Synthesis and characterization of water soluble O-carboxymethyl chitosan Schiff bases and Cu(II) complexes

In this study, mono-imine was synthesized (3a and 4a) via a condensation reaction between 2,4-pentadion and aminobenzoic acid (meta or para) in alcohol (1:1). The second-imine (CS-3a and CS-4a) was obtained as a result of the reaction of the free oxo groups of mono-imine (3a and 4a) with the amino groups on the chitosan (CS). Their structures were characterized with FTIR and 13C CP-MAS. Then, the water soluble forms of CS-3a and CS-4a were obtained through oxidation of the hydroxide groups on the chitosan to carboxymethyl groups using monochloracetic acid ([O-CMCS-3a]·2H2O and [O-CMCS-4a]·2H2O). Thus, the solubility problem of chitosan in an aqueous media was overcome and Cu(II) complexes could be synthesized more easily. Characterization of the synthesized O-carboxymethyl chitosan Schiff base derivatives and their metal complexes, [O-CMCS-3a-Cu(OAc)2]·2H2O and [O-CMCS-4a-Cu(OAc)2]·2H2O, was conducted using FTIR, UV–Vis, TG/DTA, XRD, SEM, elemental analysis, conductivities and magnetic susceptibility measurements.