Photoelectrochemical detection of copper ions based on a covalent organic framework with tunable properties.

Copper ions (Cu) play an essential role in various cellular functions, including respiration, nerve conduction, tissue maturation, oxidative stress defense, and iron metabolism. Covalent organic frameworks (COFs) are a class of porous crystalline materials with directed structural designability and high stability due to the combination of different monomers through covalent bonds. In this study, we synthesized a porphyrin-tetrathiazole COF (TT-COF(Zn)) with Zn-porphyrin and tetrathiafulvalene (TTF) as monomers and used it as a photoactive material. The strong light absorption of metalloporphyrin and the electron-rich properties of supplied TTF contribute to its photoelectrochemical performance. Additionally, the sulfur (S) in the TTF can coordinate with Cu. Based on these properties, we constructed a highly sensitive photoelectrochemical sensor for detecting Cu. The sensor exhibited a linear range from 0.5 nM to 500 nM ( = 0.9983) and a detection limit of 0.15 nM for Cu. Notably, the sensor performed well when detecting Cu in water samples.