Flow-injection liposome immunoanalysis (FILIA) for alachlor

An automated Flow-Injection Liposome ImmunoAnalysis (FILIA) system has been modified from a previous design, using a specific environmental contaminant, the herbicide alachlor, as a model analyte. Signal amplification by means of fluorescent marker-loaded, analyte-tagged liposomes provides high sensitivity. The computer controlled system is composed of commercially available components, with the exception of the column packing material, which has to be prepared for each specific analyte to be determined. The use of such components means that the system is easily modified. The relationships between antibody concentration and assay speed and sensitivity are explored, and the possibilities of using the system for determination of multiple analytes is discussed.     

Design and Asymmetric Synthesis of beta-Strand Peptidomimetics

We describe the asymmetric synthesis of non-peptidic compounds that feature rigid backbone conformations and present various side-chain functions. The key step in the synthesis of these compounds is the C-acylation of an appropriate ketone with a suitably protected aspartic acid derivative. The resulting dipeptide modules may be connected to form tetrapeptide mimics. Specifically is described the mimicry of a four-residue segment of CD4, the cellular receptor of HIV-1. The design was based on molecular modeling and the X-ray crystal structures of CD4 and intended to present the most important side chains and backbone elements of the Phe43-Lys46 segment.     

Derivatives of 2,4-diamino-6-methylpteridine

Eighteen derivatives of 2,4-diamino-6-methylpteridine related to methotrexate and aminopterin have been prepared from 6-(bromomethyl)-2,4-pteridinediamine by nucleophilic displacement reactions. None of these compounds showed any antileukemic acitivity.     

An ESR study of the reactions of trialkylsiloxyl and trialkylsilyl radicals with dialkyl sulphides

Trimethylsiloxyl radicals add to dialkyl sulphides to produce sulphuranyl radicals, whilst triethylsilyl radicals bring about homolyric dealkylation of dialkyl sulphides.     

Hydroxylation and dehydroxylation at Cu(III) surfaces

X-ray photoelectron spectroscopy has shown how both chemisorbed oxygen present at a Cu(III) surface and nitric oxide introduced into the gas phase can induce hydroxylation of the surface from an adlayer of molecularly adsorbed water at 80 K. The interaction of water vapour with a clean Cu(III) surface is also reported.     

Correlation of thermodynamic stabilities of charge transfer complexes of anthracene and chloranil with those of tetra-cyanoethylene

The formation constants of charge-transfer complexes of a number of 9- and 9,10-substituted anthracenes with chloranil have been measured by a spectrophotometric method and the corresponding thermodynamic parameters ΔG°_c, ΔH°_c and ΔS°_c evaluated in various solvents. v_max values of the chargetransfer band for chloranil were linearly related to those for tetracyanoethylene (TCNE). Good correlations were also obtained between v_max and the corresponding ionisation potentials Ip of the donor molecules. In addition ΔG°_c varied linearly with Ip and from these correlations, values of ΔG°_c, etc. for the corresponding TCNE complexes could be calculated. These values are otherwise very difficult to obtain due to the high reactivity of TCNE.     

Carbon-13 nuclear magnetic resonance studies of coumarin and related compounds

Fourier-transform ¹³C NMR spectra of nine coumarinoid compounds of medicinal interest are reported. All of the carbon resonances are assigned with the aid of various spectral techniques and stable isotopic labeling. The substituent effects on the chemical shifts in several systems are also discussed.