“…The importance of iron in biological systems has been well established. − The uptake, transport, and storage of iron in biological systems from their environment has been very thoroughly studied. − In many cases the strategy which is employed calls upon low-molecular weight iron chelators called siderophores. − When iron overload occurs, patients need treatment with ligands that act as sequestering agents. − ,− Martell et al . , have prepared the hexadentate ligand N , N -bis(2-hydroxybenzyl)ethylenediamine- N , N ‘-diacetic acid (HBED) and other similar ligands, hexadentates or higher polydentate ligands. − The stability constants that have been determined for such ligands are much higher that those for EDTA. Other kinds of chelating compounds utilized are similar to natural siderophores which are synthesized by microorganisms in order to take up iron from the extracellular medium. − ,, …”
Section: Introductionmentioning
confidence: 99%
“…Therefore, o -PhDTA, 3,4-TDTA, and 4-Cl- o -PhDTA are better sequestering agents for Be(II) than EDTA and similar ligands. , This has prompted our study of ligands derived from aromatic diamines to obtain selective chelating agents for Fe(III). We report herein on the chelating ability of o -PhDTA, 3,4-TDTA, and 4-Cl- o -PhDTA with iron(III) in aqueous solution, with a view to comparing them by speciation studies not only with EDTA but also with effective sequestering agents for iron(III) studied by Martell et al . ,− 1 …”
The coordinating ability of the ligands
3,4-toluenediamine-N,N,N‘,N‘-tetraacetic
(3,4-TDTA), ortho-phenylenediamine-N,N,N‘,N‘-tetraacetic
(o-PhDTA), and
4-chloro-1,2-phenylenediamine-N,N,N‘,N‘-tetraacetic
(4-Cl-o-PhDTA) acids, H4L, with Cu(II) and Fe(III) is
described. The stability constants and the partial molar
enthalpies
of the complexes formed (25 °C, I = 0.5 mol
dm-3 in KNO3) were respectively
determined by means of emf and
calorimetry measurements. For the system 3,4-TDTA−Fe(III)
(25 °C, I = 0.5 mol dm-3 in
NaClO4), the stability
constants of the complexes FeL- and
[FeL(OH)]2- were also determined
spectrophotometrically. The calorimetric
measurements show that the complex formation is entropy driven,
exothermic for Cu(II) and endothermic for
Fe(III). The partial molar entropy of complexation
(ΔS°) is much the same as that of the EDTA
complexes.
X-ray diffraction structural analysis of
Na[Fe(4-Cl-o-PhDTA)(H2O)]·1.5H2O
revealed that, in
[FeL(OH2)]-
(monoclinic C2/c, a = 10.693(3)
Å, b = 13.931(3) Å, c = 24.686(6)
Å, β = 94.21(2)°, V= 3667(2)
Å3, Z = 8),
the iron(III) is seven coordinated, with one water molecule
filling the seventh position, similar to the
iron(III)
anionic chelates of 3,4-TDTA, o-PhDTA, and EDTA. The
presence of the Cl atom in the aromatic ring produces
an asymmetry in the Fe−N bond distances.
“…The importance of iron in biological systems has been well established. − The uptake, transport, and storage of iron in biological systems from their environment has been very thoroughly studied. − In many cases the strategy which is employed calls upon low-molecular weight iron chelators called siderophores. − When iron overload occurs, patients need treatment with ligands that act as sequestering agents. − ,− Martell et al . , have prepared the hexadentate ligand N , N -bis(2-hydroxybenzyl)ethylenediamine- N , N ‘-diacetic acid (HBED) and other similar ligands, hexadentates or higher polydentate ligands. − The stability constants that have been determined for such ligands are much higher that those for EDTA. Other kinds of chelating compounds utilized are similar to natural siderophores which are synthesized by microorganisms in order to take up iron from the extracellular medium. − ,, …”
Section: Introductionmentioning
confidence: 99%
“…Therefore, o -PhDTA, 3,4-TDTA, and 4-Cl- o -PhDTA are better sequestering agents for Be(II) than EDTA and similar ligands. , This has prompted our study of ligands derived from aromatic diamines to obtain selective chelating agents for Fe(III). We report herein on the chelating ability of o -PhDTA, 3,4-TDTA, and 4-Cl- o -PhDTA with iron(III) in aqueous solution, with a view to comparing them by speciation studies not only with EDTA but also with effective sequestering agents for iron(III) studied by Martell et al . ,− 1 …”
The coordinating ability of the ligands
3,4-toluenediamine-N,N,N‘,N‘-tetraacetic
(3,4-TDTA), ortho-phenylenediamine-N,N,N‘,N‘-tetraacetic
(o-PhDTA), and
4-chloro-1,2-phenylenediamine-N,N,N‘,N‘-tetraacetic
(4-Cl-o-PhDTA) acids, H4L, with Cu(II) and Fe(III) is
described. The stability constants and the partial molar
enthalpies
of the complexes formed (25 °C, I = 0.5 mol
dm-3 in KNO3) were respectively
determined by means of emf and
calorimetry measurements. For the system 3,4-TDTA−Fe(III)
(25 °C, I = 0.5 mol dm-3 in
NaClO4), the stability
constants of the complexes FeL- and
[FeL(OH)]2- were also determined
spectrophotometrically. The calorimetric
measurements show that the complex formation is entropy driven,
exothermic for Cu(II) and endothermic for
Fe(III). The partial molar entropy of complexation
(ΔS°) is much the same as that of the EDTA
complexes.
X-ray diffraction structural analysis of
Na[Fe(4-Cl-o-PhDTA)(H2O)]·1.5H2O
revealed that, in
[FeL(OH2)]-
(monoclinic C2/c, a = 10.693(3)
Å, b = 13.931(3) Å, c = 24.686(6)
Å, β = 94.21(2)°, V= 3667(2)
Å3, Z = 8),
the iron(III) is seven coordinated, with one water molecule
filling the seventh position, similar to the
iron(III)
anionic chelates of 3,4-TDTA, o-PhDTA, and EDTA. The
presence of the Cl atom in the aromatic ring produces
an asymmetry in the Fe−N bond distances.
“…In order to answer it, first, we have to recall the stability of these complexes. A careful search of the vast coordination chemistry literature of iron [27][28][29][30][31] reveals that certain ligands provide significant stabilisation to the +3 oxidation state while other ligands prefer to bind iron in the +2 state. It has been established that ligands with carboxylate [32,33] groups exhibit preference towards Fe III centres.…”
The autoxidation reaction of the Fe 2+ /ethylenediaminetetraacetic acid system has been studied in solution phase at neutral pH and in solid state using Mössbauer spectroscopy. It was found that despite the proposed reaction pathway consisting of several reaction steps under similar circumstances, no intermediate species could be seen in the Mössbauer spectra and instead of the formation of the well-known [Fe III (EDTA)(H 2 O)] -species, the direct formation of its dimeric form was observed.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
