Skip to main content

Fluorescence studies and semiempirical calculations on alkali ion indicators


Two newly synthesized cryptands act as sensitive Na+- and K+-selective indicators for cation concentrations above 20 μM. The fluorescence properties change markedly upon cation binding. In addition, the free ligands exhibit a pronounced sensitivity to pH, which is considerably lower for the cation complexes. Time resolved fluorescence is characterized by a decay time of about 5 ns that is attributed to the diprotonated protolytic state of the uncomplexed ligands. Semiempirical calculations show the systematic influence of the nitrogen lone pairs or the N−H bond on the stability of the system. The cause of the strong fluorescence intensity increase observed upon protonation of the fluorescent cryptands may be attributed to an increase in the S1−T x energy gap as a consequence of bridgehead nitrogen protonation.

This is a preview of subscription content, access via your institution.


  1. F. Kastenholz (1993) Dissertation, Max-Planck-Institute of Biophysics and University of Cologne, Cologne.

  2. J. M. Lehn (1973) in J. D. Dunitz et al. (Eds.),Structure and Bonding, Vol. 16, Verlag Chemie, Weinheim, pp. 1–69.

    Google Scholar 

  3. R. H. Abu-Eittah and B. A. H. El-Tawil (1985)Can. J. Chem. 63, 1173–1179.

    Google Scholar 

  4. A. P. de Silva, H. Q. N. Gunaratne, and C. P. McCoy (1993)Nature 364, 42–44.

    Google Scholar 

  5. D. M. Ferguson and D. J. Raber (1989)J. Am. Chem. Soc. 111, 4371–4378.

    Google Scholar 

  6. M. J. S. Dewar, E. G. Zoebisch, E. F. Healy, and J. J. P. Stewart (1985)J. Am. Chem. Soc. 107, 3902–3909.

    Google Scholar 

Download references

Author information

Authors and Affiliations


Additional information

This is a peer-reviewed conference proceeding article from the Third Conference on Methods and Applications of Fluorescence Spectroscopy, Prague, Czech Republic, October 18–21, 1993.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kastenholz, F., Grell, E., Bats, J.W. et al. Fluorescence studies and semiempirical calculations on alkali ion indicators. J Fluoresc 4, 243–246 (1994).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Issue Date:

  • DOI:

Key Words

  • Cryptands
  • alkali ion indicators
  • pH sensitivity
  • semiempirical calculations
  • AM1