A self-locking molecule operative with a photoresponsive key
Takahiro Muraoka1, Kazushi Kinbara, Takuzo Aida
1Department of Chemistry and Biotechnology, School of Engineering, and Center for NanoBio Integration, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Journal of the American Chemical Society
|August 31, 2006
Summary
This study demonstrates a reversible self-locking mechanism in a molecular host. The host
Area of Science:
- Supramolecular Chemistry
- Coordination Chemistry
- Photochemistry
Background:
- Rotary host 1 features a ferrocene unit and is conformationally locked via intramolecular Zn-N coordination.
- This internal locking occurs in apolar solvents between zinc porphyrin and aniline units.
Purpose of the Study:
- To investigate the host-guest interactions between rotary host 1 and isomers of 1,2-bispyridylethylene (2).
- To demonstrate a reversible self-locking operation controlled by photochemical isomerization.
Main Methods:
- Utilized circular dichroism (CD) spectroscopy to visualize conformational changes.
- Employed cis and trans isomers of 1,2-bispyridylethylene (cis-2 and trans-2) as guests.
- Investigated photochemical isomerization of the guest molecule to control the host's locking state.
Main Results:
- The cis isomer (cis-2) readily cleaves the host's internal coordination bonds, forming an externally locked complex.
- The trans isomer (trans-2) does not disrupt the internal locking, showing differential binding affinity.
- Photochemical isomerization of cis-2 to trans-2 releases the guest and restores the internal lock.
- Photochemical isomerization of trans-2 to cis-2 in the presence of the host induces external locking.
Conclusions:
- Demonstrated a reversible self-locking operation in a molecular system.
- Highlighted the crucial role of guest isomerism and photochemical control in supramolecular assembly.
- Showcased the potential for light-responsive molecular machines and switches.
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