AND POLYMERIC MATERIALS
Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 11, pp. 1791−1797.
Pleiades Publishing, Ltd., 2013.
Original English Text © C.A. Caro, G. Cabello, E. Landaeta, J. Pérez, J.H. Zagal, L. Lillo, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86,
No. 11, pp. 1843−1849.
Synthesis and Spectroscopic and Electrochemical Studies
of Chitosan Schiff Base Derivatives
C. A. Caro
, G. Cabello
, E. Landaeta
, J. Pérez
, J. H. Zagal
, and L. Lillo
Departamento de Ciencias Basicas, Facultad de Ciencias, Universidad del Bio-Bio,
Campus Fernando May, Chillan, Chile
Departamento de Quimica de los Materiales Facultad de Quimica y Biologia,
Universidad de Santiago de Chile, Santiago, Chile
Received May 16, 2013
Abstract—Schiff derivatives were prepared by the reactions of salicylaldehyde and its derivatives (5-chloro,
5-methoxy, 5-ﬂ uoro, 5-methyl, 5-nitro) with the amino group of chitosan. The Schiff bases were studied by Fourier
IR spectroscopy and by UV-visible spectroscopy. The cyclic voltammograms of the Schiff bases were analyzed
and compared to those of chitosan and salicylaldehyde. The formal potential of the chitosan Schiff base derivative
correlates with the Hammett parameters. The oxidation potential increases and the optical density decreases with
enhancement of the electron-acceptor properties of the functional group R in the m-position to the –N=CH– group.
Chitosan (Chi) is a polysaccharide whose chains consist of recurrent units of acetamido-2-deoxy-D-glucode linked
by the 1,4-β-glycoside bond. This polysaccharide was widely studied as drug carrier [1, 2], because it is nontoxic,
biodegradable, and well biocompatible .
Selective modification of the structure of
polysaccharides by chemical or enzymatic methods
involves change in the functional group type. The
derivatives obtained are of interest for biomedicine
and pharmaceutical industry [4–6], in particular, for
the development of drug forms of prolonged effect,
of anticoagulants, and of agents decelerating the
growth of bacteria and malignant tumor cells [7–10].
These derivatives were studied by elemental analysis,
IR spectroscopy, nuclear magnetic resonance, and
conductometric titration . At the same time,
electrochemical studies of these derivatives are few.
Data on the electrochemical properties of chitosan
derivatives are of interest for the development of biosensors
and biocatalysts . The electrical conductivity of
chitosan is low , but it can be increased by preparing
composites with nanoparticles or complexes with metals.
For example, Feng et al.  studied the electrocatalysis
of proteins on chitosan-stabilized gold nanoparticles, Xu
et al.  studied nanocomposites of chitosan with gold
nanoparticles, and Huang et al.  studied biopolymeric
ﬁ lms of chitosan with the heme group whose redox peaks
are located at potentials typical of Fe
Electrochemical studies concerning chitosan
derivatives, including those with chitosan-modified
electrodes, are limited. Jiang et al.  studied oxidation
of nitrite using a glassy carbon electrode modiﬁ ed with
chitosan-coated carboxylated carbon nanotubes. Dong
et al.  incorporated hemoglobin into a chitosan ﬁ lm
for preparing modiﬁ ed electrodes. In all these studies,
the chitosan conductivity was enhanced by preparing
complexes of chitosan or its derivatives with metals of
A study of the Hammett relationships for Schiff
base derivatives involves study of the correlation with
the redox potential. The data obtained allow the trends