| Porous organic polymers (POPs) have been studied extensively over the past decade. The intrinsic porosity and tunable chemical structures have seen applications in gas storage, separations, and even catalysis. However, a vast majority of the POPs rely on a narrow class of monomeric units and polymerization conditions which limits the diversity of functionality in the polymers, and hence their chemical properties. To get around these issues, a micro- and mesoporous tetrazine-based organic framework with BET surface area of 170 m2/g was synthesized through palladium catalyzed cross-coupling reaction. The structure of the polymer was confirmed by solid-state 13C NMR, ATR-IR and EDX. The 1,2,4,5-tetrazine units on the struts of the framework were active toward inverse electron-demand Diels-Alder reactions, allowing for a post-synthetic introduction of different functionalities into the tetrazine-based organic frameworks (TzOF). The structures of modified polymers were verified by solid-state 13C NMR and ATR-IR. To eliminate the use of transition metals during synthesis, a new class of sulfur-containing tetrazine-based organic framework was designed and synthesized by nucleophilic aromatic substitution reactions. The resulting mesoporous polymer framework, with 3,6-dithio-1,2,4,5-tetrazine unit on the struts, showed BET surface area of 38 m2/g. The structure of the framework was confirmed by ATR-IR and EDX. Post-synthetic modifications of the polymer were also achieved by reacting with dienophiles through inverse electron-demand Diels-Alder reactions. The structures of modified polymers were verified by ATR-IR. These two synthetic methods we have developed for tetrazine-based organic frameworks and their ability to introduce functionality post-synthetically brought additional functionalities to the POP family. |
