A Highly Efficient Molecular Iron(II) Photocatalyst for Concurrent CO₂ Reduction and Organic Synthesis

Area of Science:

• Photocatalysis
• Green Chemistry
• Molecular Catalysis

Background:

• Molecular catalysts for CO₂ reduction typically require photosensitizers for light harvesting and electron transfer.
• Developing earth-abundant molecular photocatalysts that can independently perform CO₂ reduction is a significant challenge.

Purpose of the Study:

• To report a novel polypyridyl iron(II) molecular photocatalyst for efficient CO₂ reduction.
• To demonstrate the catalyst's ability to concurrently facilitate CO₂ reduction and organic synthesis.

Main Methods:

• Synthesis and characterization of a polypyridyl iron(II) complex (FePAbipyBn).
• Photocatalytic CO₂ reduction experiments using the iron complex under visible light irradiation.
• Analysis of reaction products (CO, indoles) and catalyst performance (TON, selectivity).

Main Results:

• The iron(II) molecular photocatalyst (FePAbipyBn) demonstrated high activity for CO₂ reduction, achieving a turnover number (TON) of 3558 for CO production with >99% selectivity.
• The photocatalyst successfully facilitated a concurrent 2e^-/2H⁺ enamine oxidation and CO₂ reduction, yielding valuable products like indoles and CO.
• This represents the first reported photoredox reaction for CO₂ reduction and organic synthesis using a molecular photocatalyst.

Conclusions:

• A single, earth-abundant molecular photocatalyst can efficiently perform CO₂ reduction and organic synthesis.
• The developed iron(II) complex offers a promising platform for sustainable chemical transformations.
• This work opens new avenues for utilizing CO₂ as a feedstock in photoredox catalysis.