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Evidence for aliphatic mixed mode coordination in copper(II)–fulvic acid complexes
Author(s) -
GREGOR J. E.,
POWELL H. K. J.,
TOWN R. M.
Publication year - 1989
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1989.tb01307.x
Subject(s) - chemistry , copper , metal , inorganic chemistry , chelation , malonate , anodic stripping voltammetry , ligand (biochemistry) , quenching (fluorescence) , metal ions in aqueous solution , fulvic acid , fluorescence , electrochemistry , electrode , organic chemistry , humic acid , biochemistry , physics , receptor , fertilizer , quantum mechanics
SUMMARY A comparative approach based on ion–selective electrode measurements is presented for studying Cu(II) complexing by fulvic acids. Metal binding curves (% free metal vs pH) and complexation capacity curves (% free metal vs total metal at fixed pH) for copper(II) fulvic acid systems are compared with those for appropriate model ligands. It is inferred that citrate, malonate and amino acid moieties could dominate complexing to Cu(II) at pH 3 to 7. The involvement of amino acid moieties is supported by fluorescence quenching and by anodic stripping voltammetry (ASV) studies. The proportion of ASV–non labile complexes is reported for Cu(II) and Pb(II) fulvic acid systems at pH 4.8. A mixed mode of coordination is proposed, with the dominant binding sites varying with pH and metal:ligand ratio.