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

Faizi, M.S.H.; Lone, M.N.; Dege, N.; Malinkin, S.; Sliva, T.Y.

doi:10.1107/S2056989018013713

research communications

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ISSN: 2056-9890

Volume 74| Part 11| November 2018| Pages 1540-1542

https://doi.org/10.1107/S2056989018013713

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

Md. Serajul Haque Faizi,^a Mohamad Nadeem Lone,^b Necmi Dege,^c Sergey Malinkin ^d ^* and Tatiana Yu. Sliva ^d

^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.

Keywords: crystal structure; syringaldehyde; 4-methoxyaniline; 4-hydroxy-3,5-dimethoxybenzaldehyde.

CCDC reference: 1843910

1. Chemical context

Syringaldehyde is a product of the catalytic decomposition of lignin (Crestini et al., 2010 ). Syringaldehyde is widely used as a molecular marker to monitor pollution sources and detect the extent of combustion (Robinson et al., 2006 ). It is also known to be an antioxidant (Ibrahim et al., 2012 ), anticancer, anti-inflammatory (Duke, 2003 ) and antifungal agent (Gurpilhares et al., 2006 ). In addition, its Schiff bases are known to exhibit a wide range of biological activities (Shi & Zhou, 2011 ; da Silva et al., 2011 ).

2. Structural commentary

The molecular structure of the title molecule is shown on Fig. 1. 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
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), forming chains along the [101] direction (Fig. 2).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	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
A view along the a axis of the crystal packing. Dashed lines indicate hydrogen bonds (see Table 1

4. Database survey

A search of the Cambridge Structural Database (CSD version 5.39, update of May 2018; Groom et al., 2016 ) revealed the structures of five similar Schiff bases based on p-methoxyaniline and p-hydroxybenzaldehyde: 4-[(4-methoxyphenylimino)methyl]phenol, (I) (VUKDEK; Yeap et al., 1992 ), (E)-5-methoxy-2-[(4-methoxyphenylimino)methyl]phenol, (II) (NURNAQ; Sahin et al., 2010 ), 2-methoxy-4-{[(4-methoxyphenyl)imino]methyl}phenol, (III) (MOTLIR; Singh et al., 2008 ), 2,6-di-tert-butyl-4-[(4-methoxyphenylimino)methyl]phenol, (IV) (WEFTEH; Xin et al., 2006 ) and 5-bromo-2-methoxy-4-{[(4-methoxyphenyl)imino]methyl}phenol monohydrate, (V) (GAPFEK; Mao et al., 2012 ). The dihedral angle between the benzene rings in the title compound [72.7 (2)°] is larger than those in compounds (I), (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 π–π interactions in the crystal structure of the title compound, in contrast to what is observed for compounds (I), (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. 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 U_iso(H) = 1.2U_eq(C) or 1.5U_eq(O, Cmethyl).

Table 2
Experimental details

Crystal data
Chemical formula	C₁₆H₁₇NO₄
M_r	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)
V (Å³)	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
R_int	0.035
(sin θ/λ)_max (Å⁻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
Δρ_max, Δρ_min (e Å⁻³)	0.17, −0.21
Computer programs: APEX2 and SAINT (Bruker, 2004 ), SHELXS97 (Sheldrick 2008 ), SHELXL2017 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ), Mercury (Macrae et al., 2008 ) and PLATON (Spek, 2009 ).

Supporting information

CCDC reference: 1843910

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989018013713/ld2146sup1.cif

Supporting information file. DOI: https://doi.org/10.1107/S2056989018013713/ld2146Isup3.cml

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989018013713/ld2146Isup3.hkl

checkCIF report

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

C₁₆H₁₇NO₄	F(000) = 608
M_r = 287.30	D_x = 1.295 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 10.4996 (15) Å	Cell parameters from 6353 reflections
b = 12.4896 (18) Å	θ = 2.3–28.3°
c = 11.8128 (17) Å	µ = 0.09 mm⁻¹
β = 107.936 (5)°	T = 296 K
V = 1473.8 (4) Å³	Prism, colorless
Z = 4	0.45 × 0.33 × 0.21 mm

Data collection top

Bruker APEXII CCD diffractometer	R_int = 0.035
φ and ω scans	θ_max = 26.0°, θ_min = 2.3°
19289 measured reflections	h = −12→12
2887 independent reflections	k = −15→15
2306 reflections with I > 2σ(I)	l = −14→14

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.044	H-atom parameters constrained
wR(F²) = 0.116	w = 1/[σ²(F_o²) + (0.0509P)² + 0.4295P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
2887 reflections	Δρ_max = 0.17 e Å⁻³
194 parameters	Δρ_min = −0.20 e Å⁻³

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

	x	y	z	U_iso*/U_eq
O2	0.34000 (12)	0.73324 (9)	0.04196 (10)	0.0465 (3)
H2	0.347012	0.797633	0.056037	0.070*
O3	0.52685 (12)	0.84064 (9)	0.20703 (10)	0.0473 (3)
O1	0.32775 (12)	0.52385 (9)	0.03728 (11)	0.0530 (4)
O4	1.04377 (13)	0.24711 (10)	0.85736 (10)	0.0524 (3)
N1	0.76944 (13)	0.53851 (10)	0.50837 (11)	0.0388 (3)
C10	0.83876 (15)	0.46251 (12)	0.59633 (13)	0.0350 (4)
C15	0.93325 (16)	0.39274 (12)	0.57930 (14)	0.0369 (4)
H15	0.951974	0.392859	0.507304	0.044*
C8	0.61237 (15)	0.56465 (13)	0.31098 (13)	0.0355 (4)
C4	0.42672 (15)	0.56804 (13)	0.12973 (13)	0.0371 (4)
C6	0.53028 (15)	0.73189 (12)	0.21930 (13)	0.0344 (4)
C14	1.00014 (16)	0.32282 (12)	0.66827 (14)	0.0384 (4)
H14	1.064957	0.277361	0.656291	0.046*
C7	0.61974 (15)	0.67549 (13)	0.30970 (13)	0.0361 (4)
H7	0.684472	0.711472	0.369303	0.043*
C9	0.69704 (15)	0.50052 (13)	0.40957 (14)	0.0377 (4)
H9	0.697878	0.426753	0.399120	0.045*
C5	0.43155 (15)	0.67913 (13)	0.13033 (13)	0.0345 (4)
C3	0.51728 (16)	0.51059 (13)	0.21959 (14)	0.0386 (4)
H3	0.514739	0.436151	0.219040	0.046*
C13	0.97179 (16)	0.31969 (13)	0.77481 (14)	0.0380 (4)
C11	0.81296 (18)	0.46051 (15)	0.70406 (15)	0.0486 (5)
H11	0.751385	0.508458	0.717490	0.058*
C12	0.87678 (18)	0.38867 (16)	0.79243 (16)	0.0505 (5)
H12	0.855831	0.386815	0.863378	0.061*
C2	0.6266 (2)	0.90036 (14)	0.29204 (16)	0.0546 (5)
H2B	0.615906	0.975079	0.272312	0.082*
H2C	0.713615	0.877111	0.291596	0.082*
H2D	0.617836	0.889302	0.369713	0.082*
C1	0.3232 (2)	0.41090 (15)	0.02729 (18)	0.0603 (5)
H1A	0.255752	0.390654	−0.044946	0.090*
H1B	0.302110	0.380713	0.094094	0.090*
H1C	0.408703	0.384713	0.025963	0.090*
C16	1.0104 (2)	0.2356 (2)	0.96441 (19)	0.0743 (7)
H16A	0.918409	0.214220	0.945995	0.111*
H16B	1.023357	0.302705	1.006081	0.111*
H16C	1.066751	0.182152	1.013549	0.111*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O2	0.0477 (7)	0.0351 (6)	0.0389 (6)	0.0019 (5)	−0.0128 (5)	0.0021 (5)
O3	0.0525 (7)	0.0317 (6)	0.0402 (6)	−0.0019 (5)	−0.0114 (5)	0.0026 (5)
O1	0.0521 (7)	0.0372 (7)	0.0488 (7)	−0.0005 (5)	−0.0152 (6)	−0.0056 (5)
O4	0.0602 (8)	0.0525 (8)	0.0453 (7)	0.0195 (6)	0.0174 (6)	0.0221 (6)
N1	0.0403 (7)	0.0353 (7)	0.0342 (7)	0.0050 (6)	0.0017 (6)	0.0049 (6)
C10	0.0353 (8)	0.0315 (8)	0.0324 (8)	−0.0008 (6)	0.0019 (6)	0.0039 (6)
C15	0.0442 (9)	0.0333 (8)	0.0314 (8)	0.0013 (7)	0.0091 (7)	0.0009 (6)
C8	0.0328 (8)	0.0371 (8)	0.0322 (8)	0.0034 (6)	0.0036 (6)	0.0025 (6)
C4	0.0341 (8)	0.0375 (9)	0.0337 (8)	−0.0001 (7)	0.0016 (6)	−0.0034 (6)
C6	0.0354 (8)	0.0323 (8)	0.0308 (8)	−0.0002 (6)	0.0034 (6)	0.0008 (6)
C14	0.0418 (9)	0.0317 (8)	0.0413 (9)	0.0055 (7)	0.0121 (7)	0.0022 (7)
C7	0.0339 (8)	0.0380 (9)	0.0291 (8)	−0.0018 (7)	−0.0011 (6)	−0.0006 (6)
C9	0.0368 (8)	0.0333 (8)	0.0389 (9)	0.0028 (7)	0.0056 (7)	0.0049 (7)
C5	0.0319 (8)	0.0373 (9)	0.0285 (8)	0.0033 (6)	0.0007 (6)	0.0030 (6)
C3	0.0402 (9)	0.0314 (8)	0.0394 (9)	0.0030 (7)	0.0052 (7)	0.0017 (7)
C13	0.0378 (9)	0.0348 (9)	0.0380 (9)	0.0031 (7)	0.0066 (7)	0.0080 (7)
C11	0.0460 (10)	0.0548 (11)	0.0458 (10)	0.0201 (8)	0.0156 (8)	0.0111 (8)
C12	0.0529 (11)	0.0624 (12)	0.0400 (9)	0.0154 (9)	0.0198 (8)	0.0145 (8)
C2	0.0591 (12)	0.0363 (10)	0.0509 (11)	−0.0115 (8)	−0.0089 (9)	0.0027 (8)
C1	0.0658 (13)	0.0427 (11)	0.0568 (11)	−0.0089 (9)	−0.0042 (10)	−0.0113 (9)
C16	0.0816 (16)	0.0896 (17)	0.0569 (13)	0.0299 (13)	0.0291 (11)	0.0395 (12)

Geometric parameters (Å, º) top

O1—C2ⁱ	3.159 (2)	C6—C7	1.379 (2)
O2—C5	1.3610 (17)	C6—C5	1.394 (2)
O2—H2	0.8200	C14—C13	1.380 (2)
O3—C6	1.3652 (19)	C14—H14	0.9300
O3—C2	1.4193 (19)	C7—H7	0.9300
O1—C4	1.3704 (18)	C9—H9	0.9300
O1—C1	1.415 (2)	C3—H3	0.9300
O4—C13	1.3748 (18)	C13—C12	1.382 (2)
O4—C16	1.420 (2)	C11—C12	1.383 (2)
N1—C9	1.2722 (19)	C11—H11	0.9300
N1—C10	1.4299 (19)	C12—H12	0.9300
C10—C11	1.380 (2)	C2—H2B	0.9600
C10—C15	1.381 (2)	C2—H2C	0.9600
C15—C14	1.381 (2)	C2—H2D	0.9600
C15—H15	0.9300	C1—H1A	0.9600
C8—C7	1.387 (2)	C1—H1B	0.9600
C8—C3	1.398 (2)	C1—H1C	0.9600
C8—C9	1.466 (2)	C16—H16A	0.9600
C4—C3	1.387 (2)	C16—H16B	0.9600
C4—C5	1.388 (2)	C16—H16C	0.9600

C5—O2—H2	109.5	C4—C5—C6	119.60 (13)
C6—O3—C2	117.27 (12)	C4—C3—C8	119.96 (15)
C4—O1—C1	117.75 (13)	C4—C3—H3	120.0
C13—O4—C16	117.76 (14)	C8—C3—H3	120.0
C9—N1—C10	116.47 (13)	O4—C13—C14	116.08 (14)
C11—C10—C15	118.47 (14)	O4—C13—C12	124.69 (15)
C11—C10—N1	118.78 (14)	C14—C13—C12	119.22 (14)
C15—C10—N1	122.73 (14)	C10—C11—C12	121.36 (16)
C14—C15—C10	120.54 (15)	C10—C11—H11	119.3
C14—C15—H15	119.7	C12—C11—H11	119.3
C10—C15—H15	119.7	C13—C12—C11	119.69 (16)
C7—C8—C3	120.18 (14)	C13—C12—H12	120.2
C7—C8—C9	122.12 (14)	C11—C12—H12	120.2
C3—C8—C9	117.62 (14)	O3—C2—H2B	109.5
O1—C4—C3	125.06 (15)	O3—C2—H2C	109.5
O1—C4—C5	115.09 (13)	H2B—C2—H2C	109.5
C3—C4—C5	119.85 (14)	O3—C2—H2D	109.5
O3—C6—C7	125.44 (13)	H2B—C2—H2D	109.5
O3—C6—C5	113.65 (13)	H2C—C2—H2D	109.5
C7—C6—C5	120.91 (14)	O1—C1—H1A	109.5
C13—C14—C15	120.67 (15)	O1—C1—H1B	109.5
C13—C14—H14	119.7	H1A—C1—H1B	109.5
C15—C14—H14	119.7	O1—C1—H1C	109.5
C6—C7—C8	119.44 (14)	H1A—C1—H1C	109.5
C6—C7—H7	120.3	H1B—C1—H1C	109.5
C8—C7—H7	120.3	O4—C16—H16A	109.5
N1—C9—C8	124.73 (15)	O4—C16—H16B	109.5
N1—C9—H9	117.6	H16A—C16—H16B	109.5
C8—C9—H9	117.6	O4—C16—H16C	109.5
O2—C5—C4	118.44 (13)	H16A—C16—H16C	109.5
O2—C5—C6	121.96 (14)	H16B—C16—H16C	109.5

C9—N1—C10—C11	−120.05 (18)	C3—C4—C5—C6	2.1 (2)
C9—N1—C10—C15	61.7 (2)	O3—C6—C5—O2	−1.2 (2)
C11—C10—C15—C14	0.0 (2)	C7—C6—C5—O2	178.26 (15)
N1—C10—C15—C14	178.20 (15)	O3—C6—C5—C4	177.70 (14)
C1—O1—C4—C3	−4.9 (3)	C7—C6—C5—C4	−2.8 (2)
C1—O1—C4—C5	175.89 (16)	O1—C4—C3—C8	−178.61 (15)
C2—O3—C6—C7	2.4 (2)	C5—C4—C3—C8	0.5 (2)
C2—O3—C6—C5	−178.17 (15)	C7—C8—C3—C4	−2.4 (2)
C10—C15—C14—C13	1.4 (2)	C9—C8—C3—C4	174.26 (15)
O3—C6—C7—C8	−179.66 (15)	C16—O4—C13—C14	−175.25 (18)
C5—C6—C7—C8	0.9 (2)	C16—O4—C13—C12	5.6 (3)
C3—C8—C7—C6	1.7 (2)	C15—C14—C13—O4	179.86 (15)
C9—C8—C7—C6	−174.84 (15)	C15—C14—C13—C12	−1.0 (3)
C10—N1—C9—C8	176.30 (14)	C15—C10—C11—C12	−1.8 (3)
C7—C8—C9—N1	10.4 (3)	N1—C10—C11—C12	179.89 (16)
C3—C8—C9—N1	−166.23 (16)	O4—C13—C12—C11	178.25 (17)
O1—C4—C5—O2	0.2 (2)	C14—C13—C12—C11	−0.8 (3)
C3—C4—C5—O2	−178.98 (14)	C10—C11—C12—C13	2.2 (3)
O1—C4—C5—C6	−178.72 (14)

Symmetry code: (i) x−1/2, −y+3/2, z−1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	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−1/2, −y+3/2, z−1/2; (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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