Effects of chemical structure, solvent and solution pH on the visible spectra of some new methine cyanine dyes

Some new dimethine and bis-dimethine, cyanine dyes derived from benzo[2,3-b; 2`,3`-b`]bis-pyrazolo[4,5-b]-l,4-(oxa-, thia-, and pyra-)-zine-6,12-dione were synthesized. Effect of chemical structure on the electronic visible absorption spectra of all the synthesized cyanine dyes was investigated in 95% ethanol solution. Effects of solvent and/or solution pH on the electronic visible absorption spectra of some selected synthesized cyanine dyes were also examined in pure solvents having different polarities and/or in aqueous universal buffer solutions, respectively. Structural confirmations were carried out through elemental analysis, mass spectroscopy, IR and 1H NMR spectra