Novel pyridine-based covalent organic framework containing N,N,N-chelating sites for selective detection and effective removal of nickel

Abstract

The development of novel materials with dual functions of simultaneous detection and removal of heavy metal ions has been an important pursuit of environmental remediation. Herein, we demonstrate that two-dimensional covalent organic frameworks (COFs) with well-defined functional chelating sites can combine the inherent advantages of COF materials to prepare novel materials with the dual functions of selective detection and effective removal of Ni²⁺ from aqueous solutions. A new pyridine-based COF material (TAPA–PCBA) containing functional N,N,N-chelating sites has been designed and synthesized by the imine condensation reactions between tris(4-aminophenyl)amine and 2,6-pyridinedicarboxaldehyde under solvothermal conditions. The newly designed TAPA–PCBA possesses high crystallinity, moderate specific surface area and robust chemical and thermal stability. These excellent properties of TAPA–PCBA, together with its extended π-conjugated framework structure and the dense distribution of functional N,N,N chelating sites, enable TAPA–PCBA to selectively detect and effectively remove Ni²⁺ from aqueous solutions. This dual function can be attributed to the coordination interactions between Ni²⁺ and N,N,N-chelating sites embedded in the skeleton structure of TAPA–PCBA. These results reveal that COFs with reasonable design have great development prospects in heavy metal ion related environmental remediation.