A colorimetric, NIR, ultrafast fluorescent probe for ferric iron detection based on the PET mechanism and its multiple applications

Abstract

Since ferric iron (Fe³⁺) plays an important role in enzymatic catalysis, cell metabolism and oxygen transport in hemoglobin, many fluorescent probes have been developed to detect Fe³⁺. However, designing and synthesizing a near-infrared (NIR), multi-application fluorescent probe to detect Fe³⁺ remains a challenge. In this paper, a novel 6-(diethylamino)-1,2-dihydrocyclopenta[b]benzopyran derivative (probe DCA-Mln) has been synthesized and characterized. The easy-to-synthesize DCA-Mln exhibits good selectivity and sensitivity, near-infrared emission, fast response and dual channel detection of Fe³⁺ in MeOH–H₂O (5/5, v/v) solution. The color of DCA-Mln changed from purple to peach pink, and a visible fluorescence change from strong pink red fluorescence to non-fluorescence was observed on treatment with Fe³⁺. Furthermore, the binding mode and the sensing mechanism of DCA-Mln to Fe³⁺ is evaluated in detail using the B3LYP/6-31G(d) method, which reveals that the stoichiometric ratio of DCA-Mln with Fe³⁺ is 2 : 1, and the photoinduced electron transfer (PET) results in the fluorescence quenching of DCA-Mln-Fe³⁺. Importantly, nontoxic DCA-Mln can be used to detect Fe³⁺ in actual water samples and image Fe³⁺ in living cells as well as be used for anti-counterfeiting ink.