Fabrication of a New Corrole-Based Covalent Organic Framework as a Highly Efficient and Selective Chemosensor for Heavy Metal Ions

Since the widespread presence of metal ions in the ecosystem, especially heavy metal ions that could bring severe damage to living organisms, the development of chemosensors for heavy metal ions is in high demand. In this contribution, we designed and synthesized a new corrole-based covalent organic framework (CorMeO-COF) with good crystallinity and high porosity. CorMeO-COF can detect Cu(II) with high sensitivity and selectivity based on the efficient fluorescence quenching caused by the photoinduced electron transfer (PET) process. More interestingly, CorMeO-COF can selectively detect trivalent metal ions such as Ga(III), Al(III), Cr(III), or Fe(III) with fluorescence enhancement. An in-depth mechanism study revealed that the binding of metal ions on the skeleton can inhibit the aggregation-caused quenching (ACQ) resulting in the improved photoluminescence (PL). Notably, this fluorescence-on/off feature of CorMeO-COF cannot be accessed by its counterpart (e.g., corrole monomer, model compound). These results point out a new direction to use corrole-based COF materials as efficient chemosensors to detect trace amounts of metal ions in the environmental and biological systems.