A Colorimetric Detection Probe for Iron(III) with a Naphthalene-Based Schiff Base

Abstract

A novel naphthalene-based Schiff base ligand (SBL) was synthesized by the condensation of naphthalene-1-8-diamine with 4-dimethylaminobenzaldehyde as a colorimetric probe for the selective detection of Fe³⁺ ions in ethanol solution. The UV-Vis spectroscopic technique was employed to study the sensing ability of the probe SBL for Fe³⁺ ions, which was monitored in ethanol solution (pH 4). The Job’s plot confirmed a 1 : 1 molar complex formation between SBL and Fe³⁺. Density functional theory computations also supported the binding framework between SBL and Fe³⁺. The limit of detection for Fe³⁺ is 6 × 10^–6 M, and the limit of quantification is 2 × 10^–5 M. The binding constant, evaluated using the Benesi–Hildebrand method, is 6.9 × 10⁴ M. Cyclic voltammetry study shows that there is no change in the electrochemical structure of SBL after complex formation with Fe³⁺.