Photoswitchable polymerization catalysis: state of the art, challenges, and perspectives.

Adjusting the length, composition, and microstructure of a polymer during the process of its formation in principle allows achieving the desired properties, thereby enabling custom-design of the thus generated polymer for its targeted function. Over the past years, different stimuli have been applied to manipulate responsive catalyst systems in situ; among them light takes center stage as perhaps the most promising stimulus. Here, we highlight recent progress in the area of photoswitchable polymerization catalysis.

Shedding Light on the Photoisomerization Pathway of Donor-Acceptor Stenhouse Adducts.

Donor-acceptor Stenhouse adducts (DASAs) are negative photochromes that hold great promise for a variety of applications. Key to optimizing their switching properties is a detailed understanding of the photoswitching mechanism, which, as yet, is absent. Here we characterize the actinic step of DASA-photoswitching and its key intermediate, which was studied using a combination of ultrafast visible and IR pump-probe spectroscopies and TD-DFT calculations.

Acylhydrazones as Widely Tunable Photoswitches.

Molecular photoswitches have attracted much attention in biological and materials contexts. Despite the fact that existing classes of these highly interesting functional molecules have been heavily investigated and optimized, distinct obstacles and inherent limitations remain. Considerable synthetic efforts and complex structure-property relationships render the development and exploitation of new photoswitch families difficult.