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
Key indicators
- Single-crystal X-ray study
- T = 291 K
- Mean (C-C) = 0.008 Å
- R factor = 0.078
- wR factor = 0.176
- Data-to-parameter ratio = 12.8
checkCIF/PLATON results
No syntax errors found
Alert level A PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low ....... 0.86
Author Response: This problem has arisen because there is not good quality crystals and the ata collected with a R-AXIS-IV. Several samples were screened. The selected sample exhibited the strongest diffraction behavior. Hence the precision of the structure is lowered.Validation issues a number of other alerts which are related to this issue. |
Alert level B REFLT03_ALERT_3_B Reflection count < 90% complete (theta max?) From the CIF: _diffrn_reflns_theta_max 25.00 From the CIF: _diffrn_reflns_theta_full 25.00 From the CIF: _reflns_number_total 3066 TEST2: Reflns within _diffrn_reflns_theta_max Count of symmetry unique reflns 3586 Completeness (_total/calc) 85.50% PLAT022_ALERT_3_B Ratio Unique / Expected Reflections too Low .... 0.86 PLAT242_ALERT_2_B Check Low Ueq as Compared to Neighbors for C14
Alert level C PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low .... 40 Perc. PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical . ? PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent ..... ? PLAT230_ALERT_2_C Hirshfeld Test Diff for C6 - C7 .. 5.26 su PLAT230_ALERT_2_C Hirshfeld Test Diff for C14 - C16 .. 6.53 su PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for N2 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C18 PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ... 8
1 ALERT level A = In general: serious problem 3 ALERT level B = Potentially serious problem 8 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 5 ALERT type 2 Indicator that the structure model may be wrong or deficient 5 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
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).
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) |
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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).