The 4-hydroxysalicylidenechitosan Schiff-base (2CS-Hdhba) was prepared by the condensation of 2,4-dihydroxybenzaldehyde with chitosan, and its metal complexes, [M(2CS-dhba)Cl(2)(H(2)O)(2)] (M(III)=Fe, Ru, Rh), [M'(2CS-dhba)(AcO)(H(2)O)(2)] (M'(II)=Co, Ni, Cu, Zn), [Pd(2CS-dhba)Cl(H(2)O)] and [Au(2CS-dhba)Cl(2)], are reported. These complexes were characterized by elemental analysis, by spectral data (FTIR, solid-phase (13)C NMR, UV-vis and ESR spectroscopy), by morphological observations (SEM and XRD), and by magnetic and thermal measurements. The Schiff base (2CS-Hdhba) behaves as a bidentate chelate with a single negative charge. The azomethine nitrogen and the deprotonated 2-hydroxy centres with the pendant glucosamine hydroxy functionality play no role in coordination. The dissociation constants of 2CS-Hdhba and the stability constants of some of its metal complexes have been determined pH-metrically.
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