Highly sensitive and selective colorimetric sensor for iron (II) ion detection based on 4-amino-antipyrine derivative

Abstract

Schiff base (E)-4-((2-hydroxybenzylidene) amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (S) has been tested as selective naked-eye detector for iron (II). The sensor S showed rapid response to Fe+2 ions with a bathochromic shift in the visible region over the other metal ions such as Co+2, Mg+2, Hg+2, Cu+2, Mn+2, Ca+2 and Cd+2, S when titrated with iron (II) from 0 to 10 equivalent, a new two peaks at 500 and 650 nm was observed with increasing concentration of iron (II). The dissociation constant of the S-iron (II) complex was calculated and equal to 2.043. EDTA test was applied for recognizing the reversibility of S-iron (II) complex, it found to be reversible after addition of (EDTA), therefore S can be successfully used as (switch colorimetric sensor) for iron (II) detection. Job's plot method displays 1:2 stoichiometry for S-iron (II) complex as resulting [Fe(S)2]+2 complex.