4-[(E)-(4-Eth­oxy­benzyl­idene)amino]­phenol

Kaewmanee, N.; Chantrapromma, S.; Boonnak, N.; Fun, H.-K.

doi:10.1107/S1600536813012580

organic compounds

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ISSN: 2056-9890

Volume 69| Part 6| June 2013| Pages o903-o904

doi:10.1107/S1600536813012580

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4-[(E)-(4-Ethoxybenzylidene)amino]phenol

Narissara Kaewmanee,^a Suchada Chantrapromma,^b ^*‡ Nawong Boonnak ^c and Hoong-Kun Fun ^d,^e §

^aDepartment of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand, ^bDepartment of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand, ^cFaculty of Traditional Thai Medicine, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand, ^dX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^eDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia
^*Correspondence e-mail: suchada.c@psu.ac.th

(Received 24 April 2013; accepted 8 May 2013; online 18 May 2013)

The molecule of the title compound, C₁₅H₁₅NO₂, adopts a trans conformation with respect to the methylidene C=N bond and is twisted with a dihedral angle of 26.31 (5)° between the two substituted benzene rings. The ethoxy group is almost coplanar with the bound benzene ring with a C—O—C—C torsion angle of −179.08 (9)°. In the crystal, molecules are linked by O—H⋯N hydrogen bonds and weak C—H⋯O interactions into chains propagating in the [011] and [01-1] directions. C—H⋯π interactions are also present.

Related literature

For standard bond lengths, see: Allen et al. (1987 ). For background to and applications of aza-stilbene, see: Cheng et al. (2010 ); da Silva et al. (2011 ); Kabir et al. (2008 ); Lu et al. (2012 ); Pavan et al. (2011 ). For related structures, see: Sun et al. (2011 ); Wang (2009 ).

Experimental

Crystal data

C₁₅H₁₅NO₂
M_r = 241.28
Orthorhombic, P n a 2₁
a = 18.6882 (11) Å
b = 10.7420 (6) Å
c = 6.3186 (4) Å
V = 1268.45 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 100 K
0.59 × 0.27 × 0.25 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.952, T_max = 0.979
16922 measured reflections
2382 independent reflections
2319 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.030
wR(F²) = 0.086
S = 1.10
2382 reflections
168 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C8–C13 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H1O2⋯N1ⁱ	0.83 (2)	1.87 (2)	2.6971 (12)	172 (2)
C6—H6A⋯O2ⁱⁱ	0.95	2.51	3.3956 (14)	156
C9—H9A⋯O2ⁱⁱⁱ	0.95	2.38	3.3229 (13)	171
C14—H14B⋯Cg1^iv	0.99	2.90	3.7668 (12)	147
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (iv) $[-x+2, -y+1, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536813012580/rz5061sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813012580/rz5061Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813012580/rz5061Isup3.cml

checkCIF report

Comment top

Aza-stilbene derivatives derived from the reaction of an aldehyde with hydrazine have been shown to possess potent biological activities such as antibacterial (Kabir et al., 2008), antifungal (da Silva et al., 2011), antimycobacterium tuberculosis (Pavan et al., 2011) and antioxidation (Cheng et al., 2010; Lu et al., 2012) properties. These interesting biological activities of aza-stilbene led us to synthesize the title compound, (I), and study its antibacterial activity. Our antibacterial assay showed that (I) exhibits moderate activity against Salmonella typhi with the minimun inhibition concentration (MIC) value of 18.75 µg/ml. We report here the crystal structure of the title compound.

The molecule of (I) (Fig. 1), C₁₅H₁₅NO₂, is twisted and exists in a trans configuration with respect to the methylidene C7═N1 double bond [1.2867 (13) Å] with the torsion angle C8–N1–C7–C1 = 179.23 (8)°. The dihedral angle between the two substituted benzene rings is 26.31 (5)°. The ethoxy group is co-planar with the bound benzene ring with the r.m.s. deviation of 0.0155 (1) Å for the nine non H-atoms and the C4–O1–C14–C15 angle is -179.08 (9)°. The bond distances are within the normal range (Allen et al., 1987) and are in agreement with those reported for related structures (Sun et al., 2011; Wang, 2009).

In the crystal structure (Fig. 2), the molecules are linked by O–H···N hydrogen bond and weak C—H···O interactions (Table 1) into chains propagating in the [011] and [011] directions. C—H···π interactions between the ethoxy group and the hydroxy substituted rings are also present (Table 1).

Related literature top

For standard bond lengths, see: Allen et al. (1987). For background to and applications of aza-stilbene, see: Cheng et al. (2010); da Silva et al. (2011); Kabir et al. (2008); Lu et al. (2012); Pavan et al. (2011). For related structures, see: Sun et al. (2011); Wang (2009).

Experimental top

The title compound (I) was prepared by dissolving 4-benzylideneaniline (5 mmol, 0.50 g) in ethanol (30 ml) and 4-ethoxybenzaldehyde (5 mmol, 0.70 ml) was slowly added with stirring. The solution was stirred at room temperature for around 3 hr yielding a white solid, which was filtered off and washed with cold ethanol and dried in air. Colourless block-shaped single crystals of (I) suitable for X-ray structure determination were recrystallized from methanol by slow evaporation at room temperature after several days, M. p. 470–472 K.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The asymmetric unit of the title compound showing 65% probability displacement ellipsoids.
	Fig. 2. Crystal packing of the title compound viewed along the c axis. Hydrogen bonds are drawn as dashed lines.

4-[(E)-(4-Ethoxybenzylidene)amino]phenol top

Crystal data top

C₁₅H₁₅NO₂	D_x = 1.263 Mg m⁻³
M_r = 241.28	Melting point = 470–472 K
Orthorhombic, Pna2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 2382 reflections
a = 18.6882 (11) Å	θ = 2.2–32.0°
b = 10.7420 (6) Å	µ = 0.08 mm⁻¹
c = 6.3186 (4) Å	T = 100 K
V = 1268.45 (13) Å³	Block, colourless
Z = 4	0.59 × 0.27 × 0.25 mm
F(000) = 512

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2382 independent reflections
Radiation source: fine-focus sealed tube	2319 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
Detector resolution: 8.33 pixels mm^-1	θ_max = 32.0°, θ_min = 2.2°
ω scans	h = −27→27
Absorption correction: multi-scan (SADABS; Bruker, 2009)	k = −16→15
T_min = 0.952, T_max = 0.979	l = −9→9
16922 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.086	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ²(F_o²) + (0.0562P)² + 0.1397P] where P = (F_o² + 2F_c²)/3
2382 reflections	(Δ/σ)_max = 0.001
168 parameters	Δρ_max = 0.35 e Å⁻³
1 restraint	Δρ_min = −0.19 e Å⁻³

Crystal data top

C₁₅H₁₅NO₂	V = 1268.45 (13) Å³
M_r = 241.28	Z = 4
Orthorhombic, Pna2₁	Mo Kα radiation
a = 18.6882 (11) Å	µ = 0.08 mm⁻¹
b = 10.7420 (6) Å	T = 100 K
c = 6.3186 (4) Å	0.59 × 0.27 × 0.25 mm

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	2382 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	2319 reflections with I > 2σ(I)
T_min = 0.952, T_max = 0.979	R_int = 0.025
16922 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	1 restraint
wR(F²) = 0.086	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	Δρ_max = 0.35 e Å⁻³
2382 reflections	Δρ_min = −0.19 e Å⁻³
168 parameters

Special details top

Experimental. The data was collected with the Oxford Cryosystem Cobra low-temperature attachment.

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 (Å²) top

	x	y	z	U_iso*/U_eq
O1	1.07262 (4)	0.90374 (7)	0.65280 (16)	0.02092 (17)
O2	0.68429 (4)	0.01683 (7)	0.72655 (13)	0.01662 (15)
H1O2	0.6732 (11)	0.000 (2)	0.851 (4)	0.038 (5)*
N1	0.85372 (4)	0.43914 (7)	0.61658 (15)	0.01367 (16)
C1	0.93803 (5)	0.59761 (9)	0.72367 (18)	0.01420 (18)
C2	0.97668 (5)	0.64779 (9)	0.89339 (19)	0.01686 (19)
H2A	0.9725	0.6113	1.0298	0.020*
C3	1.02104 (6)	0.75025 (10)	0.86479 (19)	0.0181 (2)
H3A	1.0468	0.7835	0.9813	0.022*
C4	1.02770 (5)	0.80430 (9)	0.66463 (19)	0.01595 (19)
C5	0.98933 (6)	0.75587 (10)	0.49369 (19)	0.01789 (19)
H5A	0.9934	0.7928	0.3576	0.021*
C6	0.94517 (6)	0.65320 (10)	0.52393 (19)	0.01713 (19)
H6A	0.9194	0.6201	0.4072	0.021*
C7	0.89365 (5)	0.48741 (8)	0.76077 (17)	0.01413 (18)
H7A	0.8944	0.4500	0.8970	0.017*
C8	0.81221 (5)	0.33104 (9)	0.65972 (16)	0.01283 (17)
C9	0.78245 (5)	0.30394 (9)	0.85792 (16)	0.01439 (18)
H9A	0.7915	0.3572	0.9750	0.017*
C10	0.73949 (5)	0.19880 (9)	0.88339 (16)	0.01468 (17)
H10A	0.7190	0.1811	1.0176	0.018*
C11	0.72652 (5)	0.11939 (8)	0.71249 (17)	0.01325 (17)
C12	0.75683 (6)	0.14583 (9)	0.51485 (17)	0.01527 (18)
H12A	0.7489	0.0913	0.3988	0.018*
C13	0.79848 (5)	0.25179 (9)	0.48866 (16)	0.01442 (17)
H13A	0.8178	0.2707	0.3534	0.017*
C14	1.08402 (6)	0.95958 (10)	0.4482 (2)	0.0215 (2)
H14A	1.0383	0.9914	0.3904	0.026*
H14B	1.1037	0.8975	0.3482	0.026*
C15	1.13632 (6)	1.06515 (11)	0.4787 (3)	0.0285 (3)
H15A	1.1448	1.1065	0.3427	0.043*
H15B	1.1816	1.0323	0.5335	0.043*
H15C	1.1165	1.1253	0.5795	0.043*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0213 (3)	0.0180 (3)	0.0234 (4)	−0.0072 (3)	−0.0018 (3)	−0.0007 (3)
O2	0.0230 (3)	0.0138 (3)	0.0131 (3)	−0.0056 (2)	0.0018 (3)	−0.0011 (3)
N1	0.0156 (3)	0.0116 (3)	0.0138 (4)	−0.0003 (3)	0.0002 (3)	0.0000 (3)
C1	0.0144 (4)	0.0133 (3)	0.0148 (4)	−0.0003 (3)	−0.0007 (3)	−0.0011 (3)
C2	0.0177 (4)	0.0183 (4)	0.0146 (4)	−0.0008 (3)	−0.0029 (4)	−0.0003 (4)
C3	0.0174 (4)	0.0193 (4)	0.0176 (5)	−0.0023 (3)	−0.0036 (4)	−0.0023 (4)
C4	0.0146 (4)	0.0140 (4)	0.0193 (5)	−0.0013 (3)	−0.0018 (4)	−0.0007 (4)
C5	0.0199 (4)	0.0175 (4)	0.0162 (5)	−0.0045 (3)	−0.0025 (4)	0.0009 (4)
C6	0.0188 (4)	0.0176 (4)	0.0150 (4)	−0.0044 (3)	−0.0017 (4)	−0.0002 (4)
C7	0.0153 (4)	0.0132 (4)	0.0139 (4)	−0.0001 (3)	0.0000 (3)	−0.0002 (3)
C8	0.0144 (3)	0.0114 (3)	0.0126 (4)	0.0002 (3)	−0.0005 (3)	0.0001 (3)
C9	0.0184 (4)	0.0128 (4)	0.0119 (4)	−0.0005 (3)	0.0006 (3)	−0.0015 (3)
C10	0.0192 (4)	0.0137 (4)	0.0111 (4)	−0.0010 (3)	0.0012 (4)	−0.0007 (3)
C11	0.0161 (4)	0.0113 (3)	0.0123 (4)	−0.0001 (3)	0.0005 (3)	−0.0001 (3)
C12	0.0196 (4)	0.0143 (4)	0.0119 (4)	−0.0018 (3)	0.0011 (4)	−0.0015 (3)
C13	0.0181 (4)	0.0146 (4)	0.0106 (4)	−0.0011 (3)	0.0009 (4)	−0.0010 (3)
C14	0.0199 (4)	0.0176 (4)	0.0269 (6)	−0.0038 (3)	−0.0014 (4)	0.0044 (4)
C15	0.0236 (5)	0.0201 (5)	0.0420 (8)	−0.0071 (4)	0.0000 (5)	0.0019 (5)

Geometric parameters (Å, º) top

O1—C4	1.3605 (11)	C7—H7A	0.9500
O1—C14	1.4412 (16)	C8—C13	1.3996 (14)
O2—C11	1.3581 (11)	C8—C9	1.4009 (14)
O2—H1O2	0.83 (3)	C9—C10	1.3951 (13)
N1—C7	1.2867 (13)	C9—H9A	0.9500
N1—C8	1.4228 (12)	C10—C11	1.3973 (14)
C1—C2	1.4008 (15)	C10—H10A	0.9500
C1—C6	1.4026 (16)	C11—C12	1.4004 (15)
C1—C7	1.4643 (13)	C12—C13	1.3887 (13)
C2—C3	1.3898 (14)	C12—H12A	0.9500
C2—H2A	0.9500	C13—H13A	0.9500
C3—C4	1.3972 (16)	C14—C15	1.5094 (15)
C3—H3A	0.9500	C14—H14A	0.9900
C4—C5	1.3970 (15)	C14—H14B	0.9900
C5—C6	1.3906 (14)	C15—H15A	0.9800
C5—H5A	0.9500	C15—H15B	0.9800
C6—H6A	0.9500	C15—H15C	0.9800

C4—O1—C14	117.86 (9)	C10—C9—C8	119.99 (9)
C11—O2—H1O2	112.7 (15)	C10—C9—H9A	120.0
C7—N1—C8	120.62 (9)	C8—C9—H9A	120.0
C2—C1—C6	118.43 (9)	C9—C10—C11	120.33 (9)
C2—C1—C7	118.72 (10)	C9—C10—H10A	119.8
C6—C1—C7	122.83 (9)	C11—C10—H10A	119.8
C3—C2—C1	120.85 (11)	O2—C11—C10	123.06 (9)
C3—C2—H2A	119.6	O2—C11—C12	117.25 (9)
C1—C2—H2A	119.6	C10—C11—C12	119.68 (9)
C2—C3—C4	120.00 (10)	C13—C12—C11	119.95 (9)
C2—C3—H3A	120.0	C13—C12—H12A	120.0
C4—C3—H3A	120.0	C11—C12—H12A	120.0
O1—C4—C5	124.52 (10)	C12—C13—C8	120.62 (9)
O1—C4—C3	115.52 (9)	C12—C13—H13A	119.7
C5—C4—C3	119.96 (9)	C8—C13—H13A	119.7
C6—C5—C4	119.59 (10)	O1—C14—C15	107.10 (11)
C6—C5—H5A	120.2	O1—C14—H14A	110.3
C4—C5—H5A	120.2	C15—C14—H14A	110.3
C5—C6—C1	121.18 (10)	O1—C14—H14B	110.3
C5—C6—H6A	119.4	C15—C14—H14B	110.3
C1—C6—H6A	119.4	H14A—C14—H14B	108.5
N1—C7—C1	122.74 (9)	C14—C15—H15A	109.5
N1—C7—H7A	118.6	C14—C15—H15B	109.5
C1—C7—H7A	118.6	H15A—C15—H15B	109.5
C13—C8—C9	119.41 (9)	C14—C15—H15C	109.5
C13—C8—N1	116.65 (9)	H15A—C15—H15C	109.5
C9—C8—N1	123.87 (9)	H15B—C15—H15C	109.5

C6—C1—C2—C3	0.01 (15)	C6—C1—C7—N1	−5.42 (15)
C7—C1—C2—C3	178.24 (9)	C7—N1—C8—C13	−150.56 (9)
C1—C2—C3—C4	−0.20 (15)	C7—N1—C8—C9	32.46 (13)
C14—O1—C4—C5	−2.99 (14)	C13—C8—C9—C10	−0.07 (14)
C14—O1—C4—C3	177.23 (9)	N1—C8—C9—C10	176.84 (9)
C2—C3—C4—O1	−179.72 (9)	C8—C9—C10—C11	0.67 (14)
C2—C3—C4—C5	0.48 (15)	C9—C10—C11—O2	−178.92 (9)
O1—C4—C5—C6	179.64 (9)	C9—C10—C11—C12	−0.06 (15)
C3—C4—C5—C6	−0.58 (16)	O2—C11—C12—C13	177.76 (9)
C4—C5—C6—C1	0.40 (16)	C10—C11—C12—C13	−1.16 (15)
C2—C1—C6—C5	−0.12 (15)	C11—C12—C13—C8	1.78 (15)
C7—C1—C6—C5	−178.27 (9)	C9—C8—C13—C12	−1.16 (14)
C8—N1—C7—C1	179.23 (8)	N1—C8—C13—C12	−178.29 (9)
C2—C1—C7—N1	176.43 (9)	C4—O1—C14—C15	−179.08 (9)

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C8–C13 ring.

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1O2···N1ⁱ	0.83 (2)	1.87 (2)	2.6971 (12)	172 (2)
C6—H6A···O2ⁱⁱ	0.95	2.51	3.3956 (14)	156
C9—H9A···O2ⁱⁱⁱ	0.95	2.38	3.3229 (13)	171
C14—H14B···Cg1^iv	0.99	2.90	3.7668 (12)	147

Symmetry codes: (i) −x+3/2, y−1/2, z+1/2; (ii) −x+3/2, y+1/2, z−1/2; (iii) −x+3/2, y+1/2, z+1/2; (iv) −x+2, −y+1, z−1/2.

Experimental details

Crystal data
Chemical formula	C₁₅H₁₅NO₂
M_r	241.28
Crystal system, space group	Orthorhombic, Pna2₁
Temperature (K)	100
a, b, c (Å)	18.6882 (11), 10.7420 (6), 6.3186 (4)
V (Å³)	1268.45 (13)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.59 × 0.27 × 0.25

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.952, 0.979
No. of measured, independent and observed [I > 2σ(I)] reflections	16922, 2382, 2319
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.745

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.086, 1.10
No. of reflections	2382
No. of parameters	168
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.35, −0.19

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg1 is the centroid of the C8–C13 ring.

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1O2···N1ⁱ	0.83 (2)	1.87 (2)	2.6971 (12)	172 (2)
C6—H6A···O2ⁱⁱ	0.95	2.51	3.3956 (14)	156
C9—H9A···O2ⁱⁱⁱ	0.95	2.38	3.3229 (13)	171
C14—H14B···Cg1^iv	0.99	2.90	3.7668 (12)	147

Symmetry codes: (i) −x+3/2, y−1/2, z+1/2; (ii) −x+3/2, y+1/2, z−1/2; (iii) −x+3/2, y+1/2, z+1/2; (iv) −x+2, −y+1, z−1/2.

Footnotes

‡Thomson Reuters ResearcherID: A-5085-2009.

§Additional correspondence author, e-mail: hfun@usm.my. Thomson Reuters ResearcherID: A-3561-2009.

Acknowledgements

NK thanks the Center of Excellence for Innovation in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Education, and the Graduate School, Prince of Songkla University, for financial support. The authors extend their appreciation to the Malaysian Government and Universiti Sains Malaysia for APEX DE2012 grant No. 1002/PFIZIK/910323, and the Deanship of Scientific Research and the Research Center, College of Pharmacy, King Saud University.

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Volume 69| Part 6| June 2013| Pages o903-o904

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