Chemical Research in Chinese Universities ›› 2009, Vol. 25 ›› Issue (3): 362-367.

• Articles • Previous Articles     Next Articles

Fluorescence-quenching of Tryptophan Ion-18-crown-6 Complex——A Different Observation from Its Neutral Counterpart

YU Qing1, CAO Jie1*, LIU Tao1,2 and WANG Zhi-xiang1*   

  1. 1. College of Chemistry and Chemical Engineering, Graduate School of the Chinese Academy of Sciences, Beijing 100049, P. R. China;
    2. Department of Chemistry, Jining University, Qufu 273155, P. R. China
  • Received:2008-10-15 Revised:2009-02-13 Online:2009-05-25 Published:2009-08-07
  • Contact: CAO Jie, E-mail: jcao@gucas.ac.cn; WANG Zhi-xiang, E-mail: zxwang@gucas.ac.cn
  • Supported by:

    Supported by the Foundation of President of the Chinese Academy of Sciences and the Key(Keygrant) Project of Chinese Ministry of Education(No.106064).

Abstract:

It is well-known that primary amines form inclusive complexes with crown ethers. This kind of noncovalently inclusive complexes, exemplified tryptophan complex with 18-crown-6, was studied by combination of two experimental methods, fluorimetry and mass spectrometry, with theoretical calculation. Fluorescence intensity of tryptophan in the absence and the presence of 18-crown-6 in aqueous HAc-NaAc buffer solution at pH=3.73 has been studied by fluorometry. The fluorescence intensity decreases significantly with increasing the concentration of 18-crown-6. The association constant K for the 1:1 complex of tryptophan ion-18-crown-6 was determined by means of fluorimetry. Mass spectrometric study of the complex gives direct evidence of the complex in the gas phase whose structure and binding energy are properly predicted by ab initio calculation.

Key words: Tryptophan; 18-Crown-6 complex; Fluorescence; Mass spectrometry; Ab initio calculation