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Abstract:The spectral and solvatation properties of hydrobromides of 3,3 / ,4,4,5-tetramethyldipyrromethene-2,2 / , 3,4,5-trimethyldipyrromethene-2,2 / and their oxa-and thia-analoges in benzene, n-propanol, chloroform, pyridine and N,N-dimethylformamide have been studied. The changes of relative solvation enthalpies are calculated and discussed.

Hydrobromides of dipyrrylmethenes (III), the oxa-and thia-analogues (Vc) and (Vd), as well as hydrobromides of the α,βand β,β-isomers of (IIIc), cf. (VII) and (IX), are prepared by condensation of alkylpyrroles without a substituent at one of the four ring carbon atoms with formylpyrroles in the presence of hydrobromic acid. The spectral characteristics and solvation properties of the condensation products in different organic solvents are examined by means of electronic spectroscopy and solution calorimetry. Thermooxidative destruction studies of dipyrrylmethenes and their hydrobromides are also carried out. -(SEMEIKIN*, A. S.; BEREZIN, M. B.; CHERNOVA, O. M.; ANTINA, E. V.; SYRBU, S. A.; LYUBIMOVA, T. V.; KUTEPOV, A. M.; Russ.