Phenylbenzoxazole鈥揂mide鈥揅yclen Linkage as a Ratiometric Fluorescent Receptor for Zn(II) in Water
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- 作者：Yasuhiro Shiraishi ; Yoshinao Matsunaga ; Takayuki Hirai
- 刊名：The Journal of Physical Chemistry A
- 出版年：2013
- 出版时间：April 25, 2013
- 年：2013
- 卷：117
- 期：16
- 页码：3387-3395
- 全文大小：532K
- 年卷期：v.117,no.16(April 25, 2013)
- ISSN：1520-5215
文摘
A phenylbenzoxazole鈥揳mide鈥揷yclen linkage (L) behaves as a ratiometric fluorescent receptor for Zn2+ in water. The receptor dissolved in water at neutral pH shows fluorescence at 383 nm. The addition of Zn2+, however, leads to a decrease in this emission, along with an appearance of red-shifted emission at 445 nm. This thus facilitates ratiometric Zn2+ sensing. Other metal cations do not promote such spectral change. Complexation of L with Zn2+ involves the coordination with four cyclen nitrogens and amide oxygen. IR and potentiometric analysis revealed that strong coordination of Zn2+ with amide oxygen leads to a deprotonation of the amide moiety and creates red-shifted fluorescence. Ab initio calculation indicated that the deprotonation of the amide moiety allows rotational motion of the benzoxazole moiety in the excited state and stabilizes the twisted intramolecular charge transfer (TICT) excited state. This results in the creation of red-shifted fluorescence from the TICT excited state.