An experimental and computational study on naphthylideneimine based pH sensitive fluorescence probe for zinc

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2020-01, Vol.224, p.117389, Article 117389
• Main Authors: Yu, Miao, Zuo, Chun-Shan, Zhang, Ning
• Format: Article
• Language: English
• Subjects: Fluorescence probe; Naphthylideneimine; TDDFT; Zinc
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2019.117389

Rational design chelating fluorescent sensors probing metal ions in biological system are continuously hot essays nowadays, especially for zinc detection. Herein, a naphthylideneimine based zinc fluorescence probe (3) was prepared and characterized in this work. Structural features and optical properties of 3 and its metallic complexes were characterized. Fluorescent experiment indicates 3 is extremely sensitive and selective for Zn2+ with a strong fluorescence enhancement (∼34 folds) in aqueous buffer solution with a limit of detection (LOD) of 3.78 × 10−7 mol L−1. Formation constant (logKa) of the chelating complex of 3 and Zn2+ ion was determined to be 4.45. Theoretical studies were carried out to get deep insight into the response mechanism in the sensing process. Density functional theory (DFT) methods calculated formation Gibbs free energy (ΔrGmө) of the deprotonated complexes model (32− ⊃ Zn) is −2.9 kcal/mol, which is in good agreement with the experimental result. The calculation results show that the low excitation states can be ascribe to S0 → T2 and S0 → S1 at 390–430 nm and 310–330 nm, respectively, due to the π → π∗ transition. Finally, yeast cell imaging experiments indicate that 3 can monitor intracellular Zn2+ as well. These findings would enable this fluorescent probe to be used as a Zinc sensor. [Display omitted] •A pH sensitive Zn2+ selective fluorescent probe is obtained on a basis of Schiff-base type probe.•Theoretical studies give results in good agreement with the experiments, provide deep insight into response mechanism.•Biological testing on yeast cell were performed to validate this methods in biological and environmental application.