Abstract: Copper plays an important role in various physiologic processes. The design and synthesis of chemosensors for copper ions has become a very active area of research. The synthetic Cu2+ selective fluoroionophores so far reported suffer from low sensitivity and, in general, higher concentrations of interfering metal ions disturb the selectivity towards Cu2+. We report here the synthesis of six 1-acetyl-3-(2-hydroxyl-4,6-dimethoxylphenyl)-5-aryl-2-pyrazoline (4) and the studies of them as fluorescent sensors for Cu2+ ion. The structures of all the products were determined by IR, MS, 1H NMR and elemental analysis. Their UV and fluorescence spectra were measured. The influences of eight metal ions such as Cu2+, Zn2+, Ni2+, Co2+, Na+, Al3+, Cd2+, Ca2+, Mn2+on their fluorescence properties were studied. Spectroscopic studies revealed that the compounds 4a～4f had rather strong affinity toward Cu2+, The specificity of the probes 4f toward Cu2+ were determined. Nearly no fluorescence intensity changes were observed in emission spectra with Zn2+, Ni2+, Co2+, Na+, Al3+, Cd2+, Ca2+, Mn2+. However, under identical conditions, the studies were showed fluorescence quenching with Cu2+. So we have developed an new fluorescent sensor 4f. It showed high sensitivity and selectivity toward Cu2+ in DMSO.

Key words: 1-Acetyl-3-(2-hydroxy-4,6-dimethoxy-phenyl)-5-aryl-2-pyrazoline, Cu2+, Fluorescence probes