Synthesis of thiapenta- and thiahexacarbocyanine dyes from alkoxy-substituted polymethine salts with dimethylamine residues

The possibility of the use of alkoxypolymethine salts with dimethylamine residues to obtain thiapenta- and thiahexacarbocyanine dyes is demonstrated. The synthesis of a number of meso-alkoxythiapentacarbocyanines that contain various condensed rings in the 12 and 14 positions of the polymethine chain was realized, and their photographic properties were investigated. It was established that the dyes obtained are effective infrachromatic sensitizers. The electronic absorption spectra of the synthesized compounds were measured.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1631–1636, December, 1981.     

Synthesis of the first representative of dicarbothiacyanine dyes with completely fluorinated polymethine chain

2-Iodobenzothiazole was reacted with tributyl(pentafluorobutadienyl)tin in the Stille reaction conditions to give 2-pentafluorobutadienylbenzothiazole 1. The quaternary salt of 1 via interaction with 2-fluoromethylbenzothiazole methylene base, obtained in situ, forms two cyanine dyes 8 and 9 as a result of nucleophilic attack of two different positions of perfluorobutadiene chain. The pure 2-fluoromethylbenzothiazole methylene base (in a dimer form) was obtained by deprotonation of the corresponding salt by NaH and on reacting with 1 forms the dye base 11 that underwent electrocyclization and subsequent HF addition to form the cyclohexadiene 12 identified by X-ray analysis data. Upon quaternization and HF abstraction by toluidine the recyclization occurred and dye 8 - the first representative of dicarbothiacyanine dyes with perfluorinated polymethine chain - was obtained. It has λ_max = 691 nm, that is 41 nm more than in non fluorinated dye, vinylene shift is equal to 111 nm.     

Mass spectrometry of polymethine dyes

The mass spectra of some unsubstituted (in the heteroresidues and polymethine chain) thiacarbo- and polycarbocyanines were investigated. It was ascertained that the first act of disintegration of the dye molecules is splitting out of an alkyl halide ion to give an anhydro base ion. Some regularities between the structure of the dyes and the fragmentation of the anhydro ions obtained from them are exposed. The peculiarities of the dissociative ionization of the dye molecules as the polymethine chain is lengthened are shown.     

Photochemistry of anionic polymethine dyes

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.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 713–718, April, 1993.     

Reaction of polymethine dyes with hydroperoxides and free radicals

The interaction kinetics of the cationic and anionic polymethine dyes with radicals has been studied. Azoinitiator AAPH, as well as tert-butyl hydroperoxide, and hydrogen peroxide were used as radical initiators in water and buffer solutions at 37 °C. It is shown that the dyes are active scavengers of peroxyl radicals. It is found that reactivity and behavior of dyes in relation to the peroxides are strongly dependent on the structure of lateral substituents in polymethine chains.     

Cis-trans-isomerization of cationic-anionic polymethine dyes

The effect of solvent polarity and ion pair formation oncis-trans-isomerization of cationic-anionic polymethine dyes and of related simple cationic and anionic dyes is studied by flash photolysis. The change in the rate constant for reversecis-trans- isomerization of photoisomers due to the interaction of a cation with an anion in an ion pair is observed in nonpolar solvents. A drop in the yield of the photoisomers to zero is observed for a number of cationic-anionic dyes in weakly polar and nonpolar solvents which is possibly due to steric hindrances in the photoisomerization process in ion pairs.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 719–724, April, 1993.     

Fluorescent properties of cationic-anionic polymethine dyes

The fluorescence spectra were studied and the quantum yields of the fluorescence of a number of cationic-anionic polymethine dyes were measured in polar, low-polarity, and nonpolar solvents. It was shown that the fluorescence spectra of cationic-anionic dyes in polar solvents, like the absorption spectra, represent the sum of the fluorescence spectra of the corresponding cationic and anionic dyes. For dyes in which the absorption bands of the anion and cation are close and a new short-wave band arises in the ion pairs, excitation into this band virtually does not lead to fluorescence, which is a consequence of the forbidden nature of the long-wave transition that arises as a result of the interaction of the chromophores. For a number of cationic-anionic dyes in ion pairs an energy transfer is observed: When an ion possessing short-wave absorption is excited, an ion with long-wave absorption fluoresces.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2532–2539, November, 1992.     

Photoisomerization of sterically hindered polymethine dyes

Conclusions In sterically hindered polymethine dyes the photoisomerization process, with the formation of sterically hindered trans and di-cis forms, successfully competes with the nonradiative degradation of the energy on the higher vibrational sublevels of the ground state.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1926–1930, August, 1977.     

Fluorescent aggregates of cation-anionic polymethine dyes with simple structures

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.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 476–480, March, 1995.     

Synthesis of polymethine dyes from δ-alkoxy-β-phenylbutadienyl salts of heterocyclic bases

-Phenyl-substituted dicarbocyanine dyes or -phenyl-substituted hemicyanine dyes, respectively, are obtained in the condensation of ethoxy--phenylbutadienyl salts of heterocyclic bases (I) with quaternary salts of heterocyclic bases or amines. Depending on the reaction conditions, -phenyl--ethoxyallylidene derivatives of ketomethylene compounds or -phenyl-substituted tetramethylidynemerocyanine dyes are obtained in the condensation of I with ketomethylene compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 780–785, June, 1972.     

Synthesis of calixarene-based ketocyanine fluorophores

Cup-shaped calix[4]arenes bearing one or two ketocyanine fluorophore fragments at the wide rim of the macrocycle are synthesized by condensation of formyl calix[4]arenes with arylmethylene(hetarylmethylene)cyclopentanones in the presence of the ionic liquid, dimethylammonium dimethylcarbamate (DIMCARB) and characterized using UV-vis and fluorescence spectroscopy. Strong positive solvatofluorochromism for the calixarene ketocyanines is observed.     

Synthesis and absorption spectra of polymethine dyes — Derivatives of substituted thieno- and indolothiazoles

Cyanine, merocyanine, and styryl dyes that are derivatives of halo-, alkyl-, alkylene-, and arylthieno[2,3-d]thiazoles and halo- and alkylindolo[3,2-d]thiazoles were synthesized. It is shown that both electron-donor and electron-acceptor substituents in the 5 and 5 positions of the heteroresidues of thienothiazolocarbocyanines lead to a more uniform distribution of the electron density in their chromophore than in the unsubstituted dye and to a bathochromic shift of the absorption maximum. Methyl groups in the heteroresidues of indolothiazolocarbocyanines give rise to a small bathochromic effect.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1278–1283, September, 1988.     

Study of fluorescent aggregates of polymethine dyes

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.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 69–75, January, 1993.