Framework materials (FMs), including metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have risen to prominence over the last two decades in the field of chemistry. The rigidity, structural regularity, and tunability of FMs allow precise molecular control on their structures, providing an ideal platform for developing heterogeneous catalysts with unique reactivities. My doctoral research aims at designing FMs with multiple active sites for synergistic catalysis. Specifically, I have designed and synthesized two types of FMs, metal-organic layers (MOLs) and COFs, to mediate photocatalytic synergistic reactions for fine chemical synthesis and energy conversion, with enhanced efficiency and selectivity.

Chapter 1 describes the fundamental concepts about FMs and elucidates their design strategies for synergistic catalysis. Their structural features, characterization techniques, and functionalization methods are examined to provide the basis for the subsequent discussion on how to achieve FM-catalyzed synergistic reactions.

The first part of the thesis, including chapters 2 through 5, focuses on elaborating on how the design of MOL catalysts can enhance the reactivities and selectivities of photoredox-catalyzed reactions. Four photocatalytic reactions including Giese addition, gold-catalyzed cross-coupling reactions, hydrogen atom transfer (HAT), and radical Heck-type coupling were studied with MOL catalysts comprising photosensitizers (PSs) in combination with a Lewis acid, a gold-phosphine complex or a nucleophilic pyridine. Control experiments and mechanistic studies revealed that the strategic pre-organization of catalytic sites within MOLs greatly facilitated the kinetics of targeted reactions.

The second part of the thesis, including chapters 6 and 7, focuses on the application of MOL catalysts in laboratory-scale reactions of pharmaceutical and energy interest. Systematic optimization of the components in MOLs resulted in MOL catalysts with durability, recyclability, and superior reactivities for both photocatalytic dehydrogenative coupling reactions and artificial photosynthesis, showcasing their potential in synthetic transformations and energy conversion.

The third part of the thesis, including chapters 8 and 9, describes the exploration of photocatalytic properties of COF catalysts in the nascent stage. A significant reactivity difference between a planar COF and a non-planar COF embedded with nickel-bipyridine active sites was uncovered. The planar COF demonstrated efficiency in photocatalytic borylation and trifluoromethylation of aryl halides via energy transfer catalysis, while the non-planar COF catalyzed photocatalytic C-N and C-O coupling reactions of aryl halides via photoredox catalysis.