Porous Shape-Persistent Rylene Imine Cages with Tunable Optoelectronic Properties and Delayed Fluorescence

A simultaneous combination of porosity and tunable optoelectronic properties, common in covalent organic frameworks, are rare in shape-persistent organic cages. Yet, organic cages offer important molecular advantages, the solubility and modularity. Herein, we report the synthesis of a series of chiral imine organic cages with three built-in rylene units by means of dynamic imine chemistry and we investigate their textural and optoelectronic properties. Thereby we demonstrate that the synthesized rylene cages are porous, can be reversibly reduced at accessible potentials, and can absorb from UV up to green light. We also show that they preferentially adsorb CO2 over N2 and CH4 with a good selectivity. In addition, we discovered that the cage incorporating three perylene-3,4:9,10-bis(dicarboximide) units displays a delayed fluorescence, likely as a consequence of formation of a correlated triplet pair, the multiexciton state in singlet fission. Rylene cages thus represent a unique platform to investigate the effect of electronic properties on material porosity and, at the same time, to probe excited-state phenomena in the limit of vanishing interchromophore coupling.