A Guide to Chemical Reactions Design in Carbon Nitride Photocatalysis

Abstract

Graphitic carbon nitride semiconductors are inexpensive and reusable photocatalysts, which are actively studied in organic synthesis. Successful design of photocatalytic reactions is based on the next considerations. i) Thermodynamic feasibility of photoinduced processes, which involve transfer of electrons or electron‐proton couples. ii) Redox activity of reagents. iii) Reactivity of the open‐shell intermediates generated from the reagents. Herein, we summarize current understanding of how local chemical structure of graphitic carbon nitrides and their redox potentials are used to design photocatalytic reactions. This work intends to serve as a guideline for materials scientists, who are willing to apply their carbon nitride semiconductors in reactions involving organic substrates, and for organic chemists, who are interested to dive into heterogeneous carbon nitride photocatalysis.

Graphitic carbon nitride as a photocatalyst for decarboxylative C(sp2)-C(sp3) couplings via nickel catalysis

“…Shifting our focus onto α-oxygen carboxylic acids, we found that primary (18 and 19), acyclic secondary (20), and cyclic substrates with various ring sizes (21)(22)(23) were all transformed selectively into the C-C coupled products, in addition to an α-sulphur carboxylic acid providing product 29. Cheap and abundant α-amino acids also proved to be excellent coupling partners, transforming protected glycine, alanine, proline, tryptophan, and tyrosine, in addition to two unnatural amino acids, into the corresponding C-C coupled products (24)(25)(26)(27)(28)(29)(30)(31)(32).…”

“…License: CC BY 4.0 reports have shown that metal-free graphitic carbon nitrides (gCNs) are effective photocatalysts in organic synthesis, and are capable of a growing number of transformations. [21][22][23][24][25] Indeed, it has been shown that with carboxylic acid coupling partners, efficient oxidatively induced radical decarboxylation can take place to generate alkyl radical intermediates. These radicals can then react with a range coupling partners to form C-H, 26 C-C, [26][27][28] C-N, 28 and C-O 29 bonds (Scheme 1B).…”