Bis(thiophen-2-yl-methylene) Benzene-1, 4-Diamine as Fluorescent Probe for the Detection of Fe 3+ in Aqueous Samples.

A Schiff base bis(thiophen-2-yl-methylene)benzene-1, 4-diamine (L) was synthesized and used for selective and sensitive detection of Fe 3+ . L exhibited enhanced fluorescence response at excitation of 365 nm and emission wavelength of 440 nm for Fe 3+ . The formation of a 1:1 complex between L and Fe 3+ was suggested by Job's plot by fluorescence titration and from optimized structures using Density functional theory (DFT). The fluorescence intensity was directly proportional to concentration of Fe 3+ (R 2  = 0.999) with the detection limit of 3.8 × 10 -7  M and the binding constant of 1.20 × 10 4  M -1 at pH = 6.0. The probe was used to detect Fe 3+ in different water samples with the percentage recovery of 99.7-103%. The interference of the other cations are < 5%.