Bis[4-(2-hydr­oxy-3-methoxy­benzyl­ideneamino)phen­yl] ether

Abstract

The title compound, C₂₈H₂₄N₂O₅, a flexible Schiff base ligand, was prepared in high yield by a Schiff base condensation of 3-methoxy­salicylaldehyde and bis­(4-amino­phen­yl) ether in methanol. The mol­ecule lies on a twofold rotation axis, and each half exhibits an imine E configuration and an O—H⋯N hydrogen bond. The dihedral angle between the two benzene rings attached to the central O atom is 69.22 (6)°, and that between each of these rings and the other benzene ring in the same half of the mol­ecule is 24.29 (11)°, illustrating the degree of twisting of the flexible mol­ecule.

Related literature

For related literature, see: Chu et al. (2007 ▶); Guo et al. (2002 ▶); He et al. (2000 ▶); Tesouro Vallina et al. (2001 ▶); Yoshida et al. (1999 ▶).

Experimental

Crystal data

• C₂₈H₂₄N₂O₅

• M _r = 468.49

• Monoclinic,

• a = 15.585 (7) Å

• b = 7.578 (4) Å

• c = 19.859 (9) Å

• β = 92.760 (8)°

• V = 2342.7 (19) ų

• Z = 4

• Mo Kα radiation

• μ = 0.09 mm⁻¹

• T = 173 (2) K

• 0.30 × 0.20 × 0.20 mm

Data collection

• Bruker SMART CCD diffractometer

• Absorption correction: none

• 8736 measured reflections

• 2689 independent reflections

• 2016 reflections with I > 2σ(I)

• R _int = 0.035

Refinement

• R[F ² > 2σ(F ²)] = 0.061

• wR(F ²) = 0.166

• S = 1.11

• 2689 reflections

• 165 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.15 e Å⁻³

• Δρ_min = −0.14 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H3⋯N1	0.84	1.87	2.611 (2)	147

supplementary crystallographic information

Comment

Within the field of supramolecular inorganic chemistry, self-assembly is one of the most efficient methods for complex architectures comprising spatially and geometrically well defined arrays of metal ions. Because of easy syntheses by simple one-pot condensation reactions between aldehydes (or ketones) and amines and their coordinating ability with metal ions, multidentate Schiff base ligands such as pyridylimines (He et al., 2000; Guo et al., 2002; Tesouro Vallina et al., 2001) and salicyladimines (Yoshida et al., 1999; Chu et al., 2007) were designed and used to prepare complexes in recent years. Here we report the synthesis and structure of a new flexible Schiff base ligand, bis(N-(3-methoxysalicylidene)-4-aminophenyl) ether. The molecule lies on a twofold rotation axis, and each half exhibits an imine E configuration and an O—H···N hydrogen bond. The dihedral angle between the two benzene rings attached to the central O atom is 69.22 (6)°, and that between each of these rings and the other benzene ring in the same half of the molecule is 24.29 (11)°, illustrating the degree of twisting of the flexible molecule. The bond lengths and angles are in agreement with those reported for other salicyladimines ligands (Chu et al., 2007).

Experimental

The title compound was prepared by a Schiff-base condensation of 3-methoxysalicylaldehyde (3.04 g, 20 mmol) and bis(4-aminophenyl) ether (2.02 g, 10 mmol) in methanol (40 ml). The solution was stirred and refluxed for 1 day. The orange precipitate was filtered off, washed with a small amount of methanol and dried in vacuo. Yield: 91%. Well shaped orange crystals suitable for X-ray diffraction analysis were grown by slow evaporation of a chloroform solution of the title compound at room temperature.

Refinement

H atoms were positioned geometrically (C—H = 0.96 Å; O—H = 0.84 Å), assigned isotropic displacement parameters equal to 1.2U_eq of the parent atoms, and allowed to ride on these parent atoms.

Figures

Fig. 1.

The molecular structure of the title compound with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry code A: 2-x, y, 3/2-z.]

Crystal data

C28H24N2O5	F000 = 984
Mr = 468.49	Dx = 1.328 Mg m−3
Monoclinic, C2/c	Mo Kα radiation λ = 0.71073 Å
a = 15.585 (7) Å	Cell parameters from 2635 reflections
b = 7.578 (4) Å	θ = 1.7–25.1º
c = 19.859 (9) Å	µ = 0.09 mm−1
β = 92.760 (8)º	T = 173 (2) K
V = 2342.7 (19) Å3	Prism, colourless
Z = 4	0.30 × 0.20 × 0.20 mm

Data collection

Bruker SMART CCD diffractometer	2016 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.035
Monochromator: graphite	θmax = 27.5º
T = 173(2) K	θmin = 2.6º
ω scans	h = −20→19
Absorption correction: none	k = −9→9
8736 measured reflections	l = −22→25
2689 independent reflections

Refinement

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)] = 0.062	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.166	w = 1/[σ2(Fo2) + (0.0739P)2 + 0.5764P] where P = (Fo2 + 2Fc2)/3
S = 1.11	(Δ/σ)max = 0.001
2689 reflections	Δρmax = 0.15 e Å−3
165 parameters	Δρmin = −0.13 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.88064 (10)	0.0091 (2)	0.52377 (7)	0.0561 (4)
O1	1.0000	−0.3717 (3)	0.7500	0.0694 (6)
O2	0.78593 (9)	0.02484 (16)	0.41186 (7)	0.0660 (4)
H3	0.8101	−0.0219	0.4461	0.079*
C4	0.91503 (11)	−0.0853 (3)	0.58068 (8)	0.0527 (5)
C13	0.80476 (12)	0.1980 (2)	0.41092 (9)	0.0521 (4)
O3	0.71769 (10)	0.21180 (19)	0.31172 (8)	0.0739 (5)
C12	0.77074 (13)	0.3000 (2)	0.35765 (10)	0.0572 (5)
C3	0.98968 (12)	−0.0344 (3)	0.61733 (9)	0.0574 (5)
H8	1.0210	0.0659	0.6036	0.069*
C6	0.90099 (13)	−0.3309 (3)	0.65622 (10)	0.0610 (5)
H9	0.8709	−0.4333	0.6694	0.073*
C5	0.87355 (12)	−0.2368 (3)	0.59967 (10)	0.0591 (5)
H10	0.8250	−0.2772	0.5733	0.071*
C8	0.85726 (12)	0.2774 (2)	0.46152 (10)	0.0564 (5)
C2	1.01805 (12)	−0.1291 (3)	0.67334 (9)	0.0581 (5)
H12	1.0689	−0.0941	0.6981	0.070*
C7	0.89139 (13)	0.1765 (3)	0.51873 (10)	0.0602 (5)
C1	0.97295 (13)	−0.2738 (3)	0.69341 (9)	0.0562 (5)
C11	0.79102 (15)	0.4744 (3)	0.35347 (12)	0.0718 (6)
H15	0.7685	0.5426	0.3165	0.086*
C14	0.66750 (17)	0.3156 (3)	0.26521 (12)	0.0825 (7)
H16A	0.6388	0.4096	0.2895	0.124*
H16B	0.6243	0.2408	0.2418	0.124*
H16C	0.7048	0.3679	0.2322	0.124*
C9	0.87598 (16)	0.4578 (3)	0.45639 (12)	0.0744 (6)
H17	0.9110	0.5138	0.4905	0.089*
C10	0.84410 (17)	0.5530 (3)	0.40260 (14)	0.0825 (7)
H18	0.8584	0.6743	0.3988	0.099*
H4	0.9250 (14)	0.249 (3)	0.5555 (12)	0.082 (7)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N1	0.0574 (9)	0.0669 (10)	0.0438 (8)	−0.0043 (8)	0.0010 (7)	−0.0009 (7)
O1	0.0892 (14)	0.0622 (12)	0.0554 (11)	0.000	−0.0097 (10)	0.000
O2	0.0793 (10)	0.0517 (7)	0.0653 (9)	−0.0103 (7)	−0.0143 (7)	0.0074 (6)
C4	0.0519 (10)	0.0664 (11)	0.0400 (9)	−0.0021 (8)	0.0041 (7)	−0.0068 (8)
C13	0.0562 (10)	0.0481 (10)	0.0528 (10)	−0.0019 (8)	0.0097 (8)	0.0000 (8)
O3	0.0880 (11)	0.0637 (9)	0.0679 (9)	0.0048 (7)	−0.0170 (8)	0.0087 (7)
C12	0.0614 (11)	0.0546 (11)	0.0561 (11)	0.0051 (9)	0.0081 (9)	0.0020 (9)
C3	0.0554 (10)	0.0723 (12)	0.0448 (10)	−0.0124 (9)	0.0057 (8)	−0.0027 (9)
C6	0.0654 (12)	0.0565 (11)	0.0610 (12)	−0.0098 (9)	0.0007 (10)	−0.0014 (9)
C5	0.0557 (11)	0.0639 (11)	0.0566 (11)	−0.0071 (9)	−0.0074 (9)	−0.0077 (9)
C8	0.0591 (11)	0.0536 (10)	0.0571 (11)	0.0004 (8)	0.0091 (9)	−0.0054 (8)
C2	0.0528 (10)	0.0767 (13)	0.0446 (10)	−0.0101 (9)	−0.0009 (8)	−0.0068 (9)
C7	0.0628 (12)	0.0658 (12)	0.0521 (11)	−0.0022 (10)	0.0030 (9)	−0.0116 (9)
C1	0.0614 (11)	0.0625 (11)	0.0443 (10)	0.0019 (9)	−0.0013 (8)	−0.0048 (8)
C11	0.0819 (15)	0.0571 (12)	0.0768 (14)	0.0050 (11)	0.0087 (12)	0.0074 (11)
C14	0.1016 (18)	0.0836 (15)	0.0610 (13)	0.0289 (13)	−0.0081 (12)	0.0036 (11)
C9	0.0833 (15)	0.0583 (12)	0.0814 (15)	−0.0083 (11)	0.0010 (12)	−0.0145 (11)
C10	0.1018 (18)	0.0466 (11)	0.0993 (19)	−0.0044 (12)	0.0076 (15)	0.0029 (12)

Geometric parameters (Å, °)

N1—C7	1.284 (3)	C6—C1	1.382 (3)
N1—C4	1.421 (2)	C6—H9	0.950
O1—C1i	1.394 (2)	C5—H10	0.950
O1—C1	1.394 (2)	C8—C9	1.402 (3)
O2—C13	1.345 (2)	C8—C7	1.449 (3)
O2—H3	0.840	C2—C1	1.372 (3)
C4—C5	1.379 (3)	C2—H12	0.950
C4—C3	1.397 (3)	C7—H4	1.04 (2)
C13—C12	1.394 (3)	C11—C10	1.383 (3)
C13—C8	1.401 (3)	C11—H15	0.950
O3—C12	1.375 (2)	C14—H16A	0.980
O3—C14	1.419 (2)	C14—H16B	0.980
C12—C11	1.363 (3)	C14—H16C	0.980
C3—C2	1.379 (3)	C9—C10	1.363 (3)
C3—H8	0.950	C9—H17	0.950
C6—C5	1.381 (3)	C10—H18	0.950
C7—N1—C4	120.94 (16)	C1—C2—C3	120.11 (17)
C1i—O1—C1	115.8 (2)	C1—C2—H12	119.9
C13—O2—H3	109.5	C3—C2—H12	119.9
C5—C4—C3	118.51 (17)	N1—C7—C8	122.55 (17)
C5—C4—N1	118.23 (16)	N1—C7—H4	122.3 (12)
C3—C4—N1	123.24 (18)	C8—C7—H4	115.2 (12)
O2—C13—C12	118.43 (17)	C2—C1—C6	120.57 (17)
O2—C13—C8	121.98 (16)	C2—C1—O1	121.33 (16)
C12—C13—C8	119.59 (17)	C6—C1—O1	118.06 (18)
C12—O3—C14	117.23 (17)	C12—C11—C10	120.5 (2)
C11—C12—O3	124.41 (18)	C12—C11—H15	119.8
C11—C12—C13	120.21 (19)	C10—C11—H15	119.8
O3—C12—C13	115.39 (17)	O3—C14—H16A	109.5
C2—C3—C4	120.22 (18)	O3—C14—H16B	109.5
C2—C3—H8	119.9	H16A—C14—H16B	109.5
C4—C3—H8	119.9	O3—C14—H16C	109.5
C5—C6—C1	118.99 (19)	H16A—C14—H16C	109.5
C5—C6—H9	120.5	H16B—C14—H16C	109.5
C1—C6—H9	120.5	C10—C9—C8	120.2 (2)
C4—C5—C6	121.44 (17)	C10—C9—H17	119.9
C4—C5—H10	119.3	C8—C9—H17	119.9
C6—C5—H10	119.3	C9—C10—C11	120.5 (2)
C13—C8—C9	118.89 (19)	C9—C10—H18	119.7
C13—C8—C7	121.02 (17)	C11—C10—H18	119.7
C9—C8—C7	120.09 (18)

Symmetry codes: (i) −x+2, y, −z+3/2.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H3···N1	0.84	1.87	2.611 (2)	147