A novel fluorescent turn on probe derived from Schiff base for highly selective and sensitive detection of Cu2+ ion

Lihua Cai; Kang Yan; Wenguang Xu; Yunfeng Chen; Huiping Xiao

doi:10.1016/j.saa.2023.123526

A novel fluorescent turn on probe derived from Schiff base for highly selective and sensitive detection of Cu²⁺ ion

Spectrochim Acta A Mol Biomol Spectrosc. 2024 Feb 15:307:123526. doi: 10.1016/j.saa.2023.123526. Epub 2023 Nov 2.

Authors

Lihua Cai¹, Kang Yan², Wenguang Xu², Yunfeng Chen³, Huiping Xiao⁴

Affiliations

¹ Wuhan Institute of Technology, School of Chemistry and Environmental Engineering, Wuhan 430205, PR China; Environmental and Biological Engineering Department, Wuhan Technology and Business University, Wuhan 430065, PR China.
² Environmental and Biological Engineering Department, Wuhan Technology and Business University, Wuhan 430065, PR China.
³ Wuhan Institute of Technology, School of Chemistry and Environmental Engineering, Wuhan 430205, PR China.
⁴ Environmental Engineering of City Construction Department, Wenhua College, Wuhan 430074, PR China. Electronic address: xiaohuiping422@sohu.com.

PMID: 38000124
DOI: 10.1016/j.saa.2023.123526

Abstract

A fluorescent probe (L) of bis Schiff base secondary amine ligand was designed and synthesized from 2,6-pyridinedicarboxylic acid, ethylenediamine and salicylaldehyde by condensation and reduction reaction. Its structure was characterized by IR, UV-Vis, LIF, ¹HNMR, ¹³C NMR, MS and elementary analysis. Investigation of binding test indicated that probe L could sensitively and selectively detect Cu²⁺ ion with striking fluorescent signaling responses in anhydrous ethanol solvent. Results from Job's plot, fluorescent titration, and MS experiments indicated a 1:1 binding ratio between probe L and Cu²⁺, with a complexation constant of 1.28 × 10⁸ M^-1. According to MS, IR and molar conductivity analysis, the mechanism of the probes' detection of Cu²⁺ may due to CHEF mechanism by the lone electron pairs in the N atom, and the enhancement of the molecular rigidity caused by disruption of intermolecular hydrogen bonding force, which leading to the occurrence of chelation fluorescence enhancement. The detection limit of complexation constant was 2.69 × 10^-8 M in the linear range of 0-40 μM, which provided an effective and convenient testing for trace copper in surface water and drinking water.

Keywords: Bis-Schiff base; Copper detection; Fluorescent probe.