Luminescent microporous metal-organic framework with functional Lewis basic sites on the pore surface: Specific sensing and removal of metal ions

摘要

A three-dimensional luminescent metal-organic framework, {Mg (DHT) (DMF) _2} _n (1), based on an excited-state intramolecular proton-transfer (ESIPT) responsive linker, 2,5-dihydroxyterephthalic acid (H _2DHT), has been synthesized, and its desolvated microporous framework with pendent -OH groups on the pore surface was exploited for the binding and specific sensing of metal ions via Lewis acid-base interactions. The luminescence intensity significantly quenches with Cu ~(II) among various s- and d-block metal ions, and highly selective sensing of Cu ~(II) ions has been realized in both solid and solution states (up to nanomolar concentration). The immobilized Cu ~(II) metal ions can be selectively removed by chelating agents like ethylenediaminetetra-acetic acid without any structural disintegration of the framework, as revealed by the luminescence and gas-adsorption studies.