Chiroptical Properties of a Benzotriazole–Thiophene Copolymer Bearing Chiral Ethylhexyl Side Chains

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• 作者：Stephanie L. Fronk ; Yueqin Shi ; Martin Siefrid ; Cheng-Kang Mai ; Caitlin McDowell ; Guillermo C. Bazan
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：December 27, 2016
• 年：2016
• 卷：49
• 期：24
• 页码：9301-9308
• 全文大小：494K
• ISSN：1520-5835

文摘

Conjugated polymers containing alternating thiophene units and benzotriazole structural units bearing either chiral (S)-2-ethylhexyl (PBTz-Th*) or racemic 2-ethylhexyl side chains (PBTz-Th) were synthesized. Characterization by optical absorption spectroscopy of both PBTz-Th* and its racemic counterpart reveal aggregated chains, even at dilute concentrations in good solvents. The presence of a chiral substituent permits characterization via circular dichroism (CD) spectroscopy. CD spectra provide evidence of chiral aggregates of PBTz-Th* chains even at 0.01 mg/mL in dichlorobenzene. When PBTz-Th* solutions are diluted with PBTz-Th, the resulting CD spectrum suggests that PBTz-Th* chains are chiral in the aggregate. Chiral ordering is also found to translate from aggregates in solution to the solid state.