A selective “turn-on” sensor for recognizing In3+ and Zn2+ in respective systems based on imidazo[2,1-b]thiazole

Abstract

A new simple and easily synthesized multitarget sensor, (E)-N′-(4-(diethylamino)-2-hydroxybenzylidene)imidazo[2,1-b]thiazole-6-carbohydrazide (X), was designed and synthesized using imidazo[2,1-b]thiazole-6-carboxylic acid and 4-(diethylamino)-2-hydroxybenzaldehyde. X could be used as a sensor to detect In³⁺ in DMF–H₂O buffer solution and detect Zn²⁺ in EtOH–H₂O buffer solution through fluorescence enhancement with detection limits of 1.02 × 10⁻⁹ M and 5.5 × 10⁻⁹ M, respectively. X exhibited an efficient “off–on–off” fluorescence behavior by cyclic addition of metal ions (In³⁺ and Zn²⁺) and EDTA. The stoichiometry between X and metal ions (In³⁺ and Zn²⁺) was 1 : 1. The binding mode and sensing mechanism of X with metal ions (In³⁺ and Zn²⁺) was verified by theoretical calculations using Gaussian 09 based on B3LYP/6-31G(d) and B3LYP/LANL2DZ basis, respectively. Moreover, X could be applied as a potential sensor for the quantitative detection of In³⁺ and Zn²⁺ with a satisfactory recovery and relative standard deviation (RSD) in real water samples.