(E)-2,6-Di-bromo-4-{2-[1-(1H,1H,2H,2H-perfluoro-oct-yl)pyridinium-4-yl]ethen-yl}phenolate methanol disolvate, a fluoro-ponytailed solvatochromic dye.

The title compound, C21H12Br2F13NO·2CH3OH, was obtained by condensation of 4-methyl-1-(1H,1H,2H,2H-perfluoro-oct-yl)pyridinium iodide and 3,5-di-bromo-4-hy-droxy-benzaldehyde, followed by deprotonation. It crystallizes as a methanol disolvate and exhibits short O-H⋯O hydrogen bonds and a disordered perfluoro-alkyl chain [occupancy ratio 0.538 (7):0.462 (7)]. Significant π-π stacking inter-actions are observed between the benzene and pyridine rings of neighbouring mol-ecules along the b-axis direction.