Metal Chelation-Controlled Twisted Intramolecular Charge Transfer and Its Application to Fluorescent Sensing of Metal Ions and Anions
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- 作者：Shin Aoki ; Daisuke Kagata ; Motoo Shiro ; Kei Takeda ; and Eiichi Kimura
- 刊名：Journal of the American Chemical Society
- 出版年：2004
- 出版时间：October 20, 2004
- 年：2004
- 卷：126
- 期：41
- 页码：13377 - 13390
- 全文大小：665K
- 年卷期：v.126,no.41(October 20, 2004)
- ISSN：1520-5126
文摘
Two fluorescent ligands, N-(2-(5-cyanopyridyl))cyclen (L5) and N-(2-pyridyl)cyclen (L6) (cyclen= 1,4,7,10-tetraazacyclododecane), were designed and synthesized to control twisted intramolecular chargetransfer (TICT) by metal chelation in aqueous solution. By complexation with Zn2+, L6 exhibited TICTemissions at 430 nm (excitation at 270 nm) in 10 mM HEPES (pH 7.0) with I = 0.1 (NaNO3) at 25 
C dueto the perpendicular conformation of a pyridine ring with respect to a dialkylamino group, which was fixedby Zn2+-N(pyridine) coordination, as proven by potentiometric pH, UV, and fluorescence titrations andX-ray crystal structure analysis. We further describe that the 1:1 complexation of ZnL6 with guests such assuccinimide, phosphates, thiolates, and dicarboxylates, which compete with a nitrogen in the pyridine ringfor Zn2+ in ZnL6, induces considerable emission shift from TICT emissions (at 430 nm) to locally excitedemissions (at ca. 350 nm) in neutral aqueous solution at 25 C.
C dueto the perpendicular conformation of a pyridine ring with respect to a dialkylamino group, which was fixedby Zn2+-N(pyridine) coordination, as proven by potentiometric pH, UV, and fluorescence titrations andX-ray crystal structure analysis. We further describe that the 1:1 complexation of ZnL6 with guests such assuccinimide, phosphates, thiolates, and dicarboxylates, which compete with a nitrogen in the pyridine ringfor Zn2+ in ZnL6, induces considerable emission shift from TICT emissions (at 430 nm) to locally excitedemissions (at ca. 350 nm) in neutral aqueous solution at 25 C.