Synthesis, Structure, Magnetic Properties and Aqueous Optical Citrate Detection of Chiral Dinuclear Cu-II Complexes

Abstract

Two chiral dimeric Cu-II Schiff base complexes, Na-2[Cu(S-lys)(2)center dot(H2O)(2)]center dot(ClO4)(2) (1) and [Cu(S-ornH)(2)center dot(H2O)(2)]center dot(ClO4)(2) (2) have been prepared by an easy one-pot method in which the L-lysine and L-ornithine-based Schiff base ligands are generated in situ. These complexes have been characterized by various spectroscopic techniques and single-crystal X-ray diffraction. The molecular structures show that both complexes are indeed dimeric with Cu-II centers that are phenolate-bridged. Variable-temperature magnetic analysis revealed that a strong antiferromagnetic coupling interaction was mediated through the phenolate bridge between the two Cu-II centers. Since these compounds were highly soluble in water, we explored carboxylate sensing capability through colorimetric indicator displacement assays (IDAs). By using pyrocatechol violet (PV) as a displaceable colorimetric indicator, citrate ion selectivity was demonstrated in 100% water solution in the physiological pH range. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)