Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10266428 | Dyes and Pigments | 2005 | 6 Pages |
Abstract
Visible absorption and fluorescence spectra of seven thiacarbocyanine dyes with varying substituents at 5,5â²- and meso-positions have been studied suggesting J-aggregate formation in aqueous solutions. The molar extinction coefficients of monomers and dimers (ÉM and ÉD), the dimer association constant (KD) and the dimerization enthalpy (ÎHD) were determined studying dye concentration and temperature dependencies of absorption spectra. In 0.01Â mol/dm3 KCl aqueous solutions, J-aggregates were observed due to the association of dimers at a critical dye concentration, which correlated with the KD value. In addition, the aggregation number, the molar extinction coefficient of the J-aggregate (ÉJ) and the J-aggregate association constant (KJ) were quantitatively estimated from a modified Harris-Hobbs equation. The J-aggregates were found to be oligomers composed of 20-80 monomers. KD and ÎHD suggested that substituents at the 5,5â²-position influenced dimer formation and played an important role in aggregates formation.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Engineering (General)
Authors
Daisuke Takahashi, Hayato Oda, Tsuyoshi Izumi, Ryo Hirohashi,