一种新型荧光探针的合成及其对Cu~(2+)的选择性识别

设计并合成能用于识别铜离子的荧光探针N′-(喹啉-2-亚甲基)-7-二乙胺基-3-甲酰肼-香豆素(FKBA),通过质谱、红外光谱、元素分析、~1 H NMR、~(13) C NMR等方法对该荧光探针FKBA进行表征;采用荧光光谱法和紫外-可见光谱法对FKBA与金属离子的相互作用进行了研究。结果表明FKBA对Cu~(2+)有良好的选择性和灵敏度。向含有FKBA的溶液中加入Cu~(2+),其吸收峰发生红移,且强度增大。而向该溶液中,加入Al ~(3+),Ag~+,Ba~(2+),Cd~(2+),Ca~(2+),Co~(3+),Fe~(3+),Cr~(3+),Hg~(2+),Mg~(2+),K~+,Mn~(2+),Ni ~(2+),Na~+,Zn~(2+)和Pb~(2+)等其他16种金属离子时,FKBA的紫外吸收仅发生细微的变化。FKBA作为化学传感器对Cu~(2+)的选择性是通过与一系列与环保和生物功能相关的金属离子相互作用得到验证。FKBA中加入Cu~(2+)时,FKBA的荧光强度明显猝灭,其他16种金属离子对FKBA的荧光强度几乎没有影响。不同的金属离子分别与Cu~(2+)共存时FKBA的荧光光谱猝灭程度相同,说明FKBA具有良好的抗干扰能力。向FKBA中加入EDTA,FKBA的荧光强度得到恢复。FKBA中加入Cu~(2+),溶液颜色变成棕色,加入EDTA后又恢复到初始颜色。说明FKBA的荧光减弱不是Cu~(2+)催化FKBA分解而是FKBA与Cu~(2+)络合。在酸性环境中,FKBA的希夫碱结构不稳定,部分FKBA分解成其他的荧光物质。据IUPAC(cDL=3Sb/m)测得检测限为0.13μmol·L~(-1)。对实际样品中的Cu~(2+)浓度进行分析,表明FKBA可作为荧光传感器用于实际样品的Cu~(2+)检测。

Synthesis of a Novel Fluorescent Probe and Its Application for Selectively Identifing Cu2+

A novel coumarin-based fluorescent probe 7-Diethylamino-2-oxo-2 H-chromene-3-carboxylic acid quinolin-2-ylmethyl-ene-hydrazide (FKBA)was designed and synthesized to identify Cu2+.FKBA was confirmed by means of IR,EA,MS,1 H NMR,and 13 C NMR.The interaction between FKBA and metal ions was investigated via fluorescence spectrophotometry and UV absorption spectrophotometry.The results indicated that FKBA showed excellent selectivity and high sensitivity for Cu2+. Its UV absorption peak was redshift and the maximum UV absorption peaks was also changed when Cu2+ was added.However, under same conditions,it was only a slight change of UV absorption peak after the other metal ions,such as Ag+,Al3+,Ba2+, Ca2+,Cd2+,Co3+,Cr3+,Fe3+,Hg2+,K+,Mn2+,Mg2+,Ni2+,Na+,Zn2+ and Pb2+were added.The selectivity of FKBA as a chemosensor for Cu2+ was tested by incubating FKBA with a range of environmentally and biologically important metal ions. Fluorescence spectra were notable quenching when Cu2+ was added,with only little interference by other metal ions.Fluores-cence spectra of FKBA in the presence of each of different metal ions upon the addition of Cu2+ had the same quenching.Thus, it was notable that FKBA showed good capability of resisting disturbance.The color of FKBA turned from blue to brown upon the addition of Cu2+.The brown of complex restored to the original blue upon the addition of EDTA.The fluorescence intensity regained when EDTA was added,suggesting that fading fluorescence intensity changed due to the formation of KFBA-Cu2+ com-plex but not any catalytic action of Cu2+.FKBA was not stable and easily hydrolyzed in acidic environment due to their schiff-based structure and part of the FKBA hydrolyzed into other fluorescent substance.Furthermore,the detection limit was 0.13μmol·L-1 according to the definition by IUPAC (cDL=3Sb/m).FKBA can be used as a fluorescent probe to detect Cu2+ in ac-tual samples.