Jacek Waluk

Institute of Physical Chemistry, Polish Academy of Sciences,
01-224 Warsaw, Kasprzaka 44/52, Poland;
E-mail:; Fax: (+48) 391 20 238

In most cases, the products of the excited state proton transfer reaction are energetically and chemically very distinct from the substrates. A completely different situation arises if the phototautomerization transforms a molecule into itself. Processes of this kind will be described for porphyrin and its isomers: porphycene, corrphycene and hemiporphycene. Photoinduced tautomerization involving the shift of two protons has been studied by stationary and time-resolved techniques, in particular by combination of methods of polarized spectroscopy and matrix isolation. Some aspects of the double proton transfer process make this reaction a unique tool for obtaining spectral, photophysical and structural information which would be otherwise difficult or impossible to gain. The problems to be discussed include: