Quinoline-Based Organic Frameworks with Divergent Photocatalytic Properties for Hydrogen Production and Furfuryl Alcohol Oxidation

The Sonogashira coupling reaction between 1,3,5-triethynylbenzene and two quinoline-based building units6-iodo-2-(4-iodophenyl)-4-phenylquinoline or 6-bromo-2-(5-bromopyridin-2-yl)-4-phenylquinolineresulted in the synthesis of conjugated materials designated as quinoline-based organic frameworks (QOFs), specifically QOF1 and QOF1-N. These materials exhibited comparable structural and photophysical properties and demonstrated their utility in photocatalysis, including hydrogen evolution reactions (HER) and the selective oxidation of furfuryl alcohol to 5-hydroxy-2-(5H)-furanone. Interestingly, QOF1-N outperformed QOF1 in the photocatalytic oxidation of furfuryl alcohol via singlet oxygen (1O2), whereas QOF1 exhibited superior efficiency in HER. The divergent photocatalytic activity of these frameworks was attributed to the differences in their electronic structures, which were analyzed using a combination of experimental techniques and theoretical modeling. These findings highlight the potential of tailored QOFs for diverse photocatalytic applications, emphasizing the role of structural and electronic tuning in enhancing catalytic activity.