Synthesis, absorption spectra studies, solvatochromism and halochromism of polymethine cyanine dyes

New polymethine cyanine dyes, including tetramethine and bis‐tetramethine cyanine dyes derived from benzo[2,3‐b;2′,3′‐b′]bis‐pyrazolo[4,5‐b]‐1,4‐(oxa‐, thia‐ and pyra‐)‐zine‐6,12‐dione, were synthesised. Absorption spectra for all the synthesised cyanine dyes were examined in 95% ethanol. The solvatochromism and halochromism for some selected dyes were investigated in pure solvents and in aqueous universal buffer solutions, respectively. Structural confirmations were carried out through elemental and spectroscopic analysis.