A photoresponsive hexa-arylazopyrazole-substituted tris(β-diketonato)Co(Ⅲ)complex was synthesized,and theΛ-andΔ-enantiomers were isolated.The complex shows reversible E/Z isomerization using UV(λmax=365 nm)and vi...A photoresponsive hexa-arylazopyrazole-substituted tris(β-diketonato)Co(Ⅲ)complex was synthesized,and theΛ-andΔ-enantiomers were isolated.The complex shows reversible E/Z isomerization using UV(λmax=365 nm)and visible light(λmax=520 nm),respectively.Using the Co(Ⅲ)complex as a dopant in the commercially available liquid crystal N-(4-methoxybenzylidene)-4-butylaniline(MBBA),the chiral nematic phase can be induced.Upon photoisomerization,the helical pitch of the doped liquid crystal can be reversibly modulated,leading to very high changes in terms of helical twisting power(HTP orβM).Corresponding to this change,the HTP value of the doped liquid crystals varied between 615 and 346μm^(-1)or between-563 and-352μm^(-1)at 30℃,where the positive and negative signs correspond to the P and M helix,respectively.Thus,the Co(Ⅲ)complex effects both high HTP values of the liquid crystal and large changes upon photoisomerization,enabling induction of the chiral nematic phase at very low dopant concentrations,which can be useful for the development of optical applications.展开更多
基金funded by the Deutsche Forschungsgemeinschaft(DFG IRTG 2678 Project ID 437785492)by the Japan Society for the Promotion of Science(JSPS KAKENHI Grant-in-Aid for Scientific Research(B)(23K23362)and(C)(23K04783)).
文摘A photoresponsive hexa-arylazopyrazole-substituted tris(β-diketonato)Co(Ⅲ)complex was synthesized,and theΛ-andΔ-enantiomers were isolated.The complex shows reversible E/Z isomerization using UV(λmax=365 nm)and visible light(λmax=520 nm),respectively.Using the Co(Ⅲ)complex as a dopant in the commercially available liquid crystal N-(4-methoxybenzylidene)-4-butylaniline(MBBA),the chiral nematic phase can be induced.Upon photoisomerization,the helical pitch of the doped liquid crystal can be reversibly modulated,leading to very high changes in terms of helical twisting power(HTP orβM).Corresponding to this change,the HTP value of the doped liquid crystals varied between 615 and 346μm^(-1)or between-563 and-352μm^(-1)at 30℃,where the positive and negative signs correspond to the P and M helix,respectively.Thus,the Co(Ⅲ)complex effects both high HTP values of the liquid crystal and large changes upon photoisomerization,enabling induction of the chiral nematic phase at very low dopant concentrations,which can be useful for the development of optical applications.
