Polymers with intrinsic microporosity (PIMs) have recently received increasing interest in the fields of gas separation, sensors, catalysts, and so on, due to their high microporosity and good solution processability. However, PIMs with chiral backbones are quite limited, which undoubtedly hinders their applications in many areas such as chiral separation and optoelectronics. Herein, a practical synthetic route were reported to gain cyclohexyl-fused tetrahydroxyl spirobiindanetetraol (SPINOL) monomer with high optical purity [96% enantiomeric excess (ee)] through a sequential Ir-catalyzed enantioselective hydrogenation and TiCl<sub>4</sub>-promoted intramolecular Friedel-Crafts (FC) alkylation reactions and a chiroptical polymer named (-)-CCS-PIM in tens of grams was successfully synthesized in the lab by this method. Besides some properties such as microporosity, solubility, stability, film processability, and strong FL being comparable with PIM-1 as expected, extra advantages of (-)-CCS-PIM such as more rigid dihedral angle and intrinsic chiroptical properties were obtained. More interestingly, circular polarized luminescence (CPL) emission was observed for the first time in a nonconjugated porous polymer film without any side-chain modification or grafting. Polymers offered the potential to amplify chiroptical properties. Particularly, the polymers with strong polarized luminescence and good capacity to prepare thin films for optoelectronic devices by facile solution processes have been a promising field of research. The CPL properties of (-)-CCS-PIM in both the solution form and dry film form were satisfactorily detected. The presence of a rigid chiral helical backbone of the polymer is crucial for the generation of CPL emissions. In the solid film, the degree of freedom of the polymer chains is further diminished than in the solution form, preventing luminescent chromophore aggregation-induced FL quenching, thus resulting in stronger CPL emission. The introduction of chiral SPINOL units endows the polymer with unique optical circularly polarized luminescence, producing the first example of a PIM membrane with CPL property. In addition to straightforward scalability, good film formation and flexibility herald a promising future for the CPL PIMs.

Circular polarized luminescence from chiroptical polymers of intrinsic microporosity  triggered by chiral SPINOL units

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