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Tautomerism and stereoisomerism of nitracrine, its nitro isomers and their protonated forms in solution examined by absorption and fluorescence spectroscopy

1991; Elsevier BV; Volume: 61; Issue: 3 Linguagem: Inglês

10.1016/1010-6030(91)90018-o

1873-2666

Janusz Rak, Jerzy Błażejowski, Kazimierz Nowaczyk, A. Kawski,

Photochromic and Fluorescence Chemistry

Electronic absorption, fluorescence and fluorescence excitation spectroscopy techniques were employed to examine the behaviour of N,N-dimethyl-N′-(1-nitro-9-acridinyl)-1,3-propanediamine (nitracrine), its three nitro isomers and the protonated forms of all four compounds in the liquid phase. The spectral characteristics obtained reveal that the compounds investigated in solution exist in at least two structural forms. On the basis of theoretical calculations (on the level of the AM1 method), most of the results can be interpreted in terms of tautomeric phenomena originating from the migration of the hydrogen atom, bound to the nitrogen atom attached to carbon (9), to the acridine ring nitrogen. The effect of the environment on the absorption and emission characteristics is discussed, emphasizing the influence of non-specific and specific (hydrogen-bonding) interactions on the spectral characteristics and the relative amounts of the various forms in solution.