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  • 1
    Electronic Resource
    Electronic Resource
    Photochemistry of anionic polymethine dyes (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 677-682 
    Details
    ISSN: 1573-9171
    Keywords: polymethine dyes ; cis-trans isomerization ; ion pairs ; triplet state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Spectral and kinetic properties of photoisomers and triplet molecules of a number of anionic polymethine dyes, namely, differential absorption spectra, rate constants (k i ) and activation parameters of reversecis-trans-isomerization, and triplet-state-decay rate constantsk T are studied by flash photolysis. CINDP/2 calculations of electron density in anionic dyes show thatk i andk T in polar solvents are determined primarily by the electronic effect of the substituents in themeso-position of the polymethine chain of a dye. The increase ink i due to the formation of ion pairs consisting of a dye with a counterion is observed in nonpolar solvents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00704001
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  • 2
    Electronic Resource
    Electronic Resource
    Study of fluorescent aggregates of polymethine dyes (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 60-66 
    Details
    ISSN: 1573-9171
    Keywords: fluorescence spectra ; polymethine dyes ; aggregates ; ion pairs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Absorption, fluorescence, and fluorescence excitation spectra have been studied for a number of anionic, cationic, and cationic-anionic polymethine dyes in low-polar and nonpolar solvents, as well as in binary mixtures of solvents differing in polarity. For most of the dyes studied, fluorescent aggregates have been found to form. Their broad fluorescence bands are located in the long-wave region with respect to those of the initial dyes. The quantum yield of the aggregate fluorescence is normally higher than that of the initial dyes. Fluorescence excitation spectra of some cationic-anionic dyes in nonpolar solvents disagree with their absorption spectra because of contact and solvent-separated ion pairs simultaneously present in the solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699975
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  • 3
    Electronic Resource
    Electronic Resource
    Stereochemical dependence of chemical shifts of13C carbonyl carbon atoms in conjugated ω-amino-, alkoxy-, alkyl-, dialkyl-, phenyl-α-carbonyl-, and α,α′-dicarbonyl-containing compounds (1990)
    Springer
    Russian chemical bulletin 39 (1990), S. 1172-1180 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Stereospecificity has been shown for the13C chemical shift (CS) of carbonyl carbon atoms for monoene, diene, and triene ketoesters; monoene, diene, and triene linear diketones; diene and triene cyclohexadiketones; linear diene and triene diesters, pyrazolones and imides: δCO (trans) 〉 δCO (cis). The influence of structural factors on the13C CS is examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00962379
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  • 4
    Electronic Resource
    Electronic Resource
    Reaction of aminals of conjugated unsaturated ω-dimethylaminoaldehydes with 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-diketones (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1179-1185 
    Details
    ISSN: 1573-9171
    Keywords: aminals of conjugated ω-dimethylaminoaldehydes ; diketones ; α,α′-bis(ω-dimethylaminopolyenyl)ketones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The condensation of aminals of β-dimethylaminoacrolein and 5-dimethylaminopenta-2,4-dienal with cyclic and acyclic 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-diketones was studied. A series of previously unknown bis(ω,ω′-dimethylaminopolyenyl)diketones was synthesized; their structures were established by means of1H and13C NMR spectroscopies. The electron absorption spectra were employed to study the mutual influence of ω-aminopolyene chromophores separated by two C=O groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702001
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  • 5
    Electronic Resource
    Electronic Resource
    Interaction of aminals of conjugated ω-dimethylaminoaldehydes with cyclic β-dicarbonyl compounds (1994)
    Springer
    Russian chemical bulletin 43 (1994), S. 264-268 
    Details
    ISSN: 1573-9171
    Keywords: aminals of conjugated ω-dimethylaminoaldehydes ; cyclic β-dicarbonyl compounds ; δ-dimethylaminodienones ; 2H-pyrans ; oxanine salts ; cation-anionic polymethine dyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reactions of aminals of conjugated ω-dimethylaminoaldehydes with Meldrum's acid,N,N′-(o-phenylene)malonamides, and 2,3-dihydrophenalene-1,3-dione afford δ-dimethylaminodienones, substituted 2-dimethylamino-2H-pyrans, or oxanine salts. Cation-anionic polymethine dyes have been obtained from the latter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00695825
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  • 6
    Electronic Resource
    Electronic Resource
    Fluorescent aggregates of cation-anionic polymethine dyes with simple structures (1995)
    Springer
    Russian chemical bulletin 44 (1995), S. 460-464 
    Details
    ISSN: 1573-9171
    Keywords: fluorescence and absorption spectra ; cation-anionic polymethine dyes ; aggregates ; ion pairs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The absorption, fluorescence, and excitation spectra of two cation-anionic dyes with simple structures, which have the identical anions and variable cations, were studied in weakly polar and nonpolar solvents as well as in binary mixtures of solvents with different polarity. Under these conditions heterogeneous fluorescent aggregates were found at 20 °C. The structure of the cation has a significant influence on the formation and properties of the aggregates of cation-anionic polymethine dyes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702387
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  • 7
    Electronic Resource
    Electronic Resource
    Reactions of aminals of conjugated ω-dimethylaminoaldehydes with coumarin derivatives (1995)
    Springer
    Russian chemical bulletin 44 (1995), S. 520-526 
    Details
    ISSN: 1573-9171
    Keywords: aminals of conjugated ω-dimethylamioaldehydes ; coumarins ; ω-dimethylaminopolyenones ; trimethine salts ; absorption spectra ; fluorescence spectra ; laser dyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reactions of aminals of conjugated ω-dimethylaminoaldehydes with various derivatives of 4-methyl- or 3-acetyl coumarins produce ω-dimethylaminopolyenones containing coumarin fragments. Unlike the starting coumarins, these polyenones practically do not fluoresce. Dialkyl-substituted coumarins with hydroxyl groups in positions 5 or 7 react with β-dimethylaminoacrolein aminal to give salts consisting of 1 mole of doubly charged dimethylaminopropenylidenedimethylammonium cations and 2 moles of phenoxide ions (derived from the starting coumarins). The structure and the properties of the salts in solutions have been studied by absorption and fluorescence spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702402
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  • 8
    Electronic Resource
    Electronic Resource
    A novel route of pyrrole ring formation (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 745-746 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435828
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of dyes containing fluorine atoms in the polymethine chain (1989)
    Springer
    Russian chemical bulletin 38 (1989), S. 562-571 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. The condensation of α-fluoro-β-dimethylaminoacrolein aminal with ketones, β-dicarbonyl compounds, and CH-acids was investigated. 2. The synthesized dimethylamino-γ-fluorodienones (merocyanins) exist in the open form and are not cyclized to 2H-pyrans. 3. γ-Fluoro and γ,γ′-difluoroketocyanins were synthesized; their alkylation afforded alkoxynonamethine salts. Fluorine-containing thiapentacarbocyanin dyes were obtained from the latter compounds. 4. Dimethylammonium salts of tetracyano-γ-fluoropentadiene andγ-fluorotrimethinoxanine were synthesized. These compounds were used as the anionic components in obtaining cation-anion cyanin dyes. 5. The effect of the fluorine atom on the color of the synthesized dyes was investigated. It was shown that a fluorine atom in the polymethine chain behaves like an electron donor substituent. However, in sterically hindered merocyanins it elicits a hypsochromic shift of the absorption band even at even positions of the polymethine chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00958049
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  • 10
    Electronic Resource
    Electronic Resource
    Photochemistry of ketocyanin dye — polyenic bis-ω,ω′-amino ketones substituted in the polyene chain (1990)
    Springer
    Russian chemical bulletin 39 (1990), S. 1369-1375 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The photochemistry of ketocyanin dyes, 15 polyenic bis-ω,ω′-amino ketones (PBAK), was studied by the methods of pulsed and laser photolysis. During the photoexcitation of the PBAK solutions, the formation of their cis-photoisomers is observed, whose relaxation kinetics into the initial trans-isomers is dependent on the intensity of the probing light. The energy of activation of the cis → trans-isomerization process in the dark increases with decrease in the polarity of the solvent. During the photoexcitation of fluorine-substituted PBAK with a six-membered central ring, their cyclization takes place with the formation of pyran forms (PF) absorbing in the UV region; the PF then convert into the initial dye. The formation of PF partially proceeds via the intermediate formation of a cis-isomer of the dye. During the photoexcitation of deoxygenated solutions of PBAK, the formation of their triplet states is also observed; the decay kinetics of the triplet states becomes accelerated with decrease in the solvating power of the solvent. This is explained by the decrease in the T-S0 splitting due to increase in the energy barrier of the cis-trans isomerization process. A scheme has been proposed for the potential surfaces of PBAK to explain this phenomenon. For some PBAK, the formation is observed of cis-photoisomers not only from the S1 but also from the T-state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00957840
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