Photochemistry of ketocyanin dye ? polyenic bis-?,??-amino ketones substituted in the polyene chain
摘要:
The photochemistry of ketocyanin dyes, 15 polyenic bis-omega,omega'-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 PBK, 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.
Photochemistry of ketocyanin dye ? polyenic bis-?,??-amino ketones substituted in the polyene chain
摘要:
The photochemistry of ketocyanin dyes, 15 polyenic bis-omega,omega'-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 PBK, 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.
Synthesis of dyes containing fluorine atoms in the polymethine chain
作者:Zh. A. Krasnaya、T. S. Stytsenko、V. S. Bogdanov、N. V. Monich、M. M. Kul'chitskii、S. V. Pazenok、L. M. Yagupol'skii
DOI:10.1007/bf00958049
日期:1989.3
Photochemistry of ketocyanin dye ? polyenic bis-?,??-amino ketones substituted in the polyene chain
作者:L. A. Shvedova、A. S. Tatikolov、Zh. A. Krasnaya、V. A. Kuz'min
DOI:10.1007/bf00957840
日期:1990.7
The photochemistry of ketocyanin dyes, 15 polyenic bis-omega,omega'-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 PBK, 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.