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Binaphthyl-Bipyridyl Cyclic Dyads as a Chiroptical Switch.
Kazuto Takaishi1, Makoto Yasui1, Tadashi Ema1
1Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , Tsushima, Okayama 700-8530 , Japan.
Journal of the American Chemical Society
|April 14, 2018
Summary
Researchers developed novel chiral cyclic dyads with unique ON/OFF switching capabilities. These dyads demonstrate unprecedented control over circularly polarized luminescence (CPL) and optical rotation, driven by conformational changes.
Area of Science:
- Organic Chemistry
- Supramolecular Chemistry
- Materials Science
Background:
- Axially chiral binaphthyl units are crucial building blocks in asymmetric synthesis.
- 3,3'-Bipyridyl moieties offer versatile coordination and structural properties.
- Chiral molecular switches are of great interest for advanced optical applications.
Purpose of the Study:
- To synthesize novel chiral cyclic dyads by linking binaphthyls to 3,3'-bipyridyl units.
- To investigate the circularly polarized luminescence (CPL) and optical rotation properties of these dyads.
- To understand the mechanism behind the observed switching behaviors.
Main Methods:
- Synthesis of chiral cyclic dyads.
- Circularly polarized luminescence (CPL) spectroscopy.
- Polarimetry ([α]D measurements).
- X-ray crystallography.
- Computational modeling.
Main Results:
- Dyad 2 with methoxy groups showed reversible ON/OFF switching in CPL (| glum| up to 1.6 × 10-3) without altering fluorescence intensity.
- Regioisomer 4 exhibited switching between dextro and levo optical rotation.
- X-ray structures and theoretical analyses confirmed that conformational changes drive the switching properties.
Conclusions:
- The synthesized chiral cyclic dyads exhibit unprecedented CPL and optical rotation switching.
- Conformational dynamics are key to controlling the optical properties of these molecular systems.
- These findings open new avenues for designing advanced chiral optical materials.
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