Novel Polyheterocyclic Cyanine Dyes: Synthesis, Photosensitiztion and Solvent/Electronic Transitions Correlation

Abstract

Novel polyheterocyclic cyanine dyes covering aza-cyanine dyes and bis aza-cyanine dyes derived from 3,8-diethyl-2,7-diphenyl benzo [2,3-b;quaternary salt were prepared. The electronic visible absorption spectra for all the synthesized cyanines were investigated in 95 % ethanol solution to evaluate their photosensitization/electronic transitions correlation. The cyanine dyes were thought to be better photosensitizers when they absorb the visible light to initiate the electronic transitions at higher wavelength bands (bathochromic shifted and/or red shifted dyes). Consequently, the photosensitization of the cyanine dyes decreases when they absorb the visible light to initiate the electronic transitions at lower wavelength bands (hypsochromic shifted and/or blue shifted dyes). Solvent/electronic transitions correlation study for some selected cyanine dyes were carried out 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 their solute/solvent interaction properties (general and/or specific solvent effects). Structural identification were confirmed using elemental analysis, visible spectra, IR and 1 H NMR spectral data.Keywords: cyanine dyes, aza-cyanine dyes, synthesis, photosensitization/electronic transitions correlation, visible spectra, solvent / electronic transitions correlation. IntroductionCyanine dyes Shindy, 2016;Shindy, 2018;Shindy et al., 2017a;Solomon et al., 2014;Lynch et al., 2013;Shindy et al., 2012;Arjona et al., 2016;Shindy et al., 2015;Shindy, 2015;Shindy, Koraiem, 2008) have a wide range and various applications in different fields of science and technology. Their uses and applications include but not limited to spectral sensitizers for silver halide emulsions in photographic material industry for coloured and non coloured (black and white) films (cyanine dyes were originally used, and still are, to increase the sensitivity range of photographic emulsions, i. e. to increase the range of wavelengths which will form an image on the film) (Msaki,