Intra- and InterMolecular Processes

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 Institute of Organic Chemistry


The traditional spectrophotometric analysis is based on the assumption that the individual spectra of the components in a mixture are known. Unfortunately in many cases in organic chemistry (tautomeric systems, photochemical transients, low stability complexes, intermediates, etc.) the species cannot be separated, preventing the quantitative spectral analysis as it is described in the textbooks.
We developed a procedure for mathematical resolution of overlapping bands in the absorption UV-Vis spectroscopy (also workable in IR/Raman and CD spectroscopy), which can be used as for band shape analysis (estimation of the positions and oscillator strengths of the overlapping bands in a complex spectral contour) as well as for quantitative analysis of undefined mixtures (with unknown spectra of the pure compounds).
The latter is much more interesting from practical point of view, especially after solving the problem with estimation of the number of overlapping bands. Finally we have developed a procedure, called Fishing-Net-Algorithm (FINAL), allowing quantitative analysis of fully or partially undefined mixtures. This approach has been used for analysis of tautomeric equilibria and processes of complexation formation, protonation and self-association.

The video clip is intended to give you a general idea how FINAL works in the case of two-component mixture. If you are interesting to know more - see the papers below.


Basic papers:

  • Analysis of the overlapping bands in UV-Vis absorption spectroscopy. L.Antonov & S.Stoyanov; Applied Spectroscopy, 47, 1030 (1993)
  • Resolution of overlapping UV-Vis absorption bands - quantitative analysis of tautomeric equilibria. L.Antonov & S.Stoyanov; Analytica Chimica Acta, 314, 225 (1995)
  • Resolution of overlapping UV-Vis absorption bands and quantitative analysis. L.Antonov & D.Nedeltcheva; Chemical Society Reviews, 29, 217 (2000)
  • Quantitative analysis of undefined mixtures – “Fishing net” algorithm. L.Antonov & V.Petrov; Analytical and Bioanalytical Chemistry, 374, 1312 (2002)
  • Chemometric models for quantitative analysis of tautomeric Schiff bases and azodyes. D.Nedeltcheva, L.Antonov, A.Lycka, B.Damyanova & S.Popov; Current Organic Chemistry, 13, 217 (2009)


How a controlled shift in the position of the tautomeric equilibrium can be achieved. The story.....

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AG Antonov

Institute of Organic Chemistry with Center of Phytochemistry

Acad. G.Bonchev street, bl. 9

Sofia 1113, Bulgaria

fax: 359 2 8700225