两种双发光镧系金属有机框架材料联用检测水中农药残留

Detection of pesticide residues in water using two dual-emitting lanthanide metal-organic frameworks

传统单发射响应发光传感器因发射光波长单一易受环境因素干扰而灵敏度低,以及双/多元镧系共掺杂发光传感器由于体系内镧系元素之间的能量转移效率易受温度等因素影响而使得检测灵敏度与选择性低,本文提出联用两种双发光镧系金属有机框架材料(lanthanide metal-organic frameworks,Ln-MOFs)实现水体中不同农药的定性和半定量分析。研究合成了Tb-MOF和Eu-MOF2,对其结构和性质进行了表征,并采用所制备的Ln-MOFs对水体中残留的6种农药(敌草胺、毒莠定、咪草烟、戊唑醇、氟替莫非和苯霜灵)进行了定性和半定量分析。结合各农药的紫外-可见吸收光谱测定结果表明:农药与Ln-MOFs之间通过相互作用和竞争性激发能量吸收来调节Ln-MOFs中有机配体与Ln^(3+)之间的能量转移效率,且不同农药对有机配体到Tb^(3+)和有机配体到Eu^(3+)的能量转移效率产生不同的影响。荧光强度比值的对数值lg(I_(545)/I_(616))、lg(I_(545)/I_(340))与农药浓度间具有良好的线性关系,R^(2)均在0.97以上。该研究为开发方便、有效且具有普适性的比率荧光传感器提供了一种可行的策略。

To optimize the limitations of the exisiting fluorescent sensors:conventional single-emitting fluorescent sensors have limited sensitivity because the single emission can be easily affected by environmental factors,and the limited sensitivity and selectivity of dual/multiple-emitting fluorescent sensors because the internal energy transfer between lanthanide ions is susceptible to environmental factors like temperature.Two dual-emitting lanthanide metal-organic frameworks(Ln-MOFs)were utilized to achieve qualitative and quantitative detection of different pesticides simultaneously in water.Tb-MOF and Eu-MOF2 were synthesized,and their structures and properties were characterized.The prepared Ln-MOFs were used for qualitative and quantitative analysis of six pesticides(napropamide,picloram,imazethapyr,tebuconazole,flutriafol and benalaxyl).Combined with the UV-visible absorption spectra of each pesticide,the results showed that the energy transfer efficiency between Ln^(3+) and organic ligand in Ln-MOFs was regulated through interaction and competitive excitation energy absorption,and different pesticides had different effects on the energy transfer efficiency of organic ligand to Tb^(3+)and organic ligand to EuLn^(3+).The values of lg(I_(545)/I_(616))and lg(I_(545)/I_(340))had a good linear relationship with the concentration,and R^(2) was above 0.97.This study provides a feasible strategy for developing a convenient,effective and universal ratiometric fluorescent sensor.