7-Diethylamino-3-{(E)-4-[(E)-2-(pyridin-4-yl)ethenyl]styryl}-2H-chromen-2-one

In the title coumarin derivative, C28H26N2O2, the coumarin unit is approximately planar, with a maximum deviation of 0.048 (3) Å. The central benzene ring is oriented at dihedral angles of 30.15 (14) and 10.51 (11)°, respectively, to the pyridine ring and coumarin ring system. In the crystal, weak C—H⋯O and C—H⋯N hydrogen bonds and weak C—H⋯π interactions link the molecules into a three-dimensional supramolecular architecture.

In the title coumarin derivative, C 28 H 26 N 2 O 2 , the coumarin unit is approximately planar, with a maximum deviation of 0.048 (3) Å . The central benzene ring is oriented at dihedral angles of 30.15 (14) and 10.51 (11) , respectively, to the pyridine ring and coumarin ring system. In the crystal, weak C-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds and weak C-HÁ Á Á interactions link the molecules into a three-dimensional supramolecular architecture.

Comment
The coumarin derivatives are widely used fluorescence dye with favorable optical properties including high fluorescence quantum yield, superior photostability, and extended spectral range. These outstanding optical properties allow them to be potentially utilized in a wide range of areas such as ion sensing (Gong et al., 2012), laser dyes (Jones et al., 1985), nonlinear optical chromophores (Nemkovich et al., 1997), fluorescent labeling of biomaterials (Jin et al., 2011), and so on. In addition, previous studies have demonstrated that the optical properties of the coumarin dye could be improved by introducing conjugated group at the 3 position of the coumarin ring (Helal et al., 2011). These promoted us to develop large conjugated coumarin derevatives. Herein, the synthesis and crystal structure of title molecule are presented.
The analysis of title molecule shows that it crystallizes in the monoclinic space group P 21/n with four molecules in the unit cell. In the molecule, the C17-O1 bonds, C6-C7 bonds and C14-C15 bonds show typical double-bond character ( Figure 1, Table 1). The length of the C6-C7 bonds [1.333 (4) Å] compares favorably to that of the analogous C14-  Table 1). The intermolecular hydrogen-bonding scheme features a bifurcated interaction to atom O1 and an R 2 2 (7) and R 2 2 (12) graph sets, as shown in Figure 3. The intermolecular hydrogen-bonding scheme features an interaction to atom N1, as shown in Figure 4. The crystal packing diagram are the fundamental linking units in the formation of a supramolecular structure with intermolecular C-H···O and C-H···N hydrogen-bonds, as shown in Figure 5.

Synthesis and crystallization
1N sodium hydroxide solution (1ml) was added dropwise to a solution of 7-diethylaminocoumarin-3-carbaldehyde (0.391g, 1.596mmol) and (1,4-phenylenebis(methylene))bis(triphenylphosphonium) chloride (1g, 1.596mmol) in dichloromethane (20ml). The reaction mixture was stirred overnight at room temperature. After removal of the solvent under reduced pressure, the resulting mixture was purified by column chromatography on silica gel (dichloromethane: petroleum ether = 3: 7, v/v) to afford a yellow solid. Then, 1N sodium hydroxide solution (1ml) was added dropwise to the resulting yellow solid (0.5g, 0.84mmol) and isonicotinaldehyde (0.09g, 0.84mmol) in dichloromethane (20ml). The solution was stirred for 8 hours at room temperature. After removal of the solvent under reduced pressure, the crude product was purified by column chromatography on silica gel (dichloromethane: petroleum ether = 2: 3, v/v) to afford the title compound as red solid (184mg, yield 52%). Mp 265-266 o C. The crystal appropriate for X-ray data collection was obtained from methanol-dichloromethane solution at room temperature after about a week.

Refinement
H atoms were positioned geometrically and refined with riding model, with U iso = 1.2U eq or 1.5U eq for all H atoms. The C -H bond are 0.93 (pyridyl, aromatic), 0.96 (methyl), or 0.97Å (methylene).

Figure 1
The structure of title molecule, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
The dihedral angles (°) between adjacent planes. The pink, yellow, and blue planes represent pyridine ring, the benzene ring, and the coumarin ring.    The crystal packing of title molecule, viewed along the b axis. C-H···O and C-H···N hydrogen bonds are shown as dashed lines (see Table 1 for details).

7-Diethylamino-3-{(E)-4-[(E)-2-(pyridin-4-yl)ethenyl]styryl}-2H-chromen-2-one
Crystal data 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq N1