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Chelation of chitosan derivatives with zinc ions. II. Association complexes of Zn 2+ onto O,N ‐carboxymethyl chitosan
Author(s) -
Tang LieGui,
Hon David N.S.
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/1097-4628(20010222)79:8<1476::aid-app150>3.0.co;2-a
Subject(s) - chelation , zinc , chemistry , chitosan , fourier transform infrared spectroscopy , scanning electron microscope , molecule , nuclear chemistry , polymer chemistry , inorganic chemistry , absorption spectroscopy , absorption (acoustics) , infrared spectroscopy , materials science , organic chemistry , chemical engineering , physics , quantum mechanics , engineering , composite material
Abstract The chelation of zinc ions onto O,N ‐carboxymethyl chitosan (ONCMCh) was characterized using a Fourier transform infrared (FTIR) spectrophotometer and a scanning electron microscope (SEM). From the FTIR spectra, little change in the absorption intensities and frequencies at 3300–3600 cm −1 of Zn 2+ ONCMCh chelated specimens suggested that OH and NH 2 groups were not participating in the chelation reaction. The absence of absorption bands at 1755–1700 cm −1 suggested that the carboxyl group CO was not ionized, and the ionized CO bands were observed at 1400–1600 cm −1 for chelated specimens. Thus, the chelation sites took place at the carboxyl group rather than at the OH and NH 2 groups. It also confirmed that water‐insoluble chelates, which were formed through the ZnO and ZnN bonds, presented a tetrahedral structure. The water‐soluble complexes where zinc ions connected with oxygen of CO and water molecules were only due to electron attraction. Formation of different microstructures on the surfaces, as revealed by SEM, provided evidence to distinguish different chelating mechanisms between water‐soluble and water‐insoluble complexes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1476–1485, 2001