High-performance liquid chromatographic monitoring of metabolic products resulting from the treatment of mouse hepatoma cells with N6-cycloalkylated nucleosides.

High-performance liquid chromatography was used to analyze cell lysates and growth medium of mouse hepatoma cells, separately treated with N6-cyclopropyl-, N6-cyclobutyl-, and N6-cyclopentyladenosines, in an effort to gain insight into the mechanism by which these modified nucleosides exert their cytotoxic effect(s). The corresponding 5'-monophosphate of the respective modified nucleoside was detected in the separate cell lysate samples. Both the modified nucleoside and its corresponding 5'-monophosphate were detected in the separate growth medium samples and their relative concentrations therein were determined. These results indicate that the cytotoxicity of these N6-cycloalkylated nucleosides may be attributed to their 5'-monophosphates within the cells.     

Platinum metal concentrations in urban road dust and soil in the United Kingdom

Concentrations of Pt, Pd, Rh and Au in soils and road dusts taken from areas of high and low traffic flows in the London Borough of Richmond and from a section of the Kingston bypass (A3) at New Malden, Surrey, have been measured. High concentrations of platinum are associated with high traffic densities. Samples taken from streets of lower traffic flows were found to contain the lower concentrations of the ranges. These values correlated well with the levels of lead which were also high at roundabouts. If the preliminary results obtained in this study apply more generally throughout the UK, then the potential for exposure to enhanced levels of Pt would appear to be higher for road users and for those living in urban environments or along major highways.     

Separation of inorganic anions in acidic solution by capillary electrophoresis

Inorganic anions are almost always determined by capillary electrophoresis (CE) at an alkaline pH, so the analytes will be fully ionized. However, a long-chain quaternary ammonium salt usually must be added as a flow modifier to the carrier electrolyte to reverse the direction of the electroosmotic flow. By working at a sufficiently acidic pH, the electroosmotic flow in fused-silica capillaries is virtually eliminated, and anions can be separated simply by differences in their electrophoretic mobilities. Excellent separations were obtained for AuCl₄⁻ and the chloro complexes of platinum group elements in HCl solution at pH 2.0 to 2.4. No additional buffer or flow modifier was needed. This CE technique is an excellent way to follow slow hydrolytic reactions in which one or more of the chloride ligands is replaced by water. Sharp peaks and good separations were also obtained for MnO₄⁻, VO₃⁻, chromate, molybdate, ferrocyanide, ferricyanide and stable complex ions such as chromium oxalate (CrO₃³⁻).     

Short,Enantiospecific Syntheses of Indolizidines 209B and 209D,and Piclavine A from Diethyl-L-Glutamate

The 1H-pyrrole derivative obtained from diethyl L -glutamate hydrochloride and tetrahydro-2,5-dimethoxyfuran was cyclized with BBr₃ to ethyl (5S)-5,6,7,8-tetrahydro-8-oxoindolizine-5-carboxylate ( 18 ). Catalytic hydrogenation of 18 over Pd/C in AcOH gave ethyl (5S,8aR)-octahydroindolizine-5-carboxylate ( 21 ), whereas hydrogenation over Rh/Al₂O₃ in EtOH/AcOH 99:1 afforded mainly ethyl (5S,8S,8aS)-octahydro-8-hydroxyindolizine-5-carboxylate ( 22 ). By functional-group interconversions, 21 was transformed into piclavine A ( 1 ) and indolizidine 209D ( 2 ). Similarly, (5R,8R,8aS)-octahydro-5-pentylindolizine-8-methanol ( 37 ), the final relay for indolizidine 209B ( 3 ), was obtained from 22 .     

Far infrared spectra (500–50 cm−1) of the 2,2′-bipyridine complexes of palladium and platinum halides

Summary The far-i.r. spectra of the title complexes have been examined. Band assignments are based on the shifts induced by ligand deuteration and halide substitution. Deuteration of bipyridine causes large shifts ( >10 cm^–1) in internal ligand modes, intermediate shifts between 2 and 9 cm^–1) in metal-nitrogen stretching and bending modes and small to zero shifts in metal-halide stretching and bending vibrations. Generally, the requirements for square planarC _2v synanetry [two (M–N) and two (M–X) bands] are observed. Previous ambiguities in the assignment of the (M–N) bands have been resolved by the isotopic labelling technique employed in this study.     

Infrared spectra of o-toluidine and m-toluidine complexes of Co(II), Ni(II), Cu(II) and Zn(II) halides

The infrared spectra of eighteen metal complexes of empirical formula [ML₂X₂] (M = Co, Ni, Cu or Zn; L = o^? or m-toluidine; X = Cl, Br or I) have been determined over the range 4000-150 cm^?1. Assignments of the internal vibrations of the amino group are based on the band shifts induced by ¹⁵N-labelling of the nitrogen donors. Bands within the range 400–600 cm^?1 are assigned to the metal-nitrogen stretching frequency (vM-N) on the grounds of their sensitivity to ¹⁵N-labelling and metal ion substitution and their absence of sensitivity to halide substitution. Bands within the range 350–150 cm^?1 are assigned to the metal-halogen stretching frequency (vM-X) on the basis of their sensitivity to halide and metal ion substitution and their insensitivity to ¹⁵N-labelling. Structural aspects of the spectra are discussed and the present assignments are compared with those previously reported.     

Crystal field aspects of vibrational spectra: VII. Derivation of a spectrochemical series of ligands from infrared spectra

The infrared spectra (700-200 cm^?1) of 52 complexes of general formula Na[ML₃] or [ML₂B] (where M = a divalent metal ion of the first transition series; L = α-thenoyltrifluoroacetonate or benzoyltrifluoroacetonate anion; B = 2H₂O, 2NH₃, 2pyridine, 2,2'-bipyridine or 1,10-phenanthroline) are discussed. Within each series of complexes with common L and B, the IR band near 400 cm^?1 which exhibits maximum sensitivity to the coordinated metal ion (the sensitivity being in the sequence of crystal field stabilization energies) and which generally occurs in a region free from ligand absorption, is assigned to the metal—oxygen stretching frequency (v(M—O)). For each series of complexes with common M and L, the magnitude of v(M—O) decreases progressively with increasing ligand field strength of B. This relationship enables the coordinated bases, B, to be arranged in a spectrochemical series which is practically identical with that obtained from electronic spectra.