Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827011203020X/mx3079sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827011203020X/mx3079Isup2.hkl | |
Chemical Markup Language (CML) file https://doi.org/10.1107/S010827011203020X/mx3079Isup3.cml |
CCDC reference: 899074
The lichen was scraped off twigs and branches of elder trees, and the specimens were extracted with boiling ethyl acetate. The dark-yellow solution was filtered and the solvent removed by rotary evaporation, and the remaining brown–yellow oil was subjected to column chromatography on silica gel with ethyl acetate as the eluent. From one of the fractions, shown to be pure by thin-layer chromatography, thin orange plates were obtained when the solvent was left to evaporate slowly at room temperature.
The hydroxy H atoms were refined freely. Methyl H atoms were identified in difference syntheses; the geometry was idealized (C—H = 0.98 Å and H—C—H = 109.5°) and the methyl groups refined as rigid groups allowed to rotate but not tip. For all methyl H atoms, Uiso(H) values were set at 1.5Ueq(C). Other H atoms were included in the refinement using a riding model starting from calculated positions, with aromatic C—H bond lengths of 0.98 Å and Uiso(H) = 1.2Ueq(C).
Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
C16H12O5 | F(000) = 592 |
Mr = 284.26 | Dx = 1.539 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.54184 Å |
a = 6.1986 (3) Å | Cell parameters from 17945 reflections |
b = 24.5470 (12) Å | θ = 3.6–75.7° |
c = 8.1004 (4) Å | µ = 0.97 mm−1 |
β = 95.370 (4)° | T = 130 K |
V = 1227.12 (10) Å3 | Plate, orange |
Z = 4 | 0.25 × 0.10 × 0.04 mm |
Agilent Technologies Xcalibur (Atlas, Nova) diffractometer | 2553 independent reflections |
Radiation source: Nova (Cu) X-ray Source | 2314 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.036 |
Detector resolution: 10.3543 pixels mm-1 | θmax = 75.9°, θmin = 3.6° |
ω scan | h = −7→7 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012) | k = −30→30 |
Tmin = 0.646, Tmax = 1.000 | l = −10→10 |
43156 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.043 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.126 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0676P)2 + 0.6508P] where P = (Fo2 + 2Fc2)/3 |
2553 reflections | (Δ/σ)max = 0.001 |
200 parameters | Δρmax = 0.31 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
C16H12O5 | V = 1227.12 (10) Å3 |
Mr = 284.26 | Z = 4 |
Monoclinic, P21/c | Cu Kα radiation |
a = 6.1986 (3) Å | µ = 0.97 mm−1 |
b = 24.5470 (12) Å | T = 130 K |
c = 8.1004 (4) Å | 0.25 × 0.10 × 0.04 mm |
β = 95.370 (4)° |
Agilent Technologies Xcalibur (Atlas, Nova) diffractometer | 2553 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012) | 2314 reflections with I > 2σ(I) |
Tmin = 0.646, Tmax = 1.000 | Rint = 0.036 |
43156 measured reflections |
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.126 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.31 e Å−3 |
2553 reflections | Δρmin = −0.25 e Å−3 |
200 parameters |
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. Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane) 2.9925 (0.0010) x - 1.9903 (0.0028) y + 6.6665 (0.0010) z = 2.1195 (0.0017) * -0.0011 (0.0012) C1 * -0.0526 (0.0012) C2 * -0.0515 (0.0012) C3 * -0.0097 (0.0012) C4 * 0.0333 (0.0012) C4A * -0.0044 (0.0012) C5 * -0.0480 (0.0013) C6 * -0.0231 (0.0013) C7 * 0.0295 (0.0013) C8 * 0.0580 (0.0012) C8A * 0.0859 (0.0013) C9 * 0.0383 (0.0012) C9A * 0.0533 (0.0012) C10 * 0.0478 (0.0012) C10A * -0.1123 (0.0012) C11 * -0.0991 (0.0013) C12 * -0.0371 (0.0010) O1 * -0.0299 (0.0010) O2 * -0.0714 (0.0011) O3 * 0.1404 (0.0011) O4 * 0.0539 (0.0009) O5 Rms deviation of fitted atoms = 0.0618 2.9946 (0.0023) x - 2.8088 (0.0087) y + 6.6344 (0.0021) z = 1.7346 (0.0043) Angle to previous plane (with approximate e.s.d.) = 1.92 (0.04) * -0.0015 (0.0011) C1 * -0.0083 (0.0010) C2 * 0.0011 (0.0010) C3 * 0.0078 (0.0011) C4 * 0.0059 (0.0011) C4A * 0.0028 (0.0012) C9A * 0.0037 (0.0009) C9 * -0.0114 (0.0008) C10 - 0.0084 (0.0016) O1 - 0.0301 (0.0020) C11 Rms deviation of fitted atoms = 0.0063 3.0774 (0.0023) x - 1.3155 (0.0085) y + 6.6110 (0.0021) z = 2.5977 (0.0054) Angle to previous plane (with approximate e.s.d.) = 3.57 (0.06) * 0.0056 (0.0010) C5 * -0.0117 (0.0011) C6 * -0.0036 (0.0011) C7 * 0.0058 (0.0011) C8 * 0.0084 (0.0011) C8A * 0.0139 (0.0011) C10A * -0.0096 (0.0009) C9 * -0.0088 (0.0009) C10 - 0.0013 (0.0016) O2 - 0.0237 (0.0017) O3 Rms deviation of fitted atoms = 0.0090 |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.2545 (2) | 0.45799 (6) | 0.34025 (17) | 0.0214 (3) | |
H1 | 0.1301 | 0.4629 | 0.3988 | 0.026* | |
C2 | 0.3121 (2) | 0.40551 (6) | 0.29103 (17) | 0.0216 (3) | |
C3 | 0.4950 (2) | 0.39912 (6) | 0.20716 (17) | 0.0221 (3) | |
H3 | 0.5351 | 0.3637 | 0.1743 | 0.027* | |
C4 | 0.6220 (2) | 0.44367 (6) | 0.16971 (16) | 0.0202 (3) | |
C4A | 0.5647 (2) | 0.49666 (5) | 0.21771 (16) | 0.0187 (3) | |
C5 | 0.7359 (2) | 0.64581 (6) | 0.17976 (17) | 0.0210 (3) | |
C6 | 0.6626 (2) | 0.69719 (6) | 0.22145 (18) | 0.0229 (3) | |
H6 | 0.7374 | 0.7288 | 0.1903 | 0.028* | |
C7 | 0.4803 (2) | 0.70252 (6) | 0.30861 (17) | 0.0226 (3) | |
C8 | 0.3673 (2) | 0.65641 (6) | 0.35343 (17) | 0.0219 (3) | |
H8 | 0.2429 | 0.6600 | 0.4127 | 0.026* | |
C8A | 0.4392 (2) | 0.60543 (6) | 0.31022 (16) | 0.0197 (3) | |
C9 | 0.3110 (2) | 0.55739 (6) | 0.35761 (17) | 0.0213 (3) | |
C9A | 0.3783 (2) | 0.50264 (6) | 0.30392 (16) | 0.0194 (3) | |
C10 | 0.6933 (2) | 0.54407 (5) | 0.17714 (16) | 0.0189 (3) | |
C10A | 0.6236 (2) | 0.59851 (5) | 0.22387 (16) | 0.0188 (3) | |
C11 | 0.1749 (2) | 0.35733 (6) | 0.32927 (19) | 0.0264 (3) | |
H11A | 0.2113 | 0.3262 | 0.2615 | 0.040* | |
H11B | 0.0214 | 0.3665 | 0.3043 | 0.040* | |
H11C | 0.2026 | 0.3480 | 0.4469 | 0.040* | |
C12 | 0.2300 (3) | 0.76133 (6) | 0.4271 (2) | 0.0298 (3) | |
H12A | 0.1050 | 0.7468 | 0.3581 | 0.045* | |
H12B | 0.2073 | 0.8002 | 0.4477 | 0.045* | |
H12C | 0.2467 | 0.7417 | 0.5329 | 0.045* | |
O1 | 0.79500 (17) | 0.43385 (4) | 0.08503 (13) | 0.0252 (3) | |
H01 | 0.856 (4) | 0.4649 (10) | 0.074 (3) | 0.061 (7)* | |
O2 | 0.91320 (17) | 0.64404 (4) | 0.09580 (13) | 0.0256 (3) | |
H02 | 0.938 (4) | 0.6089 (10) | 0.076 (3) | 0.054 (6)* | |
O3 | 0.42231 (18) | 0.75449 (4) | 0.34290 (14) | 0.0281 (3) | |
O4 | 0.15523 (18) | 0.56347 (4) | 0.43754 (14) | 0.0307 (3) | |
O5 | 0.85900 (15) | 0.53826 (4) | 0.10111 (12) | 0.0235 (2) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0201 (7) | 0.0264 (7) | 0.0182 (6) | −0.0014 (5) | 0.0043 (5) | 0.0005 (5) |
C2 | 0.0219 (7) | 0.0231 (7) | 0.0193 (7) | −0.0020 (5) | −0.0005 (5) | 0.0019 (5) |
C3 | 0.0224 (7) | 0.0215 (7) | 0.0223 (7) | 0.0011 (5) | 0.0013 (5) | −0.0007 (5) |
C4 | 0.0183 (7) | 0.0252 (7) | 0.0172 (6) | 0.0022 (5) | 0.0021 (5) | 0.0005 (5) |
C4A | 0.0170 (6) | 0.0225 (7) | 0.0165 (6) | 0.0001 (5) | 0.0014 (5) | 0.0007 (5) |
C5 | 0.0175 (6) | 0.0272 (7) | 0.0180 (6) | −0.0021 (5) | 0.0008 (5) | 0.0011 (5) |
C6 | 0.0236 (7) | 0.0225 (7) | 0.0227 (7) | −0.0029 (5) | 0.0019 (6) | 0.0012 (5) |
C7 | 0.0245 (7) | 0.0220 (7) | 0.0207 (7) | 0.0021 (5) | −0.0013 (5) | −0.0009 (5) |
C8 | 0.0205 (7) | 0.0265 (7) | 0.0192 (7) | 0.0005 (5) | 0.0041 (5) | −0.0009 (5) |
C8A | 0.0181 (7) | 0.0241 (7) | 0.0171 (6) | −0.0009 (5) | 0.0016 (5) | −0.0002 (5) |
C9 | 0.0197 (7) | 0.0255 (7) | 0.0193 (6) | −0.0007 (5) | 0.0047 (5) | −0.0004 (5) |
C9A | 0.0185 (7) | 0.0227 (7) | 0.0173 (6) | 0.0000 (5) | 0.0023 (5) | 0.0001 (5) |
C10 | 0.0166 (6) | 0.0247 (7) | 0.0153 (6) | 0.0002 (5) | 0.0009 (5) | 0.0006 (5) |
C10A | 0.0182 (6) | 0.0220 (7) | 0.0159 (6) | −0.0007 (5) | 0.0008 (5) | 0.0003 (5) |
C11 | 0.0273 (8) | 0.0235 (7) | 0.0285 (8) | −0.0038 (6) | 0.0039 (6) | 0.0016 (6) |
C12 | 0.0281 (8) | 0.0274 (7) | 0.0346 (8) | 0.0029 (6) | 0.0062 (6) | −0.0035 (6) |
O1 | 0.0213 (5) | 0.0240 (5) | 0.0317 (6) | 0.0017 (4) | 0.0099 (4) | −0.0017 (4) |
O2 | 0.0219 (5) | 0.0261 (6) | 0.0303 (6) | −0.0032 (4) | 0.0100 (4) | 0.0008 (4) |
O3 | 0.0307 (6) | 0.0217 (5) | 0.0326 (6) | 0.0013 (4) | 0.0072 (5) | −0.0021 (4) |
O4 | 0.0287 (6) | 0.0275 (5) | 0.0389 (6) | −0.0025 (4) | 0.0186 (5) | −0.0041 (4) |
O5 | 0.0191 (5) | 0.0267 (5) | 0.0256 (5) | 0.0000 (4) | 0.0081 (4) | −0.0002 (4) |
C1—C9A | 1.3852 (19) | C9—O4 | 1.2211 (17) |
C1—C2 | 1.4046 (19) | C9—C9A | 1.4843 (19) |
C2—C3 | 1.3843 (19) | C10—O5 | 1.2542 (16) |
C2—C11 | 1.5055 (19) | C10—C10A | 1.4651 (18) |
C3—C4 | 1.3974 (19) | C12—O3 | 1.4374 (18) |
C4—O1 | 1.3475 (16) | C1—H1 | 0.9500 |
C4—C4A | 1.4124 (19) | C3—H3 | 0.9500 |
C4A—C9A | 1.4127 (18) | C6—H6 | 0.9500 |
C4A—C10 | 1.4652 (18) | C8—H8 | 0.9500 |
C5—O2 | 1.3464 (17) | C11—H11A | 0.9800 |
C5—C6 | 1.3927 (19) | C11—H11B | 0.9800 |
C5—C10A | 1.4166 (18) | C11—H11C | 0.9800 |
C6—C7 | 1.394 (2) | C12—H12A | 0.9800 |
C7—O3 | 1.3609 (16) | C12—H12B | 0.9800 |
C7—C8 | 1.397 (2) | C12—H12C | 0.9800 |
C8—C8A | 1.3844 (19) | O1—H01 | 0.86 (2) |
C8A—C10A | 1.4048 (18) | O2—H02 | 0.89 (3) |
C8A—C9 | 1.4921 (19) | ||
C9A—C1—C2 | 120.33 (13) | O5—C10—C4A | 120.49 (12) |
C3—C2—C1 | 118.99 (12) | C10A—C10—C4A | 119.13 (12) |
C3—C2—C11 | 121.09 (13) | C8A—C10A—C5 | 117.92 (12) |
C1—C2—C11 | 119.92 (13) | C8A—C10A—C10 | 120.81 (12) |
C2—C3—C4 | 121.47 (13) | C5—C10A—C10 | 121.24 (12) |
O1—C4—C3 | 117.51 (12) | C7—O3—C12 | 116.94 (11) |
O1—C4—C4A | 122.51 (12) | C9A—C1—H1 | 119.8 |
C3—C4—C4A | 119.97 (13) | C2—C1—H1 | 119.8 |
C4—C4A—C9A | 118.05 (12) | C2—C3—H3 | 119.3 |
C4—C4A—C10 | 120.91 (12) | C4—C3—H3 | 119.3 |
C9A—C4A—C10 | 121.03 (12) | C5—C6—H6 | 119.8 |
O2—C5—C6 | 116.87 (12) | C7—C6—H6 | 119.8 |
O2—C5—C10A | 123.00 (12) | C8A—C8—H8 | 120.5 |
C6—C5—C10A | 120.13 (13) | C7—C8—H8 | 120.5 |
C5—C6—C7 | 120.41 (13) | C2—C11—H11A | 109.5 |
O3—C7—C6 | 115.69 (12) | C2—C11—H11B | 109.5 |
O3—C7—C8 | 123.93 (13) | H11A—C11—H11B | 109.5 |
C6—C7—C8 | 120.37 (13) | C2—C11—H11C | 109.5 |
C8A—C8—C7 | 119.07 (13) | H11A—C11—H11C | 109.5 |
C8—C8A—C10A | 122.09 (12) | H11B—C11—H11C | 109.5 |
C8—C8A—C9 | 117.23 (12) | O3—C12—H12A | 109.5 |
C10A—C8A—C9 | 120.68 (12) | O3—C12—H12B | 109.5 |
O4—C9—C9A | 121.59 (12) | H12A—C12—H12B | 109.5 |
O4—C9—C8A | 120.43 (12) | O3—C12—H12C | 109.5 |
C9A—C9—C8A | 117.98 (12) | H12A—C12—H12C | 109.5 |
C1—C9A—C4A | 121.18 (13) | H12B—C12—H12C | 109.5 |
C1—C9A—C9 | 118.54 (12) | C4—O1—H01 | 106.1 (16) |
C4A—C9A—C9 | 120.28 (12) | C5—O2—H02 | 106.4 (14) |
O5—C10—C10A | 120.37 (12) | ||
C9A—C1—C2—C3 | 0.6 (2) | C10—C4A—C9A—C1 | 179.01 (12) |
C9A—C1—C2—C11 | −179.24 (12) | C4—C4A—C9A—C9 | 179.86 (11) |
C1—C2—C3—C4 | −0.4 (2) | C10—C4A—C9A—C9 | −0.98 (19) |
C11—C2—C3—C4 | 179.35 (13) | O4—C9—C9A—C1 | 2.7 (2) |
C2—C3—C4—O1 | −178.79 (12) | C8A—C9—C9A—C1 | −176.96 (12) |
C2—C3—C4—C4A | 0.0 (2) | O4—C9—C9A—C4A | −177.28 (13) |
O1—C4—C4A—C9A | 179.03 (12) | C8A—C9—C9A—C4A | 3.03 (19) |
C3—C4—C4A—C9A | 0.3 (2) | C4—C4A—C10—O5 | −1.14 (19) |
O1—C4—C4A—C10 | −0.1 (2) | C9A—C4A—C10—O5 | 179.72 (12) |
C3—C4—C4A—C10 | −178.89 (12) | C4—C4A—C10—C10A | 177.75 (12) |
O2—C5—C6—C7 | −179.89 (12) | C9A—C4A—C10—C10A | −1.38 (19) |
C10A—C5—C6—C7 | 0.8 (2) | C8—C8A—C10A—C5 | −0.5 (2) |
C5—C6—C7—O3 | −179.93 (12) | C9—C8A—C10A—C5 | 178.83 (12) |
C5—C6—C7—C8 | −0.8 (2) | C8—C8A—C10A—C10 | −178.84 (12) |
O3—C7—C8—C8A | 179.15 (12) | C9—C8A—C10A—C10 | 0.49 (19) |
C6—C7—C8—C8A | 0.1 (2) | O2—C5—C10A—C8A | −179.43 (12) |
C7—C8—C8A—C10A | 0.6 (2) | C6—C5—C10A—C8A | −0.20 (19) |
C7—C8—C8A—C9 | −178.78 (12) | O2—C5—C10A—C10 | −1.1 (2) |
C8—C8A—C9—O4 | −3.1 (2) | C6—C5—C10A—C10 | 178.12 (12) |
C10A—C8A—C9—O4 | 177.51 (13) | O5—C10—C10A—C8A | −179.48 (12) |
C8—C8A—C9—C9A | 176.57 (12) | C4A—C10—C10A—C8A | 1.63 (19) |
C10A—C8A—C9—C9A | −2.80 (19) | O5—C10—C10A—C5 | 2.2 (2) |
C2—C1—C9A—C4A | −0.3 (2) | C4A—C10—C10A—C5 | −176.65 (11) |
C2—C1—C9A—C9 | 179.72 (12) | C6—C7—O3—C12 | 177.68 (12) |
C4—C4A—C9A—C1 | −0.2 (2) | C8—C7—O3—C12 | −1.4 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H01···O5 | 0.86 (2) | 1.81 (2) | 2.5947 (14) | 150 (2) |
O2—H02···O5 | 0.89 (3) | 1.82 (3) | 2.6192 (14) | 148 (2) |
O1—H01···O5i | 0.86 (2) | 2.36 (2) | 2.8191 (15) | 113.4 (19) |
O2—H02···O1i | 0.89 (3) | 2.44 (2) | 3.0934 (15) | 130.3 (18) |
C12—H12B···O2ii | 0.98 | 2.65 | 3.4091 (18) | 134 |
C12—H12C···O3iii | 0.98 | 2.64 | 3.4878 (19) | 145 |
C1—H1···O4iv | 0.95 | 2.40 | 3.2900 (17) | 157 |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x−1, −y+3/2, z+1/2; (iii) x, −y+3/2, z+1/2; (iv) −x, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C16H12O5 |
Mr | 284.26 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 130 |
a, b, c (Å) | 6.1986 (3), 24.5470 (12), 8.1004 (4) |
β (°) | 95.370 (4) |
V (Å3) | 1227.12 (10) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 0.97 |
Crystal size (mm) | 0.25 × 0.10 × 0.04 |
Data collection | |
Diffractometer | Agilent Technologies Xcalibur (Atlas, Nova) diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Agilent, 2012) |
Tmin, Tmax | 0.646, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 43156, 2553, 2314 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.629 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.126, 1.05 |
No. of reflections | 2553 |
No. of parameters | 200 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.31, −0.25 |
Computer programs: CrysAlis PRO (Agilent, 2012), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XP (Siemens, 1994).
C4A—C9A | 1.4127 (18) | C9—O4 | 1.2211 (17) |
C4A—C10 | 1.4652 (18) | C9—C9A | 1.4843 (19) |
C8A—C10A | 1.4048 (18) | C10—O5 | 1.2542 (16) |
C8A—C9 | 1.4921 (19) | C10—C10A | 1.4651 (18) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H01···O5 | 0.86 (2) | 1.81 (2) | 2.5947 (14) | 150 (2) |
O2—H02···O5 | 0.89 (3) | 1.82 (3) | 2.6192 (14) | 148 (2) |
O1—H01···O5i | 0.86 (2) | 2.36 (2) | 2.8191 (15) | 113.4 (19) |
O2—H02···O1i | 0.89 (3) | 2.44 (2) | 3.0934 (15) | 130.3 (18) |
C12—H12B···O2ii | 0.98 | 2.65 | 3.4091 (18) | 134.0 |
C12—H12C···O3iii | 0.98 | 2.64 | 3.4878 (19) | 144.5 |
C1—H1···O4iv | 0.95 | 2.40 | 3.2900 (17) | 156.6 |
Symmetry codes: (i) −x+2, −y+1, −z; (ii) x−1, −y+3/2, z+1/2; (iii) x, −y+3/2, z+1/2; (iv) −x, −y+1, −z+1. |
Physcion (7-methoxy-2-methyl-4,5-dihydroxyanthracene-9,10-dione), (I), is a secondary metabolite occurring in many plants and fungi (Podojil et al., 1979). It was studied as early as the end of the 19th century (Zopf, 1898; Hesse, 1912). Ulický et al. (1991) crystallized it from chloroform and reported its structure in the solid state, in the space group P212121 [polymorph (Io)]. In a project aimed at isolating naturally occurring dyestuffs from plants, we have obtained this anthraquinone derivative from Xanthoria parietine, a lichen growing on numerous shrubs and trees in northern Germany. Our sample was obtained from lichen growing on elder trees (Sambucus nigra). In our hands, recrystallization from ethyl acetate led to a new polymorph, (Im), in the space group P21/c, the structure of which is reported here.
The molecule of (Im) is shown in Fig. 1. Its dimensions are determined rather more precisely than in the previous analysis, which may be attributed to the low-temperature data collection, the increased 2θ(max) and the more favourable data-to-parameter ratio for a centrosymmetric structure. The major features, however, remain essentially those reported by Ulický et al. (1991) and may be summarized as follows: (i) both –OH groups form intramolecular hydrogen bonds to the quinone O5 atom (Table 2); (ii) this lengthens the C10═O5 bond slightly compared to C9═O4 (for bond lengths see Table 1); (iii) the C10—C4A and C10—C10A bonds are lengthened slightly compared to C9—C9A and C9—C8A, associated with an increased contribution from a resonance form with a more aromatic region around C10 and a negative charge at O5; (iv) the molecule is slightly bent around the central C9···C10 axis, with an interplanar angle of 3.57 (6)° between the planes C1–C4/C4A/C9A/C9/C10 and C5–C8/C8A/C10A/C9/C10 (r.m.s. deviations from planarity = 0.006 and 0.009 Å, respectively).
The molecular packing of (Im) involves tapes of molecules parallel to [201] (Fig. 2). The molecules are linked by various hydrogen bonds (Table 2); around atom O5, the intramolecular systems are extended to asymmetric three-centre hydrogen bonds across the inversion centre 0, 1/2, 0, and the opposite ends of the molecules are linked by H1···O4iv [symmetry code: (iv) -x, -y+1, -z+1] across the inversion centre 0, 1/2, 1/2. H12B···O2ii [2.66 Å; symmetry code: (ii) x-1, -y+3/2, z+1/2] contacts may also be structurally significant, but are not shown explicitly in Fig. 2 (for `weak' hydrogen bonds, the cut-off criterion H···O ≤ 2.66 Å was used). Neighbouring tapes subtend an angle of 9.30 (2)°, so that all molecules in a layer consisting of such tapes are approximately parallel to each other. The tapes are linked in the third dimension by the contact H12C···O3iii [symmetry code: (iii) x, -y+3/2, z+1/2].
In order to analyse the packing of the previously determined P212121 polymorph (Io) (Ulický et al., 1991), we have taken the coordinates from the Cambridge Structural Database (CSD, version?; Allen, 2002; refcode SOHXAO), renumbered the atoms and standardized the C—H bond lengths (which showed a considerable scatter, associated with the free refinement of the H atoms) to conform with this paper. The following hydrogen bonds are found: (i) O2—H02···O1, with H2···O1 = 2.40 Å and angle = 118° (symmetry code: x+1/2, -y+1/2, -z+2); (ii) C3—H3···O3, with H3···O3 = 2.59 Å and angle = 154° (symmetry code: -x+1, y+1/2, -z+3/2; (iii) C11—H11C···O4, with H11C···O4 = 2.65 Å and angle = 152° (symmetry code: x-1/2, -y+1/2, -z+1). Qualitatively, the intermolecular contacts of (Io) differ appreciably from those of (Im): (a) only one of the intramolecular hydrogen bonds is extended intermolecularly to form a three-centre system; (b) atoms H1 and H8, next to the C9═O4 double bond, do not act as hydrogen-bond donors; (c) atom O4 accepts a hydrogen bond from a methyl H atom; (d) there is a `side-to-side' H3···O3 linkage. Despite these differences, at first sight the packing (Fig. 3) of (Io) appears similar to that of (Im), with apparent molecular tapes parallel to the c axis. However, this is an illusion arising from the projection along the short a axis. Where two molecules related by a-axis translation are seen (there are two such pairs in Fig. 3), it is clear that the linkages to neighbouring molecules in the c direction take place at different heights; in other words, the molecules are extensively crosslinked in the third dimension and are by no means parallel, with interplanar angles of circa 50° between neighbouring molecules in the c direction.
We noted a similar effect for two concomitant polymorphs of N,N'-bis[4-(diethylamino)phenyl]terephthaldiamide (Kuś et al., 2010); the triclinic polymorph consisted of essentially planar ribbons of molecules linked by classical hydrogen bonds, whereas the monoclinic polymorph consisted of an extensively crosslinked system. For both compounds, it is tempting to surmise that the crosslinked packing represents an island of kinetic stability en route to the simpler and presumably more efficient parallel packing. The density of (Im) is higher than that of (Io) (1.539 compared to 1.51 Mg m-3), but the different measurement temperatures do not allow a meaningful comparison. However, no corresponding energy calculations have been carried out and in neither case was the amount of material sufficient to undertake extensive experimental investigations of possible transformations betweem polymorphs, e.g. at different temperatures or in different solvent systems.