N-hydroxy amides. Part 9. Synthesis and lron(III) complexes of tripodal hydroxamic acids derived from ω-(N-hydroxyamino)alkanoic acids and tris(2-aminoethyl)amine

Tripodal oligoamide hydroxamic acids with different chain lengths (compounds 8a–d) are prepared via condensation of N-hydroxysuccinimide esters of N-acyl-N-benzyloxyaminoalkanoic acids with tris-(2-aminoethyl)amine. These synthetic trihydroxamic acids form iron(III) complexes in aqueous DMF solution. The behaviour of these iron(III) complexes is investigated in terms of absorption vs pH and of iron(III) exchange reactions with EDTA. A biological assay performed with Aureobacterium flavescens reveals that the trihydroxamic acids have substantial growth-promoting activity although weak relative to that of natural desferrioxamine B.