4-Methyl-7-(salicylideneamino)coumarin

The title compound, C17H13NO3, consists of a methyl-substituted coumarin group fused to a 2-hydroxy­phenyl ring via an azomethine linkage. The coumarin and benzene ring planes form a dihedral angle of 24.0 (1)°. Intra­molecular O—H⋯N hydrogen bonding is present and the crystal structure includes inter­molecular C—H⋯O inter­actions.

The title compound, C 17 H 13 NO 3 , consists of a methylsubstituted coumarin group fused to a 2-hydroxyphenyl ring via an azomethine linkage. The coumarin and benzene ring planes form a dihedral angle of 24.0 (1) . Intramolecular O-HÁ Á ÁN hydrogen bonding is present and the crystal structure includes intermolecular C-HÁ Á ÁO interactions.

Comment
Coumarin derivatives are used as fluorescent dyes for synthetic fibres and daylight fluorescent pigments. The absorption spectrum of the title compound, (I), is comparable to that of azomethine dyes such as 6-substituted derivatives of 2Hchromen-2-one (Kachkovski et al., 2004). We report here the crystal structure of (I) (Fig. 1).
Planar molecules of Schiff bases are usually stabilized by intermolecularinteractions (Wozniak et al. 2000). However, (I) is not planar [the dihedral angle between the coumarin and benzene ring planes is 24.0 (1) ], indicating an The molecular structure of (I), showing displacement ellipsoids at the 50% probability level for non-H atoms.
absence ofcoupling. Compound (I) shows no photochromic effect in the solid state at ambient temperature, which is attributed to the presence of an intramolecular O-HÁ Á ÁN hydrogen bond. Such an interaction is considered to be vital for determining lightfastness properties (that is, retention of colour strength over time under exposure to sunlight) by providing electronic protection of the chromophore towards photochemical degradation (Chang et al., 2003).

Experimental
Salicylaldehyde (1.22 ml, 10 mmol) dissolved in 15 ml absolute ethanol was added to a warm stirred solution of 7-amino-4-methylcoumarin (1.75 g, 10 mmol) in absolute ethanol (15 ml), and the mixture was refluxed for 1 h. The resulting yellow-orange precipitate was removed, washed with ethanol followed by diethyl ether and then dried in vacuo. Suitable single crystals were grown by slow evaporation from either chloroform/methanol (1:1) or 10-15 ml ethanol (yield 85%, m.

Refinement
Refinement on F 2 R[F 2 > 2(F 2 )] = 0.037 wR(F 2 ) = 0.099 S = 1.02 2600 reflections 195 parameters H atoms treated by a mixture of independent and constrained refinement H atoms bound to C atoms were placed in calculated positions and allowed to ride during subsequent refinement, with C-H = 0.95 Å and U iso (H) = 1.2U eq (C) for Csp 2 , and C-H = 0.98 Å and U iso (H) = 1.5U eq (C) for the methyl group. The methyl group was allowed to rotate about its local threefold axis. Atom H1 of the hydroxyl group was located in a Fourier map and refined freely with an isotropic displacement parameter; the refined O-H distance is 0.92 (2) Å .