Why Are Dithienylethene-Linked Biscobaltocenes so Hard to Photoswitch?
Alejandra Escribano1, Torben Steenbock1, Conrad Stork1
1Institut für Anorganische und Angewandte Chemie, Universität Hamburg, Martin-Luther-King Platz 6, 20146, Hamburg, Germany.
Summary
Cobalt complexes with dithienylethene (DTE) molecular switches show switching behavior dependent on cobalt oxidation states. Co(I) complexes switch effectively, while Co(II,III) complexes exhibit poor switching, influenced by electronic structures.
Area of Science:
- Organometallic Chemistry
- Molecular Switches
- Materials Science
Background:
- Organometallic units attached to dithienylethene (DTE) molecular switches can modify switching and spectroscopic properties.
- DTE molecular switches offer potential for creating switchable magnetic properties.
- Tuning the cycloalkene ring size in DTE cores can influence molecular switch performance.
Purpose of the Study:
- To investigate the effect of cobalt sandwich units on DTE molecular switch properties.
- To determine how cobalt oxidation states influence the switching behavior of DTE complexes.
- To explore the mechanism of switching in DTE molecular switches bridged by cobalt units.
Main Methods:
- Synthesis of two distinct DTE molecular switches bridged by cobalt sandwich units.
- UV/Vis spectroscopy to monitor switching reactions in different cobalt oxidation states.
- Kohn-Sham density functional theory (DFT) calculations to elucidate reaction mechanisms.
Main Results:
- Cobalt complexes with DTE bridges exhibit switching behavior dependent on cobalt oxidation state.
- Co(I) complexes demonstrate efficient switching, while Co(II,III) complexes show poor switching.
- DFT calculations reveal diabatic ring-closure mechanisms and excited states that hinder cyclization.
Conclusions:
- The oxidation state of cobalt atoms is critical in determining the switching efficiency of DTE molecular switches.
- Electronic structures and excited states play a significant role in the switching mechanism and relaxation pathways.
- These findings provide insights into designing switchable organometallic materials with tunable properties.
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