Tailoring Band Gaps in Thienyltriazine based Conjugated Porous Polymers through Comonomer Variation

This study focuses on the synthesis and characterization of a series of conjugated porous polymers (CPPs) based on a 2,4,6‐tris(5‐ethynylthiophen‐2‐yl)‐1,3,5‐triazine (TT) core moiety. TT was coupled with several conjugated building blocks as comonomers, including naphthodithiophene, benzodithiophene, bithiophene, tetraphenyl porphyrin, azulene, and perylene diimide, utilizing the Sonogashira‐coupling reaction to produce narrow band gap (1.73–2.19 eV) CPPs. The solid‐state UV‐visible spectra demonstrated broad absorption in 350 nm to 900 nm region, indicating extended π‐conjugation in the polymers. The photophysical properties of the polymers have been tuned by the judicious choice of comonomer. The obtained CPPs exhibit excellent thermal stability, reaching as high as 500 °C, and porosity insights reveal dominance of mesopores and macropores. Morphological studies reveal that 2‐ethylhexyl substituted perylene diimide hinder the stacking amongst the polymeric backbone, resulting in featureless aggregates, whereas the cyclohexyl group on perylene diimide results in well‐defined nanofibrous morphology. These narrow band‐gap CPPs hold promise for applications in energy storage, organic electronics, photocatalysis and sensing technologies. The band gap of thienyltriazine containing conjugated porous polymers have been efficiently tailored by comonomer variation making use of comonomers like naphthodithiophene, benzodithiophene, bithiophene, tetraphenyl porphyrin, azulene, and perylene diimide.