Abstract
XAFS studies have been performed to clarify the relationship between the corresponding pH, color and the structural changes of metal(Cu, Ni)-(o-PHF)n [o-PHF=1-(2-hydroxyphenyl)-3-phenyl-5-(2-pyridyl)formazan; Fig.1] complex. The structural change of the Cu(o-PHF) complex has been attributed to the change of bonding mode of the -OH group in the formazan ligand to the metal. The Ni(o-PHF)n complex has been proved to form different structures, 6-coordinated 1:2 complex and 4-coordinated 1:1 complex in acid and alkaline media, respectively.