Mesoionic compounds with a bridged nitrogen atom. 4. Thiazolo[3, 2-a]quinolinium 1-oxide derivatives

It is shown that diverse 2-substituted thiazolo[3,2-a]quinolinium 1-oxides can be obtained from 2-quinolylmercaptoacetic acids. The structures of the synthesized compounds were confirmed by the PMR and mass spectra.See [1] for communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 621–626, May, 1980.     

Reaction of 3-formylchromone with methyl- and methylene-active azocycles

The reaction of 3-formylchromone with quaternary salts of nitrogen heterocycles containing active methyl or methylene groups was investigated. It is shown that the compounds obtained can be used in the synthesis of merocyanine dyes containing an o-hydroxybenzoyl substituent in the polymethine chain. Dicarbocyanines with such a substituent were not isolated, evidently because of the high electrophilicity of the polymethine chain and the ease of formation of a six-membered heteroring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1271–1275, September, 1990.     

Perturbation theory of nonbonding orbitals in polymeric dyes

In terms of the approximation of an extremely long polymethine chain a relation was obtained between the electron-donating power ₀ and the effective length L of the terminal groups in cyanine dyes, on the one hand, and the form of their asymptotic nonbonding orbital, on the other. A simple general procedure for determining the coefficients of such orbitals is indicated. Expressions were obtained through these coefficients for the derivatives of ₀ and L with respect to the elements of the topological Hamiltonian of the terminal group, and this makes it possible to assess the effect of structural perturbations of the terminal groups on ₀ and L. The possibility of refinement of the absorption region of the dyes with a short polymethine chain is considered.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 257–262, May–June, 1988.     

Condensed heterocycles with a thiazole ring. 14 Nature of the electronic spectra of symmetrical polymethine dyes of the thiazolo[3,4-b][1,2,4]triazine series

Symmetrical mono-, tri-, and pentamethinecyanine dyes with a thiazolo[3,4-b][1,2,4]triazine ring were synthesized. The electron-density distributions in the dye molecules in the ground and first and second excited states were obtained by quantum-chemical calculations. It was established that the first two electron transitions are localized on the same atoms and that charge transfer to the triazine fragment of the molecule is realized in the case of excitation. The degree of participation of the heterocyclic ring in the first electron transition, which is responsible for the color of the dye, decreases with lengthening of the polymethine chain.See [1] for communication 13.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 24, No. 3, pp. 418–423, March, 1988.     

Dual Stereochemical Control in Reaction of Di- and Trialkyl Phosphites with Aldimines

Stereochemistry of addition of di- and trialkyl phosphites to C=N compounds was investigated. Reactions of achiral dialkyl phosphites with chiral aldimines as well as that of chiral di-(1R,2S,5R)-menthyl phosphite with achiral aldimines result in low diastereomeric enrichment of the addition compound. Reaction stereoselectivity increased when supplementary chiral inductor was introduced to the reaction system. Reaction of di-(1R,2S, 5R)-menthyl phosphite with (S)-α-methylbenzylbenzaldimine proceeds as concerted asymmetric induction to form practically one diastereomer of N-substituted aminophosphonic acid. However, reaction of di-(1R,2S, 5R)-menthyl phosphite with (R)-α-methylbenzylbenzaldimine proceeded as not concerted asymmetric induction, and diastereomeric enrichment of the product was low. By chemical extrapolation, absolute configuration of compounds formed was established. Tri-(1R,2S,5R)-menthyl phosphite reacts with C=N compounds in the presence of boron trifluoride etherate to form aminophosphonic acid derivatives with the absolute configuration opposite to that appearing in the reaction of di-(1R,2S,5R)-menthyl phosphite with the same C=N compounds.     

Synthesis,nature of electronic transitions,and absorption spectra of the dye based on 4-(methyl-1-{2-[4-(1-methyl-2-oxo-1,2-dihydroquinolin-3-yl)phenyl]-2-oxoethyl}pyridinium bromide

The reaction of 3-(4-bromoacetylphenyl)-1-methylquinolin-2(1Н)-one with pyridine and 4-methylpyridine has afforded the corresponding pyridinium salts. Condensation of 4-methyl-1-{2-[4-(1-methyl-2-oxo-1,2-dihydroquinolin-3-yl)phenyl]-2-oxoethyl}pyridinium bromide with 4-dimethylaminobenzaldehyde has given a new biscyanine dye, 1-{1-[4-(1,2-dihydro-1-methyl-2-oxo-3-quinolinyl)benzoyl]-2-[4-(dimethylamino)-phenyl]ethynyl}-4-{2-[4-(dimethylamino)phenyl]ethynyl}pyridinium bromide. Its electronic spectrum has been analyzed, and quantum-chemical simulation of spatial and electronic structure of its possible isomers has been performed.     

Mesoionic compounds with a bridged nitrogen atom. 5. π-electron structure of thiazolo[3,2-α]pyridinium 3-oxide derivatives

The -electron structure of thiazolopyridinium derivatives was analyzed thoroughly by the methods of quantum chemistry in order to ascertain the reason for the development of colors in the case of mesoionic compounds.See [1] for communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1618–1623, December, 1980.     

Fluorescence Properties of Thiacarbocyanine Dyes at Low Temperatures

Measurements were carried out for time-resolved fluorescence spectra of dye solutions containing thiacarbocyanine and its derivatives with ethylene and vinylene bridges in the polymethine chain. At low temperature, an additional band appears in the spectrum related to an intramolecular electronic transition. Analysis of the transition lifetimes and a quantum-chemical model indicated that this transition should be attributed to a short-lived asymmetrical component formed along with the symmetrical component upon relaxation of the excited state but not appearing at room temperature due to conformational transformations.     

Effective length of benzannellated terminal groups in polymethine dyes

The effect of benzannellation on the effective length of the terminal groups was studied by the method of asymptotic nonbonding MOs in the approximation of dyes with an extremely long polymethine chain. Both alternant and nonalternant conjugated hydrocarbon systems were examined. The variation of the effective length in relation to the number of added benzene rings was investigated. It was shown that the effect of annellation can be assessed by using the concept of equivalent terminal groups and the theory of perturbations in the asymptotic nonbonding MOs of polymethine dyes. Examples of the extension of the obtained relationships to heterocyclic terminal groups are given. The proposed approach makes it possible to interpret the cases where benzannelation is accompanied by a hypsochromic effect.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 26, No. 2, pp. 142–148, March–April, 1990.