Chelating Vesicles Made From N,N‐Dihexadecyl‐1,2‐ethanediamine‐N′,N′‐diacetic Acid

Abstract

Aqueous suspensions of N,N-Dihexadecyl-l,2-ethanediarnine-N:N'-diacetic acid (1 d) give stable vesicles on sonication at pH = 3.5 and 9.0. The outer vesicle surface chelates copper(I1) and iron(lI1) ions without vesicle precipitation. Chelating micelles'.*) and vesicles are of interest because they allow the attachment of redox-active metal ions. If the aggregate also contains a photochemically active dye, e.g. a porphyrin, such systems may be used for light-induced charge separation3'. We report here on the synthesis and chelating properties of a vesicle with ethylenediaminediacetic acid head groups.The title compound Id was prepared from N-(2-aminoethyl)acetamide (1 a) by dialkylation with hexadecyl bromide in ethanol to give l b , removal of the acetyl protecting group in ethanolic sodium hydroxide and treatment of l c with chloroacetic acid in dirnethylformamide. The overall yield was 28 070.Ultrasonication of aqueous suspensions of 1 d gave stable, slightly opaque solutions at pH = 2 and 9. At pH = 6 the clear solution became turbid within a few hours.Electron micrographs of the evaporated solutions indicated the presence of vesicles with diameters ranging from 500-2000 A (Fig. 1). Water insoluble magnesium octaethylporphyrin could be dissolved t o a concentration of about molar in the vesicular solutions.

A Comparison of the Selectivity of Extraction of [PtCl6]2– by Mono-, Bi-, and Tripodal Receptors That Address Its Outer Coordination Sphere

“…was prepared following a literature procedure 8 and amine 5 by adaptation of a literature procedure. 9 (0.06 M) was added to these vials so that there were two molar equivalents of OHrelative to the amount of receptor in the sample, as well as sufficient water to make the final aqueous volume 4 cm 3 . The two phases were contacted for 30 min then separated.…”

“…Amine 5 was prepared, in high yield, by adaptation of a literature procedure (Scheme 4), 9 and was converted to L 14 − L 18 (Scheme 5) using similar procedures to those described above for L 6 −L 13 . Extractants L 14 and L 15 are white solids, whereas L 16 −L 18 were obtained as yellow oils after purification by column chromatography.…”

“…The general trend in the strength of an extractant for a particular type of amide in TREN-based systems, L 1 −L 18 , varies in the order tripodal > bipodal > monopodal extractant. The efficiency of loading falls off particularly sharply for the "simple" amides; e.g., when a 3-fold excess of the reagent is present, the loadings are for L 3 (tripodal) 87%, L 8 (bipodal) 30%, and for L 16 (monopodal) 13% [for their 3,5-methoxy isomers L 4 , L 9 , and L 17 , the values vary similarly: 86, 25, and 9%].…”

“…The tri-, di-, and monopodal amido extractants L 4 , L 9 , and L 17 (Figure 9) were selected for study on the basis of the good solubilities of their hydrochloride salts and chloridoplatinate complexes in chloroform, and TOA was used for comparison because this contains no pendant hydrogen-bond donor groups. The hydrochloride salts, L 4 •HCl, L 9 •HCl, and L 17 •HCl, were synthesized by bubbling hydrogen chloride into solutions in chloroform or n-hexane. (5)…”

Functionalised 1,10-phenanthroline metallocatalysts as models for hydrolytic metalloenzymes

“…Moreover, aggregates of functionalised surfactants as biomimetic hydrolytic metallocatalysts have attracted considerable attention, homo and mixed metallomicelles are effective in promoting the cleavage of p h o ~p h o r i c , ' ~-' ~ and carboxylic esters. ' 5-- 19 Recently reversed mixed micelles,20 and functionalised vesicles [21][22][23] have also been investigated as metalloenzyme models.…”