Theoretical and Experimental Studies of the Optoelectronic Properties of Polymers of Intrinsic Microporosity

Their unique combination of high surface area and solvent processability has made polymers of intrinsic microporosity (PIMs) useful in numerous separation processes in the gas or liquid phase. Recently, their optical properties have gained attention. Here, we characterize the optoelectronic properties of two representative PIMs composed of planar polyaromatic systems linked by spiro-centers, alongside their monomer and dimer analogs, using density functional theory and experimental methods. Computations reveal that the orthogonal geometry of the spiro-linked segments produces nearly degenerate frontier orbitals and split excitation transitions in the dimer models, suggesting enhanced electron delocalization by spiroconjugation. Experimental optical spectra and fluorescence quenching experiments support these findings, with polymers displaying extended electron delocalization compared to monomers and dimers, akin to phenomena observed in conjugated polymers. Overall, our results provide a new understanding of PIMs and highlight their potential for applications in chemical sensing, photocatalysis, or light harvesting, where they remain underexplored.