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New Colorimetric Detection of Glucose by Means of Electron‐Accepting Indicators: Ligand Substitution of [Fe(acac) 3− n (phen) n ] n + Complexes Triggered by Electron Transfer from Glucose Oxidase
Author(s) -
Morikawa Masaaki,
Kimizuka Nobuo,
Yoshihara Masakuni,
Endo Takeshi
Publication year - 2002
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 - 10.1002/1521-3765(20021216)8:24<5580::aid-chem5580>3.0.co;2-v
Subject(s) - chemistry , phenanthroline , cationic polymerization , ligand (biochemistry) , electron transfer , medicinal chemistry , glucose oxidase , aqueous solution , inorganic chemistry , photochemistry , polymer chemistry , organic chemistry , electrode , biochemistry , receptor
A new colorimetric detection technique for glucose, based on electron transfer from glucose oxidase (GOD red ) to iron( III ) acetylacetonate(acac)/phenanthroline(phen) mixed complexes, is developed. When GOD is added to an aqueous mixture that contains tris(acetylacetonato)iron( III ) complex (Fe III (acac) 3 ), 1,10‐phenanthroline (phen), and glucose, the color immediately changes from pale yellow to red. The red color originates from formation of tris(1,10‐phenanthroline)iron( II ) complex ([Fe II (phen) 3 ] 2+ ). Differential pulse voltammetry indicates that cationic, mixed‐ligand complexes of [Fe(acac) 3− n (phen) n ] n + are formed upon mixing the labile Fe III (acac) 3 complex and phenanthroline. The cationic mixed‐ligand complexes electrostatically bind to GOD (pI 4.2), and are easily reduced by electron transfer from GOD red . This electron transfer is not affected by the presence of oxygen. The reduced complex [Fe II (acac) 3−n (phen) n ] ( n −1)+ then undergoes rapid ligand exchange to Fe II (phen) 3 . Formation of the colored Fe II complex is repressed when the salt concentration in the mixture is increased, or when anionic bathophenanthroline disulfonate (BPS) is employed in place of phenanthroline. The use of labile metal complexes as electron acceptors would be widely applicable to the design of new biochromic detection systems.