3′,6′-Bis(ethyl­amino)-2′,7′-dimethyl-2-{2-(E)-[(thio­phen-2-yl)methyl­idene­amino]­eth­yl}spiro­[isoindoline-1,9′-xanthen]-3-one methanol monosolvate

The title compound, C₃₃H₃₄N₄O₂S·CH₃OH, was prepared as a spiro­lactam ring formation of rhodamine 6 G dye for comparison with a ring-opened form. The xanthene and spiro­lactam rings are approximately planar [r.m.s. deviations from planarity = 0.122 (3) and 0.072 (6) Å, respectively]. The dihedral angles formed by the spiro­lactam and thio­phene rings with the xanthene ring system are 89.7 (6) and 86.5 (2)°, respectively. The crystal structure features N—H...O and C—H...O hydrogen bonds.