Morphology regulation of isomeric covalent organic frameworks for high selective light scattering detection of lead

Isomerism is an essential and ubiquitous phenomenon in organic chemistry, yet it is rarely observed in covalent organic frameworks (COFs). Herein, we synthesized two framework-isomeric COFs (BATD-Dma-COF-K and BATD-Dma-COF-R) and found for the first time that the light scattering signal of the COFs can be used for the analytical detection of lead ion. By using solvothermal and room temperature solvent synthesis methods, controlling different synthesis conditions, and introducing regulators to increase the energy difference between different products, the product with the lowest energy could be synthesized under specific conditions. This method could control the morphology of the synthesized COF and realize the precise synthesis of frameworkisomeric COF by changing the experimental conditions. The structures of the two framework-isomeric COFs were characterized and confirmed by a series of analytical methods. Based on the principle that lead ions coordinate with N and O on the surface of two skeletal isomers BATD-Dma-COFs to enhance the light scattering signal of the COFs, a light scattering probe was developed by BATD-Dma-COF for the detection of metal lead ion in water samples. Lead ion concentration in the range from 2.0 to 250.0 mu M had a good linear relationship with the light scattering intensity increase of the COFs with detection limit as low as 0.8397 mu M by BATD-Dma-COF-K and 0.9207 mu M by BATD-Dma-COF-R.

Automated summary

This study synthesized two framework-isomeric covalent organic frameworks (COFs) and discovered that the light scattering signal of COFs can be used for the analytical detection of lead ions. By controlling synthesis conditions and introducing regulators, the morphology of COFs could be controlled and framework-isomeric COFs could be precisely synthesized.