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Published on: October 31, 2019
Photo-Responsive Soft Ionic Crystals: Ion-Pairing Assemblies of Azobenzene Carboxylates
Ryohei Yamakado1,2, Mitsuo Hara3, Shusaku Nagano4
1Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan.
Abstract:
This report delineates the design and synthesis of negatively charged azobenzene derivatives that form photo-responsive ion-pairing assemblies. The azobenzene carboxylates possessing aliphatic chains were prepared as photo-responsive anions that promote the formation of ion-pairing dimension-controlled assemblies, including mesophases, when used in conjunction with a tetrabutylammonium (TBA) cation. The photo-responsive properties of the ion pairs and the precursory carboxylic acids in the bulk state were examined by polarized optical microscopy (POM) and X-ray diffraction (XRD), demonstrating that liquid crystal (LC)-liquid and crystal-liquid phase transitions occurred, depending on the number and lengths of the aliphatic chains of each assembly. An ion pair exhibited photo-induced crystal-crystal phase transitions upon switching between two irradiation wavelengths (365/436 nm).
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