Porphyrin-based covalent organic frameworks (COFs) possess immense potential in adsorption, catalysis, and sensing due to their ordered pores and unique optical properties.

However, their indiscriminate coordination with various metals hinders the specific recognition of target heavy metal ions, and they typically exist as hard-to-process insoluble powders and suffer from solid-state fluorescence quenching via strong π-π stacking, limiting their analytical and adsorptive utility.

In a study published in ACS Nano, a research team led by Prof. JIANG Changlong from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences developed a new porous material that can both detect and adsorb copper ions (Cu²⁺) from complex environments.

Researchers first designed a porphyrin-based COF with a special dual-bridged structure which improves the material's ability to recognize Cu²⁺ while maintaining its optical properties. By combining the COF material with polyvinyl alcohol, they then created a lightweight porous aerogel, which reduces the stacking between COF layers and helps maintain strong fluorescence signals.

When Cu²⁺ is present, the material captures the ions and produces a visible fluorescence color change from red to light blue, allowing rapid detection. The material can detect Cu²⁺ at very low concentrations, with a detection limit of 40.76 nM. It also shows a high adsorption capacity of 1902 mg/g, enabling efficient adsorption of Cu²⁺ from contaminated environments.

Tests using real soil samples showed that the material could effectively detect and adsorb Cu²⁺ under complex conditions.

The study provides a simple approach for designing multifunctional porous materials, and contributes to the development of future technologies for heavy metal monitoring and pollution treatment.