Dynamic Covalent and Supramolecular Networks for Artificial Photosynthesis

Nature provides a blueprint for addressing the current climate crisis and the demand for clean, renewable fuels through photosynthesis, the process in which algae, cyanobacteria, and plants convert solar energy into chemical energy stored as carbohydrates. Although natural photosynthesis has been optimized over millions of years of evolution, it still operates at only 1-3% efficiency under full sunlight, revealing inherent limitations. However, its fundamental principles, such as compartmentalization, diverse pigment utilization, and efficient charge separation, offer crucial insights for the design of artificial systems. Therefore, artificial photosynthesis requires three essential components: a light-harvesting unit, stable charge separation, and redox catalysts to drive water-splitting reactions, with the Oxygen Evolution Reaction (OER) being the most challenging step. Organic chemistry plays a pivotal role in advancing artificial photosynthesis, with covalent organic materials and supramolecular assemblies offering a high degree of modularity, allowing for precise tuning of optoelectronic properties and catalytic sites. In this Thesis, both Covalent Organic Framework (COF) and supramolecular approaches were exploited to develop innovative photosynthetic systems. In particular, two novel β-ketoenamine-linked COFs, differing only in localized N-doping, were employed as a platform to study the role of COF-co-catalyst interaction in unlocking photocatalytic hydrogen evolution. Moreover, a series of perylene bisimide-based COFs (PBI-COFs) were also synthesized, and PBI-COF films demonstrated promising performance as photoanodes for water-soluble hydroquinone oxidation, a known class of redox mediators in decoupled water splitting. Additionally, a novel artificial quantasome structure was achieved by the supramolecular assembly of a bis-cationic Naphthalene Diimide with a tetra-ruthenium polyoxometalate water oxidation catalyst. This design enabled the construction of a photoelectrocatalytic system capable of driving OER using red photons, similar to natural photosystems.