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Understanding of the Mode of Action of Fe III –EDDHA as Iron Chlorosis Corrector Based on Its Photochemical and Redox Behavior
Author(s) -
GómezGallego Mar,
Pellico Daniel,
RamírezLópez Pedro,
Mancheño María J.,
Romano Santiago,
de la Torre María C.,
Sierra Miguel A.
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500286
Subject(s) - chemistry , hexacoordinate , redox , ferric , photochemistry , chelation , substrate (aquarium) , electron transfer , ethylenediamine , reactivity (psychology) , inorganic chemistry , organic chemistry , medicine , oceanography , alternative medicine , pathology , silicon , geology
The very low reduction potential of the chelate Fe III –EDDHA (EDDHA= ethylenediamine N,N′ ‐bis(2‐hydroxy)phenylacetic acid) makes it unreactive in photochemically or chemically induced electron transfer processes. The lack of reactivity of this complex toward light invalidates photodegradation as an alternative mechanism for environmental elimination. However, in spite of its low reduction potential, the biological reduction of Fe III –EDDHA is very effective. Based on electrochemical measurements, it is proposed that Fe III –EDDHA itself is not the substrate of the enzyme ferric chelate reductase. Likely, at the more acidic pH in the vicinity of the roots, the ferric chelate in a closed form (FeL − ) could generate a vacant coordination site that leads to an open hexacoordinate species (FeHL) where the reduction of the metal by the enzyme takes place.