Structure and solvent effects on the electronic transitions of some novel furo / pyrazole cyanine dyes

Abstract

Novel furo / pyrazole methine cyanine dyes covering dimethine and bis dimethine cyanine dyes derived from quinone polyheterocyclic ring system were prepared. The electronic visible absorption behavior for all the synthesized cyanine dyes were investigated in 95% ethanol solution to evaluate their structure effects on the visible electronic transitions. The dyes were thought to be better electronic transitions when they absorb light at higher wavelength bands (bathochromic shifted and/or red shifted dyes). Consequently, the electronic transitions of the dyes decreases when they absorb light at lower wavelength bands (hypsochromic shifted and/or blue shifted dyes). Solvent effects for some selected synthesized cyanine dyes were examined in pure solvents having different polarities [Water (78.54), Dimethylformamide (36.70), Ethanol (24.3), Chloroform (4.806), Benzene (2.28) and Dioxane (2.209)] to evaluate solvent effects on their visible electronic transitions (general and/or specific solvent effects). Structural identification were confirmed via elemental analysis, visible spectra, IR and 1H NMR spectral data.