organic compounds
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The title compound, C35H36N4O4, was prepared as a spirolactam ring formation of rhodamine B dye for comparison with a ring-opened form. The xanthene ring system is approximately planar. The r.m.s. deviation from planarity is 0.064 (6) Å for the xanthene ring. The dihedral angles formed by the spirolactam and 2,4-dihydroxybenzene rings with the xanthene ring system are 86.6 (9) and 88.0 (9)°, respectively.