Synthesis and properties of near-infrared absorbing asymmetric pyrylium¯squarylium dyes containing tertiary butyl groups

The absorption wavelengths and oscillator strengths of a series of organic dyes important for the dye industry (indigo, azobenzene, phenylamine, hydrazone, anthraquinone, naphthoquinone and cationic dyes) were calculated using time-dependent density-functional theory. The results were compared with experimental data. TD-DFT correctly reproduced the visible absorption of the dyes.