Tunable Photocatalytic Selectivity by Altering the Active Center Microenvironment of an Organic Polymer Photocatalyst

Abstract

The favored production of one product over another is a major challenge in synthetic chemistry, reducing the formation of byproducts and enhancing atom efficacy. The formation of catalytic species that have differing reactivities based on the substrate being converted, has been targeted to selectively control reactions. Here, we report the production of photocatalytic selfassembled amphiphilic polymers, with either hydrophilic or hydrophobic microenvironments at the reactive center. Benzothiadiazole-based photocatalysts were polymerized into either the hydrophilic or the hydrophobic compartment of a diblock copolymer by RAFT polymerization. The difference in the reactivity of each microenvironment was dictated by the physical properties of the substrate. Stark differences in reactivity were observed for polar substrates, where a hydrophilic microenvironment was favored. Conversely, both microenvironments performed similarly for very hydrophobic substrates, showing that reagent partitioning is not the only factor that drives photocatalytic conversion. Furthermore, the use of secondary swelling solvents allowed an additional reagent exchange between the continuous phase and the heterogeneous photocatalyst, resulting in a significant 5-fold increase in conversion for a radical carbon−carbon coupling.

Comonomer effects in vinyl based photocatalytic polymers

“…Depending on the position of the photocatalytic unit in the hydrophobic core or the hydrophilic corona, differences in photocatalytic efficiency could be observed. 26 Similar effects are reported in the emerging field of artificial photoenzymes, where the microenvironment of the protein scaffold can affect the photocatalytic efficiency depending on the placement of the photocatalytic moiety (Fig. 1).…”

Hydrolysis-resistant heterogeneous photocatalysts for PET-RAFT polymerization in aqueous environments

“…Light-mediated polymerization in water in particular shows signicant potential to broaden the scope of accessible materials that can be synthesized under visible light and ambient conditions. [19][20][21][22][23][24] This includes reversible deactivation radical polymerization (RDRP) to produce well-dened (super)hydrophilic polyelectrolytes, 25,26 zwitterionic materials, 27,28 or polyampholytes, 29 all of which have been considered intriguing materials for various applications, including anti-fouling, 30 anti-icing, 31 anti-fogging, 32 and many others. 33,34 Moreover, water as a solvent for RDRP can provide exciting new chemical behaviors to drive unconventional reaction pathways and accelerate advancements in photocatalysis.…”

Liquid–Liquid-Printed Graphitic Carbon Nitride-Embedded Porous Poly(ionic liquid) Beads as Highly Active Reusable Heterogenous Photocatalysts

“…A potential scale-up method for photocatalytic materials, such as g-CN, is the incorporation of the photocatalysts in porous polymer beads. , This would allow for the easy separation of the catalyst (in the form of beads) and the products. This has been attempted in the past by forming photocatalytic hydrogel-based beads via inverse suspension polymerization .…”