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ISSN: 2056-9890

1,4,5,8-Tetra­iso­propyl­anthracene

aDepartment of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan, and bDepartment of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuencho, Naka-ku, Sakai, Osaka 599-8531, Japan
*Correspondence e-mail: kitamura@eng.u-hyogo.ac.jp

(Received 28 July 2010; accepted 2 August 2010; online 11 August 2010)

The mol­ecules of the title compound, C26H34, possess crystallographically imposed inversion symmetry. The anthracene ring system is planar within 0.038 (1) Å. The two methyl groups in each independent isopropyl group are oriented on either side of the anthracene plane. In the crystal structure, the mol­ecules adopt a herringbone-like arrangement without ππ stacking.

Related literature

For the preparation and solid-state fluorescence studies of 1,4,5,8- tetra­alkyl­anthracenes, see: Kitamura et al. (2007[Kitamura, C., Abe, Y., Kawatsuki, N., Yoneda, A., Asada, K., Kobayashi, A. & Naito, H. (2007). Mol. Cryst. Liq. Cryst. 474, 119-135.]). For a related structure, see: Kitamura et al. (2010[Kitamura, C., Tsukuda, H., Yoneda, A., Kawase, T., Kobayashi, A., Naito, H. & Komatsu, T. (2010). Eur. J. Org. Chem. pp. 3033-3040.]). For related herringbone structures, see: Curtis et al. (2004[Curtis, M. D., Cao, J. & Kampf, J. W. (2004). J. Am. Chem. Soc. 126, 4318-4328.]).

[Scheme 1]

Experimental

Crystal data
  • C26H34

  • Mr = 346.53

  • Monoclinic, P 21 /c

  • a = 6.546 (3) Å

  • b = 10.357 (5) Å

  • c = 15.808 (8) Å

  • β = 98.289 (8)°

  • V = 1060.5 (9) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.06 mm−1

  • T = 223 K

  • 0.50 × 0.07 × 0.05 mm

Data collection
  • Rigaku/MSC Mercury CCD area-detector diffractometer

  • Absorption correction: numerical (NUMABS; Higashi, 2000[Higashi, T. (2000). NUMABS. Rigaku Corporation, Tokyo, Japan.]) Tmin = 0.991, Tmax = 0.996

  • 9107 measured reflections

  • 2817 independent reflections

  • 1921 reflections with I > 2σ(I)

  • Rint = 0.043

Refinement
  • R[F2 > 2σ(F2)] = 0.063

  • wR(F2) = 0.180

  • S = 1.07

  • 2817 reflections

  • 122 parameters

  • H-atom parameters constrained

  • Δρmax = 0.28 e Å−3

  • Δρmin = −0.24 e Å−3

Data collection: CrystalClear (Rigaku/MSC, 2006[Rigaku/MSC (2006). CrystalClear. Rigaku Corporation, Tokyo, Japan.]); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SIR2004 (Burla et al., 2005[Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G. & Spagna, R. (2005). J. Appl. Cryst. 38, 381-388.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

Solid-state packing effects play an important role in the performance of electronic and photonic materials (Curtis et al., 2004). However, there has been relatively little research on the correlation between solid-state packing patterns and fluorescence properties. Further, molecular design to control solid-state fluorescence is not fully understood. We have recently found that the introduction of linear alkyl side chains onto anthracene nucleus at the 1, 4, 5 and 8 positions brought about drastic changes in alkyl conformation, packing pattern, and solid-state fluorescence (Kitamura et al., 2007). To investigate the effects of branched alkyl side chains, we embarked on the investigation on 1,4,5,8-tetraisoalkylanthracenes. Herein we report the X-ray analysis of the title compound (I).

The molecular structure of (I) is shown in Fig. 1. The molecule possesses a center of inversion, and half of the formula unit is crystallographically independent. The anthracene unit is essentially planar. The molecular structure is similar to that of 1,4,7,10-tetraisopropyltetracene (Kitamura et al., 2010). Two terminal methyl groups of the two isopropyl groups at the 1 and 4 positions point upward, and two methyl groups of the other two isopropyl groups at 5 and 8 positions point downward. Thus, the torsion angles C6—C1—C8—C9 and C3—C4—C11—C13 are 80.72 (18) and 107.76 (16)°, respectively. Another two terminal methyl groups of the two isopropyl groups are nearly coplanar with the anthracene plane, and the C2—C1—C8—C10 and C3—C4—C11—C12 torsion angles are 25.6 (2) and -15.2 (2)°, respectively. In the crystal, the molecules adopt a herringbone-like (two-dimensional) arrangement as shown in Fig. 2. There are no π-π interatcions along the stacking direction.

To examine the influence of crystal packing on the solid-state fluorescence properties, the fluorescence spectrum and the absolute quantum yield of (I) were measured by a Hamamatsu Photonics PMA11 calibrated optical multichannel analyzer with a solid-state blue laser (λex = 377 nm) and a Labsphere IS-040-SF integrating sphere, respectively. Crystals of (I) exhibited a structured fluorescence spectrum with fluorescence maxima at 432 and 450 nm. The quantum yield of crystals of (I) was very high (Φ = 0.80). Among 1,4,5,8-tetraalkylanthracenes, the n-propyl derivative had the largest quantum yield of 0.85, indicating that the quantum yield of (I) is the second largest. Crystal packing without π-π stack and crystal rigidity in the presence of bulky isopropyl groups probably lead to the enhancement of the fluorescence quantum yield.

Related literature top

For the preparation and solid-state fluorescence studies of 1,4,5,8- tetraalkylanthracenes, see: Kitamura et al. (2007). For a related structure, see: Kitamura et al. (2010). For related herringbone structures, see: Curtis et al. (2004).

Experimental top

1,4,5,8-Tetraisopropylanthracene was prepared according to the method described by Kitamura et al. (2007). A mixture of 2,5-diisopropylfuran (1.03 g, 6.78 mmol) and 1,2,4,5-tetrabromobenzene (1.25 g, 3.17 mmol) in dry toluene (40 ml) was cooled to 243 K. To the mixture, 1.6 M n-BuLi in hexane (6.0 ml, 9.6 mmol) was added dropwise over 10 min. Then the mixture was warmed up to room temperature over 2 h and stirred at room temperature for additional 18 h. After quenching with water, the aqueous layer was extracted with CHCl3. The combined organic layer was washed with brine and dried over Na2SO4. After evaporation, the residue was subjected to slica-gel chromatography with (2:1)-hexane/CHCl3 to afford bis(furan)adduct as a yellow solid (432 mg, 36%). The bis(furan)adduct (432 mg, 1.14 mmol) in EtOH (55 ml) was hydrogenated over 10% Pd/C (85 mg) under atmospheric pressure at room temperature for 3 h. The catalyst was removed by filtration, and the filtrate was evaporated under reduced pressure. To the residue, an ice-cooled solution of (1:5)-conc. HCl/Ac2O (6 ml) was added. The mixture was stirred at room temperature for 3 h. After cooling with ice, water was added into the mixture. The resultant mixture was extracted with CHCl3, and the extract was washed with aqueous Na2CO3 and brine, and dried over Na2SO4. After evaporation of the solvent, column chromatography on silica gel with (2:1)-hexane/CHCl3 gave the title compound as a white solid (149 mg, 38%). Recrystallization was performed with Et2O to obtain colourless single crystals of the title compound. 1H-NMR: δ 1.50 (d, J = 6.9 Hz, 24H), 3.87–3.59 (m, 4H), 7.36 (s, 4H), 9.01 (s, 2H); 13C-NMR: δ 14.06, 23.50, 28.60, 120.60, 129.41, 142.26, 137.03; EIMS: m/z (%) 346 (100); Elemental analysis for C26H34: C 90.11, H 9.89%; found: C 89.86, H 9.86%.

Refinement top

All the H atoms were positioned geometrically and refined using a riding model with C–H = 0.94 Å and Uiso(H) = 1.2Ueq(C) for aromatic C—H, C–H = 0.99 Å and Uiso(H) = 1.2Ueq(C) for CH, and C—H = 0.97 Å and Uiso(H) = 1.5Ueq(C) for CH3 group.

Structure description top

Solid-state packing effects play an important role in the performance of electronic and photonic materials (Curtis et al., 2004). However, there has been relatively little research on the correlation between solid-state packing patterns and fluorescence properties. Further, molecular design to control solid-state fluorescence is not fully understood. We have recently found that the introduction of linear alkyl side chains onto anthracene nucleus at the 1, 4, 5 and 8 positions brought about drastic changes in alkyl conformation, packing pattern, and solid-state fluorescence (Kitamura et al., 2007). To investigate the effects of branched alkyl side chains, we embarked on the investigation on 1,4,5,8-tetraisoalkylanthracenes. Herein we report the X-ray analysis of the title compound (I).

The molecular structure of (I) is shown in Fig. 1. The molecule possesses a center of inversion, and half of the formula unit is crystallographically independent. The anthracene unit is essentially planar. The molecular structure is similar to that of 1,4,7,10-tetraisopropyltetracene (Kitamura et al., 2010). Two terminal methyl groups of the two isopropyl groups at the 1 and 4 positions point upward, and two methyl groups of the other two isopropyl groups at 5 and 8 positions point downward. Thus, the torsion angles C6—C1—C8—C9 and C3—C4—C11—C13 are 80.72 (18) and 107.76 (16)°, respectively. Another two terminal methyl groups of the two isopropyl groups are nearly coplanar with the anthracene plane, and the C2—C1—C8—C10 and C3—C4—C11—C12 torsion angles are 25.6 (2) and -15.2 (2)°, respectively. In the crystal, the molecules adopt a herringbone-like (two-dimensional) arrangement as shown in Fig. 2. There are no π-π interatcions along the stacking direction.

To examine the influence of crystal packing on the solid-state fluorescence properties, the fluorescence spectrum and the absolute quantum yield of (I) were measured by a Hamamatsu Photonics PMA11 calibrated optical multichannel analyzer with a solid-state blue laser (λex = 377 nm) and a Labsphere IS-040-SF integrating sphere, respectively. Crystals of (I) exhibited a structured fluorescence spectrum with fluorescence maxima at 432 and 450 nm. The quantum yield of crystals of (I) was very high (Φ = 0.80). Among 1,4,5,8-tetraalkylanthracenes, the n-propyl derivative had the largest quantum yield of 0.85, indicating that the quantum yield of (I) is the second largest. Crystal packing without π-π stack and crystal rigidity in the presence of bulky isopropyl groups probably lead to the enhancement of the fluorescence quantum yield.

For the preparation and solid-state fluorescence studies of 1,4,5,8- tetraalkylanthracenes, see: Kitamura et al. (2007). For a related structure, see: Kitamura et al. (2010). For related herringbone structures, see: Curtis et al. (2004).

Computing details top

Data collection: CrystalClear (Rigaku/MSC, 2006); cell refinement: CrystalClear (Rigaku/MSC, 2006); data reduction: CrystalClear (Rigaku/MSC, 2006); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing the atomic numbering numbering and 30% probability displacement ellipsoids for non-H atoms. Symmetry code: (i) 1 -x, -y, -z.
[Figure 2] Fig. 2. The packing diagram of (I). Hydrogen atoms have been omitted for clarity.
1,4,5,8-Tetraisopropylanthracene top
Crystal data top
C26H34F(000) = 380
Mr = 346.53Dx = 1.085 Mg m3
Monoclinic, P21/cMelting point: 488 K
Hall symbol: -P 2ybcMo Kα radiation, λ = 0.71073 Å
a = 6.546 (3) ÅCell parameters from 2745 reflections
b = 10.357 (5) Åθ = 2.4–31.1°
c = 15.808 (8) ŵ = 0.06 mm1
β = 98.289 (8)°T = 223 K
V = 1060.5 (9) Å3Needle, colourless
Z = 20.50 × 0.07 × 0.05 mm
Data collection top
Rigaku/MSC Mercury CCD area-detector
diffractometer
2817 independent reflections
Radiation source: rotating-anode X-ray tube1921 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.043
Detector resolution: 14.7059 pixels mm-1θmax = 29.1°, θmin = 2.4°
φ and ω scansh = 88
Absorption correction: numerical
(NUMABS; Higashi, 2000)
k = 1413
Tmin = 0.991, Tmax = 0.996l = 2113
9107 measured reflections
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.063H-atom parameters constrained
wR(F2) = 0.180 w = 1/[σ2(Fo2) + (0.0945P)2 + 0.0217P]
where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max < 0.001
2817 reflectionsΔρmax = 0.28 e Å3
122 parametersΔρmin = 0.24 e Å3
Crystal data top
C26H34V = 1060.5 (9) Å3
Mr = 346.53Z = 2
Monoclinic, P21/cMo Kα radiation
a = 6.546 (3) ŵ = 0.06 mm1
b = 10.357 (5) ÅT = 223 K
c = 15.808 (8) Å0.50 × 0.07 × 0.05 mm
β = 98.289 (8)°
Data collection top
Rigaku/MSC Mercury CCD area-detector
diffractometer
2817 independent reflections
Absorption correction: numerical
(NUMABS; Higashi, 2000)
1921 reflections with I > 2σ(I)
Tmin = 0.991, Tmax = 0.996Rint = 0.043
9107 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0630 restraints
wR(F2) = 0.180H-atom parameters constrained
S = 1.07Δρmax = 0.28 e Å3
2817 reflectionsΔρmin = 0.24 e Å3
122 parameters
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
C10.4015 (2)0.00637 (14)0.17133 (9)0.0272 (3)
C20.2347 (2)0.06330 (15)0.18742 (9)0.0323 (4)
H20.19760.06060.24270.039*
C30.1152 (2)0.13954 (15)0.12440 (9)0.0309 (4)
H30.00410.18740.13970.037*
C40.1553 (2)0.14606 (13)0.04219 (9)0.0254 (3)
C50.3279 (2)0.07195 (13)0.02069 (9)0.0245 (3)
C60.4533 (2)0.00120 (13)0.08561 (8)0.0245 (3)
C70.6226 (2)0.06900 (13)0.06259 (9)0.0263 (3)
H70.70740.11490.10540.032*
C80.5294 (2)0.08656 (16)0.24020 (9)0.0336 (4)
H80.57370.16530.21230.04*
C90.7238 (3)0.0145 (2)0.27785 (12)0.0551 (5)
H9A0.68610.06240.3070.083*
H9B0.8010.00990.23240.083*
H9C0.80830.06990.31820.083*
C100.4106 (3)0.1305 (2)0.31140 (11)0.0523 (5)
H10A0.49280.19250.34750.078*
H10B0.28170.17030.28650.078*
H10C0.38170.05650.34540.078*
C110.0299 (2)0.23022 (14)0.02482 (9)0.0293 (3)
H110.00290.17820.07760.035*
C120.1738 (2)0.27689 (16)0.00091 (11)0.0363 (4)
H12A0.24970.20370.01880.054*
H12B0.25520.31880.04750.054*
H12C0.14590.33770.04780.054*
C130.1551 (3)0.34794 (16)0.04622 (11)0.0412 (4)
H13A0.07580.39670.0920.062*
H13B0.28320.31930.06420.062*
H13C0.18550.40220.0040.062*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0275 (7)0.0305 (7)0.0245 (7)0.0017 (6)0.0070 (6)0.0001 (6)
C20.0338 (8)0.0401 (9)0.0251 (7)0.0018 (7)0.0115 (6)0.0008 (6)
C30.0279 (7)0.0345 (8)0.0321 (8)0.0042 (6)0.0107 (6)0.0020 (6)
C40.0240 (7)0.0257 (7)0.0271 (7)0.0013 (6)0.0053 (6)0.0018 (6)
C50.0225 (7)0.0263 (7)0.0252 (7)0.0018 (6)0.0056 (6)0.0028 (5)
C60.0245 (7)0.0272 (7)0.0227 (7)0.0009 (6)0.0061 (6)0.0011 (6)
C70.0257 (7)0.0294 (7)0.0238 (6)0.0020 (6)0.0038 (6)0.0007 (6)
C80.0351 (9)0.0418 (9)0.0258 (7)0.0053 (7)0.0106 (6)0.0038 (6)
C90.0487 (11)0.0736 (14)0.0393 (10)0.0036 (10)0.0065 (9)0.0062 (10)
C100.0560 (12)0.0639 (13)0.0418 (10)0.0165 (10)0.0230 (9)0.0225 (9)
C110.0286 (7)0.0305 (8)0.0292 (7)0.0049 (6)0.0054 (6)0.0009 (6)
C120.0313 (8)0.0381 (9)0.0401 (9)0.0070 (7)0.0069 (7)0.0013 (7)
C130.0412 (9)0.0374 (9)0.0462 (9)0.0056 (8)0.0107 (8)0.0105 (8)
Geometric parameters (Å, º) top
C1—C21.362 (2)C8—H80.99
C1—C61.4448 (18)C9—H9A0.97
C1—C81.521 (2)C9—H9B0.97
C2—C31.416 (2)C9—H9C0.97
C2—H20.94C10—H10A0.97
C3—C41.364 (2)C10—H10B0.97
C3—H30.94C10—H10C0.97
C4—C51.4463 (19)C11—C121.528 (2)
C4—C111.518 (2)C11—C131.534 (2)
C5—C7i1.4009 (19)C11—H110.99
C5—C61.435 (2)C12—H12A0.97
C6—C71.4033 (19)C12—H12B0.97
C7—C5i1.4009 (19)C12—H12C0.97
C7—H70.94C13—H13A0.97
C8—C91.520 (3)C13—H13B0.97
C8—C101.527 (2)C13—H13C0.97
C2—C1—C6117.28 (13)H9A—C9—H9B109.5
C2—C1—C8121.93 (12)C8—C9—H9C109.5
C6—C1—C8120.79 (12)H9A—C9—H9C109.5
C1—C2—C3122.72 (12)H9B—C9—H9C109.5
C1—C2—H2118.6C8—C10—H10A109.5
C3—C2—H2118.6C8—C10—H10B109.5
C4—C3—C2122.35 (13)H10A—C10—H10B109.5
C4—C3—H3118.8C8—C10—H10C109.5
C2—C3—H3118.8H10A—C10—H10C109.5
C3—C4—C5117.50 (13)H10B—C10—H10C109.5
C3—C4—C11122.28 (13)C4—C11—C12113.63 (12)
C5—C4—C11120.19 (12)C4—C11—C13110.97 (13)
C7i—C5—C6118.33 (12)C12—C11—C13108.77 (13)
C7i—C5—C4121.79 (13)C4—C11—H11107.7
C6—C5—C4119.88 (12)C12—C11—H11107.7
C7—C6—C5118.08 (12)C13—C11—H11107.7
C7—C6—C1121.72 (13)C11—C12—H12A109.5
C5—C6—C1120.19 (12)C11—C12—H12B109.5
C5i—C7—C6123.56 (13)H12A—C12—H12B109.5
C5i—C7—H7118.2C11—C12—H12C109.5
C6—C7—H7118.2H12A—C12—H12C109.5
C9—C8—C1110.83 (14)H12B—C12—H12C109.5
C9—C8—C10110.13 (15)C11—C13—H13A109.5
C1—C8—C10113.81 (13)C11—C13—H13B109.5
C9—C8—H8107.3H13A—C13—H13B109.5
C1—C8—H8107.3C11—C13—H13C109.5
C10—C8—H8107.3H13A—C13—H13C109.5
C8—C9—H9A109.5H13B—C13—H13C109.5
C8—C9—H9B109.5
C6—C1—C2—C30.6 (2)C8—C1—C6—C70.2 (2)
C8—C1—C2—C3179.32 (14)C2—C1—C6—C51.8 (2)
C1—C2—C3—C41.7 (2)C8—C1—C6—C5178.27 (13)
C2—C3—C4—C50.4 (2)C5—C6—C7—C5i1.8 (2)
C2—C3—C4—C11178.60 (14)C1—C6—C7—C5i176.64 (13)
C3—C4—C5—C7i177.89 (13)C2—C1—C8—C999.18 (17)
C11—C4—C5—C7i3.8 (2)C6—C1—C8—C980.72 (18)
C3—C4—C5—C62.0 (2)C2—C1—C8—C1025.6 (2)
C11—C4—C5—C6176.24 (12)C6—C1—C8—C10154.51 (15)
C7i—C5—C6—C71.7 (2)C3—C4—C11—C1215.2 (2)
C4—C5—C6—C7178.32 (12)C5—C4—C11—C12166.61 (13)
C7i—C5—C6—C1176.76 (13)C3—C4—C11—C13107.76 (16)
C4—C5—C6—C13.2 (2)C5—C4—C11—C1370.44 (17)
C2—C1—C6—C7179.72 (14)
Symmetry code: (i) x+1, y, z.

Experimental details

Crystal data
Chemical formulaC26H34
Mr346.53
Crystal system, space groupMonoclinic, P21/c
Temperature (K)223
a, b, c (Å)6.546 (3), 10.357 (5), 15.808 (8)
β (°) 98.289 (8)
V3)1060.5 (9)
Z2
Radiation typeMo Kα
µ (mm1)0.06
Crystal size (mm)0.50 × 0.07 × 0.05
Data collection
DiffractometerRigaku/MSC Mercury CCD area-detector
Absorption correctionNumerical
(NUMABS; Higashi, 2000)
Tmin, Tmax0.991, 0.996
No. of measured, independent and
observed [I > 2σ(I)] reflections
9107, 2817, 1921
Rint0.043
(sin θ/λ)max1)0.685
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.063, 0.180, 1.07
No. of reflections2817
No. of parameters122
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.28, 0.24

Computer programs: CrystalClear (Rigaku/MSC, 2006), SIR2004 (Burla et al., 2005), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

 

Acknowledgements

The authors thank the Instrument Center of the Institute for Mol­ecular Science for the X-ray structural analysis. This work was supported by a Grant-in-Aid for Scientific Research (No. 20550128) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

References

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