Naphthol-Based Shiff Base as a Selective Fluorescent Probe for Detecting Zn2+ in Living Cells

Two fluorescent probes BMO and NBMO were developed for the highly selective detection of Zn2+ based on C=N isomerization and chelation-enhanced fluorescence (CHEF) mechanism. Structure identification of the probes was confirmed by H-1 NMR, C-13 NMR, H-1-H-1 COSY, HSQC, IR and HRMS spectroscopy. The results of spectral analysis show that BMO and NBMO are sensitive and highly selective to Zn2+. The detection limit of BMO and NBMO are found to be 30 and 21 nmol.L-1 respectively. There is a good linear relationship between the fluorescence intensity of probes (BMO and NBMO) and the concentration of Zn2+ in the range of 0 to 20 mu mol.L-1. The X-ray crystal structure of the NBMO-Zn2+ complex exposes its coordination feature and the Job plots reveal a 1:1 probe-Zn2+ identification. The cell images show that NBMO can be used to detect intracellular Zn2+.