The Studies On Synthesis And Characterization Of8-formyl-7-hydroyl-4-methyl Coumarin Schiff-base Ligands As Zinc Ion Fluorescent Sensors

Zinc is the second most abundant transition metal in the human body, and it plays a critical role in enzyme regulation structure and function, neural signal transmission, and gene expression; furthermore, Zn2+is mostly trapped within proteins, as a structural or catalytic cofactor. Many severe neurological diseases, including Alzheimer’s disease, cerebral ischemia, and epilepsy are associated with the disorder of Zn2+metabolism, so it is important to explore highly selective fluorescence sensors for detecting Zn2+.Coumarin is a classical fluorescent chromophore, it has advantages such as high fluorescence quantum yield, desirable excitation and emission wavelengths, an increase in Stokes shift, good fluorescence stability. Because oxygen and nitrogen atoms from7-hydroyl and C=N bond of8-formyl-7-hydroyl-4-methyl coumarin Schiff-base, which can get the stable six ring coordination complex by coordinate bonds. In order to study the mechanism of Fluorescent Resonance Energy Transfer (FRET), a lot of fluorescent chromophores connect to8-formyl-7-hydroyl-4-methyl coumarin. Furthermore, we compared the mechanism of Fluorescent Resonance Energy Transfer (FRET) with other mechanisms such as Photoinduced Electron Transfer (PET), Intramolecular Charge Transfer (ICT), Excimer, Chelation Enhanced Fluorescence (CHEF) and so on, which has a potential application of the mechanism of Fluorescent Resonance Energy Transfer.In this paper, three fluorescence sensors based on coumarin fluorophore were designed and synthesized. The fluorescence sensors were gotten by introducing different fluorophores such as8-aminoquinoline (L1), fluorescein (L2) and rhodamine B (L3) into8-formyl-7-hydroyl-4-methyl coumarin, which could act as highly sensitive and selective fluorescence sensors for Zn2+. L2exhibited good solubility in water, L3was a Turn-On colorimetric, red fluorescent sensor, Up to now, there are only three examples of zinc sensors based on such a rhodamine dye spirocyclic ring-opening mechanism. Based on these, we believe that the sensors have potential application for detecting Zn2+.