A new colorimetric chemosensor for Fe(III): ethyl 3-oxo-2-(2-(4-(N-(pyrimidin-2-yl)sulfamoyl)phenyl) hydrazineylidene)butanoate and its applications in aqueous solutions

In this study, ethyl 3-oxo-2-(2-(4-(N-(pyrimidin-2-yl)sulfamoyl)phenyl)
hydrazineylidene)butanoate (EPSHB) was synthesized and characterized
using NMR and FT-IR spectroscopy. EPSHB functions as
a chemosensor with selective colorimetric properties for Fe(III) ions.
It demonstrated exceptional sensitivity and selectivity for Fe(III)
detection in aqueous solutions, even in the presence of various
competing cations, including Na(I), Mg(II), Al(III), K(I), Ca(II), Cr(III),
Mn(II), Fe(II), Co(II), Ni(II), Zn(II), Sr(II), Ag(I), Cd(II), and Pb(II) and
anions. Upon binding Fe(III), EPSHB exhibited a notable color transition
to pale brown, forming a complex in a 1:2 stoichiometry
(Fe(III)). The binding mechanism of EPSHB to Fe(III) was elucidated
through UV-Vis spectrometry and DFT calculations, revealing
a binding constant of 18.80 × 105 mol.dm3. Additionally, EPSHB
provided a rapid and accurate colorimetric assay for Fe(III) detection
with a detection limit of 0.3 μmol.dm−3. The chemosensor’s efficacy
was validated by successful testing in real water samples, demonstrating
its practical application for Fe(III) detection