Flexible Cyclosiloxane-Linked Fluorescent Porous Polymers for Multifunctional Chemical Sensors

The construction of porous polymers linked by flexible building units has been considered a great challenge. Here, we address this challenge by using flexible 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxanes to react with brominated pyrene, tetraphenylethene, and spirobifluorene via the Heck reaction, resulting in three cyclosiloxane-linked fluorescent porous polymers. The materials exhibit high porosity, strong fluorescence, and tunable emission colors. Such properties impart the promise of these polymers as candidates for multifunctional chemical sensors to identify latent fingerprints with a strong anti-interference ability under actual conditions (e.g., rainy environment) and to detect nitroaromatic explosives and metal ions, especially 2,4,6-trinitrotoluene or picric acid, and the Fe³⁺ ion, with low limits of detection and a high selectivity. Moreover, a paper sensor was further developed and is found to be sensitive to the solution, solid, and vapor phases of explosives and the Fe³⁺ ion, complete with a rapid response time and visual detection. These results may open up new horizons for exploring porous polymers, particularly those with a strong fluorescence, based on flexible linkers.