A new colorimetric chemosensor for Fe(III): ethyl3-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.