Abstract
Synthesis and spectral properties of cyanine dyes 1 and 2, having julolidinylethenyl and α-methyl julolidinylethenyl moieties respectively at the meso position, are described. In comparison with planer 1, the methyl group of the julolidinylethenyl group in 2 prevents the coplanarity of the whole dye system. Their characteristic electronic absorption spectra are analyzed based on the molecular orbital calculations, and the calculations well reproduce the observed data. Analysis of 1H NMR spectrum of 1 indicates that the π-electrons in the julolidinylethenyl group shift toward the cyanine main chromophore through the π-conjugation. Intramolecular charge transfer from the julolidine moiety to the cyanine main chromophore contributes to lightfastness of dyes. These findings make it possible to design a new type of stable cyanine dyes against photoirradiation with new functionalities such as intramolecular charge transfer system.
Original language | English |
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Pages (from-to) | 113-120 |
Number of pages | 8 |
Journal | Dyes and Pigments |
Volume | 54 |
Issue number | 2 |
DOIs | |
Publication status | Published - Aug 2002 |
Keywords
- Electron donor
- Intramolecular charge-transfer
- Julolidinylethenyl group
- Meso-substituted cyanine
- New functional dye
- Trimethine cyanine
ASJC Scopus subject areas
- Chemical Engineering(all)
- Process Chemistry and Technology