The anion effect and molecular association of rhodamine dyes in isotropic and anisotropic solvents

✍ Scribed by R Sariri; M.S Zakerhamidi; K Baharpaima; A Ghanadzadeh

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 259 KB
• Volume: 115
• Category: Article
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2003.12.024

✦ Synopsis

The aggregation of rhodamine 6G tetrafluoroborate and rhodamine 6G chloride in liquid crystalline solution (anisotropic host) was studied using polarized spectroscopy (the electronic absorption spectroscopy with polarized light). The self-association of these two ionic dyes in the normal solvents (isotropic hosts) was studied using absorption spectroscopy in the visible region for comparison. Therefore, the influence of the wBF x anion on the molecular interaction of the guest molecules was investigated. y1 4 The dimerization constants, K sc yc , of solutions containing rhodamine 6G tetrafluoroborate and rhodamine 6G chloride in d d m dioxane were calculated to be 183 l mol and 2363 l mol , respectively, indicating the important role of anion-cation y1 y1

interaction in their solvation. In contrast, the similarities of absorption spectra of these two dyes in aqueous solutions suggest that the type of anion has a minor effect on their absorption spectra. The nature of the interacting pairs in these dyes was discussed using the exciton theory.