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Logo of actae2this articlesearchopen accesssubmitActa Crystallographica Section E: Crystallographic CommunicationsActa Crystallographica Section E: Crystallographic Communications
 
Acta Crystallogr E Crystallogr Commun. 2017 July 1; 73(Pt 8): 1264–1267.
Published online 2017 July 28. doi:  10.1107/S2056989017010751
PMCID: PMC5598862

A new solvate of epalerstat, a drug for diabetic neuropathy

Abstract

Epalerstat {systematic name: (5Z)-5-[(2E)-2-methyl-3-phenyl­prop-2-en-1-yl­idene]-4-oxo-2-sulfanyl­idene-1,3-thia­zolidine-3-acetic acid} crystallized as an acetone monosolvate, C15H13NO3S2·C3H6O. In the epalerstat mol­ecule, the methyl­propyl­enediene moiety is inclined to the phenyl ring and the five-membered rhodamine ring by 21.4 (4) and 4.7 (4)°, respectively. In addition, the acetic acid moiety is found to be almost normal to the rhodamine ring, making a dihedral angle of 85.1 (2)°. In the crystal, a pair of O—H(...)O hydrogen bonds between the carb­oxy­lic acid groups of epalerstat mol­ecules form inversion dimers with an R 2 2(8) loop. The dimers are linked by pairs of C—H(...)O hydrogen bonds, enclosing R 2 2(20) loops, forming chains propagating along the [101] direction. In addition, the acetone mol­ecules are linked to the chain by a C—H(...)O hydrogen bond. Epalerstat acetone monosolvate was found to be isotypic with epalerstat tertra­hydro­furan solvate [Umeda et al. (2017  ). Acta Cryst. E73, 941–944].

Keywords: crystal structure, epalerstat, acetone, monosolvate, isotypic, hydrogen bonding

Chemical context  

Investigation of solid forms of pharmaceuticals has attracted a great deal of attention as different crystal forms may imply different physicochemical properties (Putra et al., 2016a  ,b  ). Moreover, pharmaceutical processing stages during manufacturing, such as crystallization, can lead to the unexpected occurrence of new crystalline phases (Putra et al., 2016c  ). One of the important classes of pharmaceutical solids that can occur during crystallization is solvates. Solvates are defined as multi-component crystalline systems in which solvent mol­ecules are included within the crystal structure in either a stoichiometric or non-stoichiometric manner (Griesser, 2006  ). It has been estimated statistically that around 33% of organic compounds have the ability to form solvates with organic solvents (Clarke et al., 2010  ).

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Object name is e-73-01264-scheme1.jpg

Herein, we report on the crystal structure of a new solvate form of epalerstat, namely epalerstat acetone monosolvate. Epalerstat [systematic name: (5Z)-5-[(2E)-2-methyl-3-phenyl­prop-2-en-1-yl­idene]-4-oxo-2-sulfanyl­idene-1,3-thia­zol­idine-3-acetic acid), is an aldose reductase inhibitor and is used for the treatment of diabetic neuropathy, a complication symptom in diabetes mellitus (Miyamoto, 2002  ). Pharmacologically, epalerstat acts to inhibit the synthesis of sorbitol from glucose (Ramirez & Borja, 2008  ). The abundant occurrences of solvates in epalerstat itself is not surprising because of the imbalance between the hydrogen-bond donors and acceptors in its mol­ecular structure. Previously, the crystal structures of the methanol mono- and disolvate (Igarashi et al., 2015  ; Nagase et al., 2016  ), the ethanol monosolvate (Ishida et al., 1989  , 1990  ), the di­methyl­formamide monosolvate (Putra et al., 2017  ), the di­methyl­sulfoxide disolvate (Putra et al., 2017  ) and the tetra­hydro­furan monosolvate (Umeda et al., 2017  ) have been reported.

Structural commentary  

The mol­ecular structure of epalerstat acetone monosolvate is illustrated in Fig. 1  . The values of the bond distances, bond angles and dihedral angles are normal according the Mogul geometry check within the CSD software (Bruno et al., 2004  ; Groom et al., 2016  ). The mean plane of the methyl­propyl­enediene (C7–C10) moiety is inclined to the phenyl ring (C1–C6) and the five-membered rhodamine ring (S1/S2/O1/N1/C11–C13) by 21.4 (4) and 4.7 (4)°, respectively. The mean plane of the acetic acid moiety (O2/O3/C14/C15) is almost normal to the rhodamine ring, making a dihedral angle of 85.1 (2) °.

Figure 1
The mol­ecular structure of epalerstat acetone monosolvate, with the atom labelling and displacement ellipsoids drawn at the 50% probability level.

Supra­molecular features  

In the crystal, the epalerstat mol­ecule is connected to two adjacent epalerstat mol­ecules and one solvent mol­ecule via both conventional and non-conventional hydrogen bonds. The details of the hydrogen bonds and hydrogen bonding architecture are listed and presented in Table 1  and Fig. 2  , respectively. A pair of O3—H3A(...)O2ii hydrogen bonds is observed between two carb­oxy­lic acid moieties forming an inversion dimer with an An external file that holds a picture, illustration, etc.
Object name is e-73-01264-efi1.jpg(8) loop. This dimer is linked to adjacent dimers by a pair of C6—H6(...)O1ii hydrogen bonds, which enclose An external file that holds a picture, illustration, etc.
Object name is e-73-01264-efi1.jpg(20) loops, and form chains along direction [101]. In addition, acetone mol­ecules are linked to the chain by a C1—H1(...)O4iii hydrogen bond (Table 1  and Fig. 2  ).

Figure 2
A view along the b axis of the crystal packing of the title compound. Blue and orange dashed lines represent O—H(...)O and C—H(...)O hydrogen bonds, respectively. Only H atoms involved in these inter­actions have been included. ...
Table 1
Hydrogen-bond geometry (Å, °)

Discussion  

Inter­estingly, the new solvate reported here is isotypic with epalerstat tetra­hydro­furan monosolvate (Umeda et al., 2017  ). Both solvates crystallize in the triclinic system with the same space group, P An external file that holds a picture, illustration, etc.
Object name is e-73-01264-efi3.jpg. As illustrated in Fig. 3  , they have a similar mol­ecular arrangement and the solvent mol­ecules are located in similar pockets in the unit cell. The unit cell similarity index (Π) and the mean elongation ([sm epsilon]) values were calculated (Fábián & Kálmán, 1999  ) and found to be Π = 0.0016 and [sm epsilon] = 0.0005. As the Π and [sm epsilon] values are nearly zero, epalerstat acetone monosolvate and tetra­hydro­furan monosolvate have isostructural crystals. The solvent-occupied spaces, in which the solvent mol­ecules were deleted from the crystal structure, and the voids were calculated using the contact surface method with probe radius and approximate grid spacing set equal to 1.2 and 0.7 Å, respectively (Putra et al., 2016d  ; Macrae et al., 2008  ). The solvent occupied spaces for the acetone and tetra­hydro­furan solvates are 199.86 and 221.89 Å3, respectively. As expected, the larger occupied space in epalerstat tetra­hydro­furan solvate corresponds to the larger solvent mol­ecule. Inter­estingly, both solvents occupy nearly the same percentage of the total volume of the unit cell; the acetone and tetra­hydro­furan mol­ecules occupy 22.2 and 23.8%, respectively.

Figure 3
The packing view along the b axis of (a) epalerstat acetone monosolvate and (b) epalerstat tetra­hydro­furan monosolvate shows the isostructurality between the two solvates. H atoms have been omitted for clarity, and the epalerstat mol­ecules ...

Database survey  

A search of the Cambridge Structural Database (CSD, V5.38, last update July 2017; Groom et al., 2016  ) for epalerstat yielded 16 hits. They include the ethanol monosolvate (Ishida et al., 1989  , 1990  ), the methanol monosolvate (Igarashi et al., 2015  ), the methanol disolvate (Nagase et al., 2016  ), the di­methyl­formamide monosolvate (Putra et al., 2017  ), the di­methyl­sulfoxide disolvate (Putra et al., 2017  ), the tetra­hydro­furan monosolvate (Umeda et al., 2017  ), Form I: triclinic, P An external file that holds a picture, illustration, etc.
Object name is e-73-01264-efi3.jpg (Igarashi et al., 2013  ; Swapna et al., 2016  ), Form II: monoclinic, C2/c (Swapna et al., 2016  ), Form III: monoclinic, P21/n (Swapna et al., 2016  ), the co-crystal with caffeine (Putra et al., 2017  ), a series of salt co-crystals with cytosine (Swapna & Nangia, 2017  ) and the Z,Z isomer (Swapna et al., 2016  ).

Synthesis and crystallization  

Epalerstat Form I (700 mg) was dissolved in 10 ml acetone and the clear solution was then kept for three days at room temperature. Epalerstat acetone monosolvate appeared concomitantly with epalerstat Form I and they could be distinguished visually based on their crystal habit. In this case, the title compound, epalerstat acetone monosolvate, and Form I appeared as yellow blocks and orange needle-like crystals, respectively.

Refinement details  

Crystal data, data collection and structure refinement details are summarized in Table 2  . The hydrogen atom attached to an oxygen atom was located in a difference-Fourier map and freely refined. The C-bound H atoms were included in calculated positions and treated using riding model: C—H = 0.9–1.0 Å with U iso(H) = 1.5U iso(C-meth­yl) and 1.2U iso(C) for other H atoms. Initially the site occupancy factor of the acetone mol­ecule was refined and determined to be 1.005 (4). In the final cycles of refinement the occupancy of the acetone mol­ecule was fixed at 1.

Table 2
Experimental details

Supplementary Material

Crystal structure: contains datablock(s) I, Global. DOI: 10.1107/S2056989017010751/su5385sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989017010751/su5385Isup2.hkl

CCDC reference: 1563705

Additional supporting information: crystallographic information; 3D view; checkCIF report

Acknowledgments

We wish to thank for Professor Hiromasa Nagase (Hoshi University) for technical support during the single-crystal X-ray measurements.

supplementary crystallographic information

Crystal data

C15H13NO3S2·C3H6OZ = 2
Mr = 377.46F(000) = 396
Triclinic, P1Dx = 1.390 Mg m3
a = 7.9623 (1) ÅCu Kα radiation, λ = 1.54187 Å
b = 8.1806 (2) ÅCell parameters from 10593 reflections
c = 15.6919 (3) Åθ = 5.9–68.2°
α = 97.852 (7)°µ = 2.87 mm1
β = 99.837 (7)°T = 93 K
γ = 113.206 (8)°Block, yellow
V = 901.83 (6) Å30.35 × 0.24 × 0.10 mm

Data collection

Rigaku R-AXIS RAPID II diffractometer3235 independent reflections
Radiation source: rotating anode X-ray, RIGAKU2790 reflections with I > 2σ(I)
Detector resolution: 10.0 pixels mm-1Rint = 0.045
ω scanθmax = 68.2°, θmin = 5.9°
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)h = −9→9
Tmin = 0.378, Tmax = 0.750k = −9→9
10593 measured reflectionsl = −18→18

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.050Hydrogen site location: mixed
wR(F2) = 0.137H atoms treated by a mixture of independent and constrained refinement
S = 1.11w = 1/[σ2(Fo2) + (0.0886P)2] where P = (Fo2 + 2Fc2)/3
3235 reflections(Δ/σ)max < 0.001
233 parametersΔρmax = 0.73 e Å3
0 restraintsΔρmin = −0.30 e Å3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles

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

xyzUiso*/Ueq
S10.32326 (7)0.22776 (7)0.40775 (3)0.0232 (2)
S20.53005 (7)0.15013 (8)0.27814 (4)0.0290 (2)
O1−0.15383 (19)−0.1417 (2)0.26694 (9)0.0270 (5)
O20.0245 (2)0.0465 (2)0.10793 (9)0.0257 (5)
O30.0821 (2)−0.1687 (2)0.02943 (10)0.0304 (5)
N10.1578 (2)−0.0247 (2)0.26497 (11)0.0214 (5)
C1−0.2491 (3)0.5295 (3)0.76805 (14)0.0256 (7)
C2−0.0768 (3)0.6025 (3)0.74641 (14)0.0252 (7)
C3−0.0449 (3)0.5163 (3)0.67266 (13)0.0232 (6)
C4−0.1877 (3)0.3532 (3)0.61713 (14)0.0214 (6)
O40.3463 (2)0.3068 (2)0.03521 (11)0.0438 (6)
C5−0.3632 (3)0.2835 (3)0.63920 (14)0.0235 (6)
C6−0.3931 (3)0.3700 (3)0.71326 (14)0.0252 (7)
C7−0.1685 (3)0.2516 (3)0.53833 (13)0.0216 (6)
C8−0.0128 (3)0.2508 (3)0.51367 (13)0.0215 (6)
C90.1858 (3)0.3596 (3)0.56879 (14)0.0242 (6)
C10−0.0467 (3)0.1284 (3)0.43048 (13)0.0218 (6)
C110.0769 (3)0.1067 (3)0.38588 (13)0.0211 (6)
C120.0075 (3)−0.0322 (3)0.30199 (13)0.0220 (7)
C130.3343 (3)0.1078 (3)0.30963 (14)0.0226 (6)
C140.1251 (3)−0.1486 (3)0.18203 (13)0.0234 (6)
C150.0718 (3)−0.0778 (3)0.10282 (14)0.0230 (6)
C160.6721 (4)0.3855 (4)0.08636 (16)0.0463 (9)
C170.4865 (3)0.2987 (3)0.01874 (15)0.0306 (7)
C180.4837 (4)0.2023 (4)−0.07037 (16)0.0397 (8)
H1−0.268530.587680.819680.0310*
H20.020890.713260.782710.0300*
H30.074670.567890.659420.0280*
H3A0.034 (4)−0.130 (4)−0.016 (2)0.066 (10)*
H5−0.462980.174740.602370.0280*
H6−0.512540.320250.726780.0300*
H7−0.284630.172300.497090.0260*
H9A0.243240.473710.549510.0360*
H9B0.259030.288680.561410.0360*
H9C0.184900.387310.631430.0360*
H10−0.175630.051240.402880.0260*
H14A0.02271−0.268890.179410.0280*
H14B0.24067−0.165840.179880.0280*
H16A0.662460.459790.138190.0690*
H16B0.769640.463150.060510.0690*
H16C0.705700.290140.104600.0690*
H18A0.353960.14160−0.107150.0590*
H18B0.532610.11105−0.062690.0590*
H18C0.562660.29111−0.099450.0590*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
S10.0185 (3)0.0257 (3)0.0223 (3)0.0072 (2)0.0049 (2)0.0033 (2)
S20.0207 (3)0.0327 (4)0.0313 (3)0.0088 (3)0.0094 (2)0.0041 (3)
O10.0193 (8)0.0290 (9)0.0267 (8)0.0060 (7)0.0039 (6)0.0033 (7)
O20.0287 (8)0.0273 (9)0.0227 (8)0.0147 (7)0.0057 (6)0.0029 (6)
O30.0355 (9)0.0386 (10)0.0221 (8)0.0233 (8)0.0047 (7)0.0020 (7)
N10.0205 (9)0.0223 (10)0.0204 (9)0.0082 (8)0.0056 (7)0.0036 (7)
C10.0304 (12)0.0290 (13)0.0238 (11)0.0168 (10)0.0099 (9)0.0091 (9)
C20.0251 (11)0.0242 (12)0.0267 (11)0.0115 (9)0.0049 (9)0.0056 (9)
C30.0196 (10)0.0233 (12)0.0266 (11)0.0081 (9)0.0064 (9)0.0074 (9)
C40.0221 (11)0.0232 (11)0.0232 (11)0.0123 (9)0.0066 (9)0.0091 (9)
O40.0331 (10)0.0508 (11)0.0447 (11)0.0144 (8)0.0180 (8)0.0027 (9)
C50.0192 (10)0.0248 (12)0.0268 (11)0.0099 (9)0.0038 (9)0.0073 (9)
C60.0205 (11)0.0300 (13)0.0281 (11)0.0119 (9)0.0082 (9)0.0096 (10)
C70.0208 (11)0.0199 (11)0.0238 (11)0.0083 (9)0.0037 (9)0.0073 (9)
C80.0231 (11)0.0223 (11)0.0217 (10)0.0106 (9)0.0074 (9)0.0079 (9)
C90.0213 (11)0.0293 (12)0.0227 (10)0.0122 (9)0.0054 (9)0.0040 (9)
C100.0205 (10)0.0220 (11)0.0232 (11)0.0085 (9)0.0052 (9)0.0081 (9)
C110.0211 (11)0.0212 (11)0.0212 (10)0.0085 (9)0.0051 (8)0.0077 (9)
C120.0216 (11)0.0236 (12)0.0226 (11)0.0101 (9)0.0056 (9)0.0091 (9)
C130.0197 (11)0.0227 (11)0.0260 (11)0.0089 (9)0.0051 (9)0.0082 (9)
C140.0251 (11)0.0215 (11)0.0230 (11)0.0095 (9)0.0084 (9)0.0012 (9)
C150.0146 (10)0.0261 (12)0.0234 (11)0.0058 (9)0.0040 (8)0.0000 (9)
C160.0394 (15)0.0540 (18)0.0356 (14)0.0151 (13)0.0027 (12)0.0022 (13)
C170.0282 (13)0.0318 (13)0.0308 (12)0.0100 (10)0.0100 (10)0.0089 (10)
C180.0330 (13)0.0541 (17)0.0317 (13)0.0211 (12)0.0078 (11)0.0016 (12)

Geometric parameters (Å, º)

S1—C111.759 (3)C11—C121.476 (3)
S1—C131.744 (2)C14—C151.507 (3)
S2—C131.636 (3)C1—H10.9500
O1—C121.213 (3)C2—H20.9500
O2—C151.213 (3)C3—H30.9500
O3—C151.316 (3)C5—H50.9500
N1—C121.401 (3)C6—H60.9500
N1—C131.377 (3)C7—H70.9500
N1—C141.451 (3)C9—H9B0.9800
O3—H3A0.91 (3)C9—H9C0.9800
C1—C61.391 (3)C9—H9A0.9800
C1—C21.387 (4)C10—H100.9500
C2—C31.386 (3)C14—H14A0.9900
C3—C41.407 (3)C14—H14B0.9900
C4—C51.410 (4)C16—C171.499 (4)
C4—C71.459 (3)C17—C181.501 (3)
O4—C171.212 (3)C16—H16A0.9800
C5—C61.382 (3)C16—H16B0.9800
C7—C81.363 (4)C16—H16C0.9800
C8—C101.445 (3)C18—H18A0.9800
C8—C91.501 (3)C18—H18B0.9800
C10—C111.352 (3)C18—H18C0.9800
C11—S1—C1393.02 (11)C4—C3—H3120.00
C12—N1—C13116.89 (18)C4—C5—H5119.00
C12—N1—C14120.69 (18)C6—C5—H5119.00
C13—N1—C14122.41 (19)C1—C6—H6120.00
C15—O3—H3A107 (2)C5—C6—H6120.00
C2—C1—C6119.2 (2)C4—C7—H7114.00
C1—C2—C3121.0 (2)C8—C7—H7114.00
C2—C3—C4120.7 (2)C8—C9—H9A109.00
C3—C4—C5117.4 (2)C8—C9—H9B109.00
C5—C4—C7117.6 (2)C8—C9—H9C109.00
C3—C4—C7125.1 (2)H9A—C9—H9B109.00
C4—C5—C6121.4 (2)H9A—C9—H9C109.00
C1—C6—C5120.3 (2)H9B—C9—H9C109.00
C4—C7—C8131.1 (2)C8—C10—H10115.00
C7—C8—C9124.49 (19)C11—C10—H10115.00
C7—C8—C10116.2 (2)N1—C14—H14A109.00
C9—C8—C10119.2 (2)N1—C14—H14B109.00
C8—C10—C11129.9 (2)C15—C14—H14A109.00
S1—C11—C12109.41 (17)C15—C14—H14B109.00
C10—C11—C12119.9 (2)H14A—C14—H14B108.00
S1—C11—C10130.59 (17)O4—C17—C16121.6 (2)
O1—C12—C11127.7 (2)O4—C17—C18121.9 (2)
N1—C12—C11110.3 (2)C16—C17—C18116.5 (2)
O1—C12—N1122.00 (19)C17—C16—H16A110.00
S1—C13—N1110.27 (17)C17—C16—H16B109.00
S2—C13—N1126.30 (17)C17—C16—H16C109.00
S1—C13—S2123.43 (14)H16A—C16—H16B109.00
N1—C14—C15111.81 (19)H16A—C16—H16C109.00
O2—C15—C14123.1 (2)H16B—C16—H16C109.00
O3—C15—C14111.3 (2)C17—C18—H18A109.00
O2—C15—O3125.6 (2)C17—C18—H18B109.00
C2—C1—H1120.00C17—C18—H18C110.00
C6—C1—H1120.00H18A—C18—H18B109.00
C1—C2—H2120.00H18A—C18—H18C109.00
C3—C2—H2119.00H18B—C18—H18C109.00
C2—C3—H3120.00
C13—S1—C11—C10−175.1 (2)C2—C3—C4—C7−179.8 (2)
C13—S1—C11—C121.91 (17)C7—C4—C5—C6179.3 (2)
C11—S1—C13—S2177.60 (16)C5—C4—C7—C8−159.0 (2)
C11—S1—C13—N1−2.90 (17)C3—C4—C5—C6−1.1 (3)
C14—N1—C13—S21.0 (3)C3—C4—C7—C821.4 (4)
C14—N1—C12—C11179.93 (18)C4—C5—C6—C10.1 (4)
C12—N1—C13—S13.3 (2)C4—C7—C8—C92.0 (4)
C13—N1—C12—O1178.6 (2)C4—C7—C8—C10178.8 (2)
C14—N1—C12—O10.4 (3)C9—C8—C10—C11−8.4 (4)
C13—N1—C12—C11−1.8 (3)C7—C8—C10—C11174.7 (2)
C13—N1—C14—C15−93.1 (3)C8—C10—C11—C12178.6 (2)
C14—N1—C13—S1−178.51 (15)C8—C10—C11—S1−4.7 (4)
C12—N1—C13—S2−177.26 (17)C10—C11—C12—O1−3.6 (4)
C12—N1—C14—C1585.1 (2)C10—C11—C12—N1176.9 (2)
C2—C1—C6—C51.3 (3)S1—C11—C12—N1−0.5 (2)
C6—C1—C2—C3−1.8 (4)S1—C11—C12—O1179.0 (2)
C1—C2—C3—C40.8 (4)N1—C14—C15—O2−14.2 (3)
C2—C3—C4—C50.7 (3)N1—C14—C15—O3166.38 (19)

Hydrogen-bond geometry (Å, º)

D—H···AD—HH···AD···AD—H···A
O3—H3A···O2i0.91 (3)1.75 (3)2.645 (2)171 (3)
C6—H6···O1ii0.952.503.440 (3)168
C1—H1···O4iii0.952.583.525 (3)171

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

References

  • Bruno, I. J., Cole, J. C., Kessler, M., Luo, J., Motherwell, W. D. S., Purkis, L. H., Smith, B. R., Taylor, R., Cooper, R. I., Harris, S. E. & Orpen, A. G. (2004). J. Chem. Inf. Comput. Sci. 44, 2133–2144. [PubMed]
  • Clarke, H. D., Arora, K. K., Bass, H., Kavuru, P., Ong, T. T., Pujari, T., Wojtas, L. & Zaworotko, M. J. (2010). Cryst. Growth Des. 10, 2152–2167.
  • Fábián, L. & Kálmán, A. (1999). Acta Cryst. B55, 1099–1108. [PubMed]
  • Griesser, U. J. (2006). Polymorphism: In the Pharmaceutical Industry, edited by R. Hilfiker, pp. 211–233. Weinheim: Wiley-Vch Verlag GmbH & Co. KGaA.
  • Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. [PMC free article] [PubMed]
  • Higashi, T. (1995). ABSCOR. Rigaku Corporation, Tokyo, Japan.
  • Igarashi, R., Nagase, H., Furuishi, T., Endo, T., Tomono, K. & Ueda, H. (2013). X-ray Struct. Anal. Online, 29, 23–24.
  • Igarashi, R., Nagase, H., Furuishi, T., Tomono, K., Endo, T. & Ueda, H. (2015). X-ray Struct. Anal. Online, 31, 1–2.
  • Ishida, T., In, Y., Inoue, M., Tanaka, C. & Hamanaka, N. (1990). J. Chem. Soc. Perkin Trans. 2, pp. 1085–1091.
  • Ishida, T., In, Y., Inoue, M., Ueno, Y., Tanaka, C. & Hamanaka, N. (1989). Tetrahedron Lett. 30, 959–962.
  • Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.
  • Miyamoto, S. (2002). Chem. Bio. Info. J, 2, 74–85.
  • Nagase, H., Kobayashi, M., Ueda, H., Furuishi, T., Gunji, M., Endo, T. & Yonemochi, E. (2016). X-ray Struct. Anal. Online, 32, 7–9.
  • Putra, O. D., Yonemochi, E. & Uekusa, H. (2016d). Cryst. Growth Des. 16, 6568–6573.
  • Putra, O. D., Furuishi, T., Yonemochi, E., Terada, K. & Uekusa, H. (2016a). Cryst. Growth Des. 16, 3577–3581.
  • Putra, O. D., Umeda, D., Nugraha, Y. P., Furuishi, T., Nagase, H., Fukuzawa, K., Uekusa, H. & Yonemochi, E. (2017). CrystEngComm, 19, 2614–2622.
  • Putra, O. D., Yoshida, T., Umeda, D., Gunji, M., Uekusa, H. & Yonemochi, E. (2016c). Cryst. Growth Des. 16, 6714–6718.
  • Putra, O. D., Yoshida, T., Umeda, D., Higashi, K., Uekusa, H. & Yonemochi, E. (2016b). Cryst. Growth Des. 16, 5223–5229.
  • Ramirez, M. A. & Borja, N. L. (2008). Pharmacotherapy, 28, 646–655. [PubMed]
  • Rigaku (1998). PROCESS-AUTO. Rigaku Corporation, Tokyo, Japan.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. [PMC free article] [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
  • Swapna, B. & Nangia, A. (2017). Cryst. Growth Des. 17, 3350–3360.
  • Swapna, B., Suresh, K. & Nangia, A. (2016). Chem. Commun. 52, 4037–4040. [PubMed]
  • Umeda, D., Putra, O. D., Gunji, M., Fukuzawa, K. & Yonemochi, E. (2017). Acta Cryst. E73, 941–944.

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