Koner Apurba L, Schatz Jürgen, Nau Werner M, Pischel Uwe
School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany.
J Org Chem. 2007 May 11;72(10):3889-95. doi: 10.1021/jo070268+. Epub 2007 Apr 14.
A water-soluble supramolecular sensing assembly, composed of an imidazolium-substituted calix[4]arene and a fluorescent aminodiacetate derivative of 1,8-naphthalimide, was studied. Addition of citrate led to a large fluorescence enhancement, while tartrate, acetate, as well as selected inorganic anions gave smaller effects. The sensing principle and selectivity for citrate rely on the formation of a ternary fluorophore-host-anion complex and complexation-induced pKa shifts of an amino group attached to the fluorophore. The complexation of citrate induces a protonation of the amino group, which switches off intramolecular photoinduced electron transfer as the fluorescence quenching pathway, leading to an enhancement of the optical output signal. The intricate sensor principle was corroborated by pH titrations, binding constants, and structural information as obtained by 1H NMR spectroscopy.
研究了一种由咪唑鎓取代的杯[4]芳烃和1,8-萘二甲酰亚胺的荧光氨基二乙酸衍生物组成的水溶性超分子传感组件。加入柠檬酸盐会导致荧光大幅增强，而酒石酸盐、乙酸盐以及选定的无机阴离子产生的影响较小。对柠檬酸盐的传感原理和选择性依赖于三元荧光团-主体-阴离子复合物的形成以及连接在荧光团上的氨基的络合诱导pKa位移。柠檬酸盐的络合诱导氨基质子化，这作为荧光猝灭途径关闭分子内光诱导电子转移，导致光输出信号增强。通过pH滴定、结合常数以及1H NMR光谱获得的结构信息证实了这种复杂的传感原理。
