A dysprosium(iii)-based triple helical-like complex as a turn-on/off fluorescence sensor for Al(iii) and 4,5-dimethyl-2-nitroaniline

Abstract

A novel triple helical-like complex [Dy₂K₂L₃(NO₃)₂]·3DMF (1) based on a designed Schiff base N′¹,N′³-bis((E)-3-ethoxy-2-hydroxybenzylidene)-malonohydrazide (H₄L) was synthesized with good chemical and thermal stabilities. Single-crystal X-ray structural analysis showed that 1 presents a tetranuclear triple helical-like structure via the coordination mode of Dy : K : L with 2 : 2 : 3 stoichiometry. Fluorescence measurements showed that 1@EtOH has excellent fluorescence turn-on/off response ability for aluminium ions and 4,5-dimethyl-2-nitroaniline (DMNA) with outstanding selectivity, sensitivity, and anti-interference ability. The calculated limit of detection (LOD) values for 1@EtOH to Al³⁺ and DMNA were found to be 0.53 and 3.33 μM, respectively. Density functional theory (DFT) calculation showed that the fluorescence response mechanism can be explained by the photoinduced electron transfer (PET) mechanism; meanwhile, the inner filter effect (IFE) of DMNA can also affect the emission of 1@EtOH.