April 8th (Thu) Graduate Seminar / Professor Minsang Kwon

Purely Organic Photocatalysts for Visible-light Driven

Polymerizations and Organic Reactions

Due to their broad structural diversity and benign environmental profiles, purely organic PCs provide

attractive alternatives to transition-metal-based catalysts. However, the full potential of organic PCs has not been realized, as the criteria for their design are not well established. Therefore, the development of new transformations using organic PCs is limited to a few organic dyes commonly used for imaging purposes and whose parameters are not straightforwardly tuned through structural alternation.

In this talk, we propose a general strategy for the design of purely organic PCs.[1] Strongly twisted donor–acceptor structures are introduced as a general scaffold design for these PCs. The charge transfer (CT) characteristics of the lowest excited states of the designed PCs greatly promote the generation of the lowest triplet excited states (T1) and allow systematic control of the essential catalyst parameters over broad ranges, thereby facilitating efficient catalytic performance. Through combined computational and experimental studies, we provide a flow chart that facilitates the computationally directed rational design of organic PCs for the development of new photoredox-mediated reactions. Based on this strategy, highly efficient organic PCs were discovered that addressed important issues associated with photoredox-mediated atom transfer radical polymerization (ATRP)[1] and reversible addition-fragmentation chain transfer (RAFT)[2].

References

1. Singh, V. K., Yu, C., Badgujar, S., Kim, Y., Kwon, Y., Kim, D., Lee, J., Akhter, T., Thangavel, G., Park, L. S., Lee, J., Nandajan, P. C., Wannemacher, R., Milian-Medina, B., Luer, L, Kim, K. S.*, Gierschner, J.* & Kwon, M. S.* “Highly efficient organic photocatalysts discovered via a computer-aided-design strategy for visible-light-driven atom transfer radical polymerization” Nat. Catal. 2018, 1, 794-804

2. Song, Y.†, Kim, Y.†, Noh, Y., Singh, V. K., Behera, S. K., Abudulimu, A., Chung, K., Wannemacher, R., Gierschner, J., Lüer, L & Kwon, M. S.* “Organic photocatalyst for ppm-level visible-light-driven reversible additionfragmentation chain transfer (RAFT) polymerization with excellent oxygen tolerance” Macromolecules, 2019, 52, 5538-5545