Equilibria in complexes of N-heterocyclic molecules,part XII. The reaction of hydroxide and alkoxide Ions with platinum(II) complexes of 5-nitro-1,10-phenanthroline and 2,2′-bipyridyl

Summary Bis-(5-nitro-1,10-phenanthroline)platinum(II) dichloride and diperchlorate have been prepared. The reaction between the parent cation and hydroxide ion has been studied using 1 FI n.m.r. spectroscopy and found to involve attack at the ligand. The bis-(2,2-bipyridyl)platinum(II) ion has been shown to be highly reactive towards methoxide ion. The dissociation of a 2,2-bipyridyl ligand is preceded by attack at the ligand.Part XI: R. D. Gillard, t.. A. P. Kane-Maguire and P. A. Williams,Transition Met. Chem., 2, 47 (1977).On leave from the University of Baghdad, Iraq.     

INTERACTION OF VIOLOGEN DYES WITH CHROMATOPHORES AND REACTION-CENTER PREPARATIONS FROM RHODOSPIRILLUM RUBRUM

Abstract —Various low-potential viologen dyes enhance light-induced absorption changes in the near-infrared region (ΔA870) in chromatophore preparations from Rhodospirillum rubrum in the presence of dichlorophenol indophenol and a high concentration of ascorbate (DCPIP + asc). An increase in ΔA870 was also observed in large reaction-center preparations from R. rubrum with viologens in the presence of ascorbate. Our results indicate that E'₀, of the primary electron acceptor X may be as low as -0.37 V, as suggested recently by P. A. Loach (1973, personal communication).     

Measurement of cell migration on surface-bound fibronectin gradients

A novel technique for the quantitative observation of cell migration along linear gradient substrates functionalized with adhesive proteins is presented. Gradients of the cell adhesion molecule fibronectin are generated by the cross diffusion of functionalizable alkanethiols on gold and characterized by X-ray photoelectron spectroscopy and surface plasmon resonance. Two distinct migration assays are described that characterize the movement of either sparsely populated noncontacting cells or a confluent monolayer of cells into free space. The drift speed of bovine aortic endothelial cells is measured and shown to increase along a fibronectin gradient when compared to a uniform control substrate using both assays. The results of these experiments establish reproducible conditions for studies of cell migration on gradients of surface-bound ligands.     

Reactions of metal carbonyl cluster complexes with multidentate phosphine ligands; reactions with bis(diphenylphosphino)methane

Reactions of Rh₆(CO)₁₆ with bis(diphenylphosphino)methane (dppm) gave Rh₆(CO)₁₄(dppm), Rh₆(CO)₁₂(dppm)₂, or Rh₆(CO)₁₀(dppm)₃, depending upon the reaction conditions. Rh₄(CO)₁₀(dppm) may be obtained from the reaction of Rh₄(CO)₁₂ with dppm, but this derivative rapidly decomposes in solution to give Rh₄(CO)₈(dppm)₂, Rh₆(CO)₁₄(dppm), and Rh₆(CO)₁₂(dppm)₂. Ir₄(CO)₁₀(dppm) and Ir₄(CO)₈(dppm)₂ have also been prepared, and their structures are discussed on the basis of infrared and ³¹P NMR spectroscopic data.     

Investigation of the metabolic fate of 2-, 3- and 4-bromobenzoic acids in bile-duct-cannulated rats by inductively coupled plasma mass spectrometry and high-performance liquid chromatography/inductively coupled plasma mass spectrometry/electrospray mass spectrometry

Inductively coupled plasma mass spectrometry (ICPMS) has been used to determine the rate and routes of excretion of bromine following the intraperitoneal administration (50 mg kg(-1)) of 2-, 3- and 4-bromobenzoic acids to male bile-duct-cannulated rats. Analysis of urine and bile for (79/81)Br using ICPMS showed that all three bromobenzoic acids were rapidly excreted (82-98%) within 48 h of dosing, primarily via the urine. High-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS) was then used to obtain metabolite profiles for bile and urine. These profiles revealed that extensive metabolism had taken place, with the unchanged bromobenzoic acids forming a minor part of the total of compound-related material detected. Concomitant MS studies, supplemented by alkaline hydrolysis, enabled the identification of the major metabolite of all three of the bromobenzoic acids as a glycine conjugate. Ester glucuronide conjugates were also identified, but formed only a small proportion of total.     

Copolymerization of styrene and diethyl fumarate with ZnBr2. IV. Comparison between photoinitiation and electroinitiation

A comparative analysis of photoinitiation and electroinitiation can help elucidate initiation processes in donor-acceptor charge-transfer copolymerization. The technique has been applied to the zinc bromide-catalyzed copolymerization of styrene and diethyl fumarate in methanol. The photocopolymer product was analyzed by GPC, NMR, and elemental analysis. The results showed that 1:1 copolymers were formed initially, but changes occurred in both the kinetics and products after the early stages of the reaction. Significant correlations found between the two initiation methods included the initial kinetic order with respect to the initiating process and the effect on product yield of equivalent increases in total initiation energy. The limiting value of zinc bromide for both initiation methods was found to be the same. The data obtained support the contention that the copolymerization proceeds through a donor–acceptor process and that photoactivation of the preformed complex, inducing electron transfer, is a likely initiation process.     

Copolymerization of acrylic acid to nylon-6 by trapped radicals—II: Liquid phase grafting and properties of copolymers

Initial rates of grafting, R_g, have been determined for film of nylon-6, which had been -,,-irradiated in vacuo and subsequently immersed in outgassed, aqueous, acrylic acid at 50'. Equilibrium swellings due to water and to monomer are attained rapidly by nylon-6 and give rise to a high R_g. During grafting a constant swelling due to water occurs immediately but the rate of uptake of monomer is less than R_g, These effects are discussed on the basis of compatibility. At a fixed equilibrium monomer concentration, [AA], in the film, R_g ∝ D^β where D is the dose and β = 0.94. At a fixed dose, R_g ∝ [AA]^α where α = 1.04. The value of β indicates mainly monomolecular termination by radical burial. This is postulated to occur by trapping of growing grafts in crystalline regions and/or transfer from them to such regions. By selectively dyeing and sectioning films of different degrees of grafting (DG), the progress of the grafting front inwards has been shown to follow closely the corresponding grafting curve of DG vs time. Grafting does not alter the moisture regain of nylon. Surface resistance and swelling in water change with DG, the effect being enhanced markedly by converting the grafts to their sodium salts.     

Assessment of silver and gold substrates for the detection of amphetamine sulfate by surface enhanced Raman scattering (SERS)

Methods of detection of amphetamine sulfate using surface enhanced Raman scattering (SERS) from colloidal suspensions and vapour deposited films of both silver and gold are compared. Different aggregating agents are required to produce effective SERS from silver and gold colloidal suspensions. Gold colloid and vapour deposited gold films give weaker scattering than the equivalent silver substrates when high concentrations of drug are analysed but they also give lower detection limits, suggesting a smaller surface enhancement but stronger surface adsorption. A 10(-5) mol dm(-3) solution (the final concentration after addition of colloid was 10(-6) mol dm(-3)) of amphetamine sulfate was detected from gold colloid with an RSD of 5.4%. 25 microl of the same solution could be detected on a roughened gold film. The intensities of the spectra varied across the film surface resulting in relatively high RSDs. The precision was improved by averaging the scattering from several points on the surface. An attempt to improve the detection limit and precision by concentrating a suspension of gold colloid and amphetamine sulfate in aluminium wells did not give effective quantitation. Thus, positive identification and semi-quantitative estimation of amphetamine sulfate can be made quickly and easily using SERS from suspended gold colloid with the appropriate aggregating agents.     

The thiolate anion as a nucleophile Part XII. Reactions of Lead(II) Benzenethiolate

The reactions of various fluoroaromatics, C₆F_6?xH_x, and C₆F₅X (X = C₆F₆, Cl, Me, NO₂, CF₃, COCl, CH₂Br, OMe, and NH₂) with lead(II) benzenethiolate in DMF have been examined. Lead thiolate acted as an excellent source of benzenethiolate anions and displacement of fluorine, chlorine or the nitro group was observed. The new products have been characterized by elemental analysis, and NMR (H?1 and F?19), infrared and mass spectroscopy.