A dye-loaded Fe₄L₄ cage for efficient photocatalytic C(sp³)-H activation

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photocatalysis

Background:

• Metal-organic cages (MOCs) offer tunable environments for host-guest chemistry.
• Photocatalysis often requires harsh conditions, limiting substrate scope and efficiency.
• Developing efficient and mild catalytic systems is a key challenge in synthetic chemistry.

Purpose of the Study:

• To rationally construct a novel cationic metal-organic cage (C1) with a Fe4L4 tetrahedral structure.
• To utilize C1 as a supramolecular host for encapsulating an anionic photosensitizer (AQDS).
• To develop a high-performance photocatalytic system for C(sp3)-H bond oxidation using the host-guest complex.

Main Methods:

• Rational design and synthesis of a Fe4L4 cationic metal-organic cage (C1).
• Encapsulation of anthraquinone-2,6-disulfonic acid disodium salt (AQDS) within the C1 cage via host-guest interactions.
• Photocatalytic oxidation of C(sp3)-H bonds using the photoactive host-guest complex under mild conditions.

Main Results:

• A novel cationic Fe4L4 metal-organic cage (C1) with a large cavity and openings was successfully constructed.
• The C1 cage effectively encapsulated AQDS, forming a photoactive host-guest complex.
• The supramolecular photocatalytic system demonstrated efficient oxidation of C(sp3)-H bonds under mild conditions, converting intermolecular to pseudo-intramolecular reactions.

Conclusions:

• The developed metal-organic cage (C1) serves as an effective supramolecular host for photocatalyst encapsulation.
• The spatial confinement within the cage enhances photocatalytic efficiency by promoting pseudo-intramolecular reactions.
• This strategy provides a valuable approach for designing high-performance photocatalytic systems under mild conditions.