3-{[Bis(pyridin-2-ylmethyl)amino]methyl}-2-hydroxy-5-methylbenzaldehyde

In the title compound, C21H21N3O2, the pyridine rings and the benzene ring lie in a propeller arrangement around the central tertiary amine N atom. The dihedral angles formed by the benzene ring with the pyridine rings are 61.0 (3) and 49.6 (3)°, while the dihedral angle between the pyridine rings is 69.7 (3)°. The molecular conformation is stabilized by intramolecular bifurcated O—H⋯N hydrogen bonds. In the crystal, inversion dimers are formed via pairs of C—H⋯N hydrogen bonds.

In the title compound, C 21 H 21 N 3 O 2 , the pyridine rings and the benzene ring lie in a propeller arrangement around the central tertiary amine N atom. The dihedral angles formed by the benzene ring with the pyridine rings are 61.0 (3) and 49.6 (3) , while the dihedral angle between the pyridine rings is 69.7 (3) . The molecular conformation is stabilized by intramolecular bifurcated O-HÁ Á ÁN hydrogen bonds. In the crystal, inversion dimers are formed via pairs of C-HÁ Á ÁN hydrogen bonds.

Experimental
The title compound was synthesized following the method reported by Lambert et al. (1997) and Koval et al. (2003).
Diffraction quality crystals were obtained by slow evaporation of an acetone solution.

Refinement
The hydroxy H atom was located in a difference Fourier map and refined freely. All other H atoms were positioned geometrically and allowed to ride on their parent atoms with C-H = 0.93-0.97 Å, and with U iso (H) = 1.2 U eq (C) or 1.5 U eq (C) for methyl H atoms.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.