Light controls light: Emission modulation of photochromic molecules
Professor Jürgen Köhler
- University of Bayreuth
Tuesday 22 November, 11.30am
Abstract
In recent years much attention has been given to design multistate molecular components with functionalities that cover the range from simple switches to logic gates. In this regard much attention has been drawn to photochromic molecules, i.e., molecules that can be interconverted between two bistable forms by light [1]. However, a serious drawback of this class of molecules is that most of the fatigue resistant photochromic molecules feature a low fluorescence quantum yield. Therefore we adapted the strategy developed by Irie and coworkers [1], to chemically synthesize more complex tailor-made molecules (dyads and triads) that consist of highly fluorescent chromophores covalently linked to a photoswitchable unit. This facilitates the combination of high fatigue resistance and high fluorescence quantum yield, and allowed us to verify the functionalities of an optical transistor and optical gating, yet where the electrons have been replaced by photons as signal carriers [2,3]. More recently, we demonstrated deliberate switching of single photochromic triads at the single molecule level [4,5].
[1] M. Irie, T. Fukaminato, K. Matsuda and S. Kobatake, Photochromism of diarylethene molecules and crystals:
memories, switches, and actuators, Chem. Rev. 114 (2014) 12174–12277;
[2] M. Pärs, C.C. Hofmann, K. Willinger, P. Bauer, M. Thelakkat, J. Köhler, An Organic Optical Transistor Operated
under Ambient Conditions, Ang. Chem. Int. Ed. 50 (2011) 11405-11408;
[3] M. Pärs, K. Gräf, P. Bauer, M. Thelakkat, J. Köhler, Optical gating of perylene bisimide fluorescence using
dithienylcyclopentene photochromic switches, Applied Physics Letters 103 (2013) 221115-1;
[4] J. Maier, M. Pärs, T. Weller, M. Thelakkat, J. Köhler, Deliberate Switching of Single Photochromic Triads,
Scientific Reports 7 (2017) 41739-1;
[5] J. Maier, T. Weller, M. Thelakkat, J. Köhler, Long-term switching of Single Photochromic Triads based on
dithienylcyclopentene and fluorophores at cryogenic temperatures, J. Chem. Phys. 155 (2021) 014901.
About the speaker
Jürgen Köhler studied physics at the University of Düsseldorf, Germany (Ph.D. 1990) followed by a postdoc period at the University of Leiden, The Netherlands. In 1999 he became an associate professor at the LMU Munich, Germany. In 2000 he commenced as professor at the University of Bayreuth. His main research interests cover the study of the electronic states of soft condensed matter, including (bio-) macromolecules and molecular aggregates, using optical (single-molecule) spectroscopy techniques.
