title: Click synthesis, aggregation-induced emission, E/Z isomerization, self-organization, and multiple chromisms of pure stereoisomers of a tetraphenylethene-cored luminogen.
abstract: It has been difficult to decipher the mechanistic issue whether E/Z isomerization is involved in the aggregation-induced emission (AIE) process of a tetraphenylethene (TPE) derivative, due to the difficulty in the synthesis of its pure E and Z conformers. In this work, pure stereoisomers of a TPE derivative named 1,2-bis{4-[1-(6-phenoxyhexyl)-4-(1,2,3-triazol)yl]phenyl}-1,2-diphenylethene (BPHTATPE) are successfully synthesized. Both isomers show remarkable AIE effect (α(AIE) ≥ 322) and high fluorescence quantum yield in the solid state (Φ(F) 100%). The conformers readily undergo E/Z isomerization upon exposure to a powerful UV light and treatment at a high temperature (>200 °C). Such conformational change, however, is not observed under normal fluorescence spectrum measurement conditions, excluding the involvement of the E/Z isomerization in the AIE process of the TPE-based luminogen. The molecules of (E)-BPHTATPE self-organize into ordered one-dimensional nanostructures such as microfibers and nanorods that show obvious optical waveguide effect. BPHTATPE shows rich chromic effects, including mechano-, piezo-, thermo-, vapo-, and chronochromisms. Its emission peak is bathochromically shifted by simple grinding and pressurization and the spectral change is reversed by fuming with a polar solvent, heating at a high temperature, or storing at room temperature for some time. The multiple chromic processes are all associated with changes in the modes of molecular packing.
authors.affiliation: MoE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Ju
authors.initials: J
authors.lastname: Mei
authors.forename: Rongrong
authors.initials: R
authors.lastname: Hu
authors.forename: Jing Zhi
authors.initials: JZ
authors.lastname: Sun
authors.forename: Anjun
authors.initials: A
authors.lastname: Qin
authors.forename: Ben Zhong
authors.initials: BZ
authors.lastname: Tang
mesh_terms: D057930:Click Chemistry; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006358:Hot Temperature; D007536:Isomerism; D049329:Nanostructures / Q000737:chemistry / Q000648:ultrastructure; D013050:Spectrometry, Fluorescence; D013267:Stilbenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D013267:Stilbenes