Palladium-catalyzed amination of aryl nonaflates

The first detailed study of the palladium-catalyzed amination of aryl nonaflates is reported. Use of ligands 2-4 and 6 allows for the catalytic amination of electron-rich and -neutral aryl nonaflates with both primary and secondary amines. With use of Xantphos 5, the catalytic amination of a variety of functionalized aryl nonaflates resulted in excellent yields of anilines; even 2-carboxymethyl aryl nonaflate is effectively coupled with a primary alkylamine. Moderate yields were obtained when coupling halo-aryl nonaflates with a variety of amines, where in most cases the aryl nonaflate reacted in preference to the aryl halide. Overall, aryl nonaflates are an effective alternative to triflates in palladium-catalyzed C-N bond-forming processes due to their increased stability under the reaction conditions.     

Reactions of diphosphineplatinum(II) oxalate complexes with phenylacetylene. Formation of phenylalkynylplatinum complexes

[Pt(C₂O₄)(dppe)] reacts thermally with PhCCH to produce [Pt(CCPh)₂(dppe)], which has been prepared by alternative routes. Similar treatment of [Pt(C₂O₄)(dppm)] initially produces [Pt(CCPh)₂(dppm)], which rearranges to give cis,cis-[Pt₂(CCPh)₄(μ-dppm)₂]. Reaction of [PtCl₂(dppm)] with PhCCH/KOH/18-crown-6, or with (PhCC)SnMe₃, gives [Pt(CCPh)₂(dppm)], which may be converted to the cis,cis-dimer by addition of oxalic acid. Ultraviolet irradiation or refluxing with a trace amount of dppm converts [Pt(CCPh)₂(dppm)] to trans,trans-[Pt₂(CCPh)₄(μ-dppm)₂], but the cis,cis-dimer is stable under these conditions. [Pt(C₂O₄)L₂] (L = PPh₃, PEt₃) complexes also react thermally with PhCCH to yield [Pt(CCPh)₂L₂] species.     

Separation of lidocaine and its metabolites by capillary electrophoresis using volatile aqueous and nonaqueous electrolyte systems

The separation of the basic drug lidocaine and six of its metabolites has been investigated both by using volatile aqueous electrolyte system, at low pH and by employing non-aqueous electrolyte systems. In aqueous systems, the best separation of the compounds under the investigated conditions was achieved by using the electrolyte 60 mM trifluoroacetic acid (TFA)/triethylamine (TEA) at pH 2.5 containing 15% methanol. With this electrolyte, all seven compounds were well separated with high efficiency and migration time repeatability. The separations with bare fused-silica capillaries and polyacrylamide-coated capillaries were compared with higher separation efficiency with the latter. On the other hand, near baseline separation of all the seven compounds was also obtained by employing the non-aqueous electrolyte, 40 mM ammonium acetate in methanol and TFA (99:1, v/v), with comparable migration time repeatability but lower separation efficiency relative to the aqueous system.     

POTENTIATION OF MEROCYANINE 540-MEDIATED PHOTODYNAMIC THERAPY BY SALICYLATE and RELATED DRUGS

Abstract— Simultaneous exposure to merocyanine 540 (MC540) and light of a suitable wavelength kills leukemia, lymphoma and neuroblastoma cells but is relatively well tolerated by normal pluripotent hematopoietic stem cells. This differential phototoxic effect has been exploited in preclinical models and a phase I clinical trial for the extracorporeal purging of autologous bone marrow grafts. Salicylate is known to potentiate the MC540-mediated photokilling of tumor cells. Assuming that salicylate induces a change in the plasma membrane of tumor cells (but not normal hematopoietic stem cells) that enhances the binding of dye molecules it has been suggested that salicylate may provide a simple and effective means of improving the therapeutic index of MC540-mediated photodynamic therapy. We report here on a direct test of this hypothesis in a murine model of bone marrow transplantation as well as in clonal cultures of normal murine hematopoietic progenitor cells. In both systems, salicylate enhanced the MC540-sensitized photoinactivation of leukemia cells and normal bone marrow cells to a similar extent and thus failed to improve the therapeutic index of MC540 significantly. On the basis of a series of dye-binding studies, we offer an alternative explanation for the potentiating effect of salicylate. Rather than invoking a salicylate-induced change in the plasma membrane of tumor cells, we propose that salicylate displaces dye molecules from serum albumin, thereby enhancing the concentration of free (active) dye available for binding to tumor as well as normal hematopoietic stem cells.     

Preparation of animal tissue samples for the determination of90Sr and actinides

A unique procedure permitting the determination of⁹⁰Sr and actinides in the same protion of sample, with good chemical yields of all analytes, is presented. Animal tissue samples containing bone are ashed, spiked with^{2 3 2}U,^{2 4 2}Pu,^{2 4 3}Am and^{8 5}Sr and solubilized. The actinides and strontium are gathered and separated by a series of coprecipitations with, cerium hydroxide and cerium fluoride. Actinide separation and determination and purification and determination of⁹⁰Sr are accomplished by a combination of several well-known procedures. The laboratory method consistently results in high chemical yields of all the analytes and overcomes interferences from phosphates and calcium.     

A novel high-performance fourier transform ion cyclotron resonance cell for improved biopolymer characterization

A new trapped ion cell design for use with Fourier transform ion cyclotron resonance mass spectrometry is described. The design employs 15 cylindrical ring electrodes to generate trapping potential wells and 32 separately assignable rod electrodes for excitation and detection. The rod electrodes are positioned internal to the ring electrodes and provide excitation fields that are thereby linearized along the magnetic field over the entire trapped ion volume. The new design also affords flexibility in the shaping of the trapping field using the 15 ring electrodes. Many different trapping well shapes can be generated by applying different voltages to the individual ring electrodes, ranging from quadratic to linearly ramped along the magnetic field axis, to a shape that is nearly flat over the entire trap volume, but rises very steeply near the ends of the trap. This feature should be useful for trapping larger ion populations and extension of the useful range of ion manipulation and dissociation experiments since the number of stages of ion manipulation or dissociation is limited in practice by the initial trapped ion population size. Predicted trapping well shapes for two different ring electrode configurations are presented, and these and several other possible configurations are discussed, as are the predicted excitation fields based on the use of rod electrodes internal to the trapping ring electrodes. Initial results are presented from an implementation of the design using a 3.5 T superconducting magnet. It was found that ions can be successfully trapped and detected with this cell design and that selected ion accumulation can be performed with the utilization of four rods for quadrupolar excitation. The initial results presented here illustrate the feasibility of this cell design and demonstrate differences in observed performance based upon different trapping well shapes.     

THE EFFECT OF 1,4-DIAZABICYCLO[2.2.2]OCTANE ON THE RADIOSENSITIVITY OF BACTERIA

Abstract— Hydroxyl radicals ('OH) are scavenged by 1,4-diazabicyclo[2.2.2]octane (DABCO) at a diffusion-controlled rate of 1.25 ± 0.1 × 10⁹ M ^-1s^-1. Unlike other efficient 'OH scavengers which exhibit protection of bacteria against irradiation both in oxic and hypoxic conditions, DABCO has been shown to protect Serratia marcescens and various strains of Escherichia coli only in oxic conditions.
DABCO appears to eliminate a component of the sensitization afforded by oxygen in all strains of E. coli tested. The level of this protection increases from ∼15% in the wild type AB 1157 to ∼100% in the recA uvrA mutant AB 2480. It is suggested that DABCO protects against lethal events that can occur on macromolecules other than DNA such as the cell membrane.
Results with added glycerol, as well as work in D₂O solution, indicate that DABCO is more likely to be acting by scavenging radicals rather than by quenching ¹O₂. If ¹O₂ is a component of the sensitization afforded by oxygen, then it is unlikely to be formed in a hydrophilic environment in the cell.     

Catalytic synthesis of diazines from 1,3-diaminopropane and 3-amino-1-propanol

The transformations of 1,3-diaminopropane and 3-amino-1-propanol under pulse conditions over tungsten trioxide in an inert atmosphere at 300–500 °C were investigated. The transformation of 1,3-diaminopropane leads to the formation of saturated pyrimidine bases; the maximum selectivity of the formation of hexahydropyrimidine bases at 300 °C is 60%, while the selectivity of the formation of tetrahydropyrimidine bases is 20% (400 °C). In the case of 3-amino-1-propanol the overall yield of heterocyclic bases was less than 5%, and piperazine and pyrazine derivatives were observed as the cyclic products; the formation of pyrimidine bases was not observed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 967–973, July, 1982.     

Comparison of Si-O-C interfacial bonding of alcohols and aldehydes on Si(111) formed from dilute solution with ultraviolet irradiation

Aliphatic alcohols and aldehydes were reacted with the Si(111)-H surface to form Si-O-C interfacial bonds from dilute solution by using ultraviolet light. The resulting monolayers were characterized by using transmission infrared spectroscopy, spectroscopic ellipsometry, and contact angle measurements. The effect of different solvents on monolayer quality is presented. The best monolayers were formed from CH(2)Cl(2). The optimized monolayers were thoroughly characterized to determine the film structure and monolayer stability. The UV-promoted, alcohol-functionalized, and aldehyde-functionalized monolayers are of comparable quality to those previously prepared by other means. Although both molecules are tethered through a Si-O-C bond, the film reactivity is distinctly different with the aldehyde films being more chemically resistant. The differences in chemical reactivity, vibrational spectra, hydrophobicity, and ellipsometric thickness between the alcohol and aldehyde monolayers are attributed to a difference in molecular coverage and monolayer formation.     

EXAFS study of Zn sorption mechanisms on hydrous ferric oxide over extended reaction time

The sorption species and coordination environment of zinc sorbed on to hydrous ferric oxide (HFO) did not change for aging times up to six months. At an initial concentration of 10(4-) M, Zn formed innersphere surface complexes on the surface of HFO. Zn was tetrahedrally coordinated with oxygen atoms at ZnO bond distance of approximately 1.94-1.97 A with coordination number of approximately 3.8-4.7. In the second shell Zn appeared to be coordinated with Fe with a bond distance of approximately 3.42-3.49 A. At an initial concentration of 10(3-) M, both innersphere and polynuclear complexes were feasible sorption products. The first shell was tetrahedrally coordinated with about four oxygen atoms at a bond distance of 1.96 A. The second shell could be attributed to either ZnFe or ZnZn correlations with almost the same bond distance of 3.42-3.44 A.