (polyethyleneglycol monostearate), in which the G-CSF concentration was 500 or 250 micrograms/ml. Each test solution was injected into the duodenum of three rats at the G-CSF dose level of 300 or 600 micrograms/kg, and BTL counts were monitored for 48 h. All of the test G-CSF solution raised the BTL levels within 24 h after injection. In particular, the HCO-60 solution increased the BTL levels over 2 times as compared to the predose level at 600 micrograms/kg dose and the effect was apparently dose-dependent. A short-term study suggested that the effect of G-CSF on the BTL level appeared at the fastest at about 5 h after administration of HCO-60 test solution, 300 micrograms/kg. In view of the pattern of BTL dynamics obtained after i.v. injection of HCO-60 solution at 25 and 50 micrograms/kg, the increase of BTL levels observed after oral administration of the HCO-60 solution is considered to be due to the orally supplied G-CSF.     

Synthesis of the new chiral tridentate ligand bis(pyrid-2-ylethyl) menthylphosphine and its use in the palladium-catalyzed allylic alkylations

We describe the synthesis of a new asymmetric P,N,N′-tridentate ligand (bis(pyrid-2-ylethyl) menthylphosphine, BPEMP), containing two pyridyl rings and (1S,2R,5S)-menthylphosphino group. The ligand is obtained in five steps from natural abundant l-menthol. The coordination behavior of the ligand toward cationic (allylic)Pd(II) moiety and its first application in palladium-catalyzed asymmetric allylic alkylation are presented. Crystallographic and spectroscopic analyses reveal that [(η³-allylic)Pd(BPEMP)]⁺ complex forms only one isomer in the solid state as well as in solution.     

Inclusion of cut and as-grown single-walled carbon nanotubes in the helical superstructure of schizophyllan and curdlan (beta-1,3-glucans)

We have found that single-chain schizophyllan and curdlan (s-SPG and s-curdlan, respectively) can dissolve as-grown and cut single-walled carbon nanotubes (ag-SWNTs and c-SWNTs, respectively) in aqueous solution. The vis-NIR spectra of the composites suggest that c-SWNTs are dissolved as a bundle, whereas ag-SWNTs exist as one or only a few pieces in the tubular hollow constructed by the helical structure inherent to these beta-1,3-glucans. EDX and CLSM measurements and TEM observation established that the distribution map of these polysaccharides overlaps well with the image of SWNTs, indicating that these two components form a composite. Very interestingly, when c-SWNTs were dissolved with the aid of s-SPG or s-curdlan in water, a clear periodical structure with inclined stripes, as detected by AFM, appeared on the fibrous composite surface. Because this periodical structure has never been recognized for the composites with other water-soluble polymers, one can regard that s-SPG or s-curdlan wraps c-SWNTs constructing a helically twined structure. High-resolution TEM observation of an ag-SWNTs/s-SPG composite gave a clearer image in that two s-SPG chains twine one ag-SWNT and the helical motif is right-handed. When this sample was subjected to the AFM measurement, the composite showed the 2-3 nm height. This height implies that one piece of ag-SWNT is included in the s-SPGs helical structure. As a summary, it has been established that beta-1,3-glucans such as s-SPG and s-curdlan not only dissolve SWNTs but also create a novel superstructure on the surface.     

Ion-exchange selectivity and chromatographic separation of trivalent metals on titanium antimonate

Summary The ion exchange selectivity of trivalent metal ions has been determined on titanium antimonate cation exchanger prepared by coprecipitation of antimony to titanium at different mole ratios. The selectivity sequence Al³⁺<Cr³⁺<Ga³⁺<In³⁺<Fe³⁺ was found for trivalent metal ions at an initial concentration of 10^–4 mol dm^–3 in nitric acid media. A high separation factor ^Ga/Al = Kd^Ga/Kd^Al, 4.8×10³, was observed for the Ga³⁺–Al³⁺ pair on titanium antimonate with an antimony to titanium ratio of 0.34. The effective separation of Ga³⁺ and In³⁺ from Al³⁺ was achieved using a 3 cm×0.5 cm i.d. column containing titanium antimonate with an antimony to titanium ratio of 0.34.