organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

1,1′-Bi­cyclo­propyl-1,1′-diyl 1,1′-bi­phenyl-2,2′-di­carboxyl­ate

aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and bSchool of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
*Correspondence e-mail: hkfun@usm.my

(Received 20 April 2012; accepted 25 April 2012; online 5 May 2012)

In the title compound, C20H16O4, the two benzene rings form a dihedral angle of 45.70 (4)°. In the crystal, mol­ecules are linked via C—H⋯O inter­actions into layers lying parallel to the bc plane.

Related literature

For the background to this study, see the first paper in this series: Fun, Quah, Wu & Zhang (2012[Fun, H.-K., Quah, C. K., Wu, D. & Zhang, Y. (2012). Acta Cryst. E68, o1627.]). For related structures in this series, see: Fun, Lim, Quah & Wu (2012[Fun, H.-K., Lim, M. Y., Quah, C. K. & Wu, D. (2012). Acta Cryst. E68, o1629.]); Fun, Quah & Wu (2012[Fun, H.-K., Quah, C. K. & Wu, D. (2012). Acta Cryst. E68, o1628.]). For standard bond-length data, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]). For the preparation, see: Wu et al. (2012[Wu, D., Wang, L., Xu, K., Song, J., Fun, H.-K., Xu, J. & Zhang, Y. (2012). Chem. Commun. 48, 1168-1170.]).

[Scheme 1]

Experimental

Crystal data
  • C20H16O4

  • Mr = 320.33

  • Monoclinic, C 2/c

  • a = 26.3197 (14) Å

  • b = 9.4184 (5) Å

  • c = 13.3606 (7) Å

  • β = 100.092 (1)°

  • V = 3260.7 (3) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 296 K

  • 0.43 × 0.34 × 0.17 mm

Data collection
  • Bruker SMART APEXII DUO CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.962, Tmax = 0.985

  • 12233 measured reflections

  • 5234 independent reflections

  • 3687 reflections with I > 2σ(I)

  • Rint = 0.019

Refinement
  • R[F2 > 2σ(F2)] = 0.043

  • wR(F2) = 0.124

  • S = 1.04

  • 5234 reflections

  • 217 parameters

  • H-atom parameters constrained

  • Δρmax = 0.24 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C3—H3A⋯O3i 0.93 2.50 3.3410 (16) 151
C4—H4A⋯O3ii 0.93 2.52 3.4104 (15) 161
C10—H10A⋯O1iii 0.93 2.57 3.496 (2) 174
Symmetry codes: (i) -x, -y+1, -z; (ii) [x, -y+1, z-{\script{1\over 2}}]; (iii) [x, -y+2, z+{\script{1\over 2}}].

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

The title compound was firstly reported as a cyclopropyl ring-fused ten-membered bislactone whose preparation could be achieved through a concise photochemical method (Wu et al., 2012). In the title compound, Fig. 1, the benzene rings (C1–C6 and C7–C12) form a dihedral angle of 45.70 (4)°. Bond lengths (Allen et al., 1987) and angles are within normal ranges and are comparable to related structures (Fun, Quah, Wu & Zhang, 2012; Fun, Lim, Quah & Wu, 2012; Fun, Quah & Wu, 2012). In the crystal (Fig. 2), molecules are linked via intermolecular C3—H3A···O3, C4—H4A···O3 and C10—H10A···O1 interactions (Table 1) into a layer parallel to the (100) plane.

Related literature top

For the background to this study, see the first paper in this series: Fun, Quah, Wu & Zhang (2012). For related structures in this series, see: Fun, Lim, Quah & Wu (2012); Fun, Quah & Wu (2012). For standard bond-length data, see: Allen et al. (1987). For the preparation, see: Wu et al. (2012).

Experimental top

The title compound was derived from the photo-induced sequential reactions of 9,10-phenanthrenedione with bicyclopropylendiene. The compound was purified by flash column chromatography with ethyl acetate/petroleum ether (1:10) as eluents. X-ray quality crystals of the title compound (m.p. 192–194 °C) were obtained from slow evaporation of an acetone and petroleum ether solution (1:10).

Refinement top

All H atoms were positioned geometrically and refined using a riding model with C—H = 0.93 or 0.97 Å and Uiso(H) = 1.2Ueq(C).

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
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids for non-H atoms.
[Figure 2] Fig. 2. A packing diagram of the title compound, viewed along the c axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.
1,1'-Bicyclopropyl-1,1'-diyl 1,1'-biphenyl-2,2'-dicarboxylate top
Crystal data top
C20H16O4F(000) = 1344
Mr = 320.33Dx = 1.305 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 5289 reflections
a = 26.3197 (14) Åθ = 2.7–31.1°
b = 9.4184 (5) ŵ = 0.09 mm1
c = 13.3606 (7) ÅT = 296 K
β = 100.092 (1)°Block, colourless
V = 3260.7 (3) Å30.43 × 0.34 × 0.17 mm
Z = 8
Data collection top
Bruker SMART APEXII DUO CCD area-detector
diffractometer
5234 independent reflections
Radiation source: fine-focus sealed tube3687 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.019
ϕ and ω scansθmax = 31.2°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
h = 3830
Tmin = 0.962, Tmax = 0.985k = 1013
12233 measured reflectionsl = 1914
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.124H-atom parameters constrained
S = 1.04 w = 1/[σ2(Fo2) + (0.0571P)2 + 0.6692P]
where P = (Fo2 + 2Fc2)/3
5234 reflections(Δ/σ)max = 0.001
217 parametersΔρmax = 0.24 e Å3
0 restraintsΔρmin = 0.19 e Å3
Crystal data top
C20H16O4V = 3260.7 (3) Å3
Mr = 320.33Z = 8
Monoclinic, C2/cMo Kα radiation
a = 26.3197 (14) ŵ = 0.09 mm1
b = 9.4184 (5) ÅT = 296 K
c = 13.3606 (7) Å0.43 × 0.34 × 0.17 mm
β = 100.092 (1)°
Data collection top
Bruker SMART APEXII DUO CCD area-detector
diffractometer
5234 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
3687 reflections with I > 2σ(I)
Tmin = 0.962, Tmax = 0.985Rint = 0.019
12233 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0430 restraints
wR(F2) = 0.124H-atom parameters constrained
S = 1.04Δρmax = 0.24 e Å3
5234 reflectionsΔρmin = 0.19 e Å3
217 parameters
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.

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 > 2sigma(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
xyzUiso*/Ueq
O10.16306 (3)0.77985 (9)0.06344 (6)0.0449 (2)
O20.14795 (3)0.54239 (8)0.06055 (6)0.03836 (18)
O30.09630 (3)0.53439 (9)0.24353 (7)0.0472 (2)
O40.17759 (3)0.62505 (9)0.26443 (6)0.03936 (19)
C10.00465 (5)0.77534 (15)0.06104 (11)0.0523 (3)
H1A0.02380.82430.10210.063*
C20.02987 (5)0.70956 (16)0.02684 (12)0.0591 (4)
H2A0.06560.71570.04420.071*
C30.00266 (5)0.63585 (15)0.08813 (10)0.0549 (4)
H3A0.01970.59300.14730.066*
C40.05052 (5)0.62568 (13)0.06123 (9)0.0447 (3)
H4A0.06910.57370.10170.054*
C50.07625 (4)0.69263 (11)0.02585 (8)0.0354 (2)
C60.04899 (4)0.76921 (12)0.08875 (9)0.0390 (2)
C70.07330 (4)0.84548 (12)0.18338 (9)0.0412 (3)
C80.05919 (5)0.98669 (15)0.19508 (13)0.0598 (4)
H8A0.03591.02990.14370.072*
C90.07889 (6)1.06313 (17)0.28054 (15)0.0731 (5)
H9A0.06871.15680.28640.088*
C100.11352 (6)1.00248 (18)0.35741 (14)0.0687 (5)
H10A0.12631.05420.41570.082*
C110.12910 (5)0.86488 (16)0.34756 (10)0.0521 (3)
H11A0.15330.82450.39870.063*
C120.10904 (4)0.78468 (13)0.26178 (9)0.0387 (2)
C130.12509 (4)0.63393 (12)0.25576 (7)0.0357 (2)
C140.19823 (4)0.49827 (13)0.22704 (9)0.0429 (3)
C150.19826 (4)0.50931 (12)0.11551 (8)0.0384 (2)
C160.13365 (4)0.68165 (12)0.05129 (7)0.0343 (2)
C170.24439 (5)0.55872 (15)0.07486 (10)0.0489 (3)
H17A0.27540.58020.12330.059*
H17B0.23870.61820.01470.059*
C180.22764 (5)0.40633 (15)0.06318 (11)0.0538 (3)
H18A0.21190.37400.00400.065*
H18B0.24850.33600.10460.065*
C190.19195 (7)0.36209 (18)0.27970 (13)0.0696 (4)
H19A0.18850.27590.23930.084*
H19B0.17220.36340.33460.084*
C200.24300 (6)0.4358 (2)0.29662 (11)0.0694 (5)
H20A0.25420.48170.36170.083*
H20B0.27050.39430.26650.083*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0411 (4)0.0398 (5)0.0524 (5)0.0053 (3)0.0041 (3)0.0041 (4)
O20.0387 (4)0.0360 (4)0.0382 (4)0.0023 (3)0.0007 (3)0.0012 (3)
O30.0456 (4)0.0456 (5)0.0504 (5)0.0062 (4)0.0084 (4)0.0037 (4)
O40.0337 (4)0.0490 (5)0.0351 (4)0.0054 (3)0.0052 (3)0.0027 (3)
C10.0362 (6)0.0546 (8)0.0642 (8)0.0055 (5)0.0043 (5)0.0055 (6)
C20.0369 (6)0.0623 (9)0.0709 (9)0.0037 (6)0.0102 (6)0.0134 (7)
C30.0519 (7)0.0561 (8)0.0486 (7)0.0126 (6)0.0135 (6)0.0087 (6)
C40.0500 (6)0.0437 (7)0.0370 (5)0.0049 (5)0.0017 (5)0.0032 (5)
C50.0360 (5)0.0331 (5)0.0351 (5)0.0022 (4)0.0005 (4)0.0064 (4)
C60.0351 (5)0.0359 (6)0.0442 (6)0.0029 (4)0.0020 (4)0.0045 (5)
C70.0367 (5)0.0373 (6)0.0502 (6)0.0015 (4)0.0091 (5)0.0051 (5)
C80.0554 (7)0.0439 (7)0.0795 (10)0.0075 (6)0.0101 (7)0.0091 (7)
C90.0669 (9)0.0481 (8)0.1057 (13)0.0041 (7)0.0188 (9)0.0300 (9)
C100.0543 (8)0.0691 (10)0.0843 (11)0.0093 (7)0.0165 (7)0.0430 (9)
C110.0368 (6)0.0655 (9)0.0539 (7)0.0037 (5)0.0077 (5)0.0234 (6)
C120.0305 (5)0.0437 (6)0.0430 (6)0.0016 (4)0.0099 (4)0.0089 (5)
C130.0352 (5)0.0447 (6)0.0273 (4)0.0002 (4)0.0059 (4)0.0003 (4)
C140.0445 (6)0.0479 (7)0.0364 (5)0.0152 (5)0.0072 (4)0.0055 (5)
C150.0379 (5)0.0409 (6)0.0353 (5)0.0081 (4)0.0036 (4)0.0031 (4)
C160.0380 (5)0.0364 (6)0.0280 (4)0.0007 (4)0.0046 (4)0.0027 (4)
C170.0420 (6)0.0606 (8)0.0451 (6)0.0037 (5)0.0105 (5)0.0069 (6)
C180.0544 (7)0.0559 (8)0.0505 (7)0.0153 (6)0.0079 (5)0.0132 (6)
C190.0852 (11)0.0595 (9)0.0680 (10)0.0263 (8)0.0240 (8)0.0266 (8)
C200.0645 (9)0.0966 (12)0.0456 (7)0.0407 (9)0.0053 (6)0.0153 (8)
Geometric parameters (Å, º) top
O1—C161.1986 (13)C9—C101.373 (2)
O2—C161.3641 (13)C9—H9A0.9300
O2—C151.4314 (12)C10—C111.373 (2)
O3—C131.1984 (13)C10—H10A0.9300
O4—C131.3688 (12)C11—C121.3967 (16)
O4—C141.4372 (14)C11—H11A0.9300
C1—C21.389 (2)C12—C131.4875 (16)
C1—C61.3966 (15)C14—C191.486 (2)
C1—H1A0.9300C14—C201.4883 (16)
C2—C31.368 (2)C14—C151.4939 (16)
C2—H2A0.9300C15—C181.4889 (17)
C3—C41.3859 (17)C15—C171.4889 (17)
C3—H3A0.9300C17—C181.502 (2)
C4—C51.3906 (15)C17—H17A0.9700
C4—H4A0.9300C17—H17B0.9700
C5—C61.3972 (17)C18—H18A0.9700
C5—C161.4930 (14)C18—H18B0.9700
C6—C71.4967 (16)C19—C201.494 (3)
C7—C81.3970 (18)C19—H19A0.9700
C7—C121.4017 (16)C19—H19B0.9700
C8—C91.372 (2)C20—H20A0.9700
C8—H8A0.9300C20—H20B0.9700
C16—O2—C15118.13 (8)O4—C13—C12110.23 (9)
C13—O4—C14117.31 (9)O4—C14—C19118.18 (11)
C2—C1—C6121.11 (13)O4—C14—C20114.67 (11)
C2—C1—H1A119.4C19—C14—C2060.30 (11)
C6—C1—H1A119.4O4—C14—C15110.81 (9)
C3—C2—C1120.63 (12)C19—C14—C15123.50 (12)
C3—C2—H2A119.7C20—C14—C15120.79 (11)
C1—C2—H2A119.7O2—C15—C18114.25 (9)
C2—C3—C4119.39 (12)O2—C15—C17119.02 (10)
C2—C3—H3A120.3C18—C15—C1760.56 (9)
C4—C3—H3A120.3O2—C15—C14111.39 (9)
C3—C4—C5120.48 (13)C18—C15—C14120.94 (10)
C3—C4—H4A119.8C17—C15—C14121.91 (10)
C5—C4—H4A119.8O1—C16—O2124.63 (10)
C4—C5—C6120.75 (10)O1—C16—C5125.52 (10)
C4—C5—C16118.95 (11)O2—C16—C5109.84 (9)
C6—C5—C16120.30 (9)C15—C17—C1859.72 (9)
C1—C6—C5117.62 (11)C15—C17—H17A117.8
C1—C6—C7117.82 (11)C18—C17—H17A117.8
C5—C6—C7124.57 (9)C15—C17—H17B117.8
C8—C7—C12117.51 (11)C18—C17—H17B117.8
C8—C7—C6117.96 (11)H17A—C17—H17B114.9
C12—C7—C6124.52 (10)C15—C18—C1759.72 (8)
C9—C8—C7121.57 (14)C15—C18—H18A117.8
C9—C8—H8A119.2C17—C18—H18A117.8
C7—C8—H8A119.2C15—C18—H18B117.8
C8—C9—C10120.58 (14)C17—C18—H18B117.8
C8—C9—H9A119.7H18A—C18—H18B114.9
C10—C9—H9A119.7C14—C19—C2059.92 (10)
C11—C10—C9119.44 (13)C14—C19—H19A117.8
C11—C10—H10A120.3C20—C19—H19A117.8
C9—C10—H10A120.3C14—C19—H19B117.8
C10—C11—C12120.87 (13)C20—C19—H19B117.8
C10—C11—H11A119.6H19A—C19—H19B114.9
C12—C11—H11A119.6C14—C20—C1959.78 (9)
C11—C12—C7120.00 (11)C14—C20—H20A117.8
C11—C12—C13119.38 (11)C19—C20—H20A117.8
C7—C12—C13120.61 (10)C14—C20—H20B117.8
O3—C13—O4124.64 (11)C19—C20—H20B117.8
O3—C13—C12125.13 (10)H20A—C20—H20B114.9
C6—C1—C2—C30.6 (2)C7—C12—C13—O4123.65 (11)
C1—C2—C3—C40.8 (2)C13—O4—C14—C1966.02 (14)
C2—C3—C4—C51.62 (19)C13—O4—C14—C20134.16 (12)
C3—C4—C5—C61.13 (17)C13—O4—C14—C1584.84 (12)
C3—C4—C5—C16178.81 (11)C16—O2—C15—C18132.94 (11)
C2—C1—C6—C51.04 (19)C16—O2—C15—C1764.44 (13)
C2—C1—C6—C7178.72 (12)C16—O2—C15—C1485.60 (12)
C4—C5—C6—C10.20 (17)O4—C14—C15—O254.61 (13)
C16—C5—C6—C1179.86 (11)C19—C14—C15—O294.42 (14)
C4—C5—C6—C7179.54 (11)C20—C14—C15—O2167.13 (12)
C16—C5—C6—C70.40 (17)O4—C14—C15—C18166.88 (11)
C1—C6—C7—C849.77 (17)C19—C14—C15—C1844.10 (18)
C5—C6—C7—C8129.97 (13)C20—C14—C15—C1828.61 (19)
C1—C6—C7—C12129.69 (13)O4—C14—C15—C1794.44 (13)
C5—C6—C7—C1250.56 (18)C19—C14—C15—C17116.54 (15)
C12—C7—C8—C90.9 (2)C20—C14—C15—C1743.82 (18)
C6—C7—C8—C9178.62 (14)C15—O2—C16—O118.83 (16)
C7—C8—C9—C100.3 (3)C15—O2—C16—C5160.13 (9)
C8—C9—C10—C111.1 (3)C4—C5—C16—O1123.22 (13)
C9—C10—C11—C121.9 (2)C6—C5—C16—O156.72 (16)
C10—C11—C12—C71.3 (2)C4—C5—C16—O257.83 (13)
C10—C11—C12—C13177.34 (13)C6—C5—C16—O2122.23 (11)
C8—C7—C12—C110.07 (18)O2—C15—C17—C18103.08 (11)
C6—C7—C12—C11179.39 (11)C14—C15—C17—C18110.12 (12)
C8—C7—C12—C13178.70 (12)O2—C15—C18—C17110.90 (11)
C6—C7—C12—C130.76 (18)C14—C15—C18—C17111.67 (13)
C14—O4—C13—O319.37 (15)O4—C14—C19—C20103.86 (13)
C14—O4—C13—C12159.59 (9)C15—C14—C19—C20109.22 (14)
C11—C12—C13—O3123.34 (13)O4—C14—C20—C19109.65 (13)
C7—C12—C13—O355.30 (16)C15—C14—C20—C19113.56 (15)
C11—C12—C13—O457.71 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3A···O3i0.932.503.3410 (16)151
C4—H4A···O3ii0.932.523.4104 (15)161
C10—H10A···O1iii0.932.573.496 (2)174
Symmetry codes: (i) x, y+1, z; (ii) x, y+1, z1/2; (iii) x, y+2, z+1/2.

Experimental details

Crystal data
Chemical formulaC20H16O4
Mr320.33
Crystal system, space groupMonoclinic, C2/c
Temperature (K)296
a, b, c (Å)26.3197 (14), 9.4184 (5), 13.3606 (7)
β (°) 100.092 (1)
V3)3260.7 (3)
Z8
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.43 × 0.34 × 0.17
Data collection
DiffractometerBruker SMART APEXII DUO CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.962, 0.985
No. of measured, independent and
observed [I > 2σ(I)] reflections
12233, 5234, 3687
Rint0.019
(sin θ/λ)max1)0.729
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.043, 0.124, 1.04
No. of reflections5234
No. of parameters217
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.24, 0.19

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

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3A···O3i0.932.503.3410 (16)151
C4—H4A···O3ii0.932.523.4104 (15)161
C10—H10A···O1iii0.932.573.496 (2)174
Symmetry codes: (i) x, y+1, z; (ii) x, y+1, z1/2; (iii) x, y+2, z+1/2.
 

Footnotes

Thomson Reuters ResearcherID: A-3561-2009.

§Thomson Reuters ResearcherID: A-5525-2009.

Acknowledgements

HKF and CKQ thank Universiti Sains Malaysia for the Research University Grant (No. 1001/PFIZIK/811160). Financial support from the National Natural Science Foundation of China (20972067) is acknowledged.

References

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