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Crystal structure of (E)-2,6-dimeth­­oxy-4-{[(4-meth­­oxy­phen­yl)imino]­meth­yl}phenol

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aDepartment of Chemistry, Langat Singh College, Babasaheb Bhimrao Ambedkar Bihar University, Muzaffarpur, Bihar, India, bDepartment of Chemistry, Govt. College For Women, Udhampur, Jammu and Kashmir 182 101, India, cOndokuz Mayıs University, Arts and Sciences Faculty, Department of Physics, Atakum 55139 Samsun, Turkey, and dDepartment of Chemistry, National Taras Shevchenko University of Kiev, 64/13, Volodymyrska Street, City of Kyiv, 01601, Ukraine
*Correspondence e-mail: malinachem88@gmail.com

Edited by S. V. Lindeman, Marquette University, USA (Received 20 August 2018; accepted 26 September 2018; online 5 October 2018)

In the title compound, C16H17NO4, the dihedral angle between benzene rings is 72.7 (2)°. The meth­oxy groups are rotated by 2.4 (2) and −4.9 (2) (benzil­idene moiety) and by 5.6 (3)° (aniline moiety) relative to the adjacent benzene ring. In the crystal, the mol­ecules are linked into chains along [101] through C—H⋯O and O—H⋯N hydrogen bonds.

1. Chemical context

Syringaldehyde is a product of the catalytic decomposition of lignin (Crestini et al., 2010[Crestini, C., Crucianelli, M., Orlandi, M. & Saladino, R. (2010). Catal. Today, 156, 8-22.]). Syringaldehyde is widely used as a mol­ecular marker to monitor pollution sources and detect the extent of combustion (Robinson et al., 2006[Robinson, A. L., Subramanian, R., Donahue, N. M., Bernardo-Bricker, A. & Rogge, W. F. (2006). Environ. Sci. Technol. 40, 7811-7819.]). It is also known to be an anti­oxidant (Ibrahim et al., 2012[Ibrahim, M. N., Sriprasanthi, R. B., Shamsudeen, S., Adam, F. & Bhawani, S. A. (2012). BioResources J. 7, 4377-4399.]), anti­cancer, anti-inflammatory (Duke, 2003[Duke, J. A. (2003). CRC book of medicinal spices. Boca Raton, Florida: CRC Press LLC.]) and anti­fungal agent (Gurpilhares et al., 2006[Gurpilhares, D. B., Pessoa, A. Jr & Roberto, I. C. (2006). Process Biochem. 41, 631-637.]). In addition, its Schiff bases are known to exhibit a wide range of biological activities (Shi & Zhou, 2011[Shi, Y. & Zhou, C. H. (2011). Bioorg. Med. Chem. Lett. 21, 956-960.]; da Silva et al., 2011[Silva, C. M. da, da Silva, D. L., Modolo, L. V., Alves, R. B., de Resende, M. A., Martins, C. V. B., de Fátima, A. & Ângelo, (2011). J. Adv. Res. 2, 1-8.]).

[Scheme 1]

2. Structural commentary

The mol­ecular structure of the title molecule is shown on Fig. 1[link]. The compound has a trans-configuration of the C9=N1 double bond. The mol­ecule has a non-planar conformation with the two benzene rings forming a dihedral angle of 72.7 (2)°. The meth­oxy groups are almost co-planar with the planes of the adjacent aromatic rings [the C1—O1—C4—C3, C2—O3—C6—C7 and C16—O4—C13—C12 torsion angles are −4.9 (2), 2.4 (2) and 5.6 (3)°, respectively].

[Figure 1]
Figure 1
A view of the mol­ecular structure of the title compound, with the atom labelling. Displacement ellipsoids are drawn at the 40% probability level.

3. Supra­molecular features

In the crystal, the mol­ecules are connected via C7—H7⋯O2ii and O2—H2⋯N1i hydrogen bonding (Table 1[link]), forming chains along the [101] direction (Fig. 2[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O2—H2⋯N1i 0.82 2.21 2.9415 (18) 149
C7—H7⋯O2ii 0.93 2.29 3.2043 (18) 167
Symmetry codes: (i) [x-{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]; (ii) [x+{\script{1\over 2}}, -y+{\script{3\over 2}}, z+{\script{1\over 2}}].
[Figure 2]
Figure 2
A view along the a axis of the crystal packing. Dashed lines indicate hydrogen bonds (see Table 1[link]).

4. Database survey

A search of the Cambridge Structural Database (CSD version 5.39, update of May 2018; Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) revealed the structures of five similar Schiff bases based on p-meth­oxy­aniline and p-hy­droxy­benzaldehyde: 4-[(4-meth­oxy­phenyl­imino)­meth­yl]phenol, (I)[link] (VUKDEK; Yeap et al., 1992[Yeap, G.-Y., Fun, H.-K., Teoh, S.-G., Teo, S.-B., Chinnakali, K. & Yip, B.-C. (1992). Acta Cryst. C48, 2257-2258.]), (E)-5-meth­oxy-2-[(4-meth­oxy­phenyl­imino)­meth­yl]phenol, (II) (NURNAQ; Sahin et al., 2010[Sahin, O., Buyukgungor, O., Albayrak, C. & Odabasoglu, M. (2010). Chin. J. Struct. Chem.(Jiegou Huaxue), 29, 359-361.]), 2-meth­oxy-4-{[(4-meth­oxy­phen­yl)imino]­meth­yl}phenol, (III) (MOTLIR; Singh et al., 2008[Singh, N. B., Das, S. S., Gupta, P., Gupta, A. & Fröhlich, R. (2008). Mol. Cryst. Liq. Cryst. 490, 106-123.]), 2,6-di-tert-butyl-4-[(4-meth­oxy­phenyl­imino)­meth­yl]phenol, (IV) (WEFTEH; Xin et al., 2006[Xin, C.-W., Zeng, T. & Li, J.-S. (2006). Acta Cryst. E62, o1560-o1561.]) and 5-bromo-2-meth­oxy-4-{[(4-meth­oxy­phen­yl)imino]­meth­yl}phenol monohydrate, (V) (GAPFEK; Mao et al., 2012[Mao, C.-G., Wang, S.-S., Su, D.-C. & Qian, S.-S. (2012). Acta Cryst. E68, o249.]). The dihedral angle between the benzene rings in the title compound [72.7 (2)°] is larger than those in compounds (I)[link], (III) and (IV) (49.75–53.63°). Compounds (II) and (V) are almost planar. In all of the compounds, the meth­oxy groups deviate from the plane of aromatic system. There are no C—H⋯π or ππ inter­actions in the crystal structure of the title compound, in contrast to what is observed for compounds (I)[link], (IV) and (V).

5. Synthesis

4-Hy­droxy-3,5-di­meth­oxy­benzaldehyde (syringaldehyde) (0.05 mol) was added to a mixture of 50 ml of methanol and p-meth­oxy­aniline (PMA) (5 ml, 0.05 mol) and 50 ml of distilled water. The reaction mixture was taken in a clean 250 ml round-bottom flask and stirred well with a magnetic stirrer. It was then refluxed for 7 h. The dark-yellow product that formed was separated by filtration, dried under vacuum and recrystallized from methanol solution upon slow evaporation for two days (yield 65%, m.p. 353–357 K).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. H atoms were positioned geom­etrically and refined using a riding model: O—H = 0.82–0.96 Å and C—H = 0.93–0.96 Å with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(O, Cmethyl).

Table 2
Experimental details

Crystal data
Chemical formula C16H17NO4
Mr 287.30
Crystal system, space group Monoclinic, P21/n
Temperature (K) 296
a, b, c (Å) 10.4996 (15), 12.4896 (18), 11.8128 (17)
β (°) 107.936 (5)
V3) 1473.8 (4)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.09
Crystal size (mm) 0.45 × 0.33 × 0.21
 
Data collection
Diffractometer Bruker APEXII CCD
No. of measured, independent and observed [I > 2σ(I)] reflections 19289, 2887, 2306
Rint 0.035
(sin θ/λ)max−1) 0.617
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.116, 1.05
No. of reflections 2887
No. of parameters 194
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.17, −0.21
Computer programs: APEX2 and SAINT (Bruker, 2004[Bruker (2004). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXS97 (Sheldrick 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2017 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. A71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick 2008); program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2017 (Sheldrick, 2015) and PLATON (Spek, 2009).

(E)-2,6-Dimethoxy-4-{[(4-methoxyphenyl)imino]methyl}phenol top
Crystal data top
C16H17NO4F(000) = 608
Mr = 287.30Dx = 1.295 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 10.4996 (15) ÅCell parameters from 6353 reflections
b = 12.4896 (18) Åθ = 2.3–28.3°
c = 11.8128 (17) ŵ = 0.09 mm1
β = 107.936 (5)°T = 296 K
V = 1473.8 (4) Å3Prism, colorless
Z = 40.45 × 0.33 × 0.21 mm
Data collection top
Bruker APEXII CCD
diffractometer
Rint = 0.035
φ and ω scansθmax = 26.0°, θmin = 2.3°
19289 measured reflectionsh = 1212
2887 independent reflectionsk = 1515
2306 reflections with I > 2σ(I)l = 1414
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.044H-atom parameters constrained
wR(F2) = 0.116 w = 1/[σ2(Fo2) + (0.0509P)2 + 0.4295P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
2887 reflectionsΔρmax = 0.17 e Å3
194 parametersΔρmin = 0.20 e Å3
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O20.34000 (12)0.73324 (9)0.04196 (10)0.0465 (3)
H20.3470120.7976330.0560370.070*
O30.52685 (12)0.84064 (9)0.20703 (10)0.0473 (3)
O10.32775 (12)0.52385 (9)0.03728 (11)0.0530 (4)
O41.04377 (13)0.24711 (10)0.85736 (10)0.0524 (3)
N10.76944 (13)0.53851 (10)0.50837 (11)0.0388 (3)
C100.83876 (15)0.46251 (12)0.59633 (13)0.0350 (4)
C150.93325 (16)0.39274 (12)0.57930 (14)0.0369 (4)
H150.9519740.3928590.5073040.044*
C80.61237 (15)0.56465 (13)0.31098 (13)0.0355 (4)
C40.42672 (15)0.56804 (13)0.12973 (13)0.0371 (4)
C60.53028 (15)0.73189 (12)0.21930 (13)0.0344 (4)
C141.00014 (16)0.32282 (12)0.66827 (14)0.0384 (4)
H141.0649570.2773610.6562910.046*
C70.61974 (15)0.67549 (13)0.30970 (13)0.0361 (4)
H70.6844720.7114720.3693030.043*
C90.69704 (15)0.50052 (13)0.40957 (14)0.0377 (4)
H90.6978780.4267530.3991200.045*
C50.43155 (15)0.67913 (13)0.13033 (13)0.0345 (4)
C30.51728 (16)0.51059 (13)0.21959 (14)0.0386 (4)
H30.5147390.4361510.2190400.046*
C130.97179 (16)0.31969 (13)0.77481 (14)0.0380 (4)
C110.81296 (18)0.46051 (15)0.70406 (15)0.0486 (5)
H110.7513850.5084580.7174900.058*
C120.87678 (18)0.38867 (16)0.79243 (16)0.0505 (5)
H120.8558310.3868150.8633780.061*
C20.6266 (2)0.90036 (14)0.29204 (16)0.0546 (5)
H2B0.6159060.9750790.2723120.082*
H2C0.7136150.8771110.2915960.082*
H2D0.6178360.8893020.3697130.082*
C10.3232 (2)0.41090 (15)0.02729 (18)0.0603 (5)
H1A0.2557520.3906540.0449460.090*
H1B0.3021100.3807130.0940940.090*
H1C0.4087030.3847130.0259630.090*
C161.0104 (2)0.2356 (2)0.96441 (19)0.0743 (7)
H16A0.9184090.2142200.9459950.111*
H16B1.0233570.3027051.0060810.111*
H16C1.0667510.1821521.0135490.111*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O20.0477 (7)0.0351 (6)0.0389 (6)0.0019 (5)0.0128 (5)0.0021 (5)
O30.0525 (7)0.0317 (6)0.0402 (6)0.0019 (5)0.0114 (5)0.0026 (5)
O10.0521 (7)0.0372 (7)0.0488 (7)0.0005 (5)0.0152 (6)0.0056 (5)
O40.0602 (8)0.0525 (8)0.0453 (7)0.0195 (6)0.0174 (6)0.0221 (6)
N10.0403 (7)0.0353 (7)0.0342 (7)0.0050 (6)0.0017 (6)0.0049 (6)
C100.0353 (8)0.0315 (8)0.0324 (8)0.0008 (6)0.0019 (6)0.0039 (6)
C150.0442 (9)0.0333 (8)0.0314 (8)0.0013 (7)0.0091 (7)0.0009 (6)
C80.0328 (8)0.0371 (8)0.0322 (8)0.0034 (6)0.0036 (6)0.0025 (6)
C40.0341 (8)0.0375 (9)0.0337 (8)0.0001 (7)0.0016 (6)0.0034 (6)
C60.0354 (8)0.0323 (8)0.0308 (8)0.0002 (6)0.0034 (6)0.0008 (6)
C140.0418 (9)0.0317 (8)0.0413 (9)0.0055 (7)0.0121 (7)0.0022 (7)
C70.0339 (8)0.0380 (9)0.0291 (8)0.0018 (7)0.0011 (6)0.0006 (6)
C90.0368 (8)0.0333 (8)0.0389 (9)0.0028 (7)0.0056 (7)0.0049 (7)
C50.0319 (8)0.0373 (9)0.0285 (8)0.0033 (6)0.0007 (6)0.0030 (6)
C30.0402 (9)0.0314 (8)0.0394 (9)0.0030 (7)0.0052 (7)0.0017 (7)
C130.0378 (9)0.0348 (9)0.0380 (9)0.0031 (7)0.0066 (7)0.0080 (7)
C110.0460 (10)0.0548 (11)0.0458 (10)0.0201 (8)0.0156 (8)0.0111 (8)
C120.0529 (11)0.0624 (12)0.0400 (9)0.0154 (9)0.0198 (8)0.0145 (8)
C20.0591 (12)0.0363 (10)0.0509 (11)0.0115 (8)0.0089 (9)0.0027 (8)
C10.0658 (13)0.0427 (11)0.0568 (11)0.0089 (9)0.0042 (10)0.0113 (9)
C160.0816 (16)0.0896 (17)0.0569 (13)0.0299 (13)0.0291 (11)0.0395 (12)
Geometric parameters (Å, º) top
O1—C2i3.159 (2)C6—C71.379 (2)
O2—C51.3610 (17)C6—C51.394 (2)
O2—H20.8200C14—C131.380 (2)
O3—C61.3652 (19)C14—H140.9300
O3—C21.4193 (19)C7—H70.9300
O1—C41.3704 (18)C9—H90.9300
O1—C11.415 (2)C3—H30.9300
O4—C131.3748 (18)C13—C121.382 (2)
O4—C161.420 (2)C11—C121.383 (2)
N1—C91.2722 (19)C11—H110.9300
N1—C101.4299 (19)C12—H120.9300
C10—C111.380 (2)C2—H2B0.9600
C10—C151.381 (2)C2—H2C0.9600
C15—C141.381 (2)C2—H2D0.9600
C15—H150.9300C1—H1A0.9600
C8—C71.387 (2)C1—H1B0.9600
C8—C31.398 (2)C1—H1C0.9600
C8—C91.466 (2)C16—H16A0.9600
C4—C31.387 (2)C16—H16B0.9600
C4—C51.388 (2)C16—H16C0.9600
C5—O2—H2109.5C4—C5—C6119.60 (13)
C6—O3—C2117.27 (12)C4—C3—C8119.96 (15)
C4—O1—C1117.75 (13)C4—C3—H3120.0
C13—O4—C16117.76 (14)C8—C3—H3120.0
C9—N1—C10116.47 (13)O4—C13—C14116.08 (14)
C11—C10—C15118.47 (14)O4—C13—C12124.69 (15)
C11—C10—N1118.78 (14)C14—C13—C12119.22 (14)
C15—C10—N1122.73 (14)C10—C11—C12121.36 (16)
C14—C15—C10120.54 (15)C10—C11—H11119.3
C14—C15—H15119.7C12—C11—H11119.3
C10—C15—H15119.7C13—C12—C11119.69 (16)
C7—C8—C3120.18 (14)C13—C12—H12120.2
C7—C8—C9122.12 (14)C11—C12—H12120.2
C3—C8—C9117.62 (14)O3—C2—H2B109.5
O1—C4—C3125.06 (15)O3—C2—H2C109.5
O1—C4—C5115.09 (13)H2B—C2—H2C109.5
C3—C4—C5119.85 (14)O3—C2—H2D109.5
O3—C6—C7125.44 (13)H2B—C2—H2D109.5
O3—C6—C5113.65 (13)H2C—C2—H2D109.5
C7—C6—C5120.91 (14)O1—C1—H1A109.5
C13—C14—C15120.67 (15)O1—C1—H1B109.5
C13—C14—H14119.7H1A—C1—H1B109.5
C15—C14—H14119.7O1—C1—H1C109.5
C6—C7—C8119.44 (14)H1A—C1—H1C109.5
C6—C7—H7120.3H1B—C1—H1C109.5
C8—C7—H7120.3O4—C16—H16A109.5
N1—C9—C8124.73 (15)O4—C16—H16B109.5
N1—C9—H9117.6H16A—C16—H16B109.5
C8—C9—H9117.6O4—C16—H16C109.5
O2—C5—C4118.44 (13)H16A—C16—H16C109.5
O2—C5—C6121.96 (14)H16B—C16—H16C109.5
C9—N1—C10—C11120.05 (18)C3—C4—C5—C62.1 (2)
C9—N1—C10—C1561.7 (2)O3—C6—C5—O21.2 (2)
C11—C10—C15—C140.0 (2)C7—C6—C5—O2178.26 (15)
N1—C10—C15—C14178.20 (15)O3—C6—C5—C4177.70 (14)
C1—O1—C4—C34.9 (3)C7—C6—C5—C42.8 (2)
C1—O1—C4—C5175.89 (16)O1—C4—C3—C8178.61 (15)
C2—O3—C6—C72.4 (2)C5—C4—C3—C80.5 (2)
C2—O3—C6—C5178.17 (15)C7—C8—C3—C42.4 (2)
C10—C15—C14—C131.4 (2)C9—C8—C3—C4174.26 (15)
O3—C6—C7—C8179.66 (15)C16—O4—C13—C14175.25 (18)
C5—C6—C7—C80.9 (2)C16—O4—C13—C125.6 (3)
C3—C8—C7—C61.7 (2)C15—C14—C13—O4179.86 (15)
C9—C8—C7—C6174.84 (15)C15—C14—C13—C121.0 (3)
C10—N1—C9—C8176.30 (14)C15—C10—C11—C121.8 (3)
C7—C8—C9—N110.4 (3)N1—C10—C11—C12179.89 (16)
C3—C8—C9—N1166.23 (16)O4—C13—C12—C11178.25 (17)
O1—C4—C5—O20.2 (2)C14—C13—C12—C110.8 (3)
C3—C4—C5—O2178.98 (14)C10—C11—C12—C132.2 (3)
O1—C4—C5—C6178.72 (14)
Symmetry code: (i) x1/2, y+3/2, z1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···N1i0.822.212.9415 (18)149
C7—H7···O2ii0.932.293.2043 (18)167
Symmetry codes: (i) x1/2, y+3/2, z1/2; (ii) x+1/2, y+3/2, z+1/2.
 

Acknowledgements

The authors are grateful to the Department of Chemistry, Langat Singh College, Babasaheb Bhimrao Ambedkar Bihar University, Muzaffarpur, Bihar, India for the research lab and National Taras Shevchenko University, Department of Chemistry, Volodymyrska Str. 64, 01601 Kyiv, Ukraine, for financial support.

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