Single-component rare-earth-free white light-emitting metal–organic framework towards nitroaromatic explosive sensing and dye adsorption

Abstract

Given the current depletion of energy resources and the escalating severity of environmental issues, it is of utmost importance to develop sustainable materials capable of detecting harmful substances and removing adverse environmental impacts. Herein, a rare-earth-free white-light-emitting MOF Cd-PNMI (PNMI, N-(4-pyridyl)-1,4,5,8-naphathalene-tetracarboxy-monoimide), deriving from an idea that involves the construction of a strong white-light-emitting MOFs using a weak white-light-emitting ligand PNMI with d¹⁰ metal based on ligand-to-ligand charge transfer (LLCT) luminescent mechanism, was designed and confirmed using time-dependent density functional theory (TDDFT) calculations. As a sustainable white-light-emitting material, CdPNMI can not only detect explosive and highly toxic substances at low limits of detection (LOD) but also adsorb the dyes from waste liquids. The CdPNMI emulsion demonstrated ratiometric sensing with remarkable dual-emission fluorescence quenching for nitro explosive and highly toxic substances, which was confirmed to be the result of a synergetic contribution of photo-induced electronic transfer (PET) and Förster resonance energy transfer (FRET) quenching mechanism. Due to the distinctive structure character, CdPNMI also exhibited rapid, selective and extensive adsorption for Rhodamine B (RhB) and fluorescein (FITC) dye, contributing to the elimination of these pollutants from waste liquids.