Dynamic Molecular Propeller: Supramolecular Chirality Sensing by Enhanced Chiroptical Response through the Transmission of Point Chirality to Mobile Helicity

详细信息    查看全文

• 作者：Ryo Katoono ; Hidetoshi Kawai ; Kenshu Fujiwara ; Takanori Suzuki
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：November 25, 2009
• 年：2009
• 卷：131
• 期：46
• 页码：16896-16904
• 全文大小：667K
• 年卷期：v.131,no.46(November 25, 2009)
• ISSN：1520-5126

文摘

The secondary terephthalamide host 1a-H attached to four aryl blades was prepared from tetrabromide 2a by Suzuki−Miyaura coupling and undergoes a conformational change from a nonpropeller anti-form to a propeller-shaped syn-form upon complexation with ditopic guests such as p-xylylenediammonium derivatives (R,R)/(S,S)-3 (chirality generation). Through transmission of the point chiralities attached on the nitrogens in the chiral guests to the mobile helicity in 1a-H, the propeller-shaped host in the complex is biased to prefer a particular handedness (chirality biasing). While chiral guests with simple point chiralities such as (R,R)/(S,S)-3 exhibit only very weak CD activity, complexation with the dynamic propeller host 1a-H results in much stronger chiroptical signals (chiroptical enhancement). The chirality generation−chirality biasing protocol was successfully applied to a neurotransmitter, (−)-phenylephrine 4, acting as a chiral ditopic guest. When the chiral auxiliaries are attached to the host as in (R,R)-1b-H, complexation with (S,S)-3 causes CD enhancement but not with (R,R)-3, due to chiral recognition.