Band gap engineering of benzotriazole and benzodithiazole based porous polymers and their application in coupling of terminal alkynes

Abstract

Here we report the synthesis of four thienyltriazine and benzodithiazole/benzotriazole containing conjugated porous polymers (CPPs) TT-PP1, TT-PP2, TT-PP3 and TT-PP4 using Stille coupling reaction and Sonogashira-Hagihara coupling reaction. By varying the spacer and heteroatom, the band gap of the polymers TT-PP2<TT-PP1<TT-PP3 (1.82, 2.04, and 2.27 eV, respectively) have been efficiently tuned. The polymers display moderate BET surface area reaching as high as 429 m2g-1 for TT-PP-2 and excellent thermal stability up to 550 oC. The rich heteroatom content of the polymers provides a platform for trapping the catalyst used during the synthesis of the polymers. This has been taken advantage of, and the polymer TT-PP3 was used as a heterogeneous catalyst for highly efficient coupling of terminal alkynes. Besides that, the porous catalyst was used for three consecutive cycles without any significant decrease in the catalytic activity.

Keywords

• Conjugated porous polymers
• Thienyltriazine
• Hetereogeneous catalysis
• Glaser coupling
• Benzotriazole