X-RAY STUDY OF CHITOSAN TRANSITION-METAL COMPLEXES

Clear fiber diffraction patterns of nine chitosan-transition metal salt [CdSO4, CdCl2, Cd(NO3)2, Cd(CH3COO)2, ZnSO4, ZnCl2, Zn(CH3COO)2, CuSO4, and CuCl2] complexes were obtained by immersing a tendon chitosan, prepared by a solid-state N-deacetylation of a crab tendon chitin, in respective metal salt solutions. The extended 2-fold helix of the chitosan molecule was retained even with the complex formation. The unit cells of all the salt complexes studied were orthorhombic though the cupric salt complexes showed some unindexed reflections. Their lattice parameters and number of water molecules in the cell depended on the counteranions of the metal salt and not on the metal ion. The ratio of glucosamine residue to metal salt was 2:1. The space group P2(1)2(1)2(1) was suggested for all the complex crystals except the CuCl2 complex.