Light-driven and aggregation-induced emission from side-chain azoindazole polymers
Light-driven and aggregation-induced emission from side-chain azoindazole polymers
Ying Li，Nianchen Zhou*，Wei Zhang，Feng Zhang, Jian Zhu，Zhengbiao Zhang， Zhenping Cheng，Yingfeng Tu，Xiulin Zhu*
J. Polym. Sci. Part A: Polym. Chem. 2011, 49, 4911-4920.
The well-defined azoindazole-containing homopolymer, poly(6-{6-[(4-dimethylamino) phenylazo]-indazole}-hexyl methacrylate) (PDHMA), and amphiphilic diblock copolymer, poly({6-[6-(4-dimethylamino)phenylazo]-indazole}-hexyl methacrylate)-b-poly(2-(dimethylamino)ethylmethacrylate) (PDHMAm-b-PDMAEMAn), were successfully prepared via reversible addition-fragmentation chain transfer polymerization technique. The homopolymer and amphiphilic diblock copolymer in CH2Cl2 exhibited intense fluorescence emission accompanied by trans–cis photoisomerization of azoindazole group under UV irradiation. The experiment results indicated that the intense fluorescence emission may be attributed to an inhibition of photoinduced electron transfer of the cis form of azoindazole. On the other hand, the intense fluorescence emission of amphiphilic diblock copolymers in water-tetrahydrofuran mixture was observed, which increased with the volume ratio of water in the mixed solvent. The self-aggregation behaviors of three amphiphilic diblock copolymers were examined by transmission electron microscopy, laser light scattering, and UV–vis spectra. The restriction of intramolecular rotation of the azoindazole groups in aggregates was considered as the main cause of aggregation-induced fluorescence emission.
