Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807040408/zl2051sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807040408/zl2051Isup2.hkl |
CCDC reference: 660320
Key indicators
- Single-crystal X-ray study
- T = 296 K
- Mean (C-C) = 0.003 Å
- R factor = 0.052
- wR factor = 0.158
- Data-to-parameter ratio = 14.1
checkCIF/PLATON results
No syntax errors found
Alert level B PLAT027_ALERT_3_B _diffrn_reflns_theta_full (too) Low ............ 24.99 Deg.
Alert level C PLAT220_ALERT_2_C Large Non-Solvent C Ueq(max)/Ueq(min) ... 2.62 Ratio PLAT241_ALERT_2_C Check High Ueq as Compared to Neighbors for C20 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C19
0 ALERT level A = In general: serious problem 1 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 3 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
The crystal structure of the title compound is closely related to that of its starting material, 4-(hexyloxy)aniline (Herrera et al., 2005; Herrera, 2006). For related imines as potential precursors for liquid crystalline compounds and polymers, see: Sudhakar et al. (2000); Cerrada et al. (1996); Wang et al. (1996). For the graph-set notation S(6), see: Bernstein et al. (1995).
To a stirred solution of 2,5-dihydroxybenzaldehyde (0.24 g, 1.76 mmol) in 60 ml of dry ethanol was added 2.10 mmol (0.41 g) of 4-hexyloxyaniline (Herrera et al., 2005) under Ar. The mixture was heated to 325 K for 4 h, and then cooled to room temperature. Ethanol was evaporated, and finally the resulting solid product was recrystallized from petroleum ether, affording thin orange crystals (yield 0.50 g, 91% based on aldehyde; m.p. 389 K). Analysis found: C 72.83, H 7.32, O 15.33, N 4.45%; Calcd. for C19H23NO3: C 72.82, H 7.40, O 15.32, N 4.47%. 1H NMR (400 MHz, DMSO-d6): δ 0.88 (t, J = 6.4 Hz, 3H, CH3), 1.42–1.30 (m, J = 7.2 Hz, 6H, CH2), 1.71 (m, J = 6.8 Hz, 2H, CH2), 3.97 (t, J = 6.8 Hz, 6.4 Hz, 2H, OCH2), 6.79 (m, J = 8.7 Hz, 2H, Ph), 6.99 (m, 3H, Ph), 7.36 (d, J = 8.8 Hz, 2H, Ph), 8.82 (s, 1H, N═CH), 9.08 (s, 1H, OH), 12.50 (s, 1H, OH).
All C-bonded H atoms were placed in idealized positions and refined using a riding model; C—H bond lengths were set to 0.96 (methyl CH3 group, considered as a free to rotate rigid group), 0.97 (methylene CH2 groups) or 0.93 Å (aromatic CH). Hydroxyl H atoms were found in a difference map and refined with a regularized geometry (O—H = 0.82 Å; C—O—H = 109.5°) allowing free rotation about the C—O axis. Isotropic displacement parameters were fixed for all H atoms: Uiso(H) = 1.2 Ueq(carrier C) for methylene and aromatic H atoms, Uiso(H) = 1.5 Ueq(carrier atom) for methyl and hydroxyl H atoms.
Imines or Schiff bases are potential precursors for liquid crystalline compounds (Sudhakar et al., 2000) and polymers (Cerrada et al., 1996; Wang et al., 1996). We are interested in the synthesis and characterization of imines, as well as in the incorporation of reactive functional groups that can undergo radical or condensation polymerization reactions (Herrera, 2006).
The title compound, (I), is such a potential precursors for liquid crystalline materials. It is an amphiphilic molecule with a hydrophobic alkyl-chain and polar hydroxyl groups (Fig. 1), and the hexyloxy chains are in an all-trans conformation. The benzene rings bonded to the imine core functionality are almost co-planar, with a dihedral angle of 8.52 (11)°. A strong intramolecular hydrogen bond is observed, involving the imine N atom and the ortho-hydroxyl functionality of the benzylidene group, forming an S(6) ring motif (Bernstein et al., 1995). The planar conformation of the molecule is probably a consequence of this contact.
The packing of the molecules in the crystal is partially facilitated by intermolecular O—H···O hydrogen bonds involving the meta-hydroxyl functionality of the benzylidene as the H-donor and the ortho-hydroxyl group of a neighboring molecules as the acceptor. The resulting crystal structure exhibits a head-to-head tail-to-tail arrangement (Fig. 2). Molecules are thus arranged in layers, and the crystal structure is further stabilized through C—H···π interlayer contacts: C6—H6 and C14—H14 groups in the asymmetric unit are close to the centroids of the C1···C6 rings of symmetry related molecules at positions -1/2 + x, y, 1/2 - z and 3/2 - x, -1/2 + y, z, respectively. H···centroids separations are 2.74 for the former, and 2.82 Å for the latter contact, with corresponding C—H···centroid tilt angles of 132 and 134°.
The arrangement of molecules in the crystal structure of (I) is reminiscent of that stabilized for the starting material, 4-(hexyloxy)aniline (Herrera et al., 2005).
The crystal structure of the title compound is closely related to that of its starting material, 4-(hexyloxy)aniline (Herrera et al., 2005; Herrera, 2006). For related imines as potential precursors for liquid crystalline compounds and polymers, see: Sudhakar et al. (2000); Cerrada et al. (1996); Wang et al. (1996). For the graph-set notation S(6), see: Bernstein et al. (1995).
Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 1998); program(s) used to refine structure: SHELXTL-Plus (Sheldrick, 1998); molecular graphics: SHELXTL-Plus (Sheldrick, 1998) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXTL-Plus (Sheldrick, 1998).
C19H23NO3 | Dx = 1.221 Mg m−3 |
Mr = 313.38 | Melting point: 389 K |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 80 reflections |
a = 7.5559 (10) Å | θ = 3.9–12.2° |
b = 12.3351 (15) Å | µ = 0.08 mm−1 |
c = 36.597 (4) Å | T = 296 K |
V = 3411.0 (7) Å3 | Plate, orange |
Z = 8 | 0.60 × 0.54 × 0.16 mm |
F(000) = 1344 |
Bruker P4 diffractometer | Rint = 0.021 |
Radiation source: fine-focus sealed tube, FN4 | θmax = 25.0°, θmin = 2.2° |
Graphite monochromator | h = −8→1 |
ω scans | k = −14→1 |
3894 measured reflections | l = −43→1 |
2996 independent reflections | 3 standard reflections every 97 reflections |
1762 reflections with I > 2σ(I) | intensity decay: 1% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.052 | H-atom parameters constrained |
wR(F2) = 0.158 | w = 1/[σ2(Fo2) + (0.0794P)2 + 0.2325P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
2996 reflections | Δρmax = 0.22 e Å−3 |
212 parameters | Δρmin = −0.18 e Å−3 |
0 restraints | Extinction correction: SHELXTL-Plus (Sheldrick, 1998), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0027 (6) |
C19H23NO3 | V = 3411.0 (7) Å3 |
Mr = 313.38 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 7.5559 (10) Å | µ = 0.08 mm−1 |
b = 12.3351 (15) Å | T = 296 K |
c = 36.597 (4) Å | 0.60 × 0.54 × 0.16 mm |
Bruker P4 diffractometer | Rint = 0.021 |
3894 measured reflections | 3 standard reflections every 97 reflections |
2996 independent reflections | intensity decay: 1% |
1762 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.052 | 0 restraints |
wR(F2) = 0.158 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.22 e Å−3 |
2996 reflections | Δρmin = −0.18 e Å−3 |
212 parameters |
x | y | z | Uiso*/Ueq | ||
C1 | 0.3979 (3) | 0.76235 (16) | 0.27705 (6) | 0.0461 (6) | |
C2 | 0.4892 (3) | 0.77627 (16) | 0.31019 (6) | 0.0449 (6) | |
C3 | 0.5559 (3) | 0.87943 (16) | 0.31853 (6) | 0.0483 (6) | |
H3C | 0.6188 | 0.8897 | 0.3401 | 0.058* | |
C4 | 0.5297 (3) | 0.96557 (16) | 0.29535 (6) | 0.0489 (6) | |
C5 | 0.4367 (3) | 0.95043 (18) | 0.26302 (6) | 0.0497 (6) | |
H5C | 0.4172 | 1.0088 | 0.2474 | 0.060* | |
C6 | 0.3732 (3) | 0.84884 (16) | 0.25397 (6) | 0.0513 (6) | |
H6C | 0.3132 | 0.8389 | 0.2320 | 0.062* | |
C7 | 0.5198 (3) | 0.68504 (18) | 0.33457 (6) | 0.0502 (6) | |
H7A | 0.5889 | 0.6948 | 0.3553 | 0.060* | |
N8 | 0.4534 (2) | 0.59150 (14) | 0.32798 (5) | 0.0502 (5) | |
C9 | 0.4813 (3) | 0.49935 (17) | 0.35029 (6) | 0.0480 (6) | |
C10 | 0.5530 (4) | 0.50164 (19) | 0.38539 (6) | 0.0607 (7) | |
H10B | 0.5873 | 0.5674 | 0.3956 | 0.073* | |
C11 | 0.5733 (4) | 0.40725 (19) | 0.40491 (6) | 0.0645 (7) | |
H11B | 0.6205 | 0.4099 | 0.4284 | 0.077* | |
C12 | 0.5246 (3) | 0.30830 (19) | 0.39013 (6) | 0.0550 (6) | |
C13 | 0.4544 (3) | 0.30473 (18) | 0.35534 (6) | 0.0567 (7) | |
H13B | 0.4222 | 0.2389 | 0.3449 | 0.068* | |
C14 | 0.4327 (3) | 0.40059 (17) | 0.33616 (6) | 0.0550 (6) | |
H14A | 0.3834 | 0.3980 | 0.3129 | 0.066* | |
O15 | 0.5508 (3) | 0.22029 (13) | 0.41222 (5) | 0.0722 (6) | |
C16 | 0.4815 (4) | 0.11738 (18) | 0.40096 (7) | 0.0617 (7) | |
H16A | 0.5476 | 0.0896 | 0.3803 | 0.074* | |
H16B | 0.3582 | 0.1243 | 0.3940 | 0.074* | |
C17 | 0.4999 (4) | 0.04240 (19) | 0.43334 (7) | 0.0651 (7) | |
H17B | 0.6228 | 0.0413 | 0.4410 | 0.078* | |
H17C | 0.4306 | 0.0711 | 0.4535 | 0.078* | |
C18 | 0.4411 (4) | −0.07187 (19) | 0.42573 (7) | 0.0727 (8) | |
H18A | 0.5081 | −0.0999 | 0.4052 | 0.087* | |
H18B | 0.3172 | −0.0710 | 0.4188 | 0.087* | |
C19 | 0.4643 (4) | −0.1480 (2) | 0.45808 (7) | 0.0788 (9) | |
H19A | 0.5858 | −0.1426 | 0.4664 | 0.095* | |
H19B | 0.3892 | −0.1226 | 0.4778 | 0.095* | |
C20 | 0.4251 (6) | −0.2609 (2) | 0.45176 (9) | 0.1174 (14) | |
H20A | 0.4927 | −0.2846 | 0.4307 | 0.141* | |
H20B | 0.3008 | −0.2669 | 0.4454 | 0.141* | |
C21 | 0.4617 (5) | −0.3377 (3) | 0.48262 (10) | 0.1139 (13) | |
H21A | 0.4262 | −0.4095 | 0.4757 | 0.171* | |
H21B | 0.3964 | −0.3154 | 0.5038 | 0.171* | |
H21C | 0.5860 | −0.3372 | 0.4881 | 0.171* | |
O22 | 0.3302 (2) | 0.66392 (11) | 0.26689 (4) | 0.0615 (5) | |
H22 | 0.3504 | 0.6192 | 0.2829 | 0.092* | |
O23 | 0.5998 (3) | 1.06534 (11) | 0.30460 (4) | 0.0687 (6) | |
H23 | 0.6040 | 1.1040 | 0.2864 | 0.103* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0512 (14) | 0.0380 (12) | 0.0490 (12) | 0.0011 (11) | −0.0011 (11) | −0.0034 (10) |
C2 | 0.0515 (14) | 0.0408 (12) | 0.0425 (11) | 0.0051 (10) | 0.0028 (10) | 0.0010 (10) |
C3 | 0.0604 (15) | 0.0448 (13) | 0.0398 (11) | −0.0015 (12) | 0.0009 (11) | −0.0040 (10) |
C4 | 0.0633 (15) | 0.0364 (12) | 0.0469 (13) | −0.0008 (11) | 0.0070 (11) | −0.0047 (10) |
C5 | 0.0583 (15) | 0.0404 (12) | 0.0505 (13) | 0.0051 (12) | 0.0014 (11) | 0.0039 (10) |
C6 | 0.0588 (14) | 0.0479 (13) | 0.0471 (12) | 0.0034 (13) | −0.0085 (11) | 0.0015 (11) |
C7 | 0.0593 (15) | 0.0491 (14) | 0.0422 (12) | 0.0033 (12) | −0.0008 (11) | 0.0011 (10) |
N8 | 0.0594 (12) | 0.0404 (11) | 0.0508 (11) | 0.0024 (10) | −0.0006 (9) | 0.0041 (8) |
C9 | 0.0561 (14) | 0.0418 (12) | 0.0460 (13) | 0.0032 (11) | −0.0004 (11) | 0.0044 (10) |
C10 | 0.0833 (19) | 0.0459 (13) | 0.0529 (14) | −0.0040 (13) | −0.0095 (13) | 0.0008 (11) |
C11 | 0.089 (2) | 0.0542 (15) | 0.0503 (14) | −0.0056 (14) | −0.0184 (13) | 0.0056 (12) |
C12 | 0.0646 (16) | 0.0467 (13) | 0.0538 (14) | −0.0001 (12) | −0.0026 (12) | 0.0097 (11) |
C13 | 0.0730 (17) | 0.0445 (13) | 0.0527 (14) | −0.0039 (13) | −0.0084 (13) | 0.0019 (11) |
C14 | 0.0685 (16) | 0.0502 (14) | 0.0463 (12) | −0.0027 (13) | −0.0084 (12) | 0.0047 (11) |
O15 | 0.1023 (15) | 0.0477 (10) | 0.0667 (11) | −0.0070 (10) | −0.0228 (10) | 0.0171 (8) |
C16 | 0.0777 (18) | 0.0459 (14) | 0.0614 (15) | −0.0004 (13) | 0.0003 (14) | 0.0083 (12) |
C17 | 0.0819 (19) | 0.0511 (14) | 0.0624 (15) | 0.0053 (14) | 0.0054 (14) | 0.0136 (12) |
C18 | 0.093 (2) | 0.0542 (15) | 0.0706 (17) | −0.0019 (15) | −0.0001 (15) | 0.0139 (13) |
C19 | 0.102 (2) | 0.0641 (17) | 0.0703 (17) | −0.0069 (16) | 0.0087 (16) | 0.0165 (14) |
C20 | 0.196 (4) | 0.0631 (19) | 0.093 (2) | −0.014 (2) | −0.020 (3) | 0.0166 (17) |
C21 | 0.139 (3) | 0.080 (2) | 0.123 (3) | −0.007 (2) | −0.014 (2) | 0.042 (2) |
O22 | 0.0849 (13) | 0.0416 (9) | 0.0581 (9) | −0.0041 (9) | −0.0170 (9) | 0.0001 (7) |
O23 | 0.1063 (14) | 0.0424 (9) | 0.0574 (10) | −0.0136 (10) | −0.0045 (11) | −0.0020 (7) |
C1—O22 | 1.369 (2) | C13—H13B | 0.9300 |
C1—C6 | 1.374 (3) | C14—H14A | 0.9300 |
C1—C2 | 1.406 (3) | O15—C16 | 1.434 (3) |
C2—C3 | 1.402 (3) | C16—C17 | 1.510 (3) |
C2—C7 | 1.455 (3) | C16—H16A | 0.9700 |
C3—C4 | 1.374 (3) | C16—H16B | 0.9700 |
C3—H3C | 0.9300 | C17—C18 | 1.504 (3) |
C4—O23 | 1.382 (2) | C17—H17B | 0.9700 |
C4—C5 | 1.388 (3) | C17—H17C | 0.9700 |
C5—C6 | 1.382 (3) | C18—C19 | 1.521 (3) |
C5—H5C | 0.9300 | C18—H18A | 0.9700 |
C6—H6C | 0.9300 | C18—H18B | 0.9700 |
C7—N8 | 1.281 (3) | C19—C20 | 1.443 (4) |
C7—H7A | 0.9300 | C19—H19A | 0.9700 |
N8—C9 | 1.415 (3) | C19—H19B | 0.9700 |
C9—C14 | 1.374 (3) | C20—C21 | 1.500 (4) |
C9—C10 | 1.395 (3) | C20—H20A | 0.9700 |
C10—C11 | 1.375 (3) | C20—H20B | 0.9700 |
C10—H10B | 0.9300 | C21—H21A | 0.9600 |
C11—C12 | 1.385 (3) | C21—H21B | 0.9600 |
C11—H11B | 0.9300 | C21—H21C | 0.9600 |
C12—O15 | 1.368 (3) | O22—H22 | 0.8200 |
C12—C13 | 1.380 (3) | O23—H23 | 0.8200 |
C13—C14 | 1.385 (3) | ||
O22—C1—C6 | 118.11 (19) | C12—O15—C16 | 118.69 (18) |
O22—C1—C2 | 121.74 (18) | O15—C16—C17 | 106.5 (2) |
C6—C1—C2 | 120.1 (2) | O15—C16—H16A | 110.4 |
C3—C2—C1 | 118.36 (19) | C17—C16—H16A | 110.4 |
C3—C2—C7 | 120.8 (2) | O15—C16—H16B | 110.4 |
C1—C2—C7 | 120.8 (2) | C17—C16—H16B | 110.4 |
C4—C3—C2 | 121.0 (2) | H16A—C16—H16B | 108.6 |
C4—C3—H3C | 119.5 | C18—C17—C16 | 113.7 (2) |
C2—C3—H3C | 119.5 | C18—C17—H17B | 108.8 |
C3—C4—O23 | 118.8 (2) | C16—C17—H17B | 108.8 |
C3—C4—C5 | 119.7 (2) | C18—C17—H17C | 108.8 |
O23—C4—C5 | 121.50 (19) | C16—C17—H17C | 108.8 |
C6—C5—C4 | 120.1 (2) | H17B—C17—H17C | 107.7 |
C6—C5—H5C | 119.9 | C17—C18—C19 | 113.6 (2) |
C4—C5—H5C | 119.9 | C17—C18—H18A | 108.8 |
C1—C6—C5 | 120.6 (2) | C19—C18—H18A | 108.8 |
C1—C6—H6C | 119.7 | C17—C18—H18B | 108.8 |
C5—C6—H6C | 119.7 | C19—C18—H18B | 108.8 |
N8—C7—C2 | 121.3 (2) | H18A—C18—H18B | 107.7 |
N8—C7—H7A | 119.4 | C20—C19—C18 | 116.6 (2) |
C2—C7—H7A | 119.4 | C20—C19—H19A | 108.1 |
C7—N8—C9 | 123.80 (19) | C18—C19—H19A | 108.1 |
C14—C9—C10 | 117.9 (2) | C20—C19—H19B | 108.1 |
C14—C9—N8 | 117.09 (19) | C18—C19—H19B | 108.1 |
C10—C9—N8 | 125.0 (2) | H19A—C19—H19B | 107.3 |
C11—C10—C9 | 120.3 (2) | C19—C20—C21 | 116.8 (3) |
C11—C10—H10B | 119.8 | C19—C20—H20A | 108.1 |
C9—C10—H10B | 119.8 | C21—C20—H20A | 108.1 |
C10—C11—C12 | 120.9 (2) | C19—C20—H20B | 108.1 |
C10—C11—H11B | 119.5 | C21—C20—H20B | 108.1 |
C12—C11—H11B | 119.5 | H20A—C20—H20B | 107.3 |
O15—C12—C13 | 125.1 (2) | C20—C21—H21A | 109.5 |
O15—C12—C11 | 115.5 (2) | C20—C21—H21B | 109.5 |
C13—C12—C11 | 119.4 (2) | H21A—C21—H21B | 109.5 |
C12—C13—C14 | 119.1 (2) | C20—C21—H21C | 109.5 |
C12—C13—H13B | 120.5 | H21A—C21—H21C | 109.5 |
C14—C13—H13B | 120.5 | H21B—C21—H21C | 109.5 |
C9—C14—C13 | 122.3 (2) | C1—O22—H22 | 109.5 |
C9—C14—H14A | 118.8 | C4—O23—H23 | 109.5 |
C13—C14—H14A | 118.8 | ||
O22—C1—C2—C3 | 179.5 (2) | C14—C9—C10—C11 | −0.1 (4) |
C6—C1—C2—C3 | −1.0 (3) | N8—C9—C10—C11 | 179.5 (2) |
O22—C1—C2—C7 | 1.9 (3) | C9—C10—C11—C12 | 0.5 (4) |
C6—C1—C2—C7 | −178.7 (2) | C10—C11—C12—O15 | −179.9 (2) |
C1—C2—C3—C4 | 1.4 (3) | C10—C11—C12—C13 | −0.1 (4) |
C7—C2—C3—C4 | 179.0 (2) | O15—C12—C13—C14 | 179.0 (2) |
C2—C3—C4—O23 | −179.3 (2) | C11—C12—C13—C14 | −0.7 (4) |
C2—C3—C4—C5 | −0.4 (3) | C10—C9—C14—C13 | −0.7 (4) |
C3—C4—C5—C6 | −1.0 (3) | N8—C9—C14—C13 | 179.7 (2) |
O23—C4—C5—C6 | 177.9 (2) | C12—C13—C14—C9 | 1.1 (4) |
O22—C1—C6—C5 | 179.2 (2) | C13—C12—O15—C16 | −8.2 (4) |
C2—C1—C6—C5 | −0.3 (4) | C11—C12—O15—C16 | 171.5 (2) |
C4—C5—C6—C1 | 1.3 (4) | C12—O15—C16—C17 | −169.6 (2) |
C3—C2—C7—N8 | 177.1 (2) | O15—C16—C17—C18 | −177.2 (2) |
C1—C2—C7—N8 | −5.3 (3) | C16—C17—C18—C19 | 178.5 (2) |
C2—C7—N8—C9 | 178.73 (19) | C17—C18—C19—C20 | −174.8 (3) |
C7—N8—C9—C14 | −167.1 (2) | C18—C19—C20—C21 | 175.2 (3) |
C7—N8—C9—C10 | 13.3 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O22—H22···N8 | 0.82 | 1.85 | 2.581 (2) | 147 |
O23—H23···O22i | 0.82 | 2.14 | 2.933 (2) | 162 |
Symmetry code: (i) −x+1, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C19H23NO3 |
Mr | 313.38 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 296 |
a, b, c (Å) | 7.5559 (10), 12.3351 (15), 36.597 (4) |
V (Å3) | 3411.0 (7) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.60 × 0.54 × 0.16 |
Data collection | |
Diffractometer | Bruker P4 |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3894, 2996, 1762 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.052, 0.158, 1.03 |
No. of reflections | 2996 |
No. of parameters | 212 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.22, −0.18 |
Computer programs: XSCANS (Siemens, 1996), SHELXTL-Plus (Sheldrick, 1998) and Mercury (Macrae et al., 2006).
D—H···A | D—H | H···A | D···A | D—H···A |
O22—H22···N8 | 0.82 | 1.85 | 2.581 (2) | 146.9 |
O23—H23···O22i | 0.82 | 2.14 | 2.933 (2) | 161.5 |
Symmetry code: (i) −x+1, y+1/2, −z+1/2. |
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Imines or Schiff bases are potential precursors for liquid crystalline compounds (Sudhakar et al., 2000) and polymers (Cerrada et al., 1996; Wang et al., 1996). We are interested in the synthesis and characterization of imines, as well as in the incorporation of reactive functional groups that can undergo radical or condensation polymerization reactions (Herrera, 2006).
The title compound, (I), is such a potential precursors for liquid crystalline materials. It is an amphiphilic molecule with a hydrophobic alkyl-chain and polar hydroxyl groups (Fig. 1), and the hexyloxy chains are in an all-trans conformation. The benzene rings bonded to the imine core functionality are almost co-planar, with a dihedral angle of 8.52 (11)°. A strong intramolecular hydrogen bond is observed, involving the imine N atom and the ortho-hydroxyl functionality of the benzylidene group, forming an S(6) ring motif (Bernstein et al., 1995). The planar conformation of the molecule is probably a consequence of this contact.
The packing of the molecules in the crystal is partially facilitated by intermolecular O—H···O hydrogen bonds involving the meta-hydroxyl functionality of the benzylidene as the H-donor and the ortho-hydroxyl group of a neighboring molecules as the acceptor. The resulting crystal structure exhibits a head-to-head tail-to-tail arrangement (Fig. 2). Molecules are thus arranged in layers, and the crystal structure is further stabilized through C—H···π interlayer contacts: C6—H6 and C14—H14 groups in the asymmetric unit are close to the centroids of the C1···C6 rings of symmetry related molecules at positions -1/2 + x, y, 1/2 - z and 3/2 - x, -1/2 + y, z, respectively. H···centroids separations are 2.74 for the former, and 2.82 Å for the latter contact, with corresponding C—H···centroid tilt angles of 132 and 134°.
The arrangement of molecules in the crystal structure of (I) is reminiscent of that stabilized for the starting material, 4-(hexyloxy)aniline (Herrera et al., 2005).