Synthesis and intramolecular charge transfer of bipyridinium-crown ether conjugates in response to alkali metal ions
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- 作者：Tetsuo Kuwabara ; kuwabara@yamanashi.ac.jp ; Haocheng Guo ; Tadahiko Okubo ; Hiroki Orii ; Kosuke Sugiyama ; Naoya Miyajima ; Yasutada Suzuki
- 关键词：Intramolecular charge transfer ; Ion-sensing ; Host&ndash ; guest chemistry
- 刊名：Tetrahedron
- 出版年：2013
- 出版时间：20 May, 2013
- 年：2013
- 卷：69
- 期：20
- 页码：4081-4087
- 全文大小：792 K
文摘
Two types of hosts, 1 and 2, in which benzocrown ether units were conjugated to monocationic pyridinium and dicationic bipyridinium units, respectively, have been prepared. 1 and 2 exhibited color-to-colorless changes induced by alkali metal ion, associated with blue shift of their intramolecular charge transfer (ICT) absorptions due to the formation of a 1:1 host-guest inclusion complex. 3 and 4 being the noncrown ether analogues of 1 and 2 also exhibited ICT absorptions, but did not shift upon addition of the guest because of no guest-binding abilities. The monocationic 1 and 3 showed red shift in their ICT bands upon addition of organic acid, such as p-toluenesulfonic acid due to their acceptor character changes by protonation on the terminal pyridine ring. Such guest-induced absorption variations of 1 and 2 were used for alkali metal ion sensing. The sensing abilities are roughly parallel to their binding constants.