research communications
of the diglycidyl ether of eugenol
aICMUB CNRS UMR 6302, Université de Bourgogne Franche-Comté, Faculté des Sciences, 9 avenue Alain Savary, 21000 Dijon, France, bFEMTO Institute, Applied Mechanics Department, UMR CNRS 6174, Université de Bourgogne Franche-Comté, 24 Chemin de l'Epitaphe, 25000 Besançon, France, and cDRIVE Laboratory, Institut Supérieur de l'Automobile et des Transports, 49 Rue Melle Bourgeois, 58027 Nevers, France
*Correspondence e-mail: laurent.plasseraud@u-bourgogne.fr, hcattey@u-bourgogne.fr
The diepoxy monomer, C13H16O4 {DGE-Eu; 2-[3-methoxy-4-(oxiran-2-ylmethoxy)benzyl]oxirane}, was synthesized from eugenol by a three-step reaction. It consists of a 1,2,4-trisubstituted benzene ring substituted by diglycidyl ether, a methoxy group and a methyloxirane group. The three-membered oxirane rings are inclined to the benzene ring by 61.0 (3) and 27.9 (3)°. The methylene C atom of one of the two terminal epoxide rings is positionally disordered [refined occupancy ratio = 0.69 (1):0.31 (1)]. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming layers parallel to the ab plane. The layers are linked by C—H⋯π interactions, forming a three-dimensional network.
Keywords: crystal structure; oxirane; bio-based molecule; eugenol derivative; epoxy thermoset prepolymer; hydrogen bonding.
CCDC reference: 1543288
1. Chemical context
The past two decades have witnessed an increasing interest in the environmental quest for the replacement of petroleum-based chemicals by monomers from renewable resources. Advances in particular in the catalytic conversion of biomass have led to a wide range of useful platform molecules (Besson et al., 2014). This sustainable approach is also strongly considered in the field of polymer synthesis (Gandini et al., 2016). In the specific domain of epoxy thermosets, numerous studies have been conducted in order to find alternatives to the diglycidyl ether of bisphenol A (BADGE), which is the main building-block used for formulation resins (Auvergne et al., 2014). Classically, the synthetic approach is based on the functionalization of bio-sourced molecules by the grafting of glycidyl ether groups. In this context and in our ongoing studies on the chemical modification of bio-based building blocks for material applications (Mhanna et al., 2014; Bigot et al., 2016; François et al., 2016), we report herein on the synthesis and of the diglycidyl ether of eugenol (DGE-Eu), prepared from eugenol in a three-step synthesis (Qin et al., 2014).
2. Structural commentary
The title compound (DGE-EU), has an asymmetrical structure, which is depicted in Fig. 1. It is composed of a benzene ring with three oxygenated functional groups: (i) 2-[(λ1-oxidanyl)methyl]oxirane, (ii) methoxy and (iii) 2-methyloxirane. While atoms O1, O2 and C11 lie in the plane of the benzene ring, the methoxy group (O1/C5/C10) is inclined to the benzene ring by 11.2 (3)°. The two oxirane rings (O3/C8/C9 and O4/C12A/C13) are inclined to the benzene ring by 61.0 (3) and 27.9 (3)°, respectively. The molecule shows disorder with an occupation factor equal to 0.69 (1) for the major component of the methylene group (C12A) of the oxirane ring (C11/C12/O3). Such disorder is commonly observed for diglycidyl ether derivatives (CSD; Groom et al., 2016).
3. Supramolecular features
The crystal packing of DGE-Eu viewed along the c-axis is depicted in Fig. 2. All oxygen atoms of DGE-Eu are involved in C—H⋯O hydrogen bonds with surrounding molecules, forming layers lying parallel to the ab plane (Fig. 2 and Table 1). In addition, the layers are linked C—H⋯π interactions, with the C7–H7A group positioned almost orthogonally to the benzene ring, so forming a three-dimensional network (Table 1 and Fig. 3).
4. Database survey
To date, and to the best of our knowledge, only nine crystallographic structures comprising diglycidyl ether-substituted benzene ring moieties have been deposited in the Cambridge Structural Database (WebCSD v1.1.2, update 2017-04-05; Groom et al., 2016). They include 2,2-bis(3,5-dibromo-4-hydroxybenzene)propane diglycidyl ether (COMNEX: Saf'yanov et al., 1984), 2,2-bis[4-(oxiran-2-ylmethoxy)-3,5-dibromophenyl]propane (COMNEY: Cheban et al., 1985), diglycidyl ether of bisphenol A (DGEBPA: Flippen-Anderson & Gilardi, 1980; DGEBPA01: Heinemann et al., 1993; DGEBPA10: Flippen-Anderson & Gilardi, 1981), p-di(2,3-epoxypropyloxy)benzene (EOXHQE: Saf'yanov et al., 1977), 2,2′-[1,3-phenylene-bis(oxymethylene)]bis(oxirane) (FITWOU: Bocelli & Grenier-Loustalot, 1987), 2-(4-{4-[4-(oxiran-2-ylmethoxy)phenoxy]phenyl}phenoxymethyl)oxirane (LAQTII: Song et al., 2012) and 10-[2,5-bis(2,3-epoxy-1-propoxy)phenyl]-9-oxa-10-phosphaphenanthren-10-one (LIPSOS: Cho et al., 1999). In some of these compounds, an epoxy ring is disordered, which is also observed for the title compound DGE-Eu. In terms of application, these compounds are used as precursors of thermosetting resins. The polymerization process involving the epoxy rings occurs in the presence of and acid and leads to cross-linked rigid materials.
5. Synthesis and crystallization
The title compound was prepared from a commercial source of eugenol (Sigma–Aldrich), according to a three-step procedure previously reported in the literature (Qin et al., 2014). The details of the synthesis of the title compound are summarized in Fig. 4. Following purification by silica gel colourless prismatic crystals were obtained by slow evaporation of an ethyl acetate solution, and were finally characterized as DGE-Eu.
6. details
Crystal data, data collection and structure . The H atoms were placed at calculated positions and refined using a riding model: C—H = 0.95–1.00 Å with Uiso(H) = 1.5Ueq(C-methyl) and 1.2Ueq(C) for other H atoms. Atom C12 atom of the epoxypropane (oxirane) group (C11/C12/O3) was found to be disordered over two positions with a refined occupancy ratio of 0.69 (1): 0.31 (1) for atoms C12A:C12B.
details are summarized in Table 2
|
Supporting information
CCDC reference: 1543288
https://doi.org/10.1107/S2056989017005370/su5360sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989017005370/su5360Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989017005370/su5360Isup3.cml
Data collection: APEX2 (Bruker, 2014); cell
SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXT2015 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2015 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).C13H16O4 | F(000) = 504 |
Mr = 236.26 | Dx = 1.340 Mg m−3 |
Monoclinic, Cc | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: C -2yc | Cell parameters from 9992 reflections |
a = 9.8262 (5) Å | θ = 2.7–33.0° |
b = 13.4434 (7) Å | µ = 0.10 mm−1 |
c = 9.4251 (8) Å | T = 115 K |
β = 109.897 (2)° | Prism, colourless |
V = 1170.71 (13) Å3 | 0.4 × 0.35 × 0.3 mm |
Z = 4 |
Bruker APEXII CCD diffractometer | 2680 independent reflections |
Radiation source: X-ray tube, Siemens KFF Mo 2K-180 | 2586 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.021 |
φ and ω scans | θmax = 27.5°, θmin = 2.7° |
Absorption correction: multi-scan (SADABS; Bruker, 2014) | h = −12→12 |
Tmin = 0.700, Tmax = 0.747 | k = −17→17 |
18897 measured reflections | l = −12→12 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.044 | H-atom parameters constrained |
wR(F2) = 0.121 | w = 1/[σ2(Fo2) + (0.0641P)2 + 1.3035P] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max < 0.001 |
2680 reflections | Δρmax = 0.69 e Å−3 |
160 parameters | Δρmin = −0.28 e Å−3 |
2 restraints | Absolute structure: Flack x determined using 1234 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.20 (18) |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
O1 | 0.3186 (2) | 0.75130 (14) | 0.4046 (2) | 0.0215 (4) | |
O2 | 0.3043 (2) | 0.59282 (15) | 0.5548 (2) | 0.0221 (4) | |
O3 | 0.0296 (3) | 0.4884 (2) | 0.5717 (4) | 0.0511 (9) | |
O4 | 0.8644 (3) | 0.79876 (18) | 0.4484 (3) | 0.0406 (7) | |
C1 | 0.6472 (3) | 0.6219 (2) | 0.3926 (3) | 0.0204 (6) | |
C2 | 0.6394 (3) | 0.5387 (2) | 0.4744 (3) | 0.0203 (5) | |
H2 | 0.7121 | 0.4890 | 0.4925 | 0.024* | |
C3 | 0.5262 (3) | 0.5260 (2) | 0.5313 (3) | 0.0204 (6) | |
H3 | 0.5220 | 0.4677 | 0.5867 | 0.025* | |
C4 | 0.4203 (3) | 0.5984 (2) | 0.5068 (3) | 0.0169 (5) | |
C5 | 0.4272 (3) | 0.6842 (2) | 0.4242 (3) | 0.0171 (5) | |
C6 | 0.5397 (3) | 0.6949 (2) | 0.3680 (3) | 0.0187 (5) | |
H6 | 0.5441 | 0.7527 | 0.3119 | 0.022* | |
C7 | 0.2935 (3) | 0.5033 (3) | 0.6333 (4) | 0.0287 (7) | |
H7A | 0.3828 | 0.4935 | 0.7213 | 0.034* | |
H7B | 0.2807 | 0.4452 | 0.5655 | 0.034* | |
C8 | 0.1678 (4) | 0.5132 (3) | 0.6838 (5) | 0.0382 (8) | |
H8 | 0.1691 | 0.5701 | 0.7526 | 0.046* | |
C9 | 0.0890 (4) | 0.4237 (4) | 0.6998 (5) | 0.0522 (12) | |
H9A | 0.1274 | 0.3584 | 0.6826 | 0.063* | |
H9B | 0.0428 | 0.4238 | 0.7782 | 0.063* | |
C10 | 0.3084 (3) | 0.8287 (2) | 0.2985 (4) | 0.0269 (6) | |
H10A | 0.3053 | 0.7997 | 0.2020 | 0.040* | |
H10B | 0.3929 | 0.8724 | 0.3366 | 0.040* | |
H10C | 0.2201 | 0.8674 | 0.2839 | 0.040* | |
C11 | 0.7701 (3) | 0.6367 (3) | 0.3324 (4) | 0.0278 (7) | |
H11A | 0.8071 | 0.5708 | 0.3159 | 0.033* | 0.690 (11) |
H11B | 0.7323 | 0.6706 | 0.2334 | 0.033* | 0.690 (11) |
H11C | 0.8536 | 0.5974 | 0.3965 | 0.033* | 0.310 (11) |
H11D | 0.7401 | 0.6074 | 0.2299 | 0.033* | 0.310 (11) |
C13 | 0.9712 (4) | 0.7691 (2) | 0.3826 (4) | 0.0324 (7) | |
H13A | 0.9471 | 0.7781 | 0.2725 | 0.039* | 0.690 (11) |
H13B | 1.0745 | 0.7788 | 0.4434 | 0.039* | 0.690 (11) |
H13C | 1.0477 | 0.7222 | 0.4401 | 0.039* | 0.310 (11) |
H13D | 1.0014 | 0.8187 | 0.3216 | 0.039* | 0.310 (11) |
C12A | 0.8911 (4) | 0.6954 (3) | 0.4331 (5) | 0.0203 (11) | 0.690 (11) |
H12A | 0.9476 | 0.6614 | 0.5295 | 0.024* | 0.690 (11) |
C12B | 0.8184 (12) | 0.7317 (8) | 0.3230 (12) | 0.032 (3)* | 0.310 (11) |
H12B | 0.7600 | 0.7658 | 0.2274 | 0.038* | 0.310 (11) |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0200 (9) | 0.0204 (9) | 0.0264 (10) | 0.0043 (7) | 0.0107 (7) | 0.0072 (8) |
O2 | 0.0216 (10) | 0.0238 (10) | 0.0222 (9) | −0.0004 (8) | 0.0089 (8) | 0.0056 (8) |
O3 | 0.0229 (12) | 0.0500 (17) | 0.070 (2) | −0.0009 (11) | 0.0028 (12) | 0.0306 (16) |
O4 | 0.0437 (14) | 0.0246 (12) | 0.0679 (18) | −0.0074 (10) | 0.0379 (13) | −0.0174 (12) |
C1 | 0.0174 (12) | 0.0230 (13) | 0.0210 (13) | −0.0033 (11) | 0.0067 (10) | −0.0078 (11) |
C2 | 0.0186 (12) | 0.0202 (12) | 0.0194 (12) | 0.0029 (10) | 0.0029 (10) | −0.0036 (10) |
C3 | 0.0226 (13) | 0.0187 (12) | 0.0168 (12) | −0.0001 (10) | 0.0026 (10) | 0.0014 (9) |
C4 | 0.0165 (12) | 0.0195 (13) | 0.0129 (11) | −0.0036 (9) | 0.0026 (10) | 0.0003 (9) |
C5 | 0.0160 (11) | 0.0170 (12) | 0.0167 (11) | 0.0005 (9) | 0.0035 (9) | −0.0010 (9) |
C6 | 0.0191 (12) | 0.0175 (12) | 0.0198 (12) | −0.0019 (9) | 0.0068 (10) | −0.0008 (9) |
C7 | 0.0218 (14) | 0.0326 (16) | 0.0299 (15) | 0.0008 (12) | 0.0067 (11) | 0.0146 (13) |
C8 | 0.0330 (17) | 0.042 (2) | 0.0429 (19) | 0.0016 (15) | 0.0170 (15) | 0.0098 (16) |
C9 | 0.0247 (16) | 0.056 (2) | 0.075 (3) | 0.0001 (16) | 0.0159 (18) | 0.040 (2) |
C10 | 0.0292 (15) | 0.0234 (14) | 0.0304 (15) | 0.0051 (12) | 0.0133 (12) | 0.0108 (12) |
C11 | 0.0215 (13) | 0.0314 (16) | 0.0346 (16) | −0.0047 (12) | 0.0146 (12) | −0.0140 (12) |
C13 | 0.0323 (16) | 0.0259 (14) | 0.049 (2) | −0.0044 (13) | 0.0267 (15) | −0.0069 (14) |
C12A | 0.021 (2) | 0.020 (2) | 0.023 (2) | 0.0008 (15) | 0.0118 (16) | −0.0013 (15) |
O1—C5 | 1.361 (3) | C8—H8 | 1.0000 |
O1—C10 | 1.423 (3) | C8—C9 | 1.467 (5) |
O2—C4 | 1.364 (3) | C9—H9A | 0.9900 |
O2—C7 | 1.435 (3) | C9—H9B | 0.9900 |
O3—C8 | 1.447 (5) | C10—H10A | 0.9800 |
O3—C9 | 1.441 (4) | C10—H10B | 0.9800 |
O4—C13 | 1.444 (4) | C10—H10C | 0.9800 |
O4—C12A | 1.430 (4) | C11—H11A | 0.9900 |
O4—C12B | 1.432 (11) | C11—H11B | 0.9900 |
C1—C2 | 1.374 (4) | C11—H11C | 0.9900 |
C1—C6 | 1.402 (4) | C11—H11D | 0.9900 |
C1—C11 | 1.513 (4) | C11—C12A | 1.473 (5) |
C2—H2 | 0.9500 | C11—C12B | 1.375 (12) |
C2—C3 | 1.400 (4) | C13—H13A | 0.9900 |
C3—H3 | 0.9500 | C13—H13B | 0.9900 |
C3—C4 | 1.386 (4) | C13—H13C | 0.9900 |
C4—C5 | 1.406 (4) | C13—H13D | 0.9900 |
C5—C6 | 1.386 (4) | C13—C12A | 1.443 (5) |
C6—H6 | 0.9500 | C13—C12B | 1.499 (12) |
C7—H7A | 0.9900 | C12A—H12A | 1.0000 |
C7—H7B | 0.9900 | C12B—H12B | 1.0000 |
C7—C8 | 1.473 (5) | ||
C5—O1—C10 | 116.4 (2) | O1—C10—H10B | 109.5 |
C4—O2—C7 | 115.7 (2) | O1—C10—H10C | 109.5 |
C9—O3—C8 | 61.1 (2) | H10A—C10—H10B | 109.5 |
C12A—O4—C13 | 60.3 (2) | H10A—C10—H10C | 109.5 |
C12B—O4—C13 | 62.8 (5) | H10B—C10—H10C | 109.5 |
C2—C1—C6 | 118.7 (3) | C1—C11—H11A | 108.8 |
C2—C1—C11 | 121.4 (3) | C1—C11—H11B | 108.8 |
C6—C1—C11 | 119.9 (3) | C1—C11—H11C | 107.6 |
C1—C2—H2 | 119.4 | C1—C11—H11D | 107.6 |
C1—C2—C3 | 121.1 (3) | H11A—C11—H11B | 107.7 |
C3—C2—H2 | 119.4 | H11C—C11—H11D | 107.0 |
C2—C3—H3 | 120.0 | C12A—C11—C1 | 113.6 (3) |
C4—C3—C2 | 120.0 (2) | C12A—C11—H11A | 108.8 |
C4—C3—H3 | 120.0 | C12A—C11—H11B | 108.8 |
O2—C4—C3 | 124.8 (2) | C12B—C11—C1 | 118.9 (5) |
O2—C4—C5 | 115.6 (2) | C12B—C11—H11C | 107.6 |
C3—C4—C5 | 119.6 (2) | C12B—C11—H11D | 107.6 |
O1—C5—C4 | 115.8 (2) | O4—C13—H13A | 117.8 |
O1—C5—C6 | 124.7 (2) | O4—C13—H13B | 117.8 |
C6—C5—C4 | 119.5 (2) | O4—C13—H13C | 118.0 |
C1—C6—H6 | 119.4 | O4—C13—H13D | 118.0 |
C5—C6—C1 | 121.2 (2) | O4—C13—C12B | 58.2 (5) |
C5—C6—H6 | 119.4 | H13A—C13—H13B | 115.0 |
O2—C7—H7A | 110.1 | H13C—C13—H13D | 115.1 |
O2—C7—H7B | 110.1 | C12A—C13—O4 | 59.4 (2) |
O2—C7—C8 | 108.0 (3) | C12A—C13—H13A | 117.8 |
H7A—C7—H7B | 108.4 | C12A—C13—H13B | 117.8 |
C8—C7—H7A | 110.1 | C12B—C13—H13C | 118.0 |
C8—C7—H7B | 110.1 | C12B—C13—H13D | 118.0 |
O3—C8—C7 | 115.2 (3) | O4—C12A—C11 | 116.8 (3) |
O3—C8—H8 | 116.8 | O4—C12A—C13 | 60.4 (2) |
O3—C8—C9 | 59.3 (2) | O4—C12A—H12A | 114.7 |
C7—C8—H8 | 116.8 | C11—C12A—H12A | 114.7 |
C9—C8—C7 | 119.3 (4) | C13—C12A—C11 | 124.5 (4) |
C9—C8—H8 | 116.8 | C13—C12A—H12A | 114.7 |
O3—C9—C8 | 59.7 (2) | O4—C12B—C13 | 59.0 (5) |
O3—C9—H9A | 117.8 | O4—C12B—H12B | 112.2 |
O3—C9—H9B | 117.8 | C11—C12B—O4 | 123.4 (8) |
C8—C9—H9A | 117.8 | C11—C12B—C13 | 127.6 (8) |
C8—C9—H9B | 117.8 | C11—C12B—H12B | 112.2 |
H9A—C9—H9B | 114.9 | C13—C12B—H12B | 112.2 |
O1—C10—H10A | 109.5 | ||
O1—C5—C6—C1 | −179.6 (3) | C3—C4—C5—O1 | 179.6 (2) |
O2—C4—C5—O1 | 0.9 (3) | C3—C4—C5—C6 | 0.2 (4) |
O2—C4—C5—C6 | −178.5 (2) | C4—O2—C7—C8 | 176.7 (3) |
O2—C7—C8—O3 | 83.5 (4) | C4—C5—C6—C1 | −0.2 (4) |
O2—C7—C8—C9 | 150.9 (4) | C6—C1—C2—C3 | 0.6 (4) |
O4—C13—C12A—C11 | 103.8 (4) | C6—C1—C11—C12A | 84.8 (4) |
O4—C13—C12B—C11 | −110.4 (10) | C6—C1—C11—C12B | 31.8 (7) |
C1—C2—C3—C4 | −0.7 (4) | C7—O2—C4—C3 | −1.3 (4) |
C1—C11—C12A—O4 | −69.5 (4) | C7—O2—C4—C5 | 177.3 (2) |
C1—C11—C12A—C13 | −140.5 (3) | C7—C8—C9—O3 | −103.5 (4) |
C1—C11—C12B—O4 | 54.5 (11) | C9—O3—C8—C7 | 110.4 (4) |
C1—C11—C12B—C13 | 128.8 (8) | C10—O1—C5—C4 | −168.6 (2) |
C2—C1—C6—C5 | −0.1 (4) | C10—O1—C5—C6 | 10.8 (4) |
C2—C1—C11—C12A | −93.8 (4) | C11—C1—C2—C3 | 179.3 (2) |
C2—C1—C11—C12B | −146.8 (6) | C11—C1—C6—C5 | −178.8 (2) |
C2—C3—C4—O2 | 178.8 (2) | C13—O4—C12A—C11 | −116.3 (4) |
C2—C3—C4—C5 | 0.3 (4) | C13—O4—C12B—C11 | 117.2 (10) |
Cg is the centroid of the benzene ring (C1–C6). |
D—H···A | D—H | H···A | D···A | D—H···A |
C7—H7B···O4i | 0.99 | 2.53 | 3.452 (4) | 155 |
C11—H11C···O3ii | 0.99 | 2.43 | 3.413 (4) | 170 |
C13—H13B···O1ii | 0.99 | 2.57 | 3.358 (4) | 136 |
C12A—H12A···O3ii | 1.00 | 2.45 | 3.177 (5) | 129 |
C7—H7A···Cgiii | 0.99 | 2.57 | 3.465 (4) | 150 |
Symmetry codes: (i) x−1/2, y−1/2, z; (ii) x+1, y, z; (iii) x, −y+1, z+1/2. |
Acknowledgements
The authors are grateful for general and financial support from the Centre National de la Recherche Scientifique (CNRS-France) and the University of Bourgogne Franche-Comté (BQR PRES 2014–2016 Bourgogne Franche-Comté). CF is thankful for a PhD fellowship awarded by the Conseil Régional de Bourgogne (France) in the frame of the `Jeunes Chercheurs Entrepreneurs-2016' program.
Funding information
Funding for this research was provided by: Centre National de la Recherche Scientifiquehttps://doi.org/10.13039/501100004794; University of Bourgogne Franche-Comté (award No. BQR PRES 2014–2016 Bourgogne Franche-Comté).
References
Auvergne, R., Caillol, S., David, G., Boutevin, B. & Pascault, J.-P. (2014). Chem. Rev. 114, 1082–1115. Web of Science CrossRef CAS PubMed Google Scholar
Besson, M., Gallezot, P. & Pinel, C. (2014). Chem. Rev. 114, 1827–1870. Web of Science CrossRef CAS PubMed Google Scholar
Bigot, S., Daghrir, M., Mhanna, A., Boni, G., Pourchet, S., Lecamp, L. & Plasseraud, L. (2016). Eur. Polym. J. 74, 26–37. Web of Science CrossRef CAS Google Scholar
Bocelli, G. & Grenier-Loustalot, M.-F. (1987). Acta Cryst. C43, 1221–1223. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
Bruker (2014). APEX2, SAINT and SADABS. Bruker AXS Inc, Madison, Wisconsin, USA. Google Scholar
Cheban, I. M., Simonov, I. A., Rotaru, V. K. & Malinovskii, T. I. (1985). Dokl. Akad. Nauk SSSR, 283, 621–624. CAS Google Scholar
Cho, C.-S., Liau, W.-B. & Chen, L.-W. (1999). Acta Cryst. B55, 525–529. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Flippen-Anderson, J. L. & Gilardi, R. (1980). ACA, ser. 2. 8, 36a. Google Scholar
Flippen-Anderson, J. L. & Gilardi, R. (1981). Acta Cryst. B37, 1433–1435. CSD CrossRef CAS Web of Science IUCr Journals Google Scholar
François, C., Pourchet, S., Boni, G., Fontaine, S., Gaillard, Y., Placet, V., Galkin, M. V., Orebom, A., Samec, J. & Plasseraud, L. (2016). RSC Adv. 6, 68732–68738. Google Scholar
Gandini, A., Lacerda, T. M., Carvalho, A. J. F. & Trovatti, E. (2016). Chem. Rev. 116, 1637–1669. Web of Science CrossRef CAS PubMed Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CSD CrossRef IUCr Journals Google Scholar
Heinemann, F., Hartung, H. & Derling, S. (1993). Z. Kristallogr. 207, 299–301. CAS Google Scholar
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. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Mhanna, A., Sadaka, F., Boni, G., Brachais, C.-H., Brachais, L., Couvercelle, J.-P., Plasseraud, L. & Lecamp, L. (2014). J. Am. Oil Chem. Soc. 91, 337–348. Web of Science CrossRef CAS Google Scholar
Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249–259. Web of Science CrossRef CAS IUCr Journals Google Scholar
Qin, J., Liu, H., Zhang, P., Wolcott, M. & Zhang, J. (2014). Polym. Int. 63, 760–765. Web of Science CrossRef CAS Google Scholar
Saf'yanov, Y. N., Bochkova, T. N., Golovachev, V. P. & Kuz'min, É. A. (1977). Zh. Struk. Khim. 18, 402–405. CAS Google Scholar
Saf'yanov, Y. N., Golovachev, V. P. & Kuz'min, É. A. (1984). Zh. Struk. Khim. 25, 156–157. CAS Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Song, T., Liu, J. & Yang, S. (2012). Acta Cryst. E68, o719. CSD CrossRef IUCr Journals Google Scholar
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