3,3,3',3'-Tetra-methyl-6,6'-bis-[(pyridin-4-yl)meth-oxy]-1,1'-spiro-biindane -monohydrate.

The asymmetric unit in the title compound, C(33)H(34)N(2)O(2)·H(2)O, consists of a V-shaped mol-ecule and a water mol-ecule to which it is hydrogen bonded. The angle between the mean planes of the two spiro-connected indane groups is 77.06 (5)°. The two five-membered rings of the indane groups have envelope conformations with the methyl-ene atoms adjacent to the spiro C atom forming the flaps. They have deviations from the mean plane of the other four atoms in the rings of 0.374 (4) and 0.362 (4) Å. In the crystal, molecules are linked to form inversion dimers via O-H⋯N hydrogen bonds involving the pyridine N atoms and the solvent water mol-ecule. The dimers are linked into a chain along the b axis by π-π stacking inter-actions between a pyridine ring and its centrosymmetrically related ring in an adjacent dimer. The centroid-centroid distance between the planes is 3.7756 (17) Å, the perpendicular distance is 3.4478 (11) Å and the offset is 1.539 Å.