The coumarin and benzoxazole ring systems in the title compound, C
16H
9NO
3, are planar. The angle between them is 5.24 (8)°. The crystal structure is stabilized by intermolecular C—H
O and C—H
N attractive interactions.
Supporting information
CCDC reference: 197465
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.003 Å
- R factor = 0.055
- wR factor = 0.120
- Data-to-parameter ratio = 16.4
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
The title compound was prepared and purified according to Luan et al. (2002). Suitable single crystals were grown from chloroform/methanol (1:1 v\v) slow evaporation.
H atoms were located by difference Fourier syntesis, the positional parameters have been refined with Uiso set to 1.2 times the value of Ueq of the atom to which they are attached. The final refined C—H distances ranged from 0.88 (2) to 1.02 (2) Å, with a mean value of 0.96 (2) Å.
Data collection: CAD-4 EXPRESS Software (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS Software; data reduction: XCAD4 (Harms & Wocadlo, 1995); 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).
Crystal data top
C16H9NO3 | F(000) = 544 |
Mr = 263.24 | Dx = 1.491 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 25 reflections |
a = 7.493 (5) Å | θ = 2.1–30° |
b = 21.276 (5) Å | µ = 0.11 mm−1 |
c = 8.024 (5) Å | T = 293 K |
β = 113.508 (5)° | Prism, yellow |
V = 1173.0 (11) Å3 | 0.25 × 0.20 × 0.10 mm |
Z = 4 | |
Data collection top
Enraf-Nonius Turbo-CAD-4 diffractometer | θmax = 30.0°, θmin = 2.9° |
non–profiled ω/2θ scans | h = 0→10 |
3638 measured reflections | k = −29→0 |
3409 independent reflections | l = −11→10 |
1232 reflections with I > 2σ(I) | 3 standard reflections every 120 min |
Rint = 0.022 | intensity decay: 6% |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Only H-atom coordinates refined |
R[F2 > 2σ(F2)] = 0.055 | w = 1/[σ2(Fo2) + (0.0479P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.120 | (Δ/σ)max = 0.001 |
S = 0.80 | Δρmax = 0.23 e Å−3 |
3409 reflections | Δρmin = −0.19 e Å−3 |
208 parameters | |
Crystal data top
C16H9NO3 | V = 1173.0 (11) Å3 |
Mr = 263.24 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.493 (5) Å | µ = 0.11 mm−1 |
b = 21.276 (5) Å | T = 293 K |
c = 8.024 (5) Å | 0.25 × 0.20 × 0.10 mm |
β = 113.508 (5)° | |
Data collection top
Enraf-Nonius Turbo-CAD-4 diffractometer | Rint = 0.022 |
3638 measured reflections | 3 standard reflections every 120 min |
3409 independent reflections | intensity decay: 6% |
1232 reflections with I > 2σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.120 | Only H-atom coordinates refined |
S = 0.80 | Δρmax = 0.23 e Å−3 |
3409 reflections | Δρmin = −0.19 e Å−3 |
208 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.2968 (2) | 0.04655 (7) | 0.78633 (19) | 0.0470 (4) | |
O2 | 0.2258 (3) | 0.00673 (8) | 0.5150 (2) | 0.0676 (6) | |
O3 | −0.0303 (2) | 0.06899 (7) | 0.21428 (18) | 0.0479 (4) | |
N | −0.1069 (3) | 0.16788 (9) | 0.2586 (2) | 0.0419 (5) | |
C2 | 0.2035 (3) | 0.05051 (11) | 0.5996 (3) | 0.0452 (6) | |
C3 | 0.0899 (3) | 0.10753 (10) | 0.5278 (3) | 0.0378 (5) | |
C4 | 0.0836 (3) | 0.15330 (10) | 0.6430 (3) | 0.0376 (5) | |
C5 | 0.1921 (3) | 0.19554 (11) | 0.9564 (3) | 0.0416 (6) | |
C6 | 0.3018 (4) | 0.18729 (12) | 1.1402 (3) | 0.0511 (7) | |
C7 | 0.4050 (4) | 0.13245 (12) | 1.2030 (3) | 0.0518 (7) | |
C8 | 0.4028 (4) | 0.08539 (12) | 1.0853 (3) | 0.0490 (7) | |
C9 | 0.2956 (3) | 0.09401 (10) | 0.9020 (3) | 0.0379 (5) | |
C10 | 0.1891 (3) | 0.14862 (10) | 0.8340 (3) | 0.0360 (5) | |
C11 | −0.0180 (3) | 0.11645 (11) | 0.3327 (3) | 0.0427 (6) | |
C12 | −0.1404 (3) | 0.09383 (10) | 0.0455 (3) | 0.0391 (5) | |
C13 | −0.1964 (4) | 0.06665 (11) | −0.1224 (3) | 0.0472 (6) | |
C14 | −0.3081 (4) | 0.10330 (12) | −0.2676 (3) | 0.0504 (6) | |
C15 | −0.3586 (4) | 0.16474 (13) | −0.2451 (3) | 0.0529 (7) | |
C16 | −0.2987 (4) | 0.19161 (12) | −0.0746 (3) | 0.0498 (7) | |
C17 | −0.1881 (3) | 0.15498 (10) | 0.0728 (3) | 0.0393 (5) | |
H4 | 0.000 (3) | 0.1907 (10) | 0.589 (3) | 0.047* | |
H5 | 0.111 (3) | 0.2323 (10) | 0.909 (3) | 0.047* | |
H6 | 0.299 (3) | 0.2147 (10) | 1.224 (3) | 0.047* | |
H7 | 0.486 (3) | 0.1252 (9) | 1.338 (3) | 0.047* | |
H8 | 0.470 (3) | 0.0502 (10) | 1.121 (3) | 0.047* | |
H13 | −0.157 (3) | 0.0244 (10) | −0.136 (3) | 0.047* | |
H14 | −0.356 (3) | 0.0843 (9) | −0.395 (3) | 0.047* | |
H15 | −0.431 (3) | 0.1870 (10) | −0.352 (3) | 0.047* | |
H16 | −0.328 (3) | 0.2334 (10) | −0.057 (3) | 0.047* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0567 (11) | 0.0348 (9) | 0.0440 (9) | 0.0056 (8) | 0.0142 (8) | −0.0012 (7) |
O2 | 0.0857 (14) | 0.0511 (11) | 0.0606 (11) | 0.0207 (10) | 0.0234 (10) | −0.0134 (9) |
O3 | 0.0592 (11) | 0.0410 (10) | 0.0392 (9) | −0.0003 (8) | 0.0150 (8) | −0.0023 (7) |
N | 0.0456 (12) | 0.0381 (11) | 0.0379 (10) | 0.0011 (9) | 0.0124 (9) | −0.0039 (9) |
C2 | 0.0451 (14) | 0.0399 (14) | 0.0475 (14) | 0.0027 (12) | 0.0153 (12) | −0.0026 (11) |
C3 | 0.0398 (14) | 0.0353 (13) | 0.0393 (12) | −0.0007 (11) | 0.0168 (11) | −0.0016 (10) |
C4 | 0.0387 (13) | 0.0336 (13) | 0.0397 (13) | 0.0002 (11) | 0.0147 (11) | 0.0046 (10) |
C5 | 0.0488 (15) | 0.0387 (13) | 0.0379 (14) | 0.0035 (12) | 0.0180 (12) | 0.0007 (10) |
C6 | 0.0632 (18) | 0.0515 (17) | 0.0404 (15) | −0.0065 (14) | 0.0224 (13) | −0.0132 (12) |
C7 | 0.0618 (18) | 0.0578 (17) | 0.0314 (13) | 0.0018 (14) | 0.0138 (12) | 0.0024 (12) |
C8 | 0.0504 (16) | 0.0436 (15) | 0.0462 (14) | 0.0051 (12) | 0.0121 (13) | 0.0094 (12) |
C9 | 0.0430 (14) | 0.0305 (12) | 0.0403 (13) | −0.0022 (11) | 0.0168 (11) | −0.0021 (10) |
C10 | 0.0376 (13) | 0.0322 (12) | 0.0372 (13) | −0.0034 (10) | 0.0138 (10) | 0.0009 (10) |
C11 | 0.0432 (15) | 0.0465 (15) | 0.0399 (13) | −0.0084 (12) | 0.0181 (11) | −0.0090 (11) |
C12 | 0.0424 (14) | 0.0382 (13) | 0.0347 (12) | −0.0026 (11) | 0.0134 (11) | 0.0023 (10) |
C13 | 0.0557 (16) | 0.0413 (14) | 0.0412 (14) | 0.0008 (13) | 0.0157 (12) | −0.0039 (12) |
C14 | 0.0555 (16) | 0.0561 (16) | 0.0384 (13) | −0.0004 (13) | 0.0173 (13) | −0.0042 (12) |
C15 | 0.0546 (17) | 0.0581 (17) | 0.0400 (14) | 0.0033 (14) | 0.0123 (12) | 0.0075 (13) |
C16 | 0.0531 (16) | 0.0418 (15) | 0.0514 (16) | 0.0068 (13) | 0.0177 (13) | 0.0027 (13) |
C17 | 0.0388 (13) | 0.0378 (13) | 0.0391 (13) | −0.0021 (11) | 0.0131 (11) | −0.0026 (10) |
Geometric parameters (Å, º) top
O1—C9 | 1.374 (2) | C6—H6 | 0.90 (2) |
O1—C2 | 1.381 (3) | C7—C8 | 1.372 (3) |
O2—C2 | 1.203 (2) | C7—H7 | 1.02 (2) |
O3—C11 | 1.364 (2) | C8—C9 | 1.379 (3) |
O3—C12 | 1.379 (2) | C8—H8 | 0.88 (2) |
N—C11 | 1.295 (3) | C9—C10 | 1.392 (3) |
N—C17 | 1.395 (3) | C12—C13 | 1.369 (3) |
C2—C3 | 1.462 (3) | C12—C17 | 1.390 (3) |
C3—C4 | 1.356 (3) | C13—C14 | 1.374 (3) |
C3—C11 | 1.460 (3) | C13—H13 | 0.97 (2) |
C4—C10 | 1.420 (3) | C14—C15 | 1.392 (3) |
C4—H4 | 1.00 (2) | C14—H14 | 1.02 (2) |
C5—C6 | 1.383 (3) | C15—C16 | 1.382 (3) |
C5—C10 | 1.394 (3) | C15—H15 | 0.940 (19) |
C5—H5 | 0.97 (2) | C16—C17 | 1.382 (3) |
C6—C7 | 1.379 (3) | C16—H16 | 0.94 (2) |
| | | |
C9—O1—C2 | 123.46 (17) | C8—C9—C10 | 121.9 (2) |
C11—O3—C12 | 104.35 (17) | C9—C10—C5 | 118.42 (19) |
C11—N—C17 | 104.44 (18) | C9—C10—C4 | 117.8 (2) |
O2—C2—O1 | 116.2 (2) | C5—C10—C4 | 123.8 (2) |
O2—C2—C3 | 127.6 (2) | N—C11—O3 | 115.25 (19) |
O1—C2—C3 | 116.19 (19) | N—C11—C3 | 124.4 (2) |
C4—C3—C11 | 118.8 (2) | O3—C11—C3 | 120.3 (2) |
C4—C3—C2 | 120.0 (2) | C13—C12—O3 | 129.3 (2) |
C11—C3—C2 | 121.11 (19) | C13—C12—C17 | 123.6 (2) |
C3—C4—C10 | 122.0 (2) | O3—C12—C17 | 107.15 (17) |
C3—C4—H4 | 117.7 (11) | C12—C13—C14 | 116.0 (2) |
C10—C4—H4 | 120.3 (11) | C12—C13—H13 | 121.0 (12) |
C6—C5—C10 | 119.7 (2) | C14—C13—H13 | 123.0 (12) |
C6—C5—H5 | 122.1 (12) | C13—C14—C15 | 121.9 (2) |
C10—C5—H5 | 118.1 (12) | C13—C14—H14 | 118.3 (12) |
C7—C6—C5 | 120.3 (2) | C15—C14—H14 | 119.9 (12) |
C7—C6—H6 | 117.0 (14) | C16—C15—C14 | 121.3 (2) |
C5—C6—H6 | 122.3 (14) | C16—C15—H15 | 122.4 (13) |
C8—C7—C6 | 121.0 (2) | C14—C15—H15 | 116.3 (13) |
C8—C7—H7 | 117.3 (11) | C15—C16—C17 | 117.4 (2) |
C6—C7—H7 | 121.7 (11) | C15—C16—H16 | 122.5 (13) |
C7—C8—C9 | 118.6 (2) | C17—C16—H16 | 120.1 (13) |
C7—C8—H8 | 123.2 (14) | C16—C17—C12 | 119.8 (2) |
C9—C8—H8 | 118.1 (14) | C16—C17—N | 131.4 (2) |
O1—C9—C8 | 117.7 (2) | C12—C17—N | 108.82 (18) |
O1—C9—C10 | 120.41 (18) | | |
| | | |
C9—O1—C2—O2 | 176.1 (2) | C17—N—C11—O3 | 0.1 (3) |
C9—O1—C2—C3 | −3.6 (3) | C17—N—C11—C3 | 179.9 (2) |
O2—C2—C3—C4 | −178.5 (3) | C12—O3—C11—N | 0.0 (3) |
O1—C2—C3—C4 | 1.2 (3) | C12—O3—C11—C3 | −179.9 (2) |
O2—C2—C3—C11 | 1.5 (4) | C4—C3—C11—N | 6.5 (3) |
O1—C2—C3—C11 | −178.9 (2) | C2—C3—C11—N | −173.4 (2) |
C11—C3—C4—C10 | −178.3 (2) | C4—C3—C11—O3 | −173.7 (2) |
C2—C3—C4—C10 | 1.7 (3) | C2—C3—C11—O3 | 6.4 (3) |
C10—C5—C6—C7 | −1.2 (4) | C11—O3—C12—C13 | 179.4 (3) |
C5—C6—C7—C8 | 0.6 (4) | C11—O3—C12—C17 | −0.1 (2) |
C6—C7—C8—C9 | 0.3 (4) | O3—C12—C13—C14 | 179.6 (2) |
C2—O1—C9—C8 | −176.7 (2) | C17—C12—C13—C14 | −1.0 (4) |
C2—O1—C9—C10 | 3.2 (3) | C12—C13—C14—C15 | 1.0 (4) |
C7—C8—C9—O1 | 179.4 (2) | C13—C14—C15—C16 | −0.2 (4) |
C7—C8—C9—C10 | −0.5 (4) | C14—C15—C16—C17 | −0.5 (4) |
O1—C9—C10—C5 | −180.0 (2) | C15—C16—C17—C12 | 0.5 (3) |
C8—C9—C10—C5 | −0.1 (3) | C15—C16—C17—N | −180.0 (2) |
O1—C9—C10—C4 | −0.1 (3) | C13—C12—C17—C16 | 0.3 (4) |
C8—C9—C10—C4 | 179.8 (2) | O3—C12—C17—C16 | 179.8 (2) |
C6—C5—C10—C9 | 0.9 (3) | C13—C12—C17—N | −179.4 (2) |
C6—C5—C10—C4 | −178.9 (2) | O3—C12—C17—N | 0.1 (2) |
C3—C4—C10—C9 | −2.2 (3) | C11—N—C17—C16 | −179.7 (2) |
C3—C4—C10—C5 | 177.6 (2) | C11—N—C17—C12 | −0.1 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···Ni | 0.97 (2) | 2.66 (2) | 3.626 (3) | 175.9 (17) |
C14—H14···O2ii | 1.02 (2) | 2.53 (2) | 3.283 (3) | 130.7 (15) |
C13—H13···O3ii | 0.97 (2) | 2.65 (2) | 3.572 (3) | 160.0 (17) |
C8—H8···O1iii | 0.88 (2) | 2.61 (2) | 3.487 (3) | 172 (2) |
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x, −y, −z; (iii) −x+1, −y, −z+2. |
Experimental details
Crystal data |
Chemical formula | C16H9NO3 |
Mr | 263.24 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 7.493 (5), 21.276 (5), 8.024 (5) |
β (°) | 113.508 (5) |
V (Å3) | 1173.0 (11) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.25 × 0.20 × 0.10 |
|
Data collection |
Diffractometer | Enraf-Nonius Turbo-CAD-4 diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3638, 3409, 1232 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.703 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.120, 0.80 |
No. of reflections | 3409 |
No. of parameters | 208 |
H-atom treatment | Only H-atom coordinates refined |
Δρmax, Δρmin (e Å−3) | 0.23, −0.19 |
Selected geometric parameters (Å, º) topO1—C9 | 1.374 (2) | C3—C4 | 1.356 (3) |
O1—C2 | 1.381 (3) | C3—C11 | 1.460 (3) |
O2—C2 | 1.203 (2) | C4—C10 | 1.420 (3) |
C2—C3 | 1.462 (3) | C9—C10 | 1.392 (3) |
| | | |
O2—C2—O1 | 116.2 (2) | C3—C4—C10 | 122.0 (2) |
O2—C2—C3 | 127.6 (2) | O1—C9—C8 | 117.7 (2) |
O1—C2—C3 | 116.19 (19) | C5—C10—C4 | 123.8 (2) |
C4—C3—C2 | 120.0 (2) | | |
| | | |
C4—C3—C11—N | 6.5 (3) | C4—C3—C11—O3 | −173.7 (2) |
C2—C3—C11—N | −173.4 (2) | C2—C3—C11—O3 | 6.4 (3) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···Ni | 0.97 (2) | 2.66 (2) | 3.626 (3) | 175.9 (17) |
C14—H14···O2ii | 1.02 (2) | 2.53 (2) | 3.283 (3) | 130.7 (15) |
C13—H13···O3ii | 0.97 (2) | 2.65 (2) | 3.572 (3) | 160.0 (17) |
C8—H8···O1iii | 0.88 (2) | 2.61 (2) | 3.487 (3) | 172 (2) |
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x, −y, −z; (iii) −x+1, −y, −z+2. |
Coumarin derivatives are known to be a very interesting class of natural and synthetic compounds, which present extensive and diverse applications (O'Kennedy & Thornes, 1997; Krasovitskii, 1988). These compounds exhibit strong fluorescence in the visible region and their properties vary according to the substituents on the coumarinic ring (Novak & Kovac, 2000; Machado & Miranda, 2001).
The title compound, (I) (Luan et al., 2002), presents good photochemical stability, high-fluorescence quantum yields (Φf) in solvents of different polarities, and generates singlet oxygen with a relatively low quantum efficiency (Machado et al., 2002). These characteristics make it suitable for use as a laser dye in the range between 438 and 450 nm.
X-Ray analysis of (I) was undertaken as a part of studies to elucidate the relationships between the characteristics of the functional dyes containing the coumarin skeletons and their molecular structures.
An ORTEP-3 (Farrugia, 1997) drawing of (I) is shown in Fig. 1, and selected geometric parameters presented in Table 1. The angle between the benzoxazole and the coumarin moieties is 5.24 (8)°, showing deviation from planarity, as observed for other coumarin derivatives (Dhaneshwar et al., 1988; Chinnakali et al., 1990). The two ring systems are planar.
The coumarin skeleton geometry can be compared with that of unsubstituted coumarin (Gavuzzo et al., 1974), of coumarin-3-carboxylic acid (Dobson & Gerkin, 1996) and of 3-(bromoacetyl)coumarin (Vasudevan et al., 1991). The double-bond character for C3—C4 is observed in all these compounds. The C2—C3 and C4—C10 bonds, adjacent to the double bond, are systematically longer than 1.40 Å in these four molecules. The angles C8—C9—O1 and C5—C10—C4 at the junction of the two rings are respectively smaller and greater than 120°. The angles around C2 follow the same behavior in all the compounds.
Compared with unsubstituted coumarin (Gavuzzo et al., 1974), the decrease in the C2—C3—C4 bond angle by 2° and increase in C3—C4—C10 by the same amount may be due to the benzoxazole group substituted at C3. The bond distances and angles in the benzoxazole moiety are within normally expected ranges. The bond length C3—C11 is in good agreement, within experimental error, with those observed in 3-(2-benzimidazolyl)-7-(diethylamino)coumarin (Chinnakali et al., 1990) and 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (Jasinski & Paight, 1995).
In this crystal, the reference molecule is linked therefore to inversion- and glide-related neighbours by several directionally specific C—H···O and C—H···N interactions, respectively (Table 2). The Csp2—H···O interaction links the molecules in an infinite zigzag in the [102] direction, while the Csp2—H···N produces an infinite zigzag in the [001] direction (Fig. 2). The shape and disposition of molecules in the structure and the rather high density (1.491 Mg m−3; values for analogous molecules typically lie in the range 1.34–1.42 Mg m−3) suggest that these close approaches are produced by attractive interactions rather than as a consequence of minimizing repulsive effects elsewhere on the molecule. Similar behavior are observed for the 7-acetoxycoumarin (Sarma & Desiraju, 1987) and coumarin 3-carboxylic acid (Dobson & Gerkin, 1996).