Lipophilic hexadentate gallium, indium and iron complexes of new phenolate-derivatized cyclohexanetriamines as potential in vivo metal-transfer reagents

Abstract

1,3,5-Tris(5-substituted sa1icylamino)cyclohexanes (H,L; R = H, NO, or OMe) have been synthesized by Schiffbase condensation between cis-1.3.5-triaminocyclohexane and a substituted salicylaldehyde, followed by reduction with KBH,. Reaction of these compounds with gallium(lll), indium(ll1) and iron(ii1) salts gave neutral six-co-ordinate N,O, complexes of type [ML] ( M = Ga, In or Fe). The complexes have been characterized by a combination of infrared, l H and 13C-{lH} NMR and mass spectroscopy. The distribution coefficients between octan-1 -01 and water indicate that the complexes are lipophilic. The electronic absorption spectra of the high-spin iron( 111) complexes show ligand-tometal charge-transfer bands in the 450-500 nm range. The structures of five of the complexes have been confirmed by single-crystal X-ray crystallography.

Hydrophilic and Lipophilic Iron Chelators with the Same Complexing Abilities

“…Partition coefficients and triphasic systems : The partition coefficients between an aqueous phase buffered at pH 7.4 (Tris buffer) and octanol or chloroform were determined by a known procedure 30. The triphasic water–octanol–water system has been described previously 7.…”

Design of Iron chelators: Syntheses and iron (III) complexing abilities of tripodal tris-bidentate ligands

“…Lipophilic enterobactin analogues (tris-catecholates) have been described ) using a spermidine spacer in which the N terminal nitrogen atom is substituted by long alkyl chains. Lipophilic chelators derived from EDTA (Galey et al 2000;Serratrice et al 2001) or trisaminophenol (Bollinger et al 1995) have also been reported. An elegant strategy has been developed by Shanzer and collaborators in which the lipophilic ferrichrome analogues with masked hydrophilic moieties (Figure 8a) A series of three tris-hydroxyquinolinate derivatives of O-TRENSOX containing a C-pivotal atom as spacer and grafted with various polyoxyethylene chains (POE) has been prepared in our group (Figure 9a, Imbert et al 2002), leading to the observation that the hydrophilic-lipophilic balance (quantified by the partition coefficients) of the overall neutral ferric complexes is tuned by the length of the polyoxyethylene chain.…”

A novel 1,3,5-triaminocyclohexane-based tripodal ligand forms a unique tetra(pyrazolate)-bridged tricopper(ii) core: solution equilibrium, structure and catecholase activity

“…The [3N3O] donor set of cis,cis-1,3,5-tris{(2-hydroxybenzyl)aminomethyl}cyclohexane forms highly stable lipophilic complexes with M(III) metal ions, 20,21 and the substitution of the benzyl-ring provided a series of Mn-SOD models with tunable reduction potentials. 22 Tachpyr (N,N',N''-tris(2-pyridylmethyl)-…”