A Turn-On Fluorescent Chemical Sensor Based on Benzo[f]Chromen Structure for Cu2+-Sensitive Detection as Well as Applications

A simple Schiff base probe ( E )- N′ -(1-(3-oxo-3 H -benzo[f]chromen-2-yl)ethylidene) picolinohydrazide (CHH) was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), 1 H nuclear magnetic resonance spectra ( 1 H NMR), 13 C nuclear magnetic resonance spectra ( 13 C NMR), and high-resolution mass spectrometry (HR-MS). The probe CHH shows high sensitivity and selectivity for the recognition of Cu 2+ in EtOH-H 2 O (1:1, v/v), and exhibits an enhanced fluorescence phenomenon. The binding constant of CHH for Cu 2+ is 2.74 × 10 5 M −1 , and the binding stoichiometry of CHH and Cu 2+ is 1:1. The fluorescence intensity of CHH (10 μM) is well linearized with the Cu 2+ concentration at 0–10 μM, and it has a detection limit of 1.42 nM, which is lower than the detection limits of most similar probes. The reusability of the probe was evaluated by successively adding Cu 2+ and disodium ethylenediaminetetraacetate (Na 2 EDTA) to the CHH solution. The probe CHH was used to quantitatively detect Cu 2+ in actual water samples from different water sources. The recovery rates were within an acceptable range, indicating that the probe CHH can be used for the quantitative detection of Cu 2+ in actual water samples. Furthermore, the probe was applied for fingerprint detection, showing great potential in fingerprint detection and anti-counterfeiting.