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Complex‐Formation Ability of Salicylaldehyde Thiosemicarbazone towards Zn II , Cu II , Fe II , Fe III and Ga III Ions
Author(s) -
Enyedy Éva A.,
Zsigó Éva,
Nagy Nóra V.,
Kowol Christian R.,
Roller Alexander,
Keppler Bernhard K.,
Kiss Tamás
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200360
Subject(s) - chemistry , semicarbazone , protonation , aqueous solution , ligand (biochemistry) , inorganic chemistry , metal , zinc , metal ions in aqueous solution , copper , nuclear chemistry , dissociation (chemistry) , electron paramagnetic resonance , stoichiometry , salicylaldehyde , medicinal chemistry , crystallography , ion , schiff base , organic chemistry , biochemistry , physics , receptor , nuclear magnetic resonance
The stoichiometry and stability of copper(II), zinc(II), iron(II)/(III) and gallium(III) complexes of salicylaldehyde thiosemicarbazone (STSC, H 2 L ) have been determined by pH potentiometry, UV/Vis spectrophotometry, and 1 H NMR and EPR spectroscopy in aqueous solution (with 30 % DMSO), together with the characterization of the proton dissociation processes. Mono‐ and bis‐ligand complexes in different protonation states were identified for Fe II , Fe III and Ga III , whereas Cu II and Zn II ions only form complexes with a 1:1 metal/ligand ratio. The coordination mode in the complex [Zn 2 (H L )( L )(OAc)EtOH] was confirmed by X‐ray diffraction. The metal‐binding ability of STSC at physiological pH is in the following order: Ga III < Zn II < Fe II < Fe III < Cu II . Ga III –STSC complexes show unambiguously higher stability, whereas Fe II –STSC species show significantly lower stability relative to the corresponding α( N )‐pyridyl thiosemicarbazones like 2‐formylpyridine thiosemicarbazone or Triapine. Furthermore, the fluorescence properties of the ligand were investigated in aqueous solution, and their changes caused by complexation with Ga III and Zn II were studied.