Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104015549/fg1755sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104015549/fg1755Isup2.hkl |
CCDC reference: 248179
Curcumin, (II), was converted to tetrahydrocurcumin, (I), by hydrogenation, with PtO2 as the catalyst, according to the method of Uehara et al. (1987). Single crystals of (I) were grown by slow evaporation of a solution in methanol.
All H atoms were visible in difference maps. It was clear that there was H-atom disorder at the O3 and O5 sites, and this was allowed for by refinement of linked occupancy parameters for atoms H3 and H5 [final values 0.54 (4) and 0.46 (4)]. All H atoms were treated as riding, with C—H = 0.93 for aromatic H, 0.97 for CH2 H and 0.96 Å for CH3 H, and with Uiso(methyl H) = 1.5Ueq(C) and all other Uiso(H) = 1.2Ueq(C).
Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON.
C21H24O6 | Z = 2 |
Mr = 372.40 | F(000) = 396 |
Triclinic, P1 | Dx = 1.266 Mg m−3 |
Hall symbol: -P 1 | Melting point = 371–372 K |
a = 7.981 (3) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 11.388 (3) Å | Cell parameters from 400 reflections |
c = 12.497 (3) Å | θ = 2.6–20.9° |
α = 117.065 (3)° | µ = 0.09 mm−1 |
β = 100.394 (10)° | T = 293 K |
γ = 94.856 (3)° | Prism, off-white |
V = 976.7 (5) Å3 | 0.40 × 0.35 × 0.30 mm |
Bruker SMART APEX CCD area-detector diffractometer | 3933 independent reflections |
Radiation source: fine-focus sealed | 3244 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.014 |
Detector resolution: 0.3 pixels mm-1 | θmax = 27.1°, θmin = 1.9° |
ϕ and ω scans | h = −9→9 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | k = −14→14 |
Tmin = 0.893, Tmax = 0.981 | l = −15→15 |
10125 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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.171 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0943P)2 + 0.1978P] where P = (Fo2 + 2Fc2)/3 |
3933 reflections | (Δ/σ)max < 0.001 |
251 parameters | Δρmax = 0.30 e Å−3 |
0 restraints | Δρmin = −0.36 e Å−3 |
C21H24O6 | γ = 94.856 (3)° |
Mr = 372.40 | V = 976.7 (5) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.981 (3) Å | Mo Kα radiation |
b = 11.388 (3) Å | µ = 0.09 mm−1 |
c = 12.497 (3) Å | T = 293 K |
α = 117.065 (3)° | 0.40 × 0.35 × 0.30 mm |
β = 100.394 (10)° |
Bruker SMART APEX CCD area-detector diffractometer | 3933 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 3244 reflections with I > 2σ(I) |
Tmin = 0.893, Tmax = 0.981 | Rint = 0.014 |
10125 measured reflections |
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.171 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.30 e Å−3 |
3933 reflections | Δρmin = −0.36 e Å−3 |
251 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. |
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 |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
O3 | 0.39116 (19) | 0.10484 (12) | 0.15185 (11) | 0.0695 (4) | |
H3 | 0.4156 | 0.1174 | 0.2233 | 0.083* | 0.54 (4) |
O5 | 0.5533 (2) | 0.20794 (16) | 0.37143 (12) | 0.0866 (5) | |
H5 | 0.5018 | 0.1472 | 0.3024 | 0.104* | 0.46 (4) |
O13 | 0.5788 (2) | 0.16537 (16) | −0.39619 (13) | 0.0808 (4) | |
O14 | 0.30604 (19) | 0.25057 (16) | −0.47282 (12) | 0.0746 (4) | |
H14 | 0.3868 | 0.2246 | −0.5040 | 0.089* | |
O73 | 1.0931 (2) | 0.91069 (13) | 0.84928 (12) | 0.0770 (4) | |
O74 | 1.17662 (19) | 0.85429 (13) | 1.03595 (12) | 0.0748 (4) | |
H74 | 1.2083 | 0.9216 | 1.0309 | 0.090* | |
C1 | 0.4644 (3) | 0.32948 (19) | 0.01914 (16) | 0.0664 (5) | |
H1A | 0.5892 | 0.3570 | 0.0517 | 0.080* | |
H1B | 0.4112 | 0.4013 | 0.0705 | 0.080* | |
C2 | 0.4046 (3) | 0.20418 (18) | 0.02555 (15) | 0.0629 (5) | |
H2A | 0.2787 | 0.1840 | 0.0016 | 0.075* | |
H2B | 0.4446 | 0.1303 | −0.0355 | 0.075* | |
C3 | 0.4626 (2) | 0.20850 (16) | 0.14839 (14) | 0.0519 (4) | |
C4 | 0.5807 (2) | 0.31142 (17) | 0.25120 (15) | 0.0586 (4) | |
H4 | 0.6312 | 0.3850 | 0.2464 | 0.070* | |
C5 | 0.6245 (2) | 0.30593 (19) | 0.36145 (15) | 0.0638 (5) | |
C6 | 0.7564 (3) | 0.4152 (3) | 0.47335 (18) | 0.0936 (8) | |
H6A | 0.8648 | 0.3833 | 0.4796 | 0.112* | |
H6B | 0.7772 | 0.4921 | 0.4600 | 0.112* | |
C7 | 0.7092 (3) | 0.4592 (2) | 0.58977 (19) | 0.0894 (7) | |
H7A | 0.6813 | 0.3809 | 0.6000 | 0.107* | |
H7B | 0.6040 | 0.4953 | 0.5843 | 0.107* | |
C11 | 0.4176 (2) | 0.30701 (18) | −0.11265 (16) | 0.0606 (4) | |
C12 | 0.5203 (2) | 0.24394 (18) | −0.19180 (16) | 0.0604 (4) | |
H12 | 0.6155 | 0.2148 | −0.1636 | 0.072* | |
C13 | 0.4842 (2) | 0.22343 (17) | −0.31199 (16) | 0.0573 (4) | |
C14 | 0.3407 (2) | 0.26661 (18) | −0.35512 (16) | 0.0585 (4) | |
C15 | 0.2363 (3) | 0.3266 (2) | −0.2782 (2) | 0.0697 (5) | |
H15 | 0.1397 | 0.3541 | −0.3069 | 0.084* | |
C16 | 0.2739 (3) | 0.3464 (2) | −0.1577 (2) | 0.0712 (5) | |
H16 | 0.2015 | 0.3867 | −0.1064 | 0.085* | |
C17 | 0.7194 (3) | 0.1110 (3) | −0.3642 (2) | 0.0909 (7) | |
H17A | 0.8035 | 0.1810 | −0.2934 | 0.136* | |
H17B | 0.7720 | 0.0720 | −0.4327 | 0.136* | |
H17C | 0.6787 | 0.0431 | −0.3447 | 0.136* | |
C71 | 0.8420 (2) | 0.56352 (18) | 0.70586 (16) | 0.0635 (5) | |
C72 | 0.9076 (2) | 0.68742 (18) | 0.71750 (15) | 0.0606 (4) | |
H72 | 0.8751 | 0.7043 | 0.6513 | 0.073* | |
C73 | 1.0208 (2) | 0.78580 (16) | 0.82674 (15) | 0.0541 (4) | |
C74 | 1.0678 (2) | 0.76016 (16) | 0.92587 (15) | 0.0536 (4) | |
C75 | 1.0056 (2) | 0.63703 (18) | 0.91353 (17) | 0.0615 (4) | |
H75 | 1.0393 | 0.6193 | 0.9791 | 0.074* | |
C76 | 0.8930 (2) | 0.53917 (19) | 0.80371 (18) | 0.0665 (5) | |
H76 | 0.8516 | 0.4563 | 0.7963 | 0.080* | |
C77 | 1.0531 (4) | 0.9437 (2) | 0.7527 (2) | 0.0900 (7) | |
H77A | 1.0913 | 0.8826 | 0.6827 | 0.135* | |
H77B | 1.1108 | 1.0338 | 0.7808 | 0.135* | |
H77C | 0.9300 | 0.9373 | 0.7290 | 0.135* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O3 | 0.0938 (9) | 0.0544 (7) | 0.0412 (6) | −0.0169 (6) | 0.0000 (6) | 0.0183 (5) |
O5 | 0.1199 (12) | 0.0797 (10) | 0.0417 (7) | −0.0229 (9) | −0.0039 (7) | 0.0293 (7) |
O13 | 0.0994 (10) | 0.1012 (11) | 0.0644 (8) | 0.0414 (9) | 0.0281 (7) | 0.0519 (8) |
O14 | 0.0819 (9) | 0.0921 (10) | 0.0566 (7) | 0.0116 (8) | −0.0003 (6) | 0.0485 (7) |
O73 | 0.1028 (10) | 0.0530 (7) | 0.0555 (7) | −0.0058 (7) | −0.0200 (7) | 0.0273 (6) |
O74 | 0.0913 (9) | 0.0552 (7) | 0.0546 (7) | −0.0109 (6) | −0.0246 (6) | 0.0264 (6) |
C1 | 0.0852 (12) | 0.0603 (10) | 0.0480 (9) | 0.0045 (9) | 0.0094 (8) | 0.0252 (8) |
C2 | 0.0742 (11) | 0.0594 (10) | 0.0432 (8) | −0.0036 (8) | 0.0028 (8) | 0.0217 (7) |
C3 | 0.0593 (9) | 0.0511 (8) | 0.0389 (7) | 0.0051 (7) | 0.0111 (6) | 0.0175 (6) |
C4 | 0.0665 (10) | 0.0553 (9) | 0.0421 (8) | −0.0086 (8) | 0.0095 (7) | 0.0183 (7) |
C5 | 0.0692 (11) | 0.0664 (11) | 0.0395 (8) | −0.0097 (8) | 0.0054 (7) | 0.0186 (8) |
C6 | 0.0854 (14) | 0.1123 (18) | 0.0437 (10) | −0.0374 (13) | −0.0029 (9) | 0.0207 (11) |
C7 | 0.0701 (12) | 0.0857 (15) | 0.0587 (12) | −0.0178 (11) | 0.0075 (10) | −0.0014 (10) |
C11 | 0.0731 (11) | 0.0568 (10) | 0.0525 (9) | 0.0052 (8) | 0.0091 (8) | 0.0301 (8) |
C12 | 0.0680 (10) | 0.0652 (10) | 0.0534 (9) | 0.0130 (8) | 0.0054 (8) | 0.0364 (8) |
C13 | 0.0671 (10) | 0.0589 (9) | 0.0515 (9) | 0.0106 (8) | 0.0098 (8) | 0.0330 (8) |
C14 | 0.0630 (10) | 0.0600 (10) | 0.0535 (9) | 0.0002 (8) | −0.0014 (7) | 0.0357 (8) |
C15 | 0.0619 (10) | 0.0831 (13) | 0.0764 (12) | 0.0160 (9) | 0.0092 (9) | 0.0511 (11) |
C16 | 0.0754 (12) | 0.0785 (13) | 0.0722 (12) | 0.0213 (10) | 0.0233 (10) | 0.0436 (11) |
C17 | 0.0986 (16) | 0.0971 (17) | 0.0854 (16) | 0.0427 (14) | 0.0287 (13) | 0.0446 (13) |
C71 | 0.0540 (9) | 0.0585 (10) | 0.0497 (9) | −0.0053 (7) | 0.0069 (7) | 0.0074 (8) |
C72 | 0.0583 (9) | 0.0628 (10) | 0.0417 (8) | 0.0052 (8) | −0.0028 (7) | 0.0157 (7) |
C73 | 0.0548 (9) | 0.0461 (8) | 0.0475 (8) | 0.0062 (7) | −0.0030 (7) | 0.0170 (7) |
C74 | 0.0527 (8) | 0.0480 (8) | 0.0456 (8) | 0.0057 (7) | −0.0038 (6) | 0.0169 (7) |
C75 | 0.0645 (10) | 0.0570 (10) | 0.0571 (10) | 0.0042 (8) | 0.0047 (8) | 0.0273 (8) |
C76 | 0.0689 (11) | 0.0526 (9) | 0.0626 (11) | −0.0031 (8) | 0.0126 (9) | 0.0188 (8) |
C77 | 0.1248 (19) | 0.0683 (12) | 0.0658 (12) | 0.0005 (12) | −0.0125 (12) | 0.0389 (11) |
O3—C3 | 1.289 (2) | C7—H7A | 0.97 |
O3—H3 | 0.82 | C7—H7B | 0.97 |
O5—C5 | 1.276 (2) | C11—C12 | 1.383 (3) |
O5—H5 | 0.82 | C11—C16 | 1.385 (3) |
O13—C13 | 1.361 (2) | C12—C13 | 1.381 (2) |
O13—C17 | 1.408 (3) | C12—H12 | 0.93 |
O14—C14 | 1.369 (2) | C13—C14 | 1.399 (2) |
O14—H14 | 0.82 | C14—C15 | 1.368 (3) |
O73—C73 | 1.369 (2) | C15—C16 | 1.388 (3) |
O73—C77 | 1.412 (2) | C15—H15 | 0.93 |
O74—C74 | 1.3657 (19) | C16—H16 | 0.93 |
O74—H74 | 0.82 | C17—H17A | 0.96 |
C1—C2 | 1.508 (3) | C17—H17B | 0.96 |
C1—C11 | 1.515 (2) | C17—H17C | 0.96 |
C1—H1A | 0.97 | C71—C76 | 1.373 (3) |
C1—H1B | 0.97 | C71—C72 | 1.395 (3) |
C2—C3 | 1.498 (2) | C72—C73 | 1.388 (2) |
C2—H2A | 0.97 | C72—H72 | 0.93 |
C2—H2B | 0.97 | C73—C74 | 1.393 (2) |
C3—C4 | 1.385 (2) | C74—C75 | 1.376 (2) |
C4—C5 | 1.390 (2) | C75—C76 | 1.388 (3) |
C4—H4 | 0.93 | C75—H75 | 0.93 |
C5—C6 | 1.509 (2) | C76—H76 | 0.93 |
C6—C7 | 1.441 (3) | C77—H77A | 0.96 |
C6—H6A | 0.97 | C77—H77B | 0.96 |
C6—H6B | 0.97 | C77—H77C | 0.96 |
C7—C71 | 1.518 (2) | ||
C3—O3—H3 | 109.5 | C11—C12—H12 | 119.4 |
C5—O5—H5 | 109.5 | O13—C13—C12 | 125.91 (16) |
C13—O13—C17 | 118.73 (16) | O13—C13—C14 | 114.48 (15) |
C14—O14—H14 | 109.5 | C12—C13—C14 | 119.61 (17) |
C73—O73—C77 | 117.94 (14) | C15—C14—O14 | 120.17 (16) |
C74—O74—H74 | 109.5 | C15—C14—C13 | 119.51 (16) |
C2—C1—C11 | 111.59 (15) | O14—C14—C13 | 120.32 (17) |
C2—C1—H1A | 109.3 | C14—C15—C16 | 120.32 (18) |
C11—C1—H1A | 109.3 | C14—C15—H15 | 119.8 |
C2—C1—H1B | 109.3 | C16—C15—H15 | 119.8 |
C11—C1—H1B | 109.3 | C11—C16—C15 | 120.89 (19) |
H1A—C1—H1B | 108.0 | C11—C16—H16 | 119.6 |
C1—C2—C3 | 116.56 (14) | C15—C16—H16 | 119.6 |
C3—C2—H2A | 108.2 | O13—C17—H17A | 109.5 |
C1—C2—H2A | 108.2 | O13—C17—H17B | 109.5 |
C3—C2—H2B | 108.2 | H17A—C17—H17B | 109.5 |
C1—C2—H2B | 108.2 | O13—C17—H17C | 109.5 |
H2A—C2—H2B | 107.3 | H17A—C17—H17C | 109.5 |
O3—C3—C2 | 113.52 (14) | H17B—C17—H17C | 109.5 |
O3—C3—C4 | 121.12 (15) | C76—C71—C72 | 119.02 (15) |
C2—C3—C4 | 125.36 (15) | C76—C71—C7 | 119.99 (19) |
C3—C4—C5 | 120.71 (16) | C72—C71—C7 | 120.92 (19) |
C3—C4—H4 | 119.6 | C73—C72—C71 | 120.80 (17) |
C5—C4—H4 | 119.6 | C73—C72—H72 | 119.6 |
O5—C5—C4 | 120.83 (15) | C71—C72—H72 | 119.6 |
O5—C5—C6 | 117.67 (17) | O73—C73—C72 | 126.16 (16) |
C4—C5—C6 | 121.50 (17) | O73—C73—C74 | 114.58 (13) |
C7—C6—C5 | 115.39 (18) | C72—C73—C74 | 119.26 (16) |
C7—C6—H6A | 108.4 | O74—C74—C75 | 118.54 (15) |
C5—C6—H6A | 108.4 | O74—C74—C73 | 121.55 (15) |
C7—C6—H6B | 108.4 | C75—C74—C73 | 119.90 (15) |
C5—C6—H6B | 108.4 | C74—C75—C76 | 120.35 (17) |
H6A—C6—H6B | 107.5 | C74—C75—H75 | 119.8 |
C6—C7—C71 | 117.27 (18) | C76—C75—H75 | 119.8 |
C6—C7—H7A | 108.0 | C71—C76—C75 | 120.65 (17) |
C71—C7—H7A | 108.0 | C71—C76—H76 | 119.7 |
C6—C7—H7B | 108.0 | C75—C76—H76 | 119.7 |
C71—C7—H7B | 108.0 | O73—C77—H77A | 109.5 |
H7A—C7—H7B | 107.2 | O73—C77—H77B | 109.5 |
C12—C11—C16 | 118.39 (17) | H77A—C77—H77B | 109.5 |
C12—C11—C1 | 119.31 (17) | O73—C77—H77C | 109.5 |
C16—C11—C1 | 122.30 (18) | H77A—C77—H77C | 109.5 |
C13—C12—C11 | 121.26 (16) | H77B—C77—H77C | 109.5 |
C13—C12—H12 | 119.4 | ||
C11—C1—C2—C3 | 172.57 (16) | O14—C14—C15—C16 | −178.18 (17) |
C1—C2—C3—O3 | 172.36 (17) | C13—C14—C15—C16 | 1.0 (3) |
C1—C2—C3—C4 | −7.5 (3) | C12—C11—C16—C15 | −1.8 (3) |
O3—C3—C4—C5 | −0.4 (3) | C1—C11—C16—C15 | 178.82 (17) |
C2—C3—C4—C5 | 179.42 (18) | C14—C15—C16—C11 | 0.5 (3) |
C3—C4—C5—O5 | −2.0 (3) | C6—C7—C71—C76 | −125.7 (3) |
C3—C4—C5—C6 | 178.3 (2) | C6—C7—C71—C72 | 57.5 (3) |
O5—C5—C6—C7 | −43.9 (4) | C76—C71—C72—C73 | −0.9 (3) |
C4—C5—C6—C7 | 135.7 (3) | C7—C71—C72—C73 | 175.95 (17) |
C5—C6—C7—C71 | 176.7 (2) | C77—O73—C73—C72 | −1.3 (3) |
C2—C1—C11—C12 | −80.3 (2) | C77—O73—C73—C74 | 179.3 (2) |
C2—C1—C11—C16 | 99.1 (2) | C71—C72—C73—O73 | −179.85 (17) |
C16—C11—C12—C13 | 1.7 (3) | C71—C72—C73—C74 | −0.5 (3) |
C1—C11—C12—C13 | −178.90 (16) | O73—C73—C74—O74 | 0.4 (3) |
C17—O13—C13—C12 | 5.2 (3) | C72—C73—C74—O74 | −178.99 (16) |
C17—O13—C13—C14 | −176.06 (19) | O73—C73—C74—C75 | −178.86 (16) |
C11—C12—C13—O13 | 178.44 (17) | C72—C73—C74—C75 | 1.7 (3) |
C11—C12—C13—C14 | −0.3 (3) | O74—C74—C75—C76 | 179.18 (17) |
O13—C13—C14—C15 | −179.96 (17) | C73—C74—C75—C76 | −1.5 (3) |
C12—C13—C14—C15 | −1.1 (3) | C72—C71—C76—C75 | 1.1 (3) |
O13—C13—C14—O14 | −0.8 (2) | C7—C71—C76—C75 | −175.75 (18) |
C12—C13—C14—O14 | 178.08 (16) | C74—C75—C76—C71 | 0.1 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O5 | 0.82 | 1.74 | 2.472 (2) | 147 |
O5—H5···O3 | 0.82 | 1.75 | 2.472 (2) | 146 |
O14—H14···O5i | 0.82 | 2.18 | 2.934 (2) | 153 |
O14—H14···O13 | 0.82 | 2.21 | 2.655 (2) | 114 |
O74—H74···O3ii | 0.82 | 2.14 | 2.773 (2) | 134 |
O74—H74···O73 | 0.82 | 2.23 | 2.678 (2) | 115 |
C7—H7A···O13iii | 0.97 | 2.54 | 3.510 (3) | 173 |
C12—H12···O74iv | 0.93 | 2.51 | 3.411 (2) | 162 |
C1—H1B···Cg1v | 0.97 | 3.29 | 3.891 | 122 |
C2—H2A···Cg2vi | 0.97 | 3.20 | 3.821 | 123 |
Symmetry codes: (i) x, y, z−1; (ii) x+1, y+1, z+1; (iii) x, y, z+1; (iv) −x+2, −y+1, −z+1; (v) −x+1, −y+1, −z; (vi) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C21H24O6 |
Mr | 372.40 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 7.981 (3), 11.388 (3), 12.497 (3) |
α, β, γ (°) | 117.065 (3), 100.394 (10), 94.856 (3) |
V (Å3) | 976.7 (5) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.40 × 0.35 × 0.30 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.893, 0.981 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10125, 3933, 3244 |
Rint | 0.014 |
(sin θ/λ)max (Å−1) | 0.641 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.171, 1.06 |
No. of reflections | 3933 |
No. of parameters | 251 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.30, −0.36 |
Computer programs: SMART (Bruker, 1998), SMART, SAINT (Bruker, 1998), SIR92 (Altomare et al., 1993), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003), PLATON.
O3—C3 | 1.289 (2) | C3—C4 | 1.385 (2) |
O5—C5 | 1.276 (2) | C4—C5 | 1.390 (2) |
C1—C2 | 1.508 (3) | C5—C6 | 1.509 (2) |
C1—C11 | 1.515 (2) | C6—C7 | 1.441 (3) |
C2—C3 | 1.498 (2) | C7—C71 | 1.518 (2) |
C1—C2—C3 | 116.56 (14) | C3—C4—C5 | 120.71 (16) |
O3—C3—C2 | 113.52 (14) | O5—C5—C4 | 120.83 (15) |
O3—C3—C4 | 121.12 (15) | O5—C5—C6 | 117.67 (17) |
C2—C3—C4 | 125.36 (15) | C4—C5—C6 | 121.50 (17) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O5 | 0.82 | 1.74 | 2.472 (2) | 147 |
O5—H5···O3 | 0.82 | 1.75 | 2.472 (2) | 146 |
O14—H14···O5i | 0.82 | 2.18 | 2.934 (2) | 153 |
O14—H14···O13 | 0.82 | 2.21 | 2.655 (2) | 114 |
O74—H74···O3ii | 0.82 | 2.14 | 2.773 (2) | 134 |
O74—H74···O73 | 0.82 | 2.23 | 2.678 (2) | 115 |
C7—H7A···O13iii | 0.97 | 2.54 | 3.510 (3) | 173 |
C12—H12···O74iv | 0.93 | 2.51 | 3.411 (2) | 162 |
C1—H1B···Cg1v | 0.97 | 3.29 | 3.891 | 122 |
C2—H2A···Cg2vi | 0.97 | 3.20 | 3.821 | 123 |
Symmetry codes: (i) x, y, z−1; (ii) x+1, y+1, z+1; (iii) x, y, z+1; (iv) −x+2, −y+1, −z+1; (v) −x+1, −y+1, −z; (vi) −x+1, −y+1, −z+1. |
Tetrahydrocurcuminoids such as the title compound, (I), are derived from curcuminoids such as (II) and may be extracted from the roots of curcuma longa, commonly called turmeric root (Govindarajan, 1980). Tetrahydrocurcuminoids are colourless, unlike the yellow curcuminoids. They could therefore be used in colour-free foods and cosmetic products, which currently employ conventional synthetic antioxidants such as butylated hydroxytoluene (BHT). An antioxidant used in a cosmetic application should have the capability to quench efficiently any radicals on the surface of the skin. In this context, compound (I) displays superior free-radical scavenging ability and also exhibits antioxidant, antiinflammatory and skin-lightening actions (Sugiyama et al., 1996; Srihari Rao et al., 1982) and anticancer activity (Huang et al., 1995). It is thought that the p-hydroxy functional groups in (I) are responsible for the compound's antioxidant and chemopreventive action (Rao et al., 1995; Halliwell et al., 1985). We have established the crystal structure of (I) in the hope that it will assist in pharmocological studies of the compound. \sch
Electron delocalization and intramolecular hydrogen bonding in the keto-enol moiety –CO—HC═C—OH have been studied in a number of molecules (Semmingsen, 1976) and in curcuminoid structures (Mostad, 1994; Arrieta et al., 2000; Tonnesen et al., 1982). Of the possible tautomeric forms, it appears that, in the crystal phase, β-diketones prefer the cis-enol arrangement stabilized by a strong intramolecular hydrogen bond.
A view of (I) with the labelling scheme is shown in Fig. 1 and the principal geometry details of the keto-enol function are given in Table 1. A difference map (Fig. 2) clearly established that there is only one H atom at C4 and that the `dione' adopts the expected keto-enol form, but with the hydroxy H atom essentially equally disordered between atoms O3 and O5 [respective hydroxy-atom occupancies 0.54 (4) and 0.46 (4)], corresponding to structures (Ia) and (Ib). The key bond lengths (Table 1) are entirely consistent with this disorder model and with strong intramolecular O3—H···O5 and O5—H···O3 hydrogen bonds (Table 2). The keto-enol moiety C3—C5/O3/O5 is planar [deviations in the range −0.012 (1) to 0.015 (1) Å]. The aromatic rings C11—C16 and C71—C76 form interplanar angles of 88.4 (1) and 9.9 (1)°, respectively, with the keto-enol plane and 88.4 (1)° with one another.
The unit-occupancy hydroxy groups O14—H14 and O74—H74 both take part in strong bifurcated intra- and intermolecular O—H···O hydrogen bonds which, with a C—H···O hydrogen bond (Table 2), serve to link the molecules into sheets in the (1,1,0) plane entirely by simple translation, as shown in Fig. 3. In this way, large R55(42) rings (Bernstein et al., 1995) are developed utilizing five O—H···O hydrogen bonds.
The packing of (I) is further stabilized into a three-dimensional network by C—H···O and by C—H···π intermolecular interactions, which serve to link inversion-related sheets. Fig. 4 shows an R22(30) ring generated by pairs of inversion-related C12—H12···O74(2 − x,1 − y,1 − z) hydrogen bonds (Table 2). The hydrogen-bonded sheets are further linked by weak C—H···π interactions between inversion- and translation-related molecules, as shown in Fig. 5 (details in Table 2). A combination of aromatic C—H···π and C—H···O interactions generate different packing motifs with altered molecular conformations. This may have a significant impact on the biological activity of the compound.
Table 2. Cg1 denotes the centroid of the C11–C16 ring and Cg2 denotes the centroid of the C71–C76 ring.