A New Spiropyran Hydrazone as an Unusual Colorimetric Sensor for Detection of Cu²⁺ and Cr³⁺ Based on Aggregation‐Induced Enhancement Effects in Aqueous Solvent Mixtures

Abstract

Though many improvements have been made on fluorescence probes for respective detection of Cu 2 + and Cr 3 + , multiply detect of the ions by a simple colorimetric way in high water content solution sensors remains scarce. In this work, a novel spiropyran hydrazone,which shows aggregation-induced enhancement effects (AIEE) phenomena in EtOH (ethanol)/H 2 O and THF (tetrahydrofuran)/H 2 O media, has been developed. It can detect Cu 2 + colorimetrically having a sensitivity of 105 nM in EtOH/ H 2 O (40/60, v/v) with an unusual specific tandem-response toCr 3 + at a detection limit of 151 nM in addition with a wide pH range of 4-10. Mechanism investigations by HRMS, 1 H NMR and UV-Vis spectroscopy have verified that the response to Cr 3 + is based on the cooperative effect between NA-SP and Cu 2 + , instead of the replacement of Cu 2 + by Cr 3 + . Moreover, NA-SP shows a robust AIEE-caused recognition for Cu 2 + in THF/H 2 O (20/80, v/v) with a detection limit of 16.5 nM. Real water tests indicate that the probe has potential detection application for Cu 2 + in environmental situations. This contribution presents a new spiropyran sensor for the detection of Cu 2 + and Cr 3 + in aqueous solutions through an uncommonly colorimetric way.