Vitamin B6Cofactor Derivative: A Dual Fluorescent Turn-On Sensor to Detect Zn2+and CN−Ions and Its Application in Live Cell Imaging

Abstract

A new fluorescence receptor (E)-2-amino-N′-((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)methylene)benzohydrazide (1) was synthesized by reacting vitamin B6 cofactor pyridoxal with 2-aminobenzohydrazide, and characterized by various spectral (FT-IR, 1H NMR, 13C NMR and ESI-MS) data. It shows high selectivity and sensitivity towards Zn2+ and CN− ions among the other tested metal ions (Cu2+, Co2+, Ni2+, Mn2+, Mg2+, Fe3+, Fe2+, Cd2+, Hg2+, Pb2+, Al3+ and Cr3+) and anions (F−, Cl−, Br−, I−, NO3−, N3−, HSO4−, H2PO4−, ClO4− and AcO−). With the addition of Zn2+ and CN−, the receptor 1 displays a drastic fluorescence enhancement around 475–480 nm without any interference from other tested cations/anions. Receptor 1 shows the detection limit down to 3.20 ×10−7 M and 1.53×10−7 M for Zn2+ and CN− ions, respectively. In addition, the receptor 1 shows selective response towards CN− by giving a new absorption band around 431 nm. The recognition mechanism was proposed through 1H NMR and DFT results. Finally, the receptor 1 was applied for the detection of bioactive Zn2+ ions in live HeLa cells.