Yang Ning-Ning, Zhou Li-Jiao, Li Peng, Sui Qi, Gao En-Qing
Shanghai Key Laboratory of Green Chemistry and Chemical Processes , School of Chemistry and Molecular Engineering , East China Normal University , Shanghai 200062 , P. R. China . Email:
Chem Sci. 2019 Jan 29;10(11):3307-3314. doi: 10.1039/c9sc00032a. eCollection 2019 Mar 21.
The indicator displacement assay (IDA) is for the first time performed within a metal-organic framework (MOF) to achieve ultrasensitive fluorescence turn-on sensing. A Zr(iv) ion MOF (UiO-67-DQ-PsO) furnished with electron-deficient diquat units (DQ, as the receptor) on the wall and electron-rich 1-pyrenesulfonate anions (PsO, as the fluorescent indicator) in the pores was prepared by postsynthetic anion exchange. The MOF is capable of sensing alkylamines owing to the competing PsO-DQ and alkylamine-DQ charge-transfer interactions, the former interaction causing a fluorescence OFF state and the latter displacing PsO to trigger its emission. Significant advantages have been demonstrated for the IDA inside the MOF. The turn-on assay exhibits much higher sensitivity and anti-interference than the turn-off sensing using the MOF without indicators (the sensitivity is enhanced by as much as six orders of magnitude to the subnanomolar level). The integration of both the receptor and indicator in the porous solid enables facile regeneration and recyclability of the IDA ensemble. Furthermore, we show that the confined space provided by the MOF significantly enhances the supramolecular interactions to make possible the IDA impossible in solution. This work not only demonstrates a novel conceptual approach to fabricate superior fluorescence turn-on sensors using porous materials but also has important implications for supramolecular chemistry in porous materials.
首次在金属有机框架（MOF）内进行指示剂置换分析（IDA），以实现超灵敏的荧光开启传感。通过后合成阴离子交换制备了一种Zr(IV)离子MOF（UiO-67-DQ-PsO），其壁上配备有缺电子的双季铵盐单元（DQ，作为受体），孔中含有富电子的1-芘磺酸盐阴离子（PsO，作为荧光指示剂）。由于竞争性的PsO-DQ和烷基胺-DQ电荷转移相互作用，该MOF能够传感烷基胺，前一种相互作用导致荧光关闭状态，后一种相互作用取代PsO以触发其发射。已证明MOF内部的IDA具有显著优势。与使用无指示剂的MOF进行的荧光关闭传感相比，开启分析表现出更高的灵敏度和抗干扰能力（灵敏度提高多达六个数量级，达到亚纳摩尔水平）。受体和指示剂在多孔固体中的整合使得IDA体系能够轻松再生和循环使用。此外，我们表明MOF提供的受限空间显著增强了超分子相互作用，使得在溶液中无法实现的IDA成为可能。这项工作不仅展示了一种使用多孔材料制造优异荧光开启传感器的新颖概念方法，而且对多孔材料中的超分子化学具有重要意义。
