Aggregation-induced chiroptical generation and photoinduced switching of achiral azobenzene- alt-fluorene copolymer endowed with left- and right-handed helical polysilanes

Hailing Chen; Lu Yin; Meng Liu; Laibing Wang; Michiya Fujiki; Wei Zhang; Xiulin Zhu

doi:10.1039/c8ra09345h

Aggregation-induced chiroptical generation and photoinduced switching of achiral azobenzene- alt-fluorene copolymer endowed with left- and right-handed helical polysilanes

RSC Adv. 2019 Feb 8;9(9):4849-4856. doi: 10.1039/c8ra09345h. eCollection 2019 Feb 5.

Authors

Hailing Chen¹, Lu Yin¹, Meng Liu¹, Laibing Wang², Michiya Fujiki², Wei Zhang¹, Xiulin Zhu^{1

3}

Affiliations

¹ Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University Suzhou Industrial Park Suzhou 215123 China weizhang@suda.edu.cn.
² Division of Materials Science, Nara Institute of Science and Technology 8946-5, Takayama Ikoma Nara 630-0192 Japan fujikim@ms.naist.jp.
³ Global Institute of Software Technology No. 5 Qingshan Road, Suzhou National Hi-Tech District Suzhou 215163 China.

Abstract

The left and right helicities of azobenzene (Azo)-containing main-chain polymer (PF8Azo) were successfully controlled with an enantiomeric pair of rigid rod-like helical polysilanes carrying (S)- and (R)-2-methylbutyl groups (PSi-S and PSi-R, respectively) as their hetero-aggregates in a mixture of chloroform and methanol solvents and in the solid state. Optimizing the good and poor cosolvents and their volume fractions showed that the molar ratio of PF8Azo to PSi-S/-R and the molecular weight of PF8Azo were crucial to boost the CD amplitudes of PF8Azo/PSi-S and PF8Azo/PSi-R hetero-aggregates. The photoresponsive trans-cis transformation caused noticeable changes in the sign and magnitude of the chiroptical behavior due to the hetero-aggregates. Moreover, the optically active PF8Azo homo-aggregates were produced by complete photoscissoring reactions at 313 nm, which could be assigned to the Siσ-Siσ* transitions of PSi-S and PSi-R.