Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807038615/hg2274sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807038615/hg2274Isup2.hkl |
CCDC reference: 660240
A mixture of 4-nitroaniline (1 mmol) and 3,5-di-tert-butyl-2- hydroxybenzaldehyde (1 mmol) in anhydrous ethanol (30 ml) was refluxed for 3 hr, and then cooled to room temperature. The precipitate was filtered and dried. The crude product was recrystallized from ethanol. Red crystals were thus obtained in 79% yield. Analysis calculated for C21H26N2O3: C, 71.16; H, 7.39; N, 7.90. Found (%): C, 71.33; H, 7.28; N, 7.76. A single-crystal suitable for an X-ray structural analysis was obtained by slowly evaporating a ethanolic solution at room temperature.
All H atoms were initially located in a difference Fourier map. The methyl H atoms were then constrained to an ideal geometry with C—H distances of 0.96 Å and Uiso(H) = 1.5Ueq(C). The hydroxyl H atoms were refined freely along with an isotropic displacement parameter. All other H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C—H distances of 0.93 Å d and Uiso(H) = 1.2Ueq(C).
Schiff bases have demonstrated significant biological activities and new examples are being tested for their antitumor, antimicrobial and antiviral activities (Siddiqui et al., 2006). Moreover, Schiff base compounds can be classified by their photochromic and thermochromic characteristics (Unver et al., 2002). Schiff bases have also been employed as ligands for metal complexes (Selvakumar et al., 2007) and as optical sensor (Oter et al., 2007). We herein report the synthesis and crystal structure of the title compound, (I), (Fig.1). The molecule of (I) is not planar and possesses normal geometric parameters. The molecule has E-configuration, across the C=N double bond. A dihedral angle of 38.5 (4)° is found between the mean planes of the two benzene rings. Also, while C14, C17, C18 and C21 are approximately coplanar with their attached benzene ring, C15,C16, C19 and C20 deviate by -1.1043 (5), 1.3469 (5), -1.2082 (6) and 1.3013 (5) Å, respectively. In addition, there is an intramolecular N···H—O hydrogen bond between the N1 and O1 atoms, which makes the phenol-imine form. Similar tautomerism has also been observed in related Schiff bases reported by Sun et al. (2007) and Aazam et al. (2006). However, this is obviously different from other reported Schiff base, in which the Schiff base exist in enamine-keto tautomeric form (Hokelek et al., 2000).
For general literature concerning applications of benzothiazole compounds, see: Siddiqui et al. (2006); Unver et al. (2002); Selvakumar et al. (2007); Oter et al. (2007). Similar tautomerism has also been observed in related Schiff bases reported by Sun et al. (2007) and Aazam et al. (2006). Other reported Schiff bases exist in enamine–keto tautomeric form (Hokelek et al., 2000).
Data collection: R-AXIS (Rigaku, 1996); cell refinement: R-AXIS; data reduction: R-AXIS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: TEXSAN (Molecular Structure Corporation, 1999); software used to prepare material for publication: TEXSAN.
C21H26N2O3 | F(000) = 760 |
Mr = 354.44 | Dx = 1.160 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 389 reflections |
a = 17.937 (4) Å | θ = 2–25.1° |
b = 6.4674 (13) Å | µ = 0.08 mm−1 |
c = 19.047 (4) Å | T = 291 K |
β = 113.31 (3)° | Prismatic, red |
V = 2029.2 (7) Å3 | 0.20 × 0.18 × 0.16 mm |
Z = 4 |
Rigaku R-AXIS-IV diffractometer | 3066 independent reflections |
Radiation source: fine-focus sealed tube | 1226 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.074 |
Detector resolution: 0 pixels mm-1 | θmax = 25.0°, θmin = 1.2° |
Oscillation frames scans | h = 0→21 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | k = −7→7 |
Tmin = 0.985, Tmax = 0.988 | l = −22→20 |
4678 measured reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.078 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.176 | w = 1/[σ2(Fo2) + (0.062P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.97 | (Δ/σ)max < 0.001 |
3066 reflections | Δρmax = 0.19 e Å−3 |
240 parameters | Δρmin = −0.15 e Å−3 |
0 restraints | Extinction correction: SHELXL97 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0059 (13) |
C21H26N2O3 | V = 2029.2 (7) Å3 |
Mr = 354.44 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 17.937 (4) Å | µ = 0.08 mm−1 |
b = 6.4674 (13) Å | T = 291 K |
c = 19.047 (4) Å | 0.20 × 0.18 × 0.16 mm |
β = 113.31 (3)° |
Rigaku R-AXIS-IV diffractometer | 3066 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1226 reflections with I > 2σ(I) |
Tmin = 0.985, Tmax = 0.988 | Rint = 0.074 |
4678 measured reflections |
R[F2 > 2σ(F2)] = 0.078 | 0 restraints |
wR(F2) = 0.176 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.97 | Δρmax = 0.19 e Å−3 |
3066 reflections | Δρmin = −0.15 e Å−3 |
240 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 | ||
N1 | 0.1937 (2) | 0.6463 (6) | 0.0192 (2) | 0.0652 (12) | |
N2 | −0.0060 (3) | 1.3225 (9) | −0.1296 (4) | 0.0959 (18) | |
O1 | 0.3061 (2) | 0.3763 (5) | 0.03105 (19) | 0.0711 (11) | |
O2 | −0.0154 (3) | 1.4634 (7) | −0.0908 (3) | 0.1241 (18) | |
O3 | −0.0361 (4) | 1.3241 (9) | −0.1982 (3) | 0.177 (3) | |
C1 | 0.3001 (3) | 0.3053 (7) | 0.0964 (3) | 0.0533 (13) | |
C2 | 0.3475 (3) | 0.1359 (7) | 0.1350 (3) | 0.0517 (13) | |
C3 | 0.3358 (3) | 0.0701 (7) | 0.1993 (2) | 0.0555 (13) | |
H3A | 0.3667 | −0.0413 | 0.2262 | 0.067* | |
C4 | 0.2812 (3) | 0.1577 (8) | 0.2269 (2) | 0.0531 (13) | |
C5 | 0.2370 (3) | 0.3253 (7) | 0.1876 (3) | 0.0580 (14) | |
H5A | 0.2010 | 0.3896 | 0.2048 | 0.070* | |
C6 | 0.2454 (3) | 0.4011 (7) | 0.1219 (3) | 0.0503 (13) | |
C7 | 0.1950 (3) | 0.5732 (8) | 0.0823 (3) | 0.0626 (15) | |
H7A | 0.1619 | 0.6341 | 0.1036 | 0.075* | |
C8 | 0.1424 (3) | 0.8192 (8) | −0.0155 (3) | 0.0612 (14) | |
C9 | 0.1280 (3) | 0.9791 (8) | 0.0259 (3) | 0.0711 (15) | |
H9A | 0.1512 | 0.9751 | 0.0791 | 0.085* | |
C10 | 0.0792 (3) | 1.1455 (8) | −0.0111 (4) | 0.0720 (16) | |
H10A | 0.0691 | 1.2521 | 0.0167 | 0.086* | |
C11 | 0.0464 (3) | 1.1489 (10) | −0.0892 (4) | 0.0708 (16) | |
C12 | 0.0606 (3) | 0.9961 (11) | −0.1317 (3) | 0.0850 (18) | |
H12A | 0.0376 | 1.0026 | −0.1848 | 0.102* | |
C13 | 0.1093 (3) | 0.8326 (9) | −0.0950 (3) | 0.0799 (17) | |
H13A | 0.1203 | 0.7295 | −0.1236 | 0.096* | |
C14 | 0.2742 (3) | 0.0730 (8) | 0.2992 (3) | 0.0622 (14) | |
C15 | 0.2590 (4) | −0.1590 (8) | 0.2925 (3) | 0.117 (2) | |
H15A | 0.3016 | −0.2263 | 0.2827 | 0.175* | |
H15B | 0.2078 | −0.1865 | 0.2512 | 0.175* | |
H15C | 0.2579 | −0.2105 | 0.3394 | 0.175* | |
C16 | 0.3554 (4) | 0.1089 (9) | 0.3677 (3) | 0.105 (2) | |
H16A | 0.3982 | 0.0398 | 0.3587 | 0.158* | |
H16B | 0.3520 | 0.0548 | 0.4133 | 0.158* | |
H16C | 0.3667 | 0.2544 | 0.3738 | 0.158* | |
C17 | 0.2078 (3) | 0.1812 (9) | 0.3168 (3) | 0.106 (2) | |
H17A | 0.2182 | 0.3272 | 0.3217 | 0.160* | |
H17B | 0.2073 | 0.1281 | 0.3637 | 0.160* | |
H17C | 0.1560 | 0.1563 | 0.2759 | 0.160* | |
C18 | 0.4088 (3) | 0.0318 (8) | 0.1086 (3) | 0.0594 (14) | |
C19 | 0.3662 (3) | −0.0516 (7) | 0.0269 (3) | 0.0775 (17) | |
H19A | 0.3270 | −0.1540 | 0.0257 | 0.116* | |
H19B | 0.4057 | −0.1128 | 0.0109 | 0.116* | |
H19C | 0.3394 | 0.0598 | −0.0069 | 0.116* | |
C20 | 0.4737 (3) | 0.1925 (8) | 0.1101 (3) | 0.0867 (18) | |
H20A | 0.4476 | 0.3068 | 0.0775 | 0.130* | |
H20B | 0.5114 | 0.1288 | 0.0924 | 0.130* | |
H20C | 0.5023 | 0.2413 | 0.1614 | 0.130* | |
C21 | 0.4521 (4) | −0.1499 (9) | 0.1605 (3) | 0.112 (2) | |
H21A | 0.4128 | −0.2518 | 0.1596 | 0.168* | |
H21B | 0.4804 | −0.1010 | 0.2118 | 0.168* | |
H21C | 0.4901 | −0.2105 | 0.1425 | 0.168* | |
H1E | 0.264 (4) | 0.487 (11) | 0.015 (4) | 0.17 (3)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.068 (3) | 0.056 (3) | 0.069 (3) | 0.001 (3) | 0.023 (3) | 0.007 (3) |
N2 | 0.082 (4) | 0.086 (5) | 0.119 (6) | 0.010 (4) | 0.039 (4) | 0.030 (5) |
O1 | 0.093 (3) | 0.072 (3) | 0.064 (2) | 0.006 (2) | 0.048 (2) | 0.011 (2) |
O2 | 0.110 (4) | 0.097 (4) | 0.166 (5) | 0.030 (3) | 0.054 (3) | 0.033 (3) |
O3 | 0.211 (6) | 0.175 (6) | 0.105 (4) | 0.071 (4) | 0.021 (4) | 0.057 (4) |
C1 | 0.063 (4) | 0.056 (3) | 0.049 (3) | −0.004 (3) | 0.031 (3) | −0.005 (3) |
C2 | 0.055 (3) | 0.056 (3) | 0.046 (3) | −0.001 (3) | 0.021 (3) | 0.000 (3) |
C3 | 0.060 (3) | 0.057 (3) | 0.053 (3) | 0.004 (3) | 0.026 (3) | 0.001 (3) |
C4 | 0.058 (3) | 0.058 (4) | 0.049 (3) | −0.004 (3) | 0.029 (3) | −0.007 (3) |
C5 | 0.071 (4) | 0.057 (3) | 0.062 (3) | 0.000 (3) | 0.042 (3) | −0.007 (3) |
C6 | 0.054 (3) | 0.042 (3) | 0.056 (3) | 0.000 (3) | 0.023 (3) | 0.000 (3) |
C7 | 0.065 (4) | 0.059 (4) | 0.069 (4) | −0.009 (3) | 0.033 (3) | −0.008 (3) |
C8 | 0.064 (4) | 0.056 (4) | 0.059 (4) | −0.011 (3) | 0.020 (3) | 0.000 (3) |
C9 | 0.077 (4) | 0.058 (4) | 0.063 (4) | −0.006 (3) | 0.012 (3) | −0.004 (4) |
C10 | 0.066 (4) | 0.055 (4) | 0.081 (5) | −0.003 (3) | 0.015 (4) | 0.001 (4) |
C11 | 0.049 (4) | 0.066 (4) | 0.091 (5) | 0.004 (3) | 0.021 (4) | 0.017 (4) |
C12 | 0.085 (5) | 0.092 (5) | 0.071 (4) | 0.012 (4) | 0.023 (4) | 0.019 (4) |
C13 | 0.095 (5) | 0.087 (5) | 0.068 (4) | 0.007 (4) | 0.044 (4) | −0.001 (4) |
C14 | 0.075 (4) | 0.069 (4) | 0.052 (3) | −0.008 (3) | 0.035 (3) | −0.007 (3) |
C15 | 0.189 (7) | 0.083 (5) | 0.124 (5) | −0.023 (5) | 0.110 (5) | 0.000 (4) |
C16 | 0.116 (5) | 0.149 (6) | 0.067 (4) | −0.001 (5) | 0.054 (4) | 0.007 (4) |
C17 | 0.120 (5) | 0.135 (5) | 0.103 (5) | 0.033 (4) | 0.086 (5) | 0.030 (4) |
C18 | 0.063 (4) | 0.069 (4) | 0.059 (3) | 0.001 (3) | 0.038 (3) | −0.007 (3) |
C19 | 0.095 (4) | 0.072 (4) | 0.085 (4) | −0.002 (3) | 0.057 (4) | −0.016 (3) |
C20 | 0.067 (4) | 0.118 (5) | 0.085 (4) | −0.014 (4) | 0.040 (3) | −0.022 (4) |
C21 | 0.130 (5) | 0.124 (5) | 0.116 (5) | 0.073 (5) | 0.086 (5) | 0.047 (5) |
N1—C7 | 1.283 (5) | C12—H12A | 0.9300 |
N1—C8 | 1.432 (6) | C13—H13A | 0.9300 |
N2—O3 | 1.200 (6) | C14—C15 | 1.521 (6) |
N2—O2 | 1.226 (6) | C14—C17 | 1.529 (6) |
N2—C11 | 1.471 (7) | C14—C16 | 1.541 (7) |
O1—C1 | 1.371 (5) | C15—H15A | 0.9600 |
O1—H1E | 1.00 (7) | C15—H15B | 0.9600 |
C1—C6 | 1.398 (5) | C15—H15C | 0.9600 |
C1—C2 | 1.403 (6) | C16—H16A | 0.9600 |
C2—C3 | 1.388 (5) | C16—H16B | 0.9600 |
C2—C18 | 1.534 (5) | C16—H16C | 0.9600 |
C3—C4 | 1.402 (5) | C17—H17A | 0.9600 |
C3—H3A | 0.9300 | C17—H17B | 0.9600 |
C4—C5 | 1.376 (5) | C17—H17C | 0.9600 |
C4—C14 | 1.533 (6) | C18—C19 | 1.534 (6) |
C5—C6 | 1.407 (5) | C18—C21 | 1.534 (6) |
C5—H5A | 0.9300 | C18—C20 | 1.553 (6) |
C6—C7 | 1.445 (6) | C19—H19A | 0.9600 |
C7—H7A | 0.9300 | C19—H19B | 0.9600 |
C8—C9 | 1.386 (6) | C19—H19C | 0.9600 |
C8—C13 | 1.394 (6) | C20—H20A | 0.9600 |
C9—C10 | 1.391 (6) | C20—H20B | 0.9600 |
C9—H9A | 0.9300 | C20—H20C | 0.9600 |
C10—C11 | 1.366 (6) | C21—H21A | 0.9600 |
C10—H10A | 0.9300 | C21—H21B | 0.9600 |
C11—C12 | 1.365 (7) | C21—H21C | 0.9600 |
C12—C13 | 1.373 (6) | ||
C7—N1—C8 | 119.3 (4) | C17—C14—C4 | 112.4 (4) |
O3—N2—O2 | 122.7 (7) | C15—C14—C16 | 107.3 (5) |
O3—N2—C11 | 119.8 (7) | C17—C14—C16 | 107.7 (4) |
O2—N2—C11 | 117.5 (6) | C4—C14—C16 | 108.7 (4) |
C1—O1—H1E | 101 (4) | C14—C15—H15A | 109.5 |
O1—C1—C6 | 119.0 (4) | C14—C15—H15B | 109.5 |
O1—C1—C2 | 119.2 (4) | H15A—C15—H15B | 109.5 |
C6—C1—C2 | 121.8 (4) | C14—C15—H15C | 109.5 |
C3—C2—C1 | 115.4 (4) | H15A—C15—H15C | 109.5 |
C3—C2—C18 | 122.2 (4) | H15B—C15—H15C | 109.5 |
C1—C2—C18 | 122.4 (4) | C14—C16—H16A | 109.5 |
C2—C3—C4 | 125.4 (4) | C14—C16—H16B | 109.5 |
C2—C3—H3A | 117.3 | H16A—C16—H16B | 109.5 |
C4—C3—H3A | 117.3 | C14—C16—H16C | 109.5 |
C5—C4—C3 | 116.8 (4) | H16A—C16—H16C | 109.5 |
C5—C4—C14 | 122.5 (4) | H16B—C16—H16C | 109.5 |
C3—C4—C14 | 120.7 (5) | C14—C17—H17A | 109.5 |
C4—C5—C6 | 121.1 (4) | C14—C17—H17B | 109.5 |
C4—C5—H5A | 119.4 | H17A—C17—H17B | 109.5 |
C6—C5—H5A | 119.4 | C14—C17—H17C | 109.5 |
C1—C6—C5 | 119.4 (4) | H17A—C17—H17C | 109.5 |
C1—C6—C7 | 122.7 (4) | H17B—C17—H17C | 109.5 |
C5—C6—C7 | 117.9 (4) | C19—C18—C2 | 110.7 (4) |
N1—C7—C6 | 123.3 (5) | C19—C18—C21 | 107.8 (4) |
N1—C7—H7A | 118.3 | C2—C18—C21 | 111.8 (4) |
C6—C7—H7A | 118.3 | C19—C18—C20 | 108.8 (3) |
C9—C8—C13 | 118.5 (5) | C2—C18—C20 | 109.3 (4) |
C9—C8—N1 | 123.4 (5) | C21—C18—C20 | 108.4 (4) |
C13—C8—N1 | 118.0 (5) | C18—C19—H19A | 109.5 |
C8—C9—C10 | 120.7 (5) | C18—C19—H19B | 109.5 |
C8—C9—H9A | 119.6 | H19A—C19—H19B | 109.5 |
C10—C9—H9A | 119.6 | C18—C19—H19C | 109.5 |
C11—C10—C9 | 118.6 (5) | H19A—C19—H19C | 109.5 |
C11—C10—H10A | 120.7 | H19B—C19—H19C | 109.5 |
C9—C10—H10A | 120.7 | C18—C20—H20A | 109.5 |
C12—C11—C10 | 122.3 (6) | C18—C20—H20B | 109.5 |
C12—C11—N2 | 118.2 (6) | H20A—C20—H20B | 109.5 |
C10—C11—N2 | 119.6 (6) | C18—C20—H20C | 109.5 |
C11—C12—C13 | 119.1 (6) | H20A—C20—H20C | 109.5 |
C11—C12—H12A | 120.5 | H20B—C20—H20C | 109.5 |
C13—C12—H12A | 120.5 | C18—C21—H21A | 109.5 |
C12—C13—C8 | 120.9 (5) | C18—C21—H21B | 109.5 |
C12—C13—H13A | 119.6 | H21A—C21—H21B | 109.5 |
C8—C13—H13A | 119.6 | C18—C21—H21C | 109.5 |
C15—C14—C17 | 109.9 (4) | H21A—C21—H21C | 109.5 |
C15—C14—C4 | 110.7 (4) | H21B—C21—H21C | 109.5 |
O1—C1—C2—C3 | −178.1 (4) | C9—C10—C11—C12 | −0.7 (8) |
C6—C1—C2—C3 | 0.5 (6) | C9—C10—C11—N2 | 179.6 (4) |
O1—C1—C2—C18 | 2.5 (6) | O3—N2—C11—C12 | 1.7 (8) |
C6—C1—C2—C18 | −178.9 (4) | O2—N2—C11—C12 | −176.8 (5) |
C1—C2—C3—C4 | 0.5 (6) | O3—N2—C11—C10 | −178.6 (6) |
C18—C2—C3—C4 | 179.9 (4) | O2—N2—C11—C10 | 2.9 (8) |
C2—C3—C4—C5 | −1.4 (7) | C10—C11—C12—C13 | 0.3 (8) |
C2—C3—C4—C14 | −179.3 (4) | N2—C11—C12—C13 | 180.0 (5) |
C3—C4—C5—C6 | 1.4 (7) | C11—C12—C13—C8 | 1.5 (8) |
C14—C4—C5—C6 | 179.2 (4) | C9—C8—C13—C12 | −2.7 (7) |
O1—C1—C6—C5 | 178.1 (4) | N1—C8—C13—C12 | −179.1 (4) |
C2—C1—C6—C5 | −0.5 (7) | C5—C4—C14—C15 | 129.0 (5) |
O1—C1—C6—C7 | −0.3 (6) | C3—C4—C14—C15 | −53.3 (6) |
C2—C1—C6—C7 | −178.9 (4) | C5—C4—C14—C17 | 5.7 (7) |
C4—C5—C6—C1 | −0.5 (7) | C3—C4—C14—C17 | −176.5 (4) |
C4—C5—C6—C7 | 177.9 (4) | C5—C4—C14—C16 | −113.4 (5) |
C8—N1—C7—C6 | −179.2 (4) | C3—C4—C14—C16 | 64.4 (6) |
C1—C6—C7—N1 | 3.0 (7) | C3—C2—C18—C19 | 121.2 (5) |
C5—C6—C7—N1 | −175.3 (4) | C1—C2—C18—C19 | −59.5 (6) |
C7—N1—C8—C9 | 35.8 (7) | C3—C2—C18—C21 | 1.0 (6) |
C7—N1—C8—C13 | −148.0 (5) | C1—C2—C18—C21 | −179.7 (4) |
C13—C8—C9—C10 | 2.3 (7) | C3—C2—C18—C20 | −119.0 (5) |
N1—C8—C9—C10 | 178.4 (4) | C1—C2—C18—C20 | 60.3 (6) |
C8—C9—C10—C11 | −0.6 (7) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1E···N1 | 1.00 (7) | 1.65 (7) | 2.609 (5) | 159 (6) |
Experimental details
Crystal data | |
Chemical formula | C21H26N2O3 |
Mr | 354.44 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 291 |
a, b, c (Å) | 17.937 (4), 6.4674 (13), 19.047 (4) |
β (°) | 113.31 (3) |
V (Å3) | 2029.2 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.20 × 0.18 × 0.16 |
Data collection | |
Diffractometer | Rigaku R-AXIS-IV |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.985, 0.988 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4678, 3066, 1226 |
Rint | 0.074 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.078, 0.176, 0.97 |
No. of reflections | 3066 |
No. of parameters | 240 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.19, −0.15 |
Computer programs: R-AXIS (Rigaku, 1996), R-AXIS, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), TEXSAN (Molecular Structure Corporation, 1999), TEXSAN.
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1E···N1 | 1.00 (7) | 1.65 (7) | 2.609 (5) | 159 (6) |
Schiff bases have demonstrated significant biological activities and new examples are being tested for their antitumor, antimicrobial and antiviral activities (Siddiqui et al., 2006). Moreover, Schiff base compounds can be classified by their photochromic and thermochromic characteristics (Unver et al., 2002). Schiff bases have also been employed as ligands for metal complexes (Selvakumar et al., 2007) and as optical sensor (Oter et al., 2007). We herein report the synthesis and crystal structure of the title compound, (I), (Fig.1). The molecule of (I) is not planar and possesses normal geometric parameters. The molecule has E-configuration, across the C=N double bond. A dihedral angle of 38.5 (4)° is found between the mean planes of the two benzene rings. Also, while C14, C17, C18 and C21 are approximately coplanar with their attached benzene ring, C15,C16, C19 and C20 deviate by -1.1043 (5), 1.3469 (5), -1.2082 (6) and 1.3013 (5) Å, respectively. In addition, there is an intramolecular N···H—O hydrogen bond between the N1 and O1 atoms, which makes the phenol-imine form. Similar tautomerism has also been observed in related Schiff bases reported by Sun et al. (2007) and Aazam et al. (2006). However, this is obviously different from other reported Schiff base, in which the Schiff base exist in enamine-keto tautomeric form (Hokelek et al., 2000).