Supramolecular Engineering and Self-Assembly Strategies in Photoredox Catalysis

Abstract

Visible-light-mediated photoredox catalysis has evolved as an efficient and mild alternative to conventional organic synthesis. Inspired by the elegance and sophistication of natural photosynthetic machinery involving complex self-assembled systems, recently researchers have resorted to the implementation of supramolecular chemistry in photoredox catalytic processes with the objective of achieving improved efficiency for known chemical reactions, as well as developing advanced methodologies for inaccessible transformations. Supramolecular engineering offers the ability to customize the existing properties of traditional photoredox catalysts by various self-assembly strategies and expands their scope in cutting-edge synthetic methodologies by means of their noncovalent interactions with different chemical components. In this review, we summarize the recent advances and key achievements in photoredox catalytic synthesis adopting various supramolecular techniques based on organic self-assembled systems and underline their advantages and mechanistic facets. Diverse directional noncovalent interaction driven photoredox catalytic systems are thoroughly discussed. Furthermore, self-assembly strategies for various photocatalytic reactions within confined nanospaces (viz. micelles, vesicles, polymersomes, polymeric nanoparticles, gels etc.) are summarized. Finally, a brief perspective on the encouraging future prospects and challenges in this contemporary field of supramolecular photoredox catalysis is presented.

Electro‐mediated PhotoRedox Catalysis for Selective C(sp3)–O Cleavages of Phosphinated Alcohols to Carbanions

“…In this context, our calculations indicate that intramolecular charge transfer in the catalyst radical anion upon photoexcitation promotes SET to the substrate. Photocatalyst‐substrate preassemblies such as EDA complexes, [36] non‐covalent interactions,[ 5a , 37 ] hydrogen bonding [38] and ordering of solvent [39] are receiving increasing attention to unveil the next generation of photocatalytic transformations and offer new frontiers in selectivity and efficiency. Further studies into the nature of interactions and structure of preassemblies, as well as catalyst stability, [40] are ongoing.…”

Electro‐mediated PhotoRedox Catalysis for Selective C(sp3)–O Cleavages of Phosphinated Alcohols to Carbanions

“…In this context, our calculations indicate that intramolecular charge transfer in the catalyst radical anion upon photoexcitation promotes SET to the substrate. Photocatalyst‐substrate preassemblies such as EDA complexes, [36] non‐covalent interactions, [5a, 37] hydrogen bonding [38] and ordering of solvent [39] are receiving increasing attention to unveil the next generation of photocatalytic transformations and offer new frontiers in selectivity and efficiency. Further studies into the nature of interactions and structure of preassemblies, as well as catalyst stability, [40] are ongoing.…”

Free Charge Carriers in Homo-Sorted π-Stacks of Donor–Acceptor Conjugates

“…The review also highlights the potential of homosorted donor–acceptor stacks in designing organic electronics with ambipolar/selective directional charge carrier properties offering novel initiatives in the area of cutting-edge electronics. The improved photoinduced charge carrier generation efficiency via charge delocalization/antiparallel charge migration across D–A stacks, the consequent long-living trait of the charge separated state, and the easy tunability of redox potentials and photophysical characteristics render self-sorted D–A systems promising candidates in the field of photoredox catalysis. , The emergent optoelectronic properties of supramolecular D–A based architectures can be exploited for multifarious purposes including photodynamic/photothermal therapy, organic field-effect transistors (OFETs), imaging, photodetectors, etc. − Furthermore, the highlight on design strategies to attain appropriate architectures and the scope of their application can galvanize new directions and opportunities into the domain of functional organic materials …”