Water-soluble titanocene complexes with sulfur-containing aminoacids: synthesis, spectroscopic, electrochemical and Ti(IV)-ransferrin interaction studies

摘要

Three new water soluble titanocene - aminoacid complexes have been synthesized via the reaction of Cp2TiCl2 and two equivalents of aminoacid ( L) in methanol, affording [Cp2Ti L-2] Cl-2, L= L- cysteine ( 2), D-penicillamine ( 3) and L- methionine ( 4). These complexes have been characterized by H-1, IR and UV-Vis spectroscopies, elemental analysis and cyclic voltammetry. Kinetic studies of ligand hydrolysis have been monitored at low pH using UV-Vis and H-1 NMR spectroscopies to assess their stability in aqueous solution. At low pH, aminoacid ligands are lost one order of magnitude faster than cyclopentadienyl. However, at physiological pH, in Tris buffer solution, the complexes decompose rapidly to form an insoluble titanium compound. The affinity of these complexes to apo-transferrin was also investigated to elucidate how the ancillary aminoacid ligands affect the titanium intake by apo-transferrin.