


Supporting information
![]() | Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104017883/de1246sup1.cif |
![]() | Structure factor file (CIF format) https://doi.org/10.1107/S0108270104017883/de1246Isup2.hkl |
CCDC reference: 251338
The synthesis of the (I) was carried out using the procedure of Migrdichian (1957). An aqueous solution of sodium hydroxide (10%, 10 ml) was added to a solution of 4-bromoacetophenone (0.02 mol) and 4-methylbenzaldehyde (0.02 mol) in 95% ethanol (30 ml). The reaction mixture was stirred at room temperature for 4 h and yielded a light-yellow solid, and was then neutralized with hydrochloric acid (10%) and water. The product was recrystallized three times from dry acetone. After 3 d, light-yellow crystals of (I) were obtained by slow evaporation from dry acetone at 286 K. Elemental analysis (Perkin-Elmer 240 C elemental analyzer): calculated for C16H13BrO: C 63.79, H 4.32%; found: C 63.66, H 4.19%. IR spectroscopy (KBr pellets, ν, cm−1): 3030 (Ar—H), 2914 (C—H), 1658 (–C═O), 1598 (–CH═CH–), 1563 (Ph), 1332 (–CH3), 1007 (–CH═C—H), 810 (Ar—H), 737 (Ar—H). 1H NMR spectroscopy (Bruker AV-400 NMR spectrometer, CDCl3, 399.97 MHz, ambient temperature, δ, p.p.m.): 2.40 (s, 3H, –CH3), 7.25 (d, 2H, Ph), 7.45 (d, 1H, –CH═CH–), 7.55 (d, 2H, Ph), 7.64 (d, 2H, Ph), 7.81 (d, 1H, –CH═CH–), 7.89 (d, 2H, Ph).
H atoms were placed in geometrical positions and treated as riding, with C—H distances in the range 0.95–0.98 Å and with Uiso(H) = 1.2Ueq(C). Please check added text.
Data collection: CrystalClear (Rigaku, 2001); cell refinement: CrystalClear; data reduction: CrystalStructure (Rigaku, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997b); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.
C16H13BrO | F(000) = 608 |
Mr = 301.17 | Dx = 1.538 Mg m−3 |
Monoclinic, P21/c | Melting point = 437–439 K |
Hall symbol: -p 2ybc | Mo Kα radiation, λ = 0.71070 Å |
a = 15.600 (3) Å | Cell parameters from 4569 reflections |
b = 14.235 (3) Å | θ = 3.2–25.0° |
c = 5.8621 (11) Å | µ = 3.14 mm−1 |
β = 92.029 (4)° | T = 193 K |
V = 1301.0 (4) Å3 | Block, light-yellow |
Z = 4 | 0.35 × 0.31 × 0.30 mm |
Rigaku MercuryCCD area-detector diffractometer | 2267 independent reflections |
Radiation source: fine-focus sealed tube | 2144 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.051 |
Detector resolution: 7.31 pixels mm-1 | θmax = 25.0°, θmin = 3.2° |
ω scans | h = −18→18 |
Absorption correction: multi-scan (Jacobson, 1998) | k = −16→16 |
Tmin = 0.356, Tmax = 0.382 | l = −6→6 |
12258 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) = 0.091 | H-atom parameters constrained |
S = 1.24 | w = 1/[σ2(Fo2) + (0.0295P)2 + 1.5303P] where P = (Fo2 + 2Fc2)/3 |
2267 reflections | (Δ/σ)max = 0.001 |
166 parameters | Δρmax = 0.53 e Å−3 |
0 restraints | Δρmin = −0.34 e Å−3 |
C16H13BrO | V = 1301.0 (4) Å3 |
Mr = 301.17 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 15.600 (3) Å | µ = 3.14 mm−1 |
b = 14.235 (3) Å | T = 193 K |
c = 5.8621 (11) Å | 0.35 × 0.31 × 0.30 mm |
β = 92.029 (4)° |
Rigaku MercuryCCD area-detector diffractometer | 2267 independent reflections |
Absorption correction: multi-scan (Jacobson, 1998) | 2144 reflections with I > 2σ(I) |
Tmin = 0.356, Tmax = 0.382 | Rint = 0.051 |
12258 measured reflections |
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.091 | H-atom parameters constrained |
S = 1.24 | Δρmax = 0.53 e Å−3 |
2267 reflections | Δρmin = −0.34 e Å−3 |
166 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 will be even larger. |
x | y | z | Uiso*/Ueq | ||
Br1 | −0.38335 (2) | 0.37129 (3) | 0.22424 (7) | 0.04250 (16) | |
O1 | 0.01755 (15) | 0.38037 (19) | −0.1995 (4) | 0.0432 (6) | |
C1 | 0.22169 (19) | 0.3884 (2) | 0.3007 (5) | 0.0228 (6) | |
C2 | 0.2183 (2) | 0.3475 (2) | 0.5172 (5) | 0.0249 (7) | |
H2 | 0.1650 | 0.3260 | 0.5705 | 0.030* | |
C3 | 0.2920 (2) | 0.3382 (2) | 0.6551 (5) | 0.0262 (7) | |
H3 | 0.2885 | 0.3095 | 0.8008 | 0.031* | |
C4 | 0.3711 (2) | 0.3702 (2) | 0.5832 (5) | 0.0265 (7) | |
C5 | 0.3741 (2) | 0.4126 (2) | 0.3704 (5) | 0.0292 (7) | |
H5 | 0.4272 | 0.4363 | 0.3201 | 0.035* | |
C6 | 0.30137 (19) | 0.4210 (2) | 0.2304 (5) | 0.0252 (7) | |
H6 | 0.3054 | 0.4493 | 0.0844 | 0.030* | |
C7 | −0.09306 (19) | 0.3758 (2) | 0.0649 (5) | 0.0236 (6) | |
C8 | −0.1539 (2) | 0.3431 (2) | −0.0966 (5) | 0.0269 (7) | |
H8 | −0.1358 | 0.3213 | −0.2403 | 0.032* | |
C9 | −0.2397 (2) | 0.3422 (2) | −0.0500 (5) | 0.0273 (7) | |
H9 | −0.2807 | 0.3195 | −0.1601 | 0.033* | |
C10 | −0.26536 (19) | 0.3747 (2) | 0.1584 (5) | 0.0261 (6) | |
C11 | −0.2069 (2) | 0.4095 (2) | 0.3208 (5) | 0.0277 (7) | |
H11 | −0.2257 | 0.4336 | 0.4615 | 0.033* | |
C12 | −0.12066 (19) | 0.4086 (2) | 0.2744 (5) | 0.0266 (7) | |
H12 | −0.0798 | 0.4304 | 0.3861 | 0.032* | |
C13 | 0.1473 (2) | 0.3945 (2) | 0.1434 (5) | 0.0248 (7) | |
H13 | 0.1581 | 0.4145 | −0.0075 | 0.030* | |
C14 | 0.06604 (19) | 0.3753 (2) | 0.1870 (5) | 0.0271 (7) | |
H14 | 0.0510 | 0.3597 | 0.3380 | 0.033* | |
C15 | −0.0012 (2) | 0.3780 (2) | 0.0020 (6) | 0.0296 (7) | |
C16 | 0.4515 (2) | 0.3583 (2) | 0.7358 (5) | 0.0315 (7) | |
H16A | 0.4992 | 0.3379 | 0.6432 | 0.047* | |
H16B | 0.4410 | 0.3110 | 0.8530 | 0.047* | |
H16C | 0.4660 | 0.4183 | 0.8092 | 0.047* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0243 (2) | 0.0459 (2) | 0.0575 (3) | 0.00039 (15) | 0.00448 (15) | −0.00353 (18) |
O1 | 0.0326 (13) | 0.0721 (19) | 0.0251 (13) | −0.0003 (12) | 0.0043 (10) | 0.0009 (12) |
C1 | 0.0261 (16) | 0.0183 (15) | 0.0242 (15) | 0.0022 (12) | 0.0034 (12) | −0.0006 (12) |
C2 | 0.0247 (16) | 0.0223 (16) | 0.0279 (16) | −0.0027 (12) | 0.0042 (12) | −0.0004 (12) |
C3 | 0.0333 (17) | 0.0250 (16) | 0.0206 (15) | 0.0010 (13) | 0.0033 (13) | 0.0023 (12) |
C4 | 0.0258 (16) | 0.0262 (16) | 0.0273 (16) | 0.0024 (13) | −0.0010 (12) | −0.0017 (13) |
C5 | 0.0238 (16) | 0.0326 (18) | 0.0313 (17) | −0.0026 (13) | 0.0048 (13) | 0.0013 (14) |
C6 | 0.0286 (17) | 0.0231 (16) | 0.0240 (16) | −0.0009 (12) | 0.0045 (12) | 0.0020 (12) |
C7 | 0.0249 (16) | 0.0230 (15) | 0.0228 (15) | 0.0012 (12) | −0.0015 (12) | 0.0030 (12) |
C8 | 0.0304 (17) | 0.0258 (16) | 0.0244 (16) | 0.0023 (13) | −0.0014 (13) | −0.0030 (12) |
C9 | 0.0286 (17) | 0.0240 (16) | 0.0288 (17) | −0.0002 (13) | −0.0080 (13) | −0.0037 (13) |
C10 | 0.0241 (16) | 0.0208 (15) | 0.0332 (17) | −0.0015 (12) | 0.0006 (12) | 0.0030 (13) |
C11 | 0.0341 (18) | 0.0268 (16) | 0.0223 (16) | 0.0015 (14) | 0.0027 (13) | −0.0017 (12) |
C12 | 0.0283 (17) | 0.0278 (16) | 0.0232 (16) | −0.0028 (13) | −0.0036 (12) | 0.0006 (13) |
C13 | 0.0296 (17) | 0.0221 (15) | 0.0228 (15) | 0.0031 (12) | 0.0035 (12) | 0.0028 (12) |
C14 | 0.0246 (16) | 0.0300 (17) | 0.0267 (16) | 0.0007 (13) | 0.0007 (12) | 0.0036 (13) |
C15 | 0.0295 (17) | 0.0290 (17) | 0.0300 (18) | 0.0000 (13) | −0.0012 (13) | 0.0000 (13) |
C16 | 0.0238 (16) | 0.041 (2) | 0.0294 (17) | 0.0026 (14) | −0.0020 (13) | 0.0033 (14) |
Br1—C10 | 1.895 (3) | C7—C15 | 1.493 (4) |
O1—C15 | 1.228 (4) | C8—C9 | 1.375 (4) |
C1—C2 | 1.398 (4) | C8—H8 | 0.9500 |
C1—C6 | 1.403 (4) | C9—C10 | 1.379 (4) |
C1—C13 | 1.460 (4) | C9—H9 | 0.9500 |
C2—C3 | 1.388 (4) | C10—C11 | 1.387 (4) |
C2—H2 | 0.9500 | C11—C12 | 1.381 (4) |
C3—C4 | 1.394 (4) | C11—H11 | 0.9500 |
C3—H3 | 0.9500 | C12—H12 | 0.9500 |
C4—C5 | 1.389 (5) | C13—C14 | 1.330 (4) |
C4—C16 | 1.524 (4) | C13—H13 | 0.9500 |
C5—C6 | 1.382 (4) | C14—C15 | 1.482 (4) |
C5—H5 | 0.9500 | C14—H14 | 0.9500 |
C6—H6 | 0.9500 | C16—H16A | 0.9800 |
C7—C12 | 1.396 (4) | C16—H16B | 0.9800 |
C7—C8 | 1.397 (4) | C16—H16C | 0.9800 |
C2—C1—C6 | 117.8 (3) | C10—C9—H9 | 120.4 |
C2—C1—C13 | 122.9 (3) | C9—C10—C11 | 121.5 (3) |
C6—C1—C13 | 119.2 (3) | C9—C10—Br1 | 119.1 (2) |
C3—C2—C1 | 120.8 (3) | C11—C10—Br1 | 119.3 (2) |
C3—C2—H2 | 119.6 | C12—C11—C10 | 118.9 (3) |
C1—C2—H2 | 119.6 | C12—C11—H11 | 120.6 |
C2—C3—C4 | 121.0 (3) | C10—C11—H11 | 120.6 |
C2—C3—H3 | 119.5 | C11—C12—C7 | 120.6 (3) |
C4—C3—H3 | 119.5 | C11—C12—H12 | 119.7 |
C5—C4—C3 | 118.2 (3) | C7—C12—H12 | 119.7 |
C5—C4—C16 | 121.4 (3) | C14—C13—C1 | 127.5 (3) |
C3—C4—C16 | 120.3 (3) | C14—C13—H13 | 116.3 |
C6—C5—C4 | 121.2 (3) | C1—C13—H13 | 116.3 |
C6—C5—H5 | 119.4 | C13—C14—C15 | 120.6 (3) |
C4—C5—H5 | 119.4 | C13—C14—H14 | 119.7 |
C5—C6—C1 | 121.0 (3) | C15—C14—H14 | 119.7 |
C5—C6—H6 | 119.5 | O1—C15—C14 | 121.3 (3) |
C1—C6—H6 | 119.5 | O1—C15—C7 | 120.1 (3) |
C12—C7—C8 | 119.0 (3) | C14—C15—C7 | 118.6 (3) |
C12—C7—C15 | 122.6 (3) | C4—C16—H16A | 109.5 |
C8—C7—C15 | 118.3 (3) | C4—C16—H16B | 109.5 |
C9—C8—C7 | 120.7 (3) | H16A—C16—H16B | 109.5 |
C9—C8—H8 | 119.6 | C4—C16—H16C | 109.5 |
C7—C8—H8 | 119.6 | H16A—C16—H16C | 109.5 |
C8—C9—C10 | 119.2 (3) | H16B—C16—H16C | 109.5 |
C8—C9—H9 | 120.4 | ||
C6—C1—C2—C3 | −1.3 (4) | C9—C10—C11—C12 | −2.1 (5) |
C13—C1—C2—C3 | 176.0 (3) | Br1—C10—C11—C12 | 177.7 (2) |
C1—C2—C3—C4 | 0.8 (5) | C10—C11—C12—C7 | 2.0 (5) |
C2—C3—C4—C5 | 0.6 (5) | C8—C7—C12—C11 | −0.6 (5) |
C2—C3—C4—C16 | −179.3 (3) | C15—C7—C12—C11 | 176.7 (3) |
C3—C4—C5—C6 | −1.6 (5) | C2—C1—C13—C14 | 9.5 (5) |
C16—C4—C5—C6 | 178.3 (3) | C6—C1—C13—C14 | −173.3 (3) |
C4—C5—C6—C1 | 1.1 (5) | C1—C13—C14—C15 | −175.1 (3) |
C2—C1—C6—C5 | 0.3 (4) | C13—C14—C15—O1 | 13.8 (5) |
C13—C1—C6—C5 | −177.1 (3) | C13—C14—C15—C7 | −167.5 (3) |
C12—C7—C8—C9 | −0.6 (5) | C12—C7—C15—O1 | −154.7 (3) |
C15—C7—C8—C9 | −178.1 (3) | C8—C7—C15—O1 | 22.7 (5) |
C7—C8—C9—C10 | 0.5 (5) | C12—C7—C15—C14 | 26.5 (4) |
C8—C9—C10—C11 | 0.9 (5) | C8—C7—C15—C14 | −156.1 (3) |
C8—C9—C10—Br1 | −178.9 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2i—H2i···O1 | 0.95 | 2.82 | 3.627 (3) | 144 |
C14i—H14i···O1 | 0.95 | 2.80 | 3.702 (4) | 160 |
C12i—H12i···O1 | 0.95 | 2.91 | 3.722 (4) | 145 |
C5ii—H5ii···Br1 | 0.95 | 3.17 | 3.953 (5) | 141 |
C16ii—H16Aii···Br1 | 0.98 | 3.15 | 4.026 (4) | 149 |
Symmetry codes: (i) x, y, z−1; (ii) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C16H13BrO |
Mr | 301.17 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 193 |
a, b, c (Å) | 15.600 (3), 14.235 (3), 5.8621 (11) |
β (°) | 92.029 (4) |
V (Å3) | 1301.0 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 3.14 |
Crystal size (mm) | 0.35 × 0.31 × 0.30 |
Data collection | |
Diffractometer | Rigaku MercuryCCD area-detector diffractometer |
Absorption correction | Multi-scan (Jacobson, 1998) |
Tmin, Tmax | 0.356, 0.382 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12258, 2267, 2144 |
Rint | 0.051 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.091, 1.24 |
No. of reflections | 2267 |
No. of parameters | 166 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.53, −0.34 |
Computer programs: CrystalClear (Rigaku, 2001), CrystalClear, CrystalStructure (Rigaku, 2001), SHELXS97 (Sheldrick, 1997b), SHELXL97 (Sheldrick, 1997b), SHELXL97.
Br1—C10 | 1.895 (3) | C4—C16 | 1.524 (4) |
O1—C15 | 1.228 (4) | C7—C15 | 1.493 (4) |
C1—C13 | 1.460 (4) | C13—C14 | 1.330 (4) |
C3—C4 | 1.394 (4) | C14—C15 | 1.482 (4) |
C2—C1—C6 | 117.8 (3) | C8—C7—C15 | 118.3 (3) |
C2—C1—C13 | 122.9 (3) | C9—C10—C11 | 121.5 (3) |
C6—C1—C13 | 119.2 (3) | C9—C10—Br1 | 119.1 (2) |
C5—C4—C3 | 118.2 (3) | C11—C10—Br1 | 119.3 (2) |
C5—C4—C16 | 121.4 (3) | C14—C13—C1 | 127.5 (3) |
C3—C4—C16 | 120.3 (3) | C13—C14—C15 | 120.6 (3) |
C12—C7—C8 | 119.0 (3) | O1—C15—C14 | 121.3 (3) |
C12—C7—C15 | 122.6 (3) | O1—C15—C7 | 120.1 (3) |
C13—C1—C2—C3 | 176.0 (3) | C1—C13—C14—C15 | −175.1 (3) |
C13—C1—C6—C5 | −177.1 (3) | C13—C14—C15—O1 | 13.8 (5) |
C15—C7—C8—C9 | −178.1 (3) | C13—C14—C15—C7 | −167.5 (3) |
C8—C9—C10—Br1 | −178.9 (2) | C12—C7—C15—O1 | −154.7 (3) |
Br1—C10—C11—C12 | 177.7 (2) | C8—C7—C15—O1 | 22.7 (5) |
C15—C7—C12—C11 | 176.7 (3) | C12—C7—C15—C14 | 26.5 (4) |
C2—C1—C13—C14 | 9.5 (5) | C8—C7—C15—C14 | −156.1 (3) |
C6—C1—C13—C14 | −173.3 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2i—H2i···O1 | 0.95 | 2.82 | 3.627 (3) | 144 |
C14i—H14i···O1 | 0.95 | 2.80 | 3.702 (4) | 160 |
C12i—H12i···O1 | 0.95 | 2.91 | 3.722 (4) | 145 |
C5ii—H5ii···Br1 | 0.95 | 3.17 | 3.953 (5) | 141 |
C16ii—H16Aii···Br1 | 0.98 | 3.15 | 4.026 (4) | 149 |
Symmetry codes: (i) x, y, z−1; (ii) x−1, y, z. |
C | H | P | H···P | C···P | C-H···P |
C3 | H3 | P1i | 2.820 | 3.530 (4) | 132 |
C11 | H11 | P2ii | 2.940 | 3.608 (3) | 129 |
C8 | H8 | P2iii | 3.007 | 3.568 (4) | 119 |
C13 | H13 | P2iv | 3.071 | 3.641 (4) | 120 |
Notes: P1 is the centre of plane 1 (the C1-C6 ring) and P2 is the centre of plane 2 (the C7-C12 ring). Symmetry codes: (i) x, 1/2 − y, z − 1/2'; (ii) −x, 1 − y, 1 − z; (iii) x, 1/2 − y, z + 1/2; (iv) −x, 1 − y, −z. |
Space group | SA (Å) | A12 (°) | µ (D) | Substituents | |
(I) | P21/c | 5.862 (1) | 47.0 (1) | 4.91 | 4-CH3, 4'-Br |
(II) | P212121 | 5.906 | 49 | 2.88 | 4,4'-CH3 |
(III) | Pc | 5.991 (1) | 48. | 3.75 | 4-Br, 4'-OCH3 |
(IV) | Cc | 5.917 (3) | 48.6 (1) | 1.95 | 4-Br |
Notes: SA is the shortest axis; A12 is the dihedral angle between planes 1 and 2 (see Table 3); µ is the dipole moment, calculated by MOPAC (Dewar et al., 1985). References: for (I), this study; for (II), Rabinovich & Shakked (1974); for (III), Li, Huang et al. (1992); for (IV), Li, Pa & Su (1992). |
Bond | H···O | C···O | C-H···O | type | ESM% | |
(I) | Ai | 2.80 | 3.702 (4) | 160 | T | 9.73 |
Bi | 2.82 | 3.627 (5) | 144 | T | ||
Ci | 2.91 | 3.722 (6) | 145 | T | ||
(II) | Aii | 2.77 | 3.718 (3) | 164 | T | 10.03 |
Bii | 2.71 | 3.561 (5) | 142 | T | ||
Cii | 3.06 | 3.841 (6) | 140 | T | ||
(III) | Aiii | 2.97 | 3.876 (3) | 158 | T | 9.24 |
Biii | 2.90 | 3.761 (5) | 150 | T | ||
Ciii | 2.94 | 3.737 (4) | 141 | T | ||
(IV) | Aiv | 2.87 | 3.787 (5) | 161 | T | 9.86 |
Biv | 2.80 | 3.622 (6) | 144 | T | ||
Civ | 2.97 | 3.795 (4) | 142 | T |
Notes: A, B and C represent C-Ha···O, C-H2···O and C-H2'···O hydrogen bonds, respectively; see scheme for Ha, H1 and H2; for type, T is translation; ESM% is the interaction energy between the interacting molecules expressed as a percentage of the total packing energy. Symmetry codes: (i) x, y, z − 1; (ii) x, y − 1, z; (iii) x, y, z − 1; (iv) x, y, z + 1. |
Chalcones with the general formula Ar—CH═CH—CO—Ar belong to an important class of compounds. The common and interesting part in the molecules of these compounds is the central part, i.e. –CH═CH—C═O–, in which the H atoms may or may not be substituted. The –C═C– double bond can be photoreactive, in which case it can react with suitable reagents through photocycloaddition to synthesize various products, and is therefore widely used in organic solid photochemistry (Satish Goud et al., 1995). On the other hand, with appropriate substitutents, chalcones are a class of non-linear optical materials (Indira et al., 2002).
In these materials, the C═O bond acts as the electron-withdrawing group, and the electron-rich substituents in the aromatic rings serve as electron-donating groups, forming a so-called D-π···A type molecule. When the electron-rich groups are located on the 4 and/or 4' positions, the electron flow follows a Λ-shaped path, and therefore the molecule is called a Λ-shaped molecule (Devia et al., 1999). During our search for chalcone non-linear optical materials, the title compound, (I), was synthesized. We present here a study of the molecular packing in the crystal of (I), and a brief study of the C—H···O hydrogen bonds in (I) and some similar crystals. \sch
The molecule of (I) is not planar. Taking the C1—C6 phenyl ring as plane 1, the C7—C12 phenyl ring as plane 2 and the central C1—C13═C14—C15 as plane 3, the dihedral angles between them, A12, A13 and A23, are 47.0 (1), 11.7 (0) and 35.4 (1)°, respectively, showing that the two phenyl rings are rotated in opposite directions with respect to the central part, plane 3. The C1—C13═C14—C15 torsion angle is 175.1 (3)°. The angle between the C═O bond and plane 3 is 14.2 (3)°.
In the crystal of (I), molecules are paired through C—H···π interactions (Suezawa et al., 2001; Table 3). The shortest distance between the parallel C═C double bonds is 4.557 (4) Å, much longer than the 4.2 Å reference value for a photoreactive crystal (Reference?). The dihedral angle between plane 3 and the plane formed by the two C═C double bonds is 45.6 (3)°, which deviates significantly from the perfect value of 90° for 2 + 2 photocycloaddition. This is consistent with the fact that the crystal of (I) is photoinert.
The molecules along [001] interact via three C—H···O interactions (Desiraju, 1991), namely C12—H12···O1, C2—H2···O1 and C14—H14···O1 (Table 2), and form hydrogen-bonded molecular chains. These chains interact further through C5—H5···Br1 and C16—H16A···Br1 hydrogen bonds (Table 2), forming (010) molecular layers. In the third direction, [010], there are only weak ordinary van der Waals interactions.
The most interesting features in the structure of (I) are the above-mentioned cooperative hydrogen bonds, formed by the phenone O atom and the three C—H bonds in the `bay area', namely the area encricled by C2'-C1'-Ce—Ca═Cb—C1—C2. From the scheme, one can see that the three C—H bonds almost point to the same site. When this site is occupied by a phenone O atom from a neighbouring molecule, the formation of three C—H···O hydrogen bonds with nearly perfect geometries can be expected. Depending on the mutual arrangement of the two molecules involved, the most favourable symmetry relation between them is a translation vector, the size of which is dependent on the size of the substituents, followed by a screw axis and a glide plane. It is almost impossible for a centre of symmetry to connect the molecules in such a manner.
From the viewpoint of designing second-harmonic generating crystals (Desiraju, 1989), which must not be centrosymmetric, the above molecular self-assembling mode is desirable. Therefore, a brief study of some similar 4,4'-substituted chalcones was carried out, and the results are summarized in Tables 4 and 5.
As shown by the Tables 4 and 5, the symmetry elements involved are indeed translation vectors and their size is around 6 Å. The cooperative C—H···O hydrogen bonds in the `bay area' certainly play an important role in the crystal packing, as shown by the ESM% column in Table 5, which expresses the interaction energy between the molecules involved as a percentage of the total packing energy, as calculated using program OPEC (Gavezzotti, 1983). However, this is not the unique factor determining the crystal packing. The dipole moment of the molecule of (I) is relatively large when compared with the others in Table 4, which leads to the molecules of (I) being arranged in an antiparallel fashion in the crystal. This may be the reason that the crystal of (I) is centrosymmetric.