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

Two chiral dimeric Cu II Schiff base complexes, Na 2 [Cu( S ‐lys) 2 · (H 2 O) 2 ] · (ClO 4 ) 2 ( 1 ) and [Cu( S ‐ornH) 2 · (H 2 O) 2 ] · (ClO 4 ) 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.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)