organic compounds
9-Methoxy-9-(2-methoxyphenyl)-9H-xanthene
aChemistry Department, Cape Peninsula University of Technology, PO Box 652, Cape Town, 8000, South Africa, and bSasol Technologies, R&D Klasie Havenga Road 1, Sasolburg 1947, South Africa
*Correspondence e-mail: jacobsa@cput.ac.za
In the title compound, C21H18O3, the xanthene system and the methoxyphenyl ring are practically orthogonal with a dihedral angle between their mean planes of 89.27 (3)°. The methoxy group attached to the phenyl ring makes a C—O—C—C torsion angle of 11.56 (18)°. In the crystal, molecules are linked by C—H⋯O interactions into chains along [010]. Weak C—H⋯π interactions also occur.
Related literature
For the synthesis of the parent xanthenol compound 9-(2-methoxyphenyl)-9H-xanthen-9-ol, see: Dilthey et al. (1939). For related inclusion chemistry of 9-(2-methoxyphenyl)-9H-xanthen-9-ol, see: Jacobs et al. (2005, 2007, 2009). For related structures, see: Das et al. (2007). For the design of host compounds, see: Weber (1991) and for a review of C—H⋯O interactions, see: Steiner (1997).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2005); cell SAINT-Plus (Bruker, 2005); data reduction: SAINT-Plus and XPREP (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536812037415/hg5247sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812037415/hg5247Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536812037415/hg5247Isup3.cml
A crystal of 9-methoxy-9-(2-methoxyphenyl)-9H-xanthene was prepared serendipitously by slow evaporation of a
of 9-(2-methoxyphenyl)-9H-xanthen-9-ol and theophylline in a 50:50 mixture of methanol/chloroform.The aromatic and methyl hydrogen atoms were geometrically constrained, with C—H distances fixed at 0.95 Å and 0.98 Å respectively. For the aromatic H atoms Uiso(H) = 1.2Ueq(Caryl) and for the methyl H atoms Uiso(H) = 1.5Ueq(Cmethyl).
The starting material, 9-(2-methoxyphenyl)-9H-xanthen-9-ol, was synthesized by reported methods (Dilthey et al., 1939). Xanthenol compounds have been used extensively in host–guest chemistry as versatile hosts for the inclusion of small organic guests (Jacobs et al., 2005), solvent free reactions (Jacobs et al., 2009) and guest exchange experiments (Jacobs et al., 2007). This class of compounds conforms to Weber's rules (Weber, 1991) for efficient hosts in that they are bulky and contain functionalities that can participate in hydrogen bonding. Charge delocalization into the adjacent aromatic rings of the xanthene moiety can stabilize a cationic centre at C13 (Fig. 1), facilitating nucleophilic attack. The loss of the hydroxyl group yields a compound without a strong hydrogen bond donor.
The structure crystallized in P21/c with one molecule in the π-bond systems. An intramolecular C—H··· O contact [C···O = 2.663 (1) Å and C—H··· O = 102°] gives rise to a torsion angle O2—C13—C14—C19 = -0.14 (17)°.
Short C—H··· O contacts [C···O = 3.303 (2) Å and C—H···O = 136°] link adjacent molecules into anti-parallel chains along [010] (Fig. 2). Similar resonance assisted weak hydrogen bonding has been described (Steiner, 1997) for polarisableWeaker C—H···π interactions include C20···π(C14—C19) = 3.680 Å and an intramolecular C21···π(O1—C13) = 2.974 Å. The shortest π–π contact of 4.034 Å is an intramolecular edge to face interaction between π(O1—C13) and π(C14—C19). Ten xanthene derivatives were synthesized from the parent compound 9-phenyl-9H-xanthene-9-ol and selected (Das et al., 2007). C—H···π, C—H···O and π–π interactions dominated the structures with typical distances of 2.664 Å, 3.378 Å and 4.691 Å respectively.
The packing diagram down [010] is shown in Fig. 3. The xanthene ring and the methoxyphenyl moiety are practically orthogonal with a dihedral angle between the least squares planes of 89.27 (3)°. The methoxy moiety attached to the phenyl ring deviates from the C14—C19 plane with a resultant C20—O3—C15—C16 torsion angle of 11.56 (18)°.
For the synthesis of the parent xanthenol compound 9-(2-methoxyphenyl)-9H-xanthen-9-ol, see: Dilthey et al. (1939). For related inclusion chemistry of 9-(2-methoxyphenyl)-9H-xanthen-9-ol, see: Jacobs et al. (2005, 2007, 2009). For related structures, see: Das et al. (2007). For the design of host compounds, see: Weber (1991) and for a review of C—H···O interactions, see: Steiner (1997).
Data collection: APEX2 (Bruker, 2005); cell
SAINT-Plus (Bruker, 2005); data reduction: SAINT-Plus and XPREP (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).C21H18O3 | F(000) = 672 |
Mr = 318.35 | Dx = 1.307 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 15054 reflections |
a = 8.0665 (6) Å | θ = 0.1–28.4° |
b = 9.7653 (7) Å | µ = 0.09 mm−1 |
c = 21.3191 (15) Å | T = 173 K |
β = 105.560 (2)° | Block, colourless |
V = 1617.8 (2) Å3 | 0.22 × 0.16 × 0.03 mm |
Z = 4 |
Bruker Kappa DUO APEXII diffractometer | 4041 independent reflections |
Radiation source: fine-focus sealed tube | 2779 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.039 |
1.2° φ scans and ω scans | θmax = 28.4°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −10→10 |
Tmin = 0.833, Tmax = 0.997 | k = −13→13 |
15054 measured reflections | l = −28→28 |
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) = 0.117 | H-atom parameters not refined |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0561P)2 + 0.1933P] where P = (Fo2 + 2Fc2)/3 |
4041 reflections | (Δ/σ)max < 0.001 |
219 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
C21H18O3 | V = 1617.8 (2) Å3 |
Mr = 318.35 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 8.0665 (6) Å | µ = 0.09 mm−1 |
b = 9.7653 (7) Å | T = 173 K |
c = 21.3191 (15) Å | 0.22 × 0.16 × 0.03 mm |
β = 105.560 (2)° |
Bruker Kappa DUO APEXII diffractometer | 4041 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2779 reflections with I > 2σ(I) |
Tmin = 0.833, Tmax = 0.997 | Rint = 0.039 |
15054 measured reflections |
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.117 | H-atom parameters not refined |
S = 1.02 | Δρmax = 0.27 e Å−3 |
4041 reflections | Δρmin = −0.19 e Å−3 |
219 parameters |
Experimental. Absorption corrections were made using the program SADABS (Sheldrick, 1996) |
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. |
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 | ||
O1 | 0.82930 (15) | 0.95042 (11) | 0.39263 (5) | 0.0427 (3) | |
C1 | 0.73618 (16) | 0.76549 (14) | 0.31531 (6) | 0.0251 (3) | |
O2 | 0.47131 (11) | 0.66412 (10) | 0.32726 (5) | 0.0325 (2) | |
C2 | 0.73692 (18) | 0.71286 (16) | 0.25441 (7) | 0.0313 (3) | |
H2 | 0.6815 | 0.6280 | 0.2406 | 0.038* | |
O3 | 0.99412 (11) | 0.65133 (9) | 0.42002 (5) | 0.0279 (2) | |
C3 | 0.8170 (2) | 0.78202 (17) | 0.21389 (7) | 0.0371 (4) | |
H3 | 0.8166 | 0.7445 | 0.1727 | 0.045* | |
C4 | 0.8974 (2) | 0.90572 (18) | 0.23344 (7) | 0.0399 (4) | |
H4 | 0.9525 | 0.9533 | 0.2057 | 0.048* | |
C5 | 0.8977 (2) | 0.96002 (17) | 0.29298 (8) | 0.0407 (4) | |
H5 | 0.9520 | 1.0454 | 0.3065 | 0.049* | |
C6 | 0.81755 (19) | 0.88880 (15) | 0.33336 (7) | 0.0312 (3) | |
C7 | 0.66711 (16) | 0.76469 (14) | 0.42281 (6) | 0.0246 (3) | |
C8 | 0.59500 (16) | 0.71138 (16) | 0.47021 (7) | 0.0296 (3) | |
H8 | 0.5380 | 0.6254 | 0.4630 | 0.036* | |
C9 | 0.60486 (18) | 0.78131 (17) | 0.52757 (7) | 0.0365 (4) | |
H9 | 0.5537 | 0.7442 | 0.5591 | 0.044* | |
C10 | 0.6899 (2) | 0.90574 (17) | 0.53863 (7) | 0.0396 (4) | |
H10 | 0.6972 | 0.9540 | 0.5780 | 0.047* | |
C11 | 0.7638 (2) | 0.95994 (16) | 0.49306 (7) | 0.0380 (4) | |
H11 | 0.8230 | 1.0450 | 0.5009 | 0.046* | |
C12 | 0.75102 (18) | 0.88861 (15) | 0.43524 (7) | 0.0299 (3) | |
C13 | 0.65042 (16) | 0.68674 (14) | 0.35959 (6) | 0.0241 (3) | |
C14 | 0.72913 (16) | 0.54401 (13) | 0.37383 (6) | 0.0233 (3) | |
C15 | 0.90553 (16) | 0.53114 (13) | 0.40499 (6) | 0.0228 (3) | |
C16 | 0.98038 (18) | 0.40271 (14) | 0.41893 (6) | 0.0278 (3) | |
H16 | 1.0993 | 0.3948 | 0.4406 | 0.033* | |
C17 | 0.88084 (19) | 0.28611 (15) | 0.40104 (7) | 0.0318 (3) | |
H17 | 0.9321 | 0.1983 | 0.4104 | 0.038* | |
C18 | 0.70841 (19) | 0.29672 (15) | 0.36984 (7) | 0.0336 (3) | |
H18 | 0.6412 | 0.2164 | 0.3574 | 0.040* | |
C19 | 0.63261 (18) | 0.42523 (14) | 0.35658 (7) | 0.0296 (3) | |
H19 | 0.5132 | 0.4319 | 0.3354 | 0.035* | |
C20 | 1.17721 (17) | 0.64420 (16) | 0.44035 (7) | 0.0330 (3) | |
H20C | 1.2137 | 0.5977 | 0.4826 | 0.050* | |
H20A | 1.2251 | 0.7370 | 0.4444 | 0.050* | |
H20B | 1.2188 | 0.5930 | 0.4081 | 0.050* | |
C21 | 0.3706 (2) | 0.78492 (18) | 0.31020 (8) | 0.0416 (4) | |
H21A | 0.3727 | 0.8370 | 0.3497 | 0.062* | |
H21B | 0.2517 | 0.7598 | 0.2880 | 0.062* | |
H21C | 0.4181 | 0.8412 | 0.2811 | 0.062* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0741 (8) | 0.0255 (5) | 0.0355 (6) | −0.0153 (5) | 0.0270 (6) | −0.0072 (5) |
C1 | 0.0279 (7) | 0.0237 (7) | 0.0234 (7) | 0.0048 (5) | 0.0063 (5) | 0.0034 (5) |
O2 | 0.0226 (5) | 0.0347 (6) | 0.0355 (6) | 0.0027 (4) | −0.0002 (4) | 0.0000 (5) |
C2 | 0.0361 (7) | 0.0310 (8) | 0.0253 (7) | 0.0053 (6) | 0.0054 (6) | −0.0008 (6) |
O3 | 0.0222 (5) | 0.0243 (5) | 0.0349 (5) | −0.0020 (4) | 0.0038 (4) | −0.0015 (4) |
C3 | 0.0445 (8) | 0.0451 (9) | 0.0234 (7) | 0.0123 (7) | 0.0121 (6) | 0.0038 (7) |
C4 | 0.0473 (9) | 0.0440 (10) | 0.0330 (8) | 0.0056 (7) | 0.0188 (7) | 0.0121 (7) |
C5 | 0.0581 (10) | 0.0297 (8) | 0.0391 (9) | −0.0066 (7) | 0.0212 (8) | 0.0030 (7) |
C6 | 0.0433 (8) | 0.0265 (7) | 0.0263 (7) | 0.0021 (6) | 0.0134 (6) | 0.0007 (6) |
C7 | 0.0234 (6) | 0.0268 (7) | 0.0237 (6) | 0.0068 (5) | 0.0061 (5) | 0.0021 (5) |
C8 | 0.0230 (6) | 0.0359 (8) | 0.0307 (7) | 0.0033 (6) | 0.0083 (5) | 0.0049 (6) |
C9 | 0.0331 (8) | 0.0520 (10) | 0.0280 (7) | 0.0100 (7) | 0.0144 (6) | 0.0068 (7) |
C10 | 0.0464 (9) | 0.0469 (10) | 0.0263 (8) | 0.0159 (8) | 0.0114 (7) | −0.0041 (7) |
C11 | 0.0532 (9) | 0.0293 (8) | 0.0331 (8) | 0.0039 (7) | 0.0141 (7) | −0.0072 (7) |
C12 | 0.0391 (8) | 0.0263 (7) | 0.0268 (7) | 0.0037 (6) | 0.0128 (6) | 0.0010 (6) |
C13 | 0.0220 (6) | 0.0242 (7) | 0.0246 (7) | 0.0007 (5) | 0.0035 (5) | −0.0004 (5) |
C14 | 0.0260 (6) | 0.0221 (6) | 0.0223 (6) | −0.0006 (5) | 0.0074 (5) | 0.0003 (5) |
C15 | 0.0272 (6) | 0.0215 (7) | 0.0210 (6) | −0.0017 (5) | 0.0087 (5) | −0.0008 (5) |
C16 | 0.0319 (7) | 0.0273 (7) | 0.0255 (7) | 0.0055 (6) | 0.0098 (6) | 0.0037 (6) |
C17 | 0.0461 (8) | 0.0214 (7) | 0.0318 (7) | 0.0042 (6) | 0.0174 (6) | 0.0021 (6) |
C18 | 0.0437 (8) | 0.0226 (7) | 0.0368 (8) | −0.0081 (6) | 0.0147 (7) | −0.0039 (6) |
C19 | 0.0305 (7) | 0.0289 (7) | 0.0291 (7) | −0.0055 (6) | 0.0077 (6) | −0.0022 (6) |
C20 | 0.0238 (7) | 0.0382 (9) | 0.0365 (8) | −0.0024 (6) | 0.0071 (6) | −0.0056 (7) |
C21 | 0.0338 (8) | 0.0505 (10) | 0.0377 (9) | 0.0128 (7) | 0.0047 (7) | 0.0065 (8) |
O1—C12 | 1.3769 (17) | C9—H9 | 0.9500 |
O1—C6 | 1.3796 (17) | C10—C11 | 1.375 (2) |
C1—C6 | 1.376 (2) | C10—H10 | 0.9500 |
C1—C2 | 1.3979 (19) | C11—C12 | 1.396 (2) |
C1—C13 | 1.5202 (18) | C11—H11 | 0.9500 |
O2—C21 | 1.4230 (18) | C13—C14 | 1.5279 (18) |
O2—C13 | 1.4412 (15) | C14—C19 | 1.3904 (18) |
C2—C3 | 1.385 (2) | C14—C15 | 1.4052 (18) |
C2—H2 | 0.9500 | C15—C16 | 1.3890 (18) |
O3—C15 | 1.3668 (15) | C16—C17 | 1.387 (2) |
O3—C20 | 1.4250 (16) | C16—H16 | 0.9500 |
C3—C4 | 1.382 (2) | C17—C18 | 1.375 (2) |
C3—H3 | 0.9500 | C17—H17 | 0.9500 |
C4—C5 | 1.375 (2) | C18—C19 | 1.391 (2) |
C4—H4 | 0.9500 | C18—H18 | 0.9500 |
C5—C6 | 1.393 (2) | C19—H19 | 0.9500 |
C5—H5 | 0.9500 | C20—H20C | 0.9800 |
C7—C12 | 1.377 (2) | C20—H20A | 0.9800 |
C7—C8 | 1.3950 (18) | C20—H20B | 0.9800 |
C7—C13 | 1.5221 (18) | C21—H21A | 0.9800 |
C8—C9 | 1.384 (2) | C21—H21B | 0.9800 |
C8—H8 | 0.9500 | C21—H21C | 0.9800 |
C9—C10 | 1.384 (2) | ||
C12—O1—C6 | 118.82 (11) | C7—C12—C11 | 121.65 (14) |
C6—C1—C2 | 117.45 (13) | O2—C13—C1 | 110.21 (10) |
C6—C1—C13 | 122.10 (12) | O2—C13—C7 | 109.83 (10) |
C2—C1—C13 | 120.44 (12) | C1—C13—C7 | 110.48 (11) |
C21—O2—C13 | 115.17 (11) | O2—C13—C14 | 105.37 (10) |
C3—C2—C1 | 121.25 (14) | C1—C13—C14 | 110.54 (10) |
C3—C2—H2 | 119.4 | C7—C13—C14 | 110.30 (11) |
C1—C2—H2 | 119.4 | C19—C14—C15 | 118.33 (12) |
C15—O3—C20 | 117.61 (11) | C19—C14—C13 | 122.35 (12) |
C4—C3—C2 | 119.87 (14) | C15—C14—C13 | 119.32 (11) |
C4—C3—H3 | 120.1 | O3—C15—C16 | 123.72 (12) |
C2—C3—H3 | 120.1 | O3—C15—C14 | 115.69 (11) |
C5—C4—C3 | 119.99 (14) | C16—C15—C14 | 120.59 (12) |
C5—C4—H4 | 120.0 | C17—C16—C15 | 119.75 (13) |
C3—C4—H4 | 120.0 | C17—C16—H16 | 120.1 |
C4—C5—C6 | 119.46 (15) | C15—C16—H16 | 120.1 |
C4—C5—H5 | 120.3 | C18—C17—C16 | 120.47 (13) |
C6—C5—H5 | 120.3 | C18—C17—H17 | 119.8 |
C1—C6—O1 | 123.24 (13) | C16—C17—H17 | 119.8 |
C1—C6—C5 | 121.98 (14) | C17—C18—C19 | 119.91 (13) |
O1—C6—C5 | 114.77 (13) | C17—C18—H18 | 120.0 |
C12—C7—C8 | 117.87 (13) | C19—C18—H18 | 120.0 |
C12—C7—C13 | 122.14 (12) | C14—C19—C18 | 120.95 (13) |
C8—C7—C13 | 119.99 (12) | C14—C19—H19 | 119.5 |
C9—C8—C7 | 121.30 (14) | C18—C19—H19 | 119.5 |
C9—C8—H8 | 119.3 | O3—C20—H20C | 109.5 |
C7—C8—H8 | 119.3 | O3—C20—H20A | 109.5 |
C10—C9—C8 | 119.48 (14) | H20C—C20—H20A | 109.5 |
C10—C9—H9 | 120.3 | O3—C20—H20B | 109.5 |
C8—C9—H9 | 120.3 | H20C—C20—H20B | 109.5 |
C11—C10—C9 | 120.44 (14) | H20A—C20—H20B | 109.5 |
C11—C10—H10 | 119.8 | O2—C21—H21A | 109.5 |
C9—C10—H10 | 119.8 | O2—C21—H21B | 109.5 |
C10—C11—C12 | 119.25 (15) | H21A—C21—H21B | 109.5 |
C10—C11—H11 | 120.4 | O2—C21—H21C | 109.5 |
C12—C11—H11 | 120.4 | H21A—C21—H21C | 109.5 |
O1—C12—C7 | 123.16 (13) | H21B—C21—H21C | 109.5 |
O1—C12—C11 | 115.19 (13) | ||
C6—C1—C2—C3 | 0.2 (2) | C2—C1—C13—O2 | −58.56 (16) |
C13—C1—C2—C3 | −178.88 (12) | C6—C1—C13—C7 | 0.85 (17) |
C1—C2—C3—C4 | −0.3 (2) | C2—C1—C13—C7 | 179.88 (11) |
C2—C3—C4—C5 | −0.1 (2) | C6—C1—C13—C14 | −121.52 (14) |
C3—C4—C5—C6 | 0.5 (2) | C2—C1—C13—C14 | 57.51 (16) |
C2—C1—C6—O1 | −178.58 (13) | C12—C7—C13—O2 | −122.18 (13) |
C13—C1—C6—O1 | 0.5 (2) | C8—C7—C13—O2 | 57.33 (15) |
C2—C1—C6—C5 | 0.2 (2) | C12—C7—C13—C1 | −0.39 (17) |
C13—C1—C6—C5 | 179.28 (13) | C8—C7—C13—C1 | 179.12 (11) |
C12—O1—C6—C1 | −2.3 (2) | C12—C7—C13—C14 | 122.12 (13) |
C12—O1—C6—C5 | 178.78 (13) | C8—C7—C13—C14 | −58.37 (15) |
C4—C5—C6—C1 | −0.6 (2) | O2—C13—C14—C19 | −0.14 (17) |
C4—C5—C6—O1 | 178.33 (14) | C1—C13—C14—C19 | −119.20 (14) |
C12—C7—C8—C9 | 0.9 (2) | C7—C13—C14—C19 | 118.33 (14) |
C13—C7—C8—C9 | −178.59 (12) | O2—C13—C14—C15 | 179.34 (11) |
C7—C8—C9—C10 | −0.9 (2) | C1—C13—C14—C15 | 60.29 (15) |
C8—C9—C10—C11 | 0.1 (2) | C7—C13—C14—C15 | −62.19 (15) |
C9—C10—C11—C12 | 0.5 (2) | C20—O3—C15—C16 | 11.56 (18) |
C6—O1—C12—C7 | 2.8 (2) | C20—O3—C15—C14 | −168.57 (11) |
C6—O1—C12—C11 | −177.83 (13) | C19—C14—C15—O3 | 179.21 (12) |
C8—C7—C12—O1 | 179.04 (13) | C13—C14—C15—O3 | −0.29 (17) |
C13—C7—C12—O1 | −1.4 (2) | C19—C14—C15—C16 | −0.92 (19) |
C8—C7—C12—C11 | −0.3 (2) | C13—C14—C15—C16 | 179.58 (12) |
C13—C7—C12—C11 | 179.25 (13) | O3—C15—C16—C17 | −179.11 (12) |
C10—C11—C12—O1 | −179.81 (13) | C14—C15—C16—C17 | 1.02 (19) |
C10—C11—C12—C7 | −0.5 (2) | C15—C16—C17—C18 | −0.3 (2) |
C21—O2—C13—C1 | −61.78 (14) | C16—C17—C18—C19 | −0.6 (2) |
C21—O2—C13—C7 | 60.16 (15) | C15—C14—C19—C18 | 0.1 (2) |
C21—O2—C13—C14 | 178.95 (11) | C13—C14—C19—C18 | 179.55 (13) |
C6—C1—C13—O2 | 122.41 (14) | C17—C18—C19—C14 | 0.7 (2) |
Cg is the centroid of the C14–C19 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
C17—H17···O1i | 0.95 | 2.55 | 3.303 (2) | 136 |
C19—H19···O2 | 0.95 | 2.29 | 2.663 (1) | 102 |
C20—H20C···Cgii | 0.98 | 2.82 | 3.6802 (16) | 147 |
Symmetry codes: (i) x, y−1, z; (ii) −x+2, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C21H18O3 |
Mr | 318.35 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 173 |
a, b, c (Å) | 8.0665 (6), 9.7653 (7), 21.3191 (15) |
β (°) | 105.560 (2) |
V (Å3) | 1617.8 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.22 × 0.16 × 0.03 |
Data collection | |
Diffractometer | Bruker Kappa DUO APEXII |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.833, 0.997 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 15054, 4041, 2779 |
Rint | 0.039 |
(sin θ/λ)max (Å−1) | 0.670 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.117, 1.02 |
No. of reflections | 4041 |
No. of parameters | 219 |
H-atom treatment | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.27, −0.19 |
Computer programs: APEX2 (Bruker, 2005), SAINT-Plus (Bruker, 2005), SAINT-Plus and XPREP (Bruker, 2005), SHELXS97 (Sheldrick, 2008), X-SEED (Barbour, 2001), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
Cg is the centroid of the C14–C19 ring. |
D—H···A | D—H | H···A | D···A | D—H···A |
C17—H17···O1i | 0.95 | 2.55 | 3.303 (2) | 136 |
C20—H20C···Cgii | 0.98 | 2.82 | 3.6802 (16) | 147 |
Symmetry codes: (i) x, y−1, z; (ii) −x+2, −y+1, −z+1. |
Acknowledgements
We thank the Cape Peninsula University of Technology and the National Research Foundation.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The starting material, 9-(2-methoxyphenyl)-9H-xanthen-9-ol, was synthesized by reported methods (Dilthey et al., 1939). Xanthenol compounds have been used extensively in host–guest chemistry as versatile hosts for the inclusion of small organic guests (Jacobs et al., 2005), solvent free reactions (Jacobs et al., 2009) and guest exchange experiments (Jacobs et al., 2007). This class of compounds conforms to Weber's rules (Weber, 1991) for efficient hosts in that they are bulky and contain functionalities that can participate in hydrogen bonding. Charge delocalization into the adjacent aromatic rings of the xanthene moiety can stabilize a cationic centre at C13 (Fig. 1), facilitating nucleophilic attack. The loss of the hydroxyl group yields a compound without a strong hydrogen bond donor.
The structure crystallized in P21/c with one molecule in the asymmetric unit. Short C—H··· O contacts [C···O = 3.303 (2) Å and C—H···O = 136°] link adjacent molecules into anti-parallel chains along [010] (Fig. 2). Similar resonance assisted weak hydrogen bonding has been described (Steiner, 1997) for polarisable π-bond systems. An intramolecular C—H··· O contact [C···O = 2.663 (1) Å and C—H··· O = 102°] gives rise to a torsion angle O2—C13—C14—C19 = -0.14 (17)°.
Weaker C—H···π interactions include C20···π(C14—C19) = 3.680 Å and an intramolecular C21···π(O1—C13) = 2.974 Å. The shortest π–π contact of 4.034 Å is an intramolecular edge to face interaction between π(O1—C13) and π(C14—C19). Ten xanthene derivatives were synthesized from the parent compound 9-phenyl-9H-xanthene-9-ol and selected ketones (Das et al., 2007). C—H···π, C—H···O and π–π interactions dominated the structures with typical distances of 2.664 Å, 3.378 Å and 4.691 Å respectively.
The packing diagram down [010] is shown in Fig. 3. The xanthene ring and the methoxyphenyl moiety are practically orthogonal with a dihedral angle between the least squares planes of 89.27 (3)°. The methoxy moiety attached to the phenyl ring deviates from the C14—C19 plane with a resultant C20—O3—C15—C16 torsion angle of 11.56 (18)°.