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Teoret. i eksperim. khimiya. 2004. Vol.40 No. 4. p. 256-261

Spectral and Acid-Base Properties of Arylidene Derivatives
of Dicyclopenta[b,e]pyridines - the Fluorescent pH Indicators


V. F. Valuk, V. G. Pivovarenko, O. V. Grygorovych, A. O, Doroshenko

Taras Shevchenko Kyiv National University
64 Volodymyrska Vul., 01033 Kyiv, Ukraine. E-mail: pvg@univ.kiev.ua

* Institute for Chemistry at Kharkov V. N. Karazin National University
4 Pl. Svobody, 61077 Kharkiv, Ukraine. E-mail: andrey.o.doroshenko@univer.kharkov.ua

Bathochromic shifts of absorption and emission bands at protonation of dicyclopenta[b,e]pyridines reach the values of 3500-5500 cm-1. The both forms - neutral and protonated - are characterized by high fluo- rescence quantum yields. Spectral and acid-base properties of the studied compounds can be regulated in the wide range by the insertion of electron donor substituents in the side aromatic rings. The protonation constants in the ground and excited states have close values for each of the compound as a result of steric hindrance appearing at the protonation of pyridine nitrogen atom.

Key words dicyclopenta[b,e]pyridines, fluorescent pH indicators, absorption and emission spectra.