Solvent-Free Visible Light Photocatalytic Oxidation Processes Mediated by Transparent Films of an Imine-Based Organic Polymer

Abstract

Reaction between concentrated solutions of phenotiazine containing trialdehyde building block 4,4′,4″-(10-phenothiazine-3,7,10-triyl)tribenzaldehyde and (1R,2R)-cyclohexane-1,2-diamine results in the formation of a yellow transparent film. Exhaustive characterization of this material indicates that it is the result of the assembly of a linear polymer resulting from the linking of imine-based macrocycles. Phenotiazine units confer to this plastic the optical properties characteristic of photocatalytic materials. The transparency of the obtained material enabled the performance of solvent-free photocatalytic processes. This concept is illustrated by the oxidation of liquid organic sulfides, which can be performed in a recyclable manner. According to selective quenching experiments, such processes are the result of the energy transfer to oxygen molecule, generating singlet oxygen that is able to activate the sulfide molecules directly.

Recent Advances in the Use of Covalent Organic Frameworks as Heterogenous Photocatalysts in Organic Synthesis

“…This photocatalytic overoxidation to sulfone is a challenging process, which has also been observed in solvent‐free reactions using a phenyl PTH‐containing imine‐based polymer that forms luminescent transparent membranes. [ 214 ]…”

“…This photocatalytic overoxidation to sulfone is a challenging process, which has also been observed in solvent-free reactions using a phenyl PTH-containing imine-based polymer that forms luminescent transparent membranes. [214] Finally, an outstanding example of an enantioselective synthesis of sulfoxides from organic sulfides was recently reported. [168] The enantio-induction was achieved through the covalent immobilization of a quaternary ammonium bromide salt through a chiral Cu-catalyzed propargylation of the iminelinkages of the COF, resulting in an amine-based material that contains porphyrins as photosensitizers (Figure 15).…”