Polyoxometallates trapped in a zeolitic imidazolate framework leading to high uptake and selectivity of bioactive molecules

We report a strategy to synthesize materials in which POMs are enclosed in the cages of ZIFs. In three new compounds, H3PW12O40 subset of ZIF-8 (BIT-1), H4SiW12O40 subset of ZIF-8 (BIT-2) and H3PMo12O40 subset of ZIF-8 (BIT-3), different POM cages are 'trapped' inside the well-defined cages of ZIF-8 by one-pot mechanochemical synthesis. They show the highest capacity for methylene blue and controlled release of the anti-cancer agent 5-fluorouracil. BITs can be fully recovered and reused without losing their uptake capacity.