2-[(3,3-Di­methyl­indolin-2-yl­idene)meth­yl]-4-[(3,3-dimethyl-3H-indol-1-ium-2-yl)methyl­idene]-3-oxo­cyclo­but-1-en-1-olate chloro­form disolvate

In the title squaraine dye solvate, C₂₆H₂₄N₂O₂·2CHCl₃, the dye mol­ecule is essentially planar, except for the methyl groups, having a maximum deviation over the 26-membered delocalized bond system of 0.060 (2) Å. It possesses crystallographic twofold rotational symmetry with the indole ring systems adopting a syn conformation. The mol­ecular structure features intra­molecular N—H...O hydrogen bonds enclosing conjoint S7 ring motifs about one of the dioxo­cyclo­butene O atoms, while the two chloro­form solvent mol­ecules are linked to the second O atom through C—H...O hydrogen bonds.