3-(Benzoxazol-2-yl)-7-hydroxy­chromen-2-one methanol solvate

The title compound, C₁₆H₉NO₄·CH₄O, is a coumarin deriv­ative suitable for use as a laser dye. The coumarin and the benzoxazole ring systems in the mol­ecule are planar. The angle between them is 8.03 (7)°. The crystal packing is characterized by hydrogen bonds that form dimers which are, in turn, linked by C—H...O intermolecular interactions in the [100] direction.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.048
• wR factor = 0.121
• Data-to-parameter ratio = 9.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Coumarins are compounds extensively studied due to their practical applications (Krasovitskii, 1988; Dall'Acqua et al., 1996). Biological and chemical sensors, fluorescent probes, laser dyes, are some of their applications (Christie, 1999; Chandrasekharan & Kelly, 2002). Additionally, coumarins that contains an electron-releasing group in the 7-position, and a heterocyclic electron–acceptor residue in the 3-position, are recognized as fluorescent dyes suitable for application to synthetic fibers (Sokodowska et al., 2001).

The compound 3-benzoxazol-2-yl-7-hydroxy-chromen-2-one, (I), due to a dissociation equilibrium based on the hydroxyl group, results in a neutral and anionic form in protic solvents. This coumarin is suitable for use as a laser dye since it shows high fluorescence quantum yields in solvents of different polarities (Machado & Miranda, 2001). Even at low temperature (77 K), phosphorescence was not detected. Meanwhile, a quantum yield of 0.06 for singlet-oxygen generation was measured for the neutral species in chloroform, indicating the possibility of intersystem crossing to a low extent (Machado & Miranda, 2001).

The X-ray analysis of (I) was undertaken as part of a study to elucidate the relationships between the characteristics of functional dyes containing the coumarin skeleton and their molecular structures.

An ORTEP-3 (Farrugia, 1997) drawing of the asymmetric unit, which is composed of one coumarin molecule and one methanol molecule of crystallization, is shown in Fig. 1. Selected geometric parameters are presented in Table 1.

The angle between the benzoxazole and coumarin moieties is 8.03 (7)°, showing more deviation from planarity than another analogue in which the angle is 5.24 (8)° (Guilardi et al., 2002). Atom O4 deviates by 0.12 Å from the coumarin plane, probably because of the hydrogen bonding.

The bond length C3—C11 is in good agreement, within experimental error, with those observed in 3-(benzoxazol-2-yl)cromen-2-one (Guilardi et al., 2002) and 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (Jasinski & Paight, 1995).

The bond C3—C4 has double-bond character. The bonds C2—C3 and C4—C10, adjacent to double bonds, are systematically longer than 1.40 Å. The bond angles C8—C9—O1 and C5—C10—C4 at the junction of the two rings are, respectively, smaller and greater than 120°. Similar behavior is observed for an unsubstituted coumarin (Gavuzzo et al., 1974), a coumarin-3-carboxylic acid (Dobson & Gerkin, 1996) and a 3-(bromoacetyl)coumarin (Vasudevan et al., 1991).

In comparison with coumarins have no substituent at the 7-position (Gavuzzo et al., 1974; Guilardi et al., 2002), the title compound shows an increase in the bond lengths C6—C7 and C7—C8, and a decrease in the C6—C7—C8 bond angle of ~2° that may be due to the presence of the hydroxyl group at the 7-position. Other hidroxycoumarins, such as 7-hydroxycoumarin (Ueno, 1985), 7-hydroxyphenylcoumarin (Honda et al., 1995) and 7-hydroxy-4-methycoumarin monohydrate (Jasinski and Woudenberg, 1994), exhibit similar behavior.

The methanol O atom is involved in three hydrogen bonds. It is a donor in a two-centered bond to N and O2 and an acceptor from O4 such that dimmers are formed around an inversion center, involving two methanol molecules and two molecules of compound (I) (Table 2 and Fig. 2). The dimers are linked by C—H···O intermolecular interactions in the [100] direction (Fig. 3).

S2. Experimental

The title compound was prepared, purified and crystallized according to Luan et al. (2002).

S3. Refinement

H atoms were located in a difference Fourier synthesis.

Computing details

Data collection: COLLECT (Nonius, 1997-2000); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. An ORTEP-3 view (Farrugia, 1997) of the asymmetric unit, showing ellipsoids at the 50% probability level.
	Fig. 2. A Mercury view (Cambridge Crystallographic Data Centre, 2003) of the hydrogen bonds between the dimers.
	Fig. 3. A Mercury view (Cambridge Crystallographic Data Centre, 2003) of the C—H···O intermolecular interaction in the [100] direction.

(I)

Crystal data

C16H9NO4·CH4O	Z = 2
Mr = 311.28	F(000) = 324
Triclinic, P1	Dx = 1.492 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.5606 (3) Å	Cell parameters from 11153 reflections
b = 7.3493 (3) Å	θ = 2.9–27.5°
c = 15.3575 (7) Å	µ = 0.11 mm^−1
α = 79.724 (2)°	T = 120 K
β = 78.980 (2)°	Prism, yellow
γ = 74.194 (5)°	0.23 × 0.14 × 0.03 mm
V = 693.1 (2) Å^3

Data collection

KappaCCD diffractometer	Rint = 0.079
CCD scans	θmax = 25°, θmin = 2.9°
11153 measured reflections	h = −7→7
2424 independent reflections	k = −8→8
1844 reflections with I > 2σ(I)	l = 0→18

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.048	w = 1/[σ^2(Fo^2) + (0.0613P)^2 + 0.2086P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.121	(Δ/σ)max < 0.001
S = 1.05	Δρmax = 0.24 e Å^−3
2424 reflections	Δρmin = −0.22 e Å^−3
260 parameters

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N	0.3576 (3)	−0.0198 (3)	0.75094 (11)	0.0299 (4)
O1	0.2209 (2)	0.2953 (2)	0.48874 (9)	0.0278 (4)
O2	0.0845 (2)	0.1527 (2)	0.61679 (10)	0.0328 (4)
O3	0.7058 (2)	−0.0320 (2)	0.69629 (9)	0.0279 (4)
O4	0.4674 (2)	0.6395 (2)	0.21454 (10)	0.0341 (4)
C2	0.2460 (3)	0.1877 (3)	0.57174 (13)	0.0263 (5)
C3	0.4613 (3)	0.1303 (3)	0.59488 (13)	0.0247 (5)
C4	0.6279 (3)	0.1790 (3)	0.53600 (14)	0.0254 (5)
C5	0.7595 (3)	0.3476 (3)	0.38811 (14)	0.0288 (5)
C6	0.7156 (3)	0.4614 (3)	0.30993 (14)	0.0297 (5)
C7	0.5029 (3)	0.5210 (3)	0.29148 (13)	0.0283 (5)
C8	0.3381 (3)	0.4632 (3)	0.35152 (14)	0.0269 (5)
C9	0.3879 (3)	0.3484 (3)	0.43013 (13)	0.0253 (5)
C10	0.5963 (3)	0.2887 (3)	0.45139 (13)	0.0243 (5)
C11	0.4949 (3)	0.0245 (3)	0.68294 (14)	0.0267 (5)
C12	0.4848 (3)	−0.1131 (3)	0.81762 (14)	0.0303 (5)
C13	0.4305 (4)	−0.1906 (3)	0.90577 (15)	0.0385 (6)
C14	0.5948 (4)	−0.2672 (3)	0.95668 (16)	0.0397 (6)
C15	0.8072 (4)	−0.2684 (3)	0.92029 (15)	0.0367 (6)
C16	0.8651 (4)	−0.1945 (3)	0.83229 (15)	0.0318 (5)
C17	0.6967 (3)	−0.1183 (3)	0.78402 (14)	0.0280 (5)
C	−0.0072 (4)	0.2311 (4)	0.88318 (16)	0.0437 (6)
O	−0.0556 (3)	0.2482 (2)	0.79544 (10)	0.0373 (4)
H1	0.155 (5)	0.251 (4)	0.8814 (18)	0.063 (8)*
H2	−0.117 (4)	0.341 (4)	0.9136 (17)	0.049 (7)*
H3	−0.023 (4)	0.099 (4)	0.9211 (19)	0.060 (8)*
H4	0.773 (4)	0.141 (3)	0.5525 (14)	0.031 (6)*
H5	0.903 (4)	0.309 (3)	0.4025 (15)	0.038 (6)*
H6	0.824 (4)	0.505 (3)	0.2666 (16)	0.039 (6)*
H8	0.193 (4)	0.501 (3)	0.3403 (15)	0.041 (7)*
H13	0.279 (4)	−0.184 (3)	0.9309 (15)	0.034 (6)*
H14	0.569 (4)	−0.324 (3)	1.0198 (18)	0.045 (7)*
H15	0.921 (4)	−0.321 (3)	0.9601 (16)	0.041 (6)*
H16	1.019 (4)	−0.196 (3)	0.8076 (14)	0.031 (6)*
H	0.061 (7)	0.148 (6)	0.759 (3)	0.112 (13)*
HO4	0.296 (5)	0.685 (4)	0.210 (2)	0.076 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N	0.0269 (9)	0.0344 (10)	0.0285 (10)	−0.0100 (8)	−0.0036 (7)	−0.0014 (8)
O1	0.0214 (7)	0.0335 (8)	0.0282 (8)	−0.0083 (6)	−0.0038 (6)	−0.0012 (6)
O2	0.0233 (8)	0.0419 (9)	0.0329 (8)	−0.0102 (7)	−0.0029 (6)	−0.0021 (7)
O3	0.0239 (7)	0.0344 (8)	0.0256 (8)	−0.0080 (6)	−0.0055 (6)	−0.0011 (6)
O4	0.0331 (9)	0.0375 (9)	0.0310 (8)	−0.0118 (7)	−0.0075 (6)	0.0049 (7)
C2	0.0274 (11)	0.0274 (11)	0.0253 (11)	−0.0068 (9)	−0.0048 (9)	−0.0056 (9)
C3	0.0246 (11)	0.0255 (11)	0.0257 (11)	−0.0071 (8)	−0.0047 (8)	−0.0057 (9)
C4	0.0235 (11)	0.0258 (11)	0.0284 (11)	−0.0057 (9)	−0.0046 (8)	−0.0074 (9)
C5	0.0258 (11)	0.0304 (11)	0.0316 (12)	−0.0087 (9)	−0.0042 (9)	−0.0054 (9)
C6	0.0272 (11)	0.0314 (12)	0.0307 (12)	−0.0103 (9)	0.0003 (9)	−0.0048 (9)
C7	0.0331 (12)	0.0269 (11)	0.0260 (11)	−0.0079 (9)	−0.0047 (9)	−0.0056 (9)
C8	0.0247 (12)	0.0285 (11)	0.0287 (11)	−0.0067 (9)	−0.0069 (9)	−0.0039 (9)
C9	0.0244 (11)	0.0244 (11)	0.0298 (11)	−0.0093 (8)	−0.0022 (8)	−0.0078 (9)
C10	0.0238 (11)	0.0241 (10)	0.0267 (11)	−0.0072 (8)	−0.0040 (8)	−0.0054 (9)
C11	0.0225 (11)	0.0277 (11)	0.0316 (12)	−0.0058 (9)	−0.0057 (9)	−0.0073 (9)
C12	0.0275 (11)	0.0327 (12)	0.0308 (12)	−0.0068 (9)	−0.0052 (9)	−0.0040 (9)
C13	0.0371 (14)	0.0448 (14)	0.0326 (13)	−0.0130 (11)	−0.0034 (10)	0.0001 (10)
C14	0.0484 (15)	0.0417 (14)	0.0290 (13)	−0.0150 (11)	−0.0086 (11)	0.0041 (10)
C15	0.0424 (14)	0.0349 (13)	0.0340 (13)	−0.0067 (10)	−0.0149 (11)	−0.0022 (10)
C16	0.0301 (12)	0.0311 (12)	0.0352 (13)	−0.0052 (9)	−0.0098 (9)	−0.0049 (10)
C17	0.0326 (12)	0.0265 (11)	0.0254 (11)	−0.0081 (9)	−0.0055 (9)	−0.0027 (9)
C	0.0484 (16)	0.0484 (16)	0.0330 (13)	−0.0080 (13)	−0.0099 (11)	−0.0038 (12)
O	0.0365 (9)	0.0437 (10)	0.0307 (9)	−0.0097 (7)	−0.0063 (7)	−0.0015 (7)

Geometric parameters (Å, º)

N—C11	1.299 (3)	C7—C8	1.389 (3)
N—C12	1.407 (3)	C8—C9	1.383 (3)
O1—C9	1.376 (2)	C8—H8	0.96 (2)
O1—C2	1.388 (2)	C9—C10	1.400 (3)
O2—C2	1.213 (3)	C12—C17	1.380 (3)
O3—C11	1.376 (3)	C12—C13	1.391 (3)
O3—C17	1.381 (2)	C13—C14	1.387 (3)
O4—C7	1.355 (2)	C13—H13	0.98 (2)
O4—HO4	1.09 (3)	C14—C15	1.397 (4)
C2—C3	1.454 (3)	C14—H14	0.99 (3)
C3—C4	1.364 (3)	C15—C16	1.386 (3)
C3—C11	1.459 (3)	C15—H15	1.01 (2)
C4—C10	1.421 (3)	C16—C17	1.383 (3)
C4—H4	0.98 (2)	C16—H16	1.00 (2)
C5—C6	1.366 (3)	C—O	1.419 (3)
C5—C10	1.408 (3)	C—H1	1.11 (3)
C5—H5	0.96 (2)	C—H2	1.04 (3)
C6—C7	1.412 (3)	C—H3	1.06 (3)
C6—H6	0.96 (3)	O—H	1.06 (4)
C11—N—C12	103.88 (18)	C5—C10—C4	124.49 (19)
C9—O1—C2	122.98 (16)	N—C11—O3	115.37 (18)
C11—O3—C17	103.87 (15)	N—C11—C3	130.33 (19)
C7—O4—HO4	110.9 (16)	O3—C11—C3	114.26 (17)
O2—C2—O1	115.89 (17)	C17—C12—C13	119.5 (2)
O2—C2—C3	127.46 (19)	C17—C12—N	109.11 (18)
O1—C2—C3	116.65 (18)	C13—C12—N	131.3 (2)
C4—C3—C2	120.42 (19)	C14—C13—C12	117.5 (2)
C4—C3—C11	120.65 (19)	C14—C13—H13	122.2 (13)
C2—C3—C11	118.90 (18)	C12—C13—H13	120.2 (13)
C3—C4—C10	121.36 (19)	C13—C14—C15	121.1 (2)
C3—C4—H4	120.0 (13)	C13—C14—H14	122.4 (14)
C10—C4—H4	118.6 (13)	C15—C14—H14	116.5 (14)
C6—C5—C10	121.3 (2)	C16—C15—C14	122.2 (2)
C6—C5—H5	120.8 (14)	C16—C15—H15	119.0 (14)
C10—C5—H5	117.9 (14)	C14—C15—H15	118.7 (14)
C5—C6—C7	119.7 (2)	C17—C16—C15	114.9 (2)
C5—C6—H6	122.5 (14)	C17—C16—H16	124.1 (12)
C7—C6—H6	117.8 (14)	C15—C16—H16	121.0 (12)
O4—C7—C8	122.12 (19)	C12—C17—O3	107.74 (17)
O4—C7—C6	117.20 (19)	C12—C17—C16	124.7 (2)
C8—C7—C6	120.7 (2)	O3—C17—C16	127.55 (19)
C9—C8—C7	118.2 (2)	O—C—H1	111.2 (14)
C9—C8—H8	119.6 (14)	O—C—H2	106.5 (14)
C7—C8—H8	122.2 (14)	H1—C—H2	108 (2)
O1—C9—C8	116.82 (18)	O—C—H3	111.8 (15)
O1—C9—C10	120.35 (18)	H1—C—H3	111 (2)
C8—C9—C10	122.83 (19)	H2—C—H3	109 (2)
C9—C10—C5	117.29 (19)	C—O—H	110 (2)
C9—C10—C4	118.19 (18)
C9—O1—C2—O2	179.39 (17)	C3—C4—C10—C5	178.6 (2)
C9—O1—C2—C3	−0.5 (3)	C12—N—C11—O3	0.8 (2)
O2—C2—C3—C4	179.1 (2)	C12—N—C11—C3	−177.1 (2)
O1—C2—C3—C4	−1.1 (3)	C17—O3—C11—N	−1.4 (2)
O2—C2—C3—C11	−2.7 (3)	C17—O3—C11—C3	176.87 (16)
O1—C2—C3—C11	177.22 (16)	C4—C3—C11—N	172.8 (2)
C2—C3—C4—C10	0.9 (3)	C2—C3—C11—N	−5.5 (3)
C11—C3—C4—C10	−177.37 (17)	C4—C3—C11—O3	−5.1 (3)
C10—C5—C6—C7	−0.3 (3)	C2—C3—C11—O3	176.62 (17)
C5—C6—C7—O4	177.57 (19)	C11—N—C12—C17	0.1 (2)
C5—C6—C7—C8	−0.8 (3)	C11—N—C12—C13	178.7 (2)
O4—C7—C8—C9	−177.36 (18)	C17—C12—C13—C14	1.2 (3)
C6—C7—C8—C9	1.0 (3)	N—C12—C13—C14	−177.2 (2)
C2—O1—C9—C8	−177.03 (17)	C12—C13—C14—C15	−0.8 (4)
C2—O1—C9—C10	2.2 (3)	C13—C14—C15—C16	−0.2 (4)
C7—C8—C9—O1	179.27 (17)	C14—C15—C16—C17	0.6 (3)
C7—C8—C9—C10	0.0 (3)	C13—C12—C17—O3	−179.70 (19)
O1—C9—C10—C5	179.69 (17)	N—C12—C17—O3	−0.9 (2)
C8—C9—C10—C5	−1.1 (3)	C13—C12—C17—C16	−0.8 (3)
O1—C9—C10—C4	−2.4 (3)	N—C12—C17—C16	178.0 (2)
C8—C9—C10—C4	176.86 (18)	C11—O3—C17—C12	1.3 (2)
C6—C5—C10—C9	1.2 (3)	C11—O3—C17—C16	−177.5 (2)
C6—C5—C10—C4	−176.59 (19)	C15—C16—C17—C12	−0.1 (3)
C3—C4—C10—C9	0.8 (3)	C15—C16—C17—O3	178.53 (19)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O—H···N	1.06 (4)	1.99 (4)	2.926 (3)	145 (3)
O—H···O2	1.06 (4)	2.15 (4)	2.870 (2)	123 (3)
O4—HO4···O^i	1.09 (3)	1.53 (3)	2.627 (3)	179 (3)
C5—H5···O1^ii	0.96 (2)	2.65 (3)	3.555 (3)	157 (2)
C4—H4···O2^ii	0.98 (2)	2.46 (2)	3.402 (3)	160 (2)

Symmetry codes: (i) −x, −y+1, −z+1; (ii) x+1, y, z.