Abstract
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Ions have essential effects in nature, however, in excess, they can be dangeruos for living
systems and the environment. For example, copper ion, which plays a very important role in
living systems ((tyrosinase, ferroxidase, and many others), is poisonous to living cells. The
presence of free copper ion can causes blood hemolysis or kidney and liver damage [1-2].
Chemosensors are based on molecules that can be bind selectively and reversibily with an
anion or a cation [3-4]. Here we report colorimetric studies on cation sensing by one
chromogenic azo Schiff-base L by UV-vis spectroscopy in DMSO. The results showed When
L treats with Cu2+ ion, the largest blue shift from n→ transition at 56o nm to 493 nm
(-67 nm) is obtained. It can be seen as color change of solution from violet-blue to orange.
The binding constant (Ka) and stoichiometry of the host-guest complex were determined by
the Benesi- Hildebrand plot and Job's method, respectively.
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