Optically Controlled Recovery and Recycling of Homogeneous Organocatalysts Enabled by Photoswitches

Author(s)
Qianfeng Qiu , Zhenhuan Sun , Danielle Joubran , Xiang Li , Joshua Wan , Klaus Schmidt-Rohr and Grace G. D. Han
Publisher
Angewandte Chemie
Year
2023
Volume
135
Issue
13
DOI
10.1002/ange.202300723

Abstract

We address a critical challenge of recovering and recycling homogeneous organocatalysts by designing photoswitchable catalyst structures that display a reversible solubility change in response to light. Initially insoluble catalysts are UV-switched to a soluble isomeric state, which catalyzes the reaction, then back-isomerizes to the insoluble state upon completion of the reaction to be filtered and recycled. The molecular design principles that allow for the drastic solubility change over 10 times between the isomeric states, 87 % recovery by the light-induced precipitation, and multiple rounds of catalyst recycling are revealed. This proof of concept will open up opportunities to develop highly recyclable homogeneous catalysts that are important for the synthesis of critical compounds in various industries, which is anticipated to significantly reduce environmental impact and costs.