A water-soluble bis(thiosemicarbazone) ligand. A sensitive probe and metal buffer for zinc

Abstract

The first member of a water-soluble family of bis(thiosemicarbazone) ligands is reported. It forms a 1:1 complex with Zn" that absorbs intensely in the visible region (λmax= 414 nm; ε= 1.8(4) x 104M-1 cm-1; pH 7.3). Its affinity for ZnII (KD = 5.9(3) x 10-9 M at pH 7.3) was determined by competition with ligand ethylene glycol O,O-bis(2-aminoethyl)-N,N,N,N-tetraacetic acid. Its potential application as a chromophoric probe was demonstrated by estimation of the ZnII binding affinities of the soluble metal-binding domains of two plant metal-transporting proteins. © 2010 American Chemical Society.