2-Hydr­oxy-1,6,7,8-tetra­meth­oxy-3-methyl­anthraquinone

Zhu, L.-C.; Zhao, Z.-G.; Yu, S.-J.

doi:10.1107/S1600536807067864

organic compounds

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ISSN: 2056-9890

Volume 64| Part 2| February 2008| Page o371

doi:10.1107/S1600536807067864

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2-Hydroxy-1,6,7,8-tetramethoxy-3-methylanthraquinone

Li-Cai Zhu,^a Zhen-Gang Zhao ^a and Shu-Juan Yu ^a ^*

^aCollege of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510641, People's Republic of China
^*Correspondence e-mail: lfshjyu@scut.edu.cn

(Received 15 November 2007; accepted 20 December 2007; online 4 January 2008)

The title compound, C₁₉H₁₈O₇, also known as chrysoobtusin, was isolated from Cassia tora L. (Leguminosae). The anthraquinone ring system is almost planar, the dihedral angle between the two benzene rings being 4.27 (4)°. The structure is stabilized by intra- and intermolecular O—H⋯O and C—H⋯O hydrogen bonds, and by weak π–π stacking interactions along the b axis, with a centroid–centroid distance between related benzene rings of 3.800 (4) Å.

Related literature

For related literature, see: Boonnak et al. (2005 ); Hao et al. (1995 ); Jia et al. (2007 ); Ng et al. (2005 ); Patil et al. (2004 ); Wu & Yen (2004 ); Allen et al. (1987 ).

Experimental

Crystal data

C₁₉H₁₈O₇
M_r = 358.33
Monoclinic, P 2₁ /n
a = 12.2960 (3) Å
b = 7.8545 (2) Å
c = 18.3361 (5) Å
β = 106.581 (2)°
V = 1697.24 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 296 (2) K
0.30 × 0.28 × 0.26 mm

Data collection

Bruker APEXII area-detector diffractometer
Absorption correction: none
13295 measured reflections
3871 independent reflections
2527 reflections with I > 2σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.046
wR(F²) = 0.133
S = 1.02
3871 reflections
241 parameters
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.21 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C18—H18A⋯O4	0.96	2.53	3.074 (3)	116
C17—H17A⋯O4	0.96	2.60	3.046 (3)	109
C16—H16A⋯O1	0.96	2.50	3.049 (3)	116
O7—H7⋯O6	0.82	2.19	2.6482 (17)	116
O7—H7⋯O3ⁱ	0.82	2.02	2.7221 (16)	144
Symmetry code: (i) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2004); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807067864/rz2185sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536807067864/rz2185Isup2.hkl

checkCIF report

Comment top

Anthraquinone derivatives extracted from the seeds of Cassia tora L. (most common familiar name in China: Juemingzi) have been used traditionally to improve visual acuity. Recent studies have demonstrated that they have multiple pharmacological actions such as antimicrobial, diuretic, antidiarrhoic, antioxidant, antihepatotoxic and antimutagenic activities (Wu & Yen, 2004). One component found in Cassia tora L., 2-hydroxy-1,6,7,8-tetramethoxy-3-methylanthraquinone, is known as chrysoobusin and exhibits a variety of potent biological effects such as suppression of mutagenicity of mycotoxins (Hao et al., 1995), antioxidant activity (Jia et al., 2007) and hypolipidemic activity (Patil et al., 2004). We report here the structure of the title compound.

In the title compound (Fig. 1), the C—C bond lengths show normal values (Allen et al., 1987), and the C—O and C=O bond lengths are comparable to those observed in similar structures (Ng et al., 2005; Boonnak et al., 2005). The anthraquinone ring system is substantially planar, the dihedral angle between the two benzene rings being 4.27 (4)°. The molecules are self-assembled by intra- and intermolecular C—H···O and O—H···.O hydrogen bonding interactions (Table 1) into a superamolecular network. The crystal structure is further stabilized by weak π-π stacking interactions along the b axis (Fig. 2) occurring between centrosymmetrically related anthraquinone ring systems. The centroid-to-centriod distances between related benzene rings of the stacked molecules is 3.800 (4) Å.

Related literature top

For related literature, see: Boonnak et al. (2005); Hao et al. (1995); Jia et al. (2007); Ng et al. (2005); Patil et al. (2004); Wu & Yen (2004); Allen et al. (1987); Sheldrick (1996).

Experimental top

The seeds of Cassia tora L. (800 g) were shattered to powder (about 30 mesh) and extracted with 60% ethanol (3000 ml) for 40 min by microwave irradiation at 333 K. The extraction procedure was repeated three times. The extracts were combined and evaporated to dryness under reduced pressure at 333 K, the residue was redissolved in water (600 ml) and was added 400 ml light petroleum to remove low-polar substaces three times. Then the enriched extracts were extracted with chloroform four times (500 ml for each time), the chlorofrom solution were combined and evaporated to dryness under reduced pressure at 333 K, 4.52 g crude extracts was obtained. The crude extracts were separated with n-hexane-ethyl acetate-methanol-water (11: 90: 10: 10, v/v) using high-speed counter-current chromatography (HSCCC) to obtain 2-hydroxy-1,6,7,8-tetramethoxy-3-methylanthraquinone (yield 46.2 mg). Single crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution.

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, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2004); software used to prepare material for publication: SHELXTL (Bruker, 2004).

Figures top

	Fig. 1. The molecular structure of the title compound showing the atomic-numbering scheme and displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. The molecular packing of the title compound showing the intra- and intermolecular hydrogen bonding interactions as broken lines.

2-Hydroxy-1,6,7,8-tetramethoxy-3-methylanthraquinone top

Crystal data top

C₁₉H₁₈O₇	F(000) = 752
M_r = 358.33	D_x = 1.402 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3645 reflections
a = 12.2960 (3) Å	θ = 1.4–28.0°
b = 7.8545 (2) Å	µ = 0.11 mm⁻¹
c = 18.3361 (5) Å	T = 296 K
β = 106.581 (2)°	Block, yellow
V = 1697.24 (8) Å³	0.30 × 0.28 × 0.26 mm
Z = 4

Data collection top

Bruker APEXII area-detector diffractometer	2527 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.032
Graphite monochromator	θ_max = 27.5°, θ_min = 1.8°
f and ω scans	h = −15→15
13295 measured reflections	k = −10→10
3871 independent reflections	l = −23→23

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.133	H-atom parameters constrained
S = 1.02	w = 1/[σ²(F_o²) + (0.0598P)² + 0.2883P] where P = (F_o² + 2F_c²)/3
3871 reflections	(Δ/σ)_max < 0.001
241 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.21 e Å⁻³

Crystal data top

C₁₉H₁₈O₇	V = 1697.24 (8) Å³
M_r = 358.33	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 12.2960 (3) Å	µ = 0.11 mm⁻¹
b = 7.8545 (2) Å	T = 296 K
c = 18.3361 (5) Å	0.30 × 0.28 × 0.26 mm
β = 106.581 (2)°

Data collection top

Bruker APEXII area-detector diffractometer	2527 reflections with I > 2σ(I)
13295 measured reflections	R_int = 0.032
3871 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.046	0 restraints
wR(F²) = 0.133	H-atom parameters constrained
S = 1.02	Δρ_max = 0.19 e Å⁻³
3871 reflections	Δρ_min = −0.21 e Å⁻³
241 parameters

Special details top

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
C1	0.12772 (16)	0.3847 (2)	−0.08053 (10)	0.0478 (4)
C2	0.23670 (15)	0.3514 (2)	−0.03234 (10)	0.0479 (4)
C3	0.25066 (14)	0.2624 (2)	0.03525 (9)	0.0417 (4)
C4	0.15663 (13)	0.2073 (2)	0.05800 (9)	0.0391 (4)
C5	0.04861 (13)	0.2443 (2)	0.00932 (9)	0.0394 (4)
C6	0.03506 (15)	0.3313 (2)	−0.05891 (9)	0.0452 (4)
H6	−0.0376	0.3536	−0.0902	0.054*
C7	−0.05610 (14)	0.1888 (2)	0.02762 (9)	0.0419 (4)
C8	−0.04420 (13)	0.10489 (19)	0.10100 (9)	0.0391 (4)
C9	0.06335 (13)	0.07377 (19)	0.15239 (9)	0.0385 (4)
C10	0.16909 (14)	0.1101 (2)	0.12996 (9)	0.0420 (4)
C11	0.06680 (13)	−0.0001 (2)	0.22235 (9)	0.0404 (4)
C12	−0.03346 (14)	−0.0496 (2)	0.23820 (9)	0.0447 (4)
C13	−0.14001 (14)	−0.0222 (2)	0.18680 (9)	0.0459 (4)
C14	−0.14247 (14)	0.0570 (2)	0.11918 (9)	0.0444 (4)
H14	−0.2124	0.0793	0.0844	0.053*
C15	0.01444 (17)	0.4980 (3)	−0.19883 (11)	0.0645 (5)
H15A	−0.0223	0.3913	−0.2157	0.097*
H15B	0.0236	0.5600	−0.2418	0.097*
H15C	−0.0311	0.5634	−0.1744	0.097*
C16	0.3571 (2)	0.5740 (3)	−0.04686 (16)	0.0795 (7)
H16A	0.2951	0.6370	−0.0794	0.119*
H16B	0.4246	0.5946	−0.0619	0.119*
H16C	0.3690	0.6098	0.0049	0.119*
C17	0.41092 (17)	0.0855 (3)	0.06199 (13)	0.0682 (6)
H17A	0.3652	−0.0108	0.0666	0.102*
H17B	0.4855	0.0729	0.0967	0.102*
H17C	0.4163	0.0920	0.0109	0.102*
C18	0.21311 (19)	0.1135 (3)	0.32189 (12)	0.0727 (6)
H18A	0.2443	0.1858	0.2907	0.109*
H18B	0.2723	0.0790	0.3660	0.109*
H18C	0.1559	0.1745	0.3375	0.109*
C19	−0.24641 (16)	−0.0758 (3)	0.20556 (12)	0.0666 (6)
H19A	−0.3114	−0.0311	0.1680	0.100*
H19B	−0.2450	−0.0327	0.2548	0.100*
H19C	−0.2507	−0.1978	0.2058	0.100*
O1	0.12327 (11)	0.46722 (18)	−0.14620 (7)	0.0641 (4)
O2	0.33123 (11)	0.39758 (17)	−0.05315 (8)	0.0617 (4)
O3	0.36000 (9)	0.23760 (15)	0.07962 (6)	0.0495 (3)
O4	0.26068 (10)	0.05769 (19)	0.16791 (7)	0.0642 (4)
O5	−0.14949 (10)	0.21417 (18)	−0.01744 (7)	0.0581 (4)
O6	0.16389 (10)	−0.03329 (16)	0.27947 (6)	0.0510 (3)
O7	−0.02886 (10)	−0.12633 (19)	0.30522 (7)	0.0599 (4)
H7	0.0376	−0.1434	0.3291	0.090*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0551 (11)	0.0446 (9)	0.0446 (9)	0.0084 (8)	0.0161 (8)	0.0035 (8)
C2	0.0478 (10)	0.0460 (9)	0.0522 (10)	0.0032 (8)	0.0180 (8)	−0.0028 (8)
C3	0.0395 (9)	0.0421 (9)	0.0407 (9)	0.0039 (7)	0.0069 (7)	−0.0082 (7)
C4	0.0396 (9)	0.0387 (8)	0.0363 (8)	0.0037 (7)	0.0064 (7)	−0.0053 (7)
C5	0.0412 (9)	0.0371 (8)	0.0367 (8)	0.0034 (7)	0.0061 (7)	−0.0039 (7)
C6	0.0450 (9)	0.0420 (9)	0.0455 (9)	0.0075 (7)	0.0080 (7)	0.0007 (8)
C7	0.0409 (9)	0.0399 (9)	0.0401 (8)	0.0051 (7)	0.0038 (7)	−0.0022 (7)
C8	0.0399 (9)	0.0369 (8)	0.0368 (8)	0.0029 (7)	0.0047 (7)	−0.0036 (7)
C9	0.0396 (8)	0.0349 (8)	0.0376 (8)	0.0017 (7)	0.0056 (7)	−0.0034 (7)
C10	0.0388 (9)	0.0431 (9)	0.0392 (9)	0.0036 (7)	0.0032 (7)	−0.0049 (7)
C11	0.0386 (8)	0.0389 (8)	0.0379 (8)	0.0025 (7)	0.0017 (7)	−0.0031 (7)
C12	0.0474 (10)	0.0459 (9)	0.0379 (8)	0.0022 (8)	0.0078 (7)	0.0005 (7)
C13	0.0426 (9)	0.0484 (10)	0.0450 (9)	0.0006 (8)	0.0098 (7)	−0.0017 (8)
C14	0.0368 (8)	0.0475 (9)	0.0435 (9)	0.0043 (7)	0.0026 (7)	−0.0019 (8)
C15	0.0741 (14)	0.0684 (13)	0.0482 (10)	0.0172 (11)	0.0129 (10)	0.0118 (10)
C16	0.0717 (15)	0.0681 (14)	0.1065 (19)	−0.0097 (12)	0.0382 (14)	0.0046 (14)
C17	0.0536 (11)	0.0765 (14)	0.0700 (13)	0.0212 (10)	0.0104 (10)	−0.0125 (11)
C18	0.0665 (13)	0.0868 (16)	0.0526 (11)	−0.0165 (12)	−0.0026 (10)	−0.0160 (11)
C19	0.0477 (11)	0.0890 (15)	0.0636 (12)	−0.0002 (10)	0.0165 (9)	0.0115 (11)
O1	0.0621 (8)	0.0764 (9)	0.0543 (8)	0.0081 (7)	0.0177 (7)	0.0207 (7)
O2	0.0554 (8)	0.0657 (9)	0.0712 (9)	0.0024 (7)	0.0298 (7)	0.0041 (7)
O3	0.0375 (6)	0.0581 (7)	0.0487 (7)	0.0028 (5)	0.0056 (5)	−0.0093 (6)
O4	0.0424 (7)	0.0934 (11)	0.0526 (7)	0.0150 (7)	0.0069 (6)	0.0189 (7)
O5	0.0399 (7)	0.0773 (9)	0.0495 (7)	0.0038 (6)	0.0005 (6)	0.0141 (7)
O6	0.0447 (7)	0.0585 (7)	0.0411 (6)	−0.0002 (6)	−0.0016 (5)	0.0051 (6)
O7	0.0489 (7)	0.0822 (10)	0.0461 (7)	0.0018 (7)	0.0096 (6)	0.0156 (7)

Geometric parameters (Å, º) top

C1—O1	1.355 (2)	C13—C14	1.380 (2)
C1—C6	1.374 (2)	C13—C19	1.505 (2)
C1—C2	1.403 (2)	C14—H14	0.9300
C2—O2	1.372 (2)	C15—O1	1.429 (2)
C2—C3	1.390 (2)	C15—H15A	0.9600
C3—O3	1.3723 (19)	C15—H15B	0.9600
C3—C4	1.405 (2)	C15—H15C	0.9600
C4—C5	1.403 (2)	C16—O2	1.419 (2)
C4—C10	1.494 (2)	C16—H16A	0.9600
C5—C6	1.393 (2)	C16—H16B	0.9600
C5—C7	1.485 (2)	C16—H16C	0.9600
C6—H6	0.9300	C17—O3	1.428 (2)
C7—O5	1.2245 (19)	C17—H17A	0.9600
C7—C8	1.468 (2)	C17—H17B	0.9600
C8—C14	1.394 (2)	C17—H17C	0.9600
C8—C9	1.409 (2)	C18—O6	1.425 (2)
C9—C11	1.397 (2)	C18—H18A	0.9600
C9—C10	1.499 (2)	C18—H18B	0.9600
C10—O4	1.2144 (19)	C18—H18C	0.9600
C11—O6	1.3699 (18)	C19—H19A	0.9600
C11—C12	1.400 (2)	C19—H19B	0.9600
C12—O7	1.355 (2)	C19—H19C	0.9600
C12—C13	1.395 (2)	O7—H7	0.8200

O1—C1—C6	125.14 (16)	C13—C14—C8	122.57 (15)
O1—C1—C2	115.97 (16)	C13—C14—H14	118.7
C6—C1—C2	118.88 (16)	C8—C14—H14	118.7
O2—C2—C3	118.82 (16)	O1—C15—H15A	109.5
O2—C2—C1	120.56 (16)	O1—C15—H15B	109.5
C3—C2—C1	120.52 (16)	H15A—C15—H15B	109.5
O3—C3—C2	116.80 (15)	O1—C15—H15C	109.5
O3—C3—C4	122.02 (15)	H15A—C15—H15C	109.5
C2—C3—C4	121.13 (15)	H15B—C15—H15C	109.5
C5—C4—C3	117.20 (15)	O2—C16—H16A	109.5
C5—C4—C10	120.50 (14)	O2—C16—H16B	109.5
C3—C4—C10	122.29 (14)	H16A—C16—H16B	109.5
C6—C5—C4	121.45 (15)	O2—C16—H16C	109.5
C6—C5—C7	117.22 (14)	H16A—C16—H16C	109.5
C4—C5—C7	121.32 (15)	H16B—C16—H16C	109.5
C1—C6—C5	120.80 (16)	O3—C17—H17A	109.5
C1—C6—H6	119.6	O3—C17—H17B	109.5
C5—C6—H6	119.6	H17A—C17—H17B	109.5
O5—C7—C8	121.37 (16)	O3—C17—H17C	109.5
O5—C7—C5	120.42 (15)	H17A—C17—H17C	109.5
C8—C7—C5	118.21 (14)	H17B—C17—H17C	109.5
C14—C8—C9	120.37 (15)	O6—C18—H18A	109.5
C14—C8—C7	118.30 (14)	O6—C18—H18B	109.5
C9—C8—C7	121.33 (15)	H18A—C18—H18B	109.5
C11—C9—C8	117.57 (15)	O6—C18—H18C	109.5
C11—C9—C10	121.97 (14)	H18A—C18—H18C	109.5
C8—C9—C10	120.37 (14)	H18B—C18—H18C	109.5
O4—C10—C4	121.60 (15)	C13—C19—H19A	109.5
O4—C10—C9	120.89 (15)	C13—C19—H19B	109.5
C4—C10—C9	117.48 (13)	H19A—C19—H19B	109.5
O6—C11—C9	124.92 (15)	C13—C19—H19C	109.5
O6—C11—C12	114.54 (14)	H19A—C19—H19C	109.5
C9—C11—C12	120.53 (14)	H19B—C19—H19C	109.5
O7—C12—C13	118.00 (15)	C1—O1—C15	118.27 (15)
O7—C12—C11	120.03 (14)	C2—O2—C16	115.05 (15)
C13—C12—C11	121.98 (15)	C3—O3—C17	113.79 (13)
C14—C13—C12	116.89 (15)	C11—O6—C18	113.88 (14)
C14—C13—C19	122.28 (16)	C12—O7—H7	109.5
C12—C13—C19	120.83 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C18—H18A···O4	0.96	2.53	3.074 (3)	116
C17—H17A···O4	0.96	2.60	3.046 (3)	109
C16—H16A···O1	0.96	2.50	3.049 (3)	116
O7—H7···O6	0.82	2.19	2.6482 (17)	116
O7—H7···O3ⁱ	0.82	2.02	2.7221 (16)	144

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

Experimental details

Crystal data
Chemical formula	C₁₉H₁₈O₇
M_r	358.33
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	12.2960 (3), 7.8545 (2), 18.3361 (5)
β (°)	106.581 (2)
V (Å³)	1697.24 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.11
Crystal size (mm)	0.30 × 0.28 × 0.26

Data collection
Diffractometer	Bruker APEXII area-detector diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	13295, 3871, 2527
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.133, 1.02
No. of reflections	3871
No. of parameters	241
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.21

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 2004).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C18—H18A···O4	0.96	2.53	3.074 (3)	116.2
C17—H17A···O4	0.96	2.60	3.046 (3)	108.7
C16—H16A···O1	0.96	2.50	3.049 (3)	116.0
O7—H7···O6	0.82	2.19	2.6482 (17)	115.5
O7—H7···O3ⁱ	0.82	2.02	2.7221 (16)	144.1

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

Acknowledgements

The authors acknowledge the Ministry of Science and Technology of China (fund No. 2006BAD27B03) for financial support, and South China University of Technology and South China Normal University for supporting this work.

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