A fluorescent probe with a coumarin moiety bound to rhodamine 6G hydrazide（l） was synthesized. Its sensing behavior toward various metal ions was investigated with fluorescence methods. Compound I displays different fluorescence emission responses to Al^3＋ and Ca^2＋ at the same excitation wavelength in the visible light region, while no changes occur after the addition of other metal ions. The binding ratios of the complexs of 1-Al^3＋ and 1-Ca^2＋ are both 2：1 according to the Job plot and high resolution mass spectrometer（HRMS） experiments. Moreover, emission spectrum of 1-Ca^2＋ complex and absorption spectrum of the rbodamine dyes overlap largely. When Al^3＋ was added to the 1-Ca2＋ system, calcium in complex 1-Ca2＋ can be displaced by Al^3＋, resulting in the output of another ratiometric sensing signal, which demonstrates that the 1-Ca^2＋ complex can be served as a new and effective fluorescence resonance energy transfer（FRET） donor for rhodamine derivatives.
CAO Li JIA Chunman ZHANG Qi CHEN Da ZHANG Chunyan QIAN Yaao
Difluoromethylation of 2-hydroxychalcones using sodium 2-chloro-2,2-difluoroacetate as the difluoro- methylating agent was developed. Under facile conditions, a wide range of aryl difluoromethyl ethers were obtained in yields of 36%--80%. It is noteworthy that the new addition products, 2,2-difluoro-2H-benzofuran derivatives, were also synthesized in the reactions. The yield of 2,2-difluoro-2H-benzofuran derivative could be up to 35% when 3-methyl-2-hydroxychalcone was used as the reactant. A plausible reaction mechanism was proposed.
WANG WeiHUA MingqingHUANG YanZHANG QiZHANG XiaoyanWU JingboZHANG Qi
A new chemosensor based on a Schiff base has been designed and synthesized. Its sensing behavior toward various metal ions was investigated by fluorescence and UV-Vis spectroscopic methods. The fluorescence of the sensor was quenched and the color rapidly changed from canary yellow to brown after the addition of Cu2＋, while no changes occurred after the addition of other metal ions, which contributes to the detection of Cu2＋ with naked eyes. The fluorescence quantum yield of the ligand was calculated to be 0.52. The corresponding detection limit of Cu2＋ was 5.721 × 10-7 mol/L, and the 1：1 binding mode of the sensor with Cu2＋ was revealed by Job＇s plot.
