Light-Triggered, Non-Centrosymmetric Self-Assembly of Aqueous Arylazopyrazoles at the Air-Water Interface and Switching of Second-Harmonic Generation

Yuki Nagai; Keita Ishiba; Ryosuke Yamamoto; Teppei Yamada; Masa-Aki Morikawa; Nobuo Kimizuka

doi:10.1002/anie.202013650

Light-Triggered, Non-Centrosymmetric Self-Assembly of Aqueous Arylazopyrazoles at the Air-Water Interface and Switching of Second-Harmonic Generation

Angew Chem Int Ed Engl. 2021 Mar 15;60(12):6333-6338. doi: 10.1002/anie.202013650. Epub 2021 Feb 9.

Authors

Yuki Nagai¹, Keita Ishiba¹, Ryosuke Yamamoto¹, Teppei Yamada^{1

2

3}, Masa-Aki Morikawa^{1

2}, Nobuo Kimizuka^{1

2}

Affiliations

¹ Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka Nishi-ku, Fukuoka, 819-0395, Japan.
² Center for Molecular Systems (CMS), Kyushu University, 744 Moto-oka Nishi-ku, Fukuoka, 819-0395, Japan.
³ Department of Chemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

PMID: 33350044
DOI: 10.1002/anie.202013650

Abstract

Trans-p-methoxy arylazopyrazole spontaneously forms non-centrosymmetric polar crystals, which reversibly undergo liquefaction upon photoisomerization to the cis-isomer. This liquid cis-isomer has a large electric dipole moment and is highly soluble in water (solubility up to ≈58 mM), which is remarkably higher than that of the trans-isomer (690 μM). Vis-light illumination of the aqueous cis-isomer generates macroscopically oriented, non-centrosymmetric crystals at the air-water interface. Polar crystals are also formed in sandwich glass cells (spacing, 20 μm) upon photo-induced crystallization of the liquid cis-isomer. The trans-crystals thus formed showed second harmonic generation (SHG) whose intensity is switched on/off in response to the photo-induced phase transition.

Keywords: arylazopyrazoles; photoisomerization; photoliquefaction; second harmonic generation; self-assembly.

Abstract

Grants and funding