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Cis/trans Photoisomerization: From Photoswitches to Light-Activated Molecular Rotary Motors

Ayesha Nisathar
Ayesha Nisathar
Department of Chemistry
University of Georgia
Organic Seminar

Over the past few decades synthetic chemists were striving to make a leap from simple molecular switches to molecular systems with controlled dynamic behavior. These research efforts were inspired by directional motion in living systems that are key to almost every essential process in the cell. The structure of molecular rotary motors resembles the layout of macroscopic electric motors which are widely used to convert energy into motion. However, controlling the dynamic behavior at the molecular level is challenging. The major challenge is to achieve controlled, unidirectional rotary motion upon consumption of energy.1 The first light-driven unidirectional rotary motor was reported by Ben Feringa. The scientific value of this discovery was highlighted by the award of 2016 Nobel Prize in Chemistry. Photoswitches that employ the cis/trans photoisomerization of the double bond serve as a foundation of the design of the first light-driven molecular rotary motors.2 This presentation will focus on the origin, mechanism of the first light activated molecular rotary motor and exciting applications in the field of catalysis,3 medicine4 and nanocar development. 5

1. Feringa, B. L. The art of building small: from molecular switches to motors (Nobel lecture). Angew. Chem., Intl. Ed. 2017, 56 (37), 11060-11078

2. Koumura, N.; Zijlstra R. W. J.; van Delden, R. A.; Harada, N.; Feringa, B. L. Light-driven monodirectional molecular rotor. Nature 1999, 401, 152-155

3. Wang, J.; Feringa, B. L. Dynamic control of chiral space in a catalytic asymmetric reaction using a molecular motor. Science 2011, 331 (6023), 1429-1432

4. García-López, V; Chen, F.; Nilewski, L. G.; Duret, G.; Aliyan, A.; Kolomeisky, A. B.; Robinson, J. T.; Wang, G.; Pal, R.; Tour, J. M. Molecular machines open cell membranes. Nature 2017, 548 (7669), 567-572

5. Saywell, A.; Bakker, A.; Mielke, J.; Kumagai, T.; Wolf, M.; García-López, V; Chiang, P.; Tour, J. M.; Grill, L. Light-induced translation of motorized molecules on a surface. ACS Nano 2016, 10 (12), 10945−10952

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