(S)-2-(1-Methyl­indolin-2-yl)-1,3-diphenyl­propan-2-ol

Lin, N.; Chen, M.-M.; Deng, Y.-Q.; Luo, R.-S.; Ng, S.W.

doi:10.1107/S1600536811019143

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 67| Part 6| June 2011| Page o1515

doi:10.1107/S1600536811019143

Open

access

(S)-2-(1-Methylindolin-2-yl)-1,3-diphenylpropan-2-ol

Ning Lin,^a Miao-Miao Chen,^a Yan-Qiu Deng,^a Ren-Shi Luo ^a and Seik Weng Ng ^b ^*

^aInstitute of Drug Synthesis and Pharmaceutical Processes, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, People's Republic of China, and ^bDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
^*Correspondence e-mail: seikweng@um.edu.my

(Received 17 May 2011; accepted 19 May 2011; online 25 May 2011)

The five-membered ring in the the title molecule, C₂₄H₂₅NO, fused with the phenylene ring, is almost planar (r.m.s. deviation = 0.023 Å), with the methylene C atom deviating most from this mean plane [0.031 (1) Å]. The tertiary N atom shows a flattened pyramidal configuration [Σ(angles at N) = 350.3 (6)°].

Related literature

For the synthesis of the methyl (S)-1-methylindoline-2-carboxylate reactant, see: Torisu et al. (2003 ).

Experimental

Crystal data

C₂₄H₂₅NO
M_r = 343.45
Orthorhombic, P 2₁ 2₁ 2₁
a = 9.8501 (6) Å
b = 12.0880 (7) Å
c = 15.4883 (10) Å
V = 1844.2 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 293 K
0.40 × 0.20 × 0.20 mm

Data collection

Bruker SMART CCD diffractometer
10040 measured reflections
2341 independent reflections
2118 reflections with I > 2σ(I)
R_int = 0.052

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.120
S = 1.05
2341 reflections
240 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.18 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: X-SEED (Barbour, 2001 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811019143/zs2115sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811019143/zs2115Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811019143/zs2115Isup3.cml

checkCIF report

Comment top

The optically active compound (Scheme I) is intended for a study on its pharmaceutical property in expectation of activity more enhanced than that of its precursor, methyl (S)-1-methylindoline-2-carboxylate (Torisu et al., 2003), which possesses the crucial indoline unit. The five-membered ring in the C₂₄H₂₅NO molecule is almost planar (r.m.s. deviation 0.023 Å), with the methylene C atom deviating most from this mean plane by 0.031 (1) Å (Fig. 1). The tertiary N atom shows a flattened pyramidal configuration [Σ_{angles at N} 350.3 (6) °]. The hydroxy group is not involved in a hydrogen-bonding interaction.

Related literature top

For the synthesis of the methyl (S)-1-methylindoline-2-carboxylate reactant, see: Torisu et al. (2003)

Experimental top

The Grignard reagent, benzyl magnesium bromide (40 ml, 50 mmol; 1.25 M in ether), was added dropwise at 273 K to a solution of methyl (S)-1-methylindoline-2-carboxylate (Torisu et al., 2003) (2.39 g, 12.5 mmol) dissolved in ether (20 ml). The mixture was warmed to room temperature and stirring was continued for 24 h under a nitrogen atmosphere. The reaction was quenched with saturated ammonium chloride (20 ml). The organic compound was extracted by using dichloromethane (3 × 15 ml). The organic extract was dried over magnesium sulfate. The solvent was removed and the product separated by column chromatography with hexane/ethyl acetate (45:1) as eluant to afford (S)-2-(1-methylindolin-2-yl)-1,3-diphenylpropan-2-ol (3.95 g) in nearly quantative yield.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of C₂₄H₂₅NO at the 50% probability level. Hydrogen atoms are drawn as spheres of arbitrary radius.

(S)-2-(1-Methylindolin-2-yl)-1,3-diphenylpropan-2-ol top

Crystal data top

C₂₄H₂₅NO	F(000) = 736
M_r = 343.45	D_x = 1.237 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 3877 reflections
a = 9.8501 (6) Å	θ = 2.5–27.1°
b = 12.0880 (7) Å	µ = 0.08 mm⁻¹
c = 15.4883 (10) Å	T = 293 K
V = 1844.2 (2) Å³	Block, colorless
Z = 4	0.40 × 0.20 × 0.20 mm

Data collection top

Bruker SMART CCD diffractometer	2118 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.052
Graphite monochromator	θ_max = 27.5°, θ_min = 2.1°
ϕ and ω scans	h = −12→9
10040 measured reflections	k = −15→15
2341 independent reflections	l = −20→18

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.120	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ²(F_o²) + (0.0715P)² + 0.2207P] where P = (F_o² + 2F_c²)/3
2341 reflections	(Δ/σ)_max = 0.001
240 parameters	Δρ_max = 0.25 e Å⁻³
1 restraint	Δρ_min = −0.18 e Å⁻³

Crystal data top

C₂₄H₂₅NO	V = 1844.2 (2) Å³
M_r = 343.45	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 9.8501 (6) Å	µ = 0.08 mm⁻¹
b = 12.0880 (7) Å	T = 293 K
c = 15.4883 (10) Å	0.40 × 0.20 × 0.20 mm

Data collection top

Bruker SMART CCD diffractometer	2118 reflections with I > 2σ(I)
10040 measured reflections	R_int = 0.052
2341 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	1 restraint
wR(F²) = 0.120	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 0.25 e Å⁻³
2341 reflections	Δρ_min = −0.18 e Å⁻³
240 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.15461 (16)	0.34594 (13)	0.80221 (11)	0.0323 (4)
H1	0.174 (3)	0.357 (2)	0.7499 (9)	0.045 (8)*
N1	0.01846 (18)	0.55982 (17)	0.80990 (12)	0.0308 (4)
C1	0.3692 (2)	0.42422 (18)	0.85258 (15)	0.0297 (5)
H1A	0.4052	0.4780	0.8930	0.036*
H1B	0.3908	0.3513	0.8747	0.036*
C2	0.4405 (2)	0.43916 (18)	0.76668 (15)	0.0285 (5)
C3	0.4989 (3)	0.5395 (2)	0.74430 (19)	0.0399 (6)
H3	0.4962	0.5979	0.7833	0.048*
C4	0.5614 (3)	0.5546 (2)	0.6646 (2)	0.0497 (7)
H4	0.5993	0.6227	0.6505	0.060*
C5	0.5668 (2)	0.4677 (2)	0.60614 (18)	0.0442 (7)
H5	0.6072	0.4776	0.5524	0.053*
C6	0.5125 (2)	0.3670 (2)	0.62797 (17)	0.0410 (6)
H6	0.5174	0.3083	0.5893	0.049*
C7	0.4499 (2)	0.3523 (2)	0.70783 (17)	0.0336 (5)
H7	0.4139	0.2835	0.7220	0.040*
C8	0.1523 (2)	0.42783 (19)	0.94128 (14)	0.0305 (5)
H8A	0.1791	0.4931	0.9734	0.037*
H8B	0.0541	0.4292	0.9364	0.037*
C9	0.1919 (2)	0.32691 (18)	0.99352 (15)	0.0289 (5)
C10	0.1463 (2)	0.22140 (19)	0.97106 (17)	0.0365 (5)
H10	0.0929	0.2124	0.9220	0.044*
C11	0.1792 (3)	0.1302 (2)	1.0205 (2)	0.0441 (6)
H11	0.1472	0.0607	1.0046	0.053*
C12	0.2595 (3)	0.1412 (2)	1.09372 (18)	0.0428 (6)
H12	0.2821	0.0795	1.1266	0.051*
C13	0.3054 (3)	0.2453 (2)	1.11701 (18)	0.0434 (6)
H13	0.3587	0.2540	1.1661	0.052*
C14	0.2717 (2)	0.3366 (2)	1.06703 (15)	0.0361 (5)
H14	0.3034	0.4060	1.0832	0.043*
C15	0.2125 (2)	0.43663 (17)	0.84985 (14)	0.0275 (4)
C16	0.1685 (2)	0.54640 (17)	0.80736 (15)	0.0282 (5)
H16	0.1975	0.5455	0.7468	0.034*
C17	0.2251 (2)	0.65260 (17)	0.85054 (15)	0.0302 (5)
H17A	0.2844	0.6342	0.8984	0.036*
H17B	0.2752	0.6970	0.8092	0.036*
C18	0.1009 (2)	0.71306 (17)	0.88161 (14)	0.0271 (4)
C19	0.0897 (2)	0.81040 (18)	0.92767 (15)	0.0297 (5)
H19	0.1671	0.8479	0.9459	0.036*
C20	−0.0393 (2)	0.85191 (19)	0.94665 (15)	0.0325 (5)
H20	−0.0485	0.9176	0.9773	0.039*
C21	−0.1534 (2)	0.79467 (19)	0.91952 (15)	0.0327 (5)
H21	−0.2389	0.8228	0.9327	0.039*
C22	−0.1440 (2)	0.69653 (18)	0.87326 (14)	0.0305 (5)
H22	−0.2216	0.6588	0.8558	0.037*
C23	−0.0148 (2)	0.65606 (17)	0.85368 (14)	0.0268 (4)
C24	−0.0615 (2)	0.5207 (2)	0.73715 (16)	0.0342 (5)
H24A	−0.1539	0.5446	0.7438	0.051*
H24B	−0.0584	0.4414	0.7351	0.051*
H24C	−0.0250	0.5504	0.6846	0.051*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0333 (8)	0.0377 (8)	0.0259 (8)	−0.0021 (7)	0.0010 (7)	−0.0070 (7)
N1	0.0245 (8)	0.0407 (10)	0.0271 (9)	0.0026 (8)	−0.0034 (7)	−0.0052 (8)
C1	0.0298 (10)	0.0330 (10)	0.0263 (11)	0.0031 (8)	−0.0014 (9)	−0.0031 (10)
C2	0.0235 (9)	0.0340 (10)	0.0280 (11)	0.0048 (8)	−0.0020 (8)	−0.0022 (9)
C3	0.0355 (10)	0.0367 (12)	0.0476 (15)	0.0037 (10)	0.0114 (11)	−0.0043 (11)
C4	0.0403 (13)	0.0460 (14)	0.0627 (19)	0.0086 (12)	0.0166 (13)	0.0142 (14)
C5	0.0285 (11)	0.0723 (18)	0.0318 (13)	0.0137 (11)	0.0061 (10)	0.0137 (13)
C6	0.0280 (10)	0.0625 (15)	0.0326 (13)	0.0086 (10)	−0.0017 (10)	−0.0152 (12)
C7	0.0263 (10)	0.0386 (11)	0.0359 (12)	0.0026 (9)	−0.0010 (9)	−0.0068 (11)
C8	0.0311 (10)	0.0358 (11)	0.0245 (11)	0.0026 (9)	0.0024 (9)	−0.0050 (9)
C9	0.0244 (9)	0.0364 (11)	0.0259 (10)	0.0009 (8)	0.0058 (8)	−0.0022 (9)
C10	0.0313 (10)	0.0413 (12)	0.0368 (14)	−0.0032 (10)	−0.0024 (10)	−0.0014 (11)
C11	0.0409 (13)	0.0373 (11)	0.0540 (17)	−0.0025 (10)	0.0047 (13)	0.0012 (12)
C12	0.0383 (12)	0.0454 (13)	0.0446 (14)	0.0063 (10)	0.0054 (11)	0.0133 (13)
C13	0.0414 (12)	0.0582 (15)	0.0306 (13)	0.0023 (11)	−0.0020 (11)	0.0073 (12)
C14	0.0396 (11)	0.0421 (13)	0.0265 (11)	−0.0045 (10)	0.0006 (10)	−0.0010 (10)
C15	0.0265 (9)	0.0326 (10)	0.0233 (10)	0.0027 (9)	−0.0008 (8)	−0.0050 (9)
C16	0.0255 (10)	0.0353 (11)	0.0239 (10)	0.0020 (9)	−0.0006 (9)	−0.0020 (9)
C17	0.0272 (10)	0.0344 (10)	0.0288 (11)	0.0002 (9)	−0.0034 (9)	−0.0003 (10)
C18	0.0272 (9)	0.0309 (10)	0.0231 (10)	0.0000 (8)	0.0000 (9)	0.0046 (8)
C19	0.0308 (10)	0.0331 (10)	0.0251 (11)	−0.0014 (9)	−0.0002 (9)	0.0028 (9)
C20	0.0395 (11)	0.0308 (10)	0.0271 (11)	0.0038 (9)	0.0050 (10)	0.0003 (9)
C21	0.0286 (10)	0.0404 (11)	0.0290 (12)	0.0072 (9)	0.0033 (9)	0.0065 (10)
C22	0.0270 (9)	0.0392 (11)	0.0254 (11)	−0.0001 (9)	−0.0017 (9)	0.0054 (9)
C23	0.0297 (10)	0.0312 (10)	0.0195 (10)	0.0010 (8)	−0.0019 (8)	0.0046 (9)
C24	0.0310 (10)	0.0458 (12)	0.0258 (11)	−0.0029 (9)	−0.0044 (9)	−0.0040 (10)

Geometric parameters (Å, º) top

O1—C15	1.439 (3)	C10—H10	0.9300
O1—H1	0.843 (10)	C11—C12	1.389 (4)
N1—C23	1.386 (3)	C11—H11	0.9300
N1—C24	1.454 (3)	C12—C13	1.385 (4)
N1—C16	1.487 (3)	C12—H12	0.9300
C1—C2	1.516 (3)	C13—C14	1.388 (4)
C1—C15	1.551 (3)	C13—H13	0.9300
C1—H1A	0.9700	C14—H14	0.9300
C1—H1B	0.9700	C15—C16	1.543 (3)
C2—C3	1.386 (3)	C16—C17	1.551 (3)
C2—C7	1.394 (3)	C16—H16	0.9800
C3—C4	1.391 (4)	C17—C18	1.504 (3)
C3—H3	0.9300	C17—H17A	0.9700
C4—C5	1.388 (4)	C17—H17B	0.9700
C4—H4	0.9300	C18—C19	1.380 (3)
C5—C6	1.371 (4)	C18—C23	1.400 (3)
C5—H5	0.9300	C19—C20	1.397 (3)
C6—C7	1.393 (4)	C19—H19	0.9300
C6—H6	0.9300	C20—C21	1.385 (3)
C7—H7	0.9300	C20—H20	0.9300
C8—C9	1.515 (3)	C21—C22	1.389 (3)
C8—C15	1.539 (3)	C21—H21	0.9300
C8—H8A	0.9700	C22—C23	1.397 (3)
C8—H8B	0.9700	C22—H22	0.9300
C9—C14	1.389 (3)	C24—H24A	0.9600
C9—C10	1.396 (3)	C24—H24B	0.9600
C10—C11	1.381 (4)	C24—H24C	0.9600

C15—O1—H1	106 (2)	C12—C13—H13	120.0
C23—N1—C24	121.61 (18)	C14—C13—H13	120.0
C23—N1—C16	109.84 (17)	C13—C14—C9	121.7 (2)
C24—N1—C16	118.84 (18)	C13—C14—H14	119.1
C2—C1—C15	115.22 (18)	C9—C14—H14	119.1
C2—C1—H1A	108.5	O1—C15—C8	105.45 (17)
C15—C1—H1A	108.5	O1—C15—C16	108.96 (17)
C2—C1—H1B	108.5	C8—C15—C16	110.09 (17)
C15—C1—H1B	108.5	O1—C15—C1	109.54 (17)
H1A—C1—H1B	107.5	C8—C15—C1	110.58 (18)
C3—C2—C7	117.9 (2)	C16—C15—C1	111.99 (18)
C3—C2—C1	121.1 (2)	N1—C16—C15	111.21 (18)
C7—C2—C1	121.0 (2)	N1—C16—C17	104.81 (17)
C2—C3—C4	121.3 (2)	C15—C16—C17	115.25 (17)
C2—C3—H3	119.3	N1—C16—H16	108.4
C4—C3—H3	119.3	C15—C16—H16	108.4
C5—C4—C3	119.8 (3)	C17—C16—H16	108.4
C5—C4—H4	120.1	C18—C17—C16	104.33 (17)
C3—C4—H4	120.1	C18—C17—H17A	110.9
C6—C5—C4	119.7 (2)	C16—C17—H17A	110.9
C6—C5—H5	120.2	C18—C17—H17B	110.9
C4—C5—H5	120.2	C16—C17—H17B	110.9
C5—C6—C7	120.3 (2)	H17A—C17—H17B	108.9
C5—C6—H6	119.8	C19—C18—C23	121.0 (2)
C7—C6—H6	119.8	C19—C18—C17	130.1 (2)
C6—C7—C2	120.9 (2)	C23—C18—C17	108.90 (18)
C6—C7—H7	119.6	C18—C19—C20	119.2 (2)
C2—C7—H7	119.6	C18—C19—H19	120.4
C9—C8—C15	116.63 (17)	C20—C19—H19	120.4
C9—C8—H8A	108.1	C21—C20—C19	119.7 (2)
C15—C8—H8A	108.1	C21—C20—H20	120.2
C9—C8—H8B	108.1	C19—C20—H20	120.2
C15—C8—H8B	108.1	C20—C21—C22	121.9 (2)
H8A—C8—H8B	107.3	C20—C21—H21	119.0
C14—C9—C10	117.6 (2)	C22—C21—H21	119.0
C14—C9—C8	121.1 (2)	C21—C22—C23	118.2 (2)
C10—C9—C8	121.3 (2)	C21—C22—H22	120.9
C11—C10—C9	121.1 (2)	C23—C22—H22	120.9
C11—C10—H10	119.5	N1—C23—C22	127.99 (19)
C9—C10—H10	119.5	N1—C23—C18	111.84 (18)
C10—C11—C12	120.6 (2)	C22—C23—C18	120.14 (19)
C10—C11—H11	119.7	N1—C24—H24A	109.5
C12—C11—H11	119.7	N1—C24—H24B	109.5
C13—C12—C11	119.0 (2)	H24A—C24—H24B	109.5
C13—C12—H12	120.5	N1—C24—H24C	109.5
C11—C12—H12	120.5	H24A—C24—H24C	109.5
C12—C13—C14	119.9 (2)	H24B—C24—H24C	109.5

C15—C1—C2—C3	97.5 (3)	C23—N1—C16—C17	−3.8 (2)
C15—C1—C2—C7	−82.7 (2)	C24—N1—C16—C17	142.8 (2)
C7—C2—C3—C4	1.9 (4)	O1—C15—C16—N1	61.9 (2)
C1—C2—C3—C4	−178.3 (2)	C8—C15—C16—N1	−53.2 (2)
C2—C3—C4—C5	−0.5 (4)	C1—C15—C16—N1	−176.71 (18)
C3—C4—C5—C6	−1.0 (4)	O1—C15—C16—C17	−178.96 (18)
C4—C5—C6—C7	1.1 (4)	C8—C15—C16—C17	65.9 (2)
C5—C6—C7—C2	0.4 (3)	C1—C15—C16—C17	−57.6 (2)
C3—C2—C7—C6	−1.9 (3)	N1—C16—C17—C18	5.1 (2)
C1—C2—C7—C6	178.3 (2)	C15—C16—C17—C18	−117.5 (2)
C15—C8—C9—C14	113.0 (2)	C16—C17—C18—C19	177.1 (2)
C15—C8—C9—C10	−68.9 (3)	C16—C17—C18—C23	−4.9 (2)
C14—C9—C10—C11	0.3 (3)	C23—C18—C19—C20	0.2 (3)
C8—C9—C10—C11	−177.9 (2)	C17—C18—C19—C20	178.0 (2)
C9—C10—C11—C12	−0.5 (4)	C18—C19—C20—C21	0.4 (3)
C10—C11—C12—C13	0.6 (4)	C19—C20—C21—C22	−0.3 (3)
C11—C12—C13—C14	−0.5 (4)	C20—C21—C22—C23	−0.4 (3)
C12—C13—C14—C9	0.3 (4)	C24—N1—C23—C22	37.3 (3)
C10—C9—C14—C13	−0.2 (3)	C16—N1—C23—C22	−177.2 (2)
C8—C9—C14—C13	178.0 (2)	C24—N1—C23—C18	−144.7 (2)
C9—C8—C15—O1	65.5 (2)	C16—N1—C23—C18	0.8 (3)
C9—C8—C15—C16	−177.09 (18)	C21—C22—C23—N1	178.8 (2)
C9—C8—C15—C1	−52.8 (2)	C21—C22—C23—C18	1.0 (3)
C2—C1—C15—O1	68.1 (2)	C19—C18—C23—N1	−179.06 (19)
C2—C1—C15—C8	−176.10 (17)	C17—C18—C23—N1	2.7 (2)
C2—C1—C15—C16	−52.9 (2)	C19—C18—C23—C22	−0.9 (3)
C23—N1—C16—C15	121.39 (19)	C17—C18—C23—C22	−179.1 (2)
C24—N1—C16—C15	−92.0 (2)

Experimental details

Crystal data
Chemical formula	C₂₄H₂₅NO
M_r	343.45
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	293
a, b, c (Å)	9.8501 (6), 12.0880 (7), 15.4883 (10)
V (Å³)	1844.2 (2)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.40 × 0.20 × 0.20

Data collection
Diffractometer	Bruker SMART CCD diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	10040, 2341, 2118
R_int	0.052
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.120, 1.05
No. of reflections	2341
No. of parameters	240
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)	0.25, −0.18

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2010).

Acknowledgements

We thank the Scientific Research Foundation for Returned Overseas Chinese Scholars and the Program for New Century Excellent Talents in Universities (both from the State Education Ministry of China), the Project of International Science and Technology Cooperation (from the Ministry of Science and Technology of China) and the University of Malaya for supporting this study.

References

Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191. CrossRef CAS Google Scholar
Bruker (2001). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Torisu, K., Hasegawa, T., Kobayashi, K. & Nambu, F. (2003). Jpn Patent PCT/JP2002/009077. Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar