research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

Crystal structure and Hirshfeld surface analysis of 3,6-bis­­(pyrimidin-2-yl)-1,4-di­hydro-1,2,4,5-tetra­zine dihydrate

aMultifunctional Crystalline Materials and Applications, Division of Chemistry, Faculty of Science and Technology, Thammasat University, Khlong Luang, Pathum Thani, 12121, Thailand, and bMultifunctional Crystalline Materials and Applications, Materials and Textile Technology, Faculty of Science and Technology, Thammasat University, Khlong Luang, Pathum Thani, 12121, Thailand
*Correspondence e-mail: kc@tu.ac.th

Edited by W. T. A. Harrison, University of Aberdeen, Scotland (Received 17 February 2020; accepted 27 February 2020; online 3 March 2020)

In the title compound, C10H8N8·2H2O or H2bmtz·2H2O [bmtz = 3,6-bis­(2′-pyrimid­yl)-1,2,4,5-tetra­zine], the asymmetric unit consists of one-half mol­ecule of H2bmtz and one water mol­ecule, the whole H2bmtz mol­ecule being generated by a crystallographic twofold rotation axis passing through the middle point of the 1,4-di­hydro-1,2,4,5-tetra­zine moiety. In the crystal, N—H⋯O, N—H⋯N, O—H⋯O hydrogen bonds and aromatic ππ stacking inter­actions link the components into a three-dimensional supra­molecular network. Hirshfeld surface analysis was used to further investigate the inter­molecular inter­actions in the crystal structure.

1. Chemical context

The chemistry of nitro­gen-containing heterocyclic compounds has attracted the attention of the scientific community for over a century. Many compounds of this class are bioactive (Jubeen et al., 2018[Jubeen, F., Iqbal, S. Z., Shafiq, N., Khan, M., Parveen, S., Iqbal, M. & Nazir, A. (2018). Synth. Commun. 48, 601-625.]) and show promising pharmacological properties (Alcaide et al., 2016[Alcaide, A., Marconi, L., Marek, A., Haym, I., Nielsen, B., Møllerud, S., Jensen, M., Conti, P., Pickering, D. S. & Bunch, L. (2016). Med. Chem. Commun. 7, 2136-2144.]; Varano et al., 2016[Varano, F., Catarzi, D., Vincenzi, F., Betti, M., Falsini, M., Ravani, A., Borea, P. A., Colotta, V. & Varani, K. (2016). J. Med. Chem. 59, 10564-10576.]). Among these, numerous pyrimidine derivatives have been studied extensively in the context of synthetic organic chemistry and coordination chemistry (Kaim, 2002[Kaim, W. (2002). Coord. Chem. Rev. 230, 127-139.]). For instance, the tetra­zine-based ligand 3,6-bis­(2′-pyrimid­yl)-1,2,4,5-tetra­zine (bmtz) has been used as a polydentate ligand for the formation of silver(I) coordination polymers (Chainok et al., 2012[Chainok, K., Neville, S. M., Forsyth, C. M., Gee, W. J., Murray, K. S. & Batten, S. R. (2012). CrystEngComm, 14, 3717-3726.]) and for the self-assembly of the highly stable FeII penta­gonal metallacycles (Giles et al., 2011[Giles, I. D., Chifotides, H. T., Shatruk, M. & Dunbar, K. R. (2011). Chem. Commun. 47, 12604-12606.]). Herein, the crystal and mol­ecular structures of the di­hydro­tetra­zine-based compound 3,6-bis(pyrimidin-2-yl)-1,4-di­hydro-1,2,4,5-tetra­zine dihydrate, C10H8N8·2H2O or H2bmtz·2H2O (I), is described along with an analysis of its Hirshfeld surface.

[Scheme 1]

2. Structural commentary

The mol­ecular structure of (I) is shown in Fig. 1[link]. The asymmetric unit consists of one-half mol­ecule of H2bmtz and one water mol­ecule, in which the whole mol­ecule of the H2bmtz is generated by a crystallographic twofold rotation axis passing through the middle point of the 1,4-di­hydro-1,2,4,5-tetra­zine moiety. The H2bmtz mol­ecule is therefore not planar (r.m.s. deviation from planarity = 0.598 Å) with a C4—C5—N3—N4i torsion angle of 178.46 (14)° [symmetry code: (i) −x, y, [{3\over 2}] − z]. The pyrimidine rings are twisted with respect to each other, making a dihedral angle of 43.67 (9)°. The 1,4-di­hydro-1,2,4,5-tetra­zine moiety adopts a twist-boat conformation with a C5—N3—N4i—C5i torsion angle of −41.17 (17)°. The N3—N4i and C5—N4 bond lengths of 1.423 (2) and 1.395 (2) Å, confirm their single-bond character, while the C3—N5 bond length of 1.278 (2) Å, is consistent with a double bond (compare QORNAM, Glöckle et al., 2001[Glöckle, M., Hübler, K., Kümmerer, H.-J., Denninger, G. & Kaim, W. (2001). Inorg. Chem. 40, 2263-2269.]; ZASTAQ, Chainok et al., 2012[Chainok, K., Neville, S. M., Forsyth, C. M., Gee, W. J., Murray, K. S. & Batten, S. R. (2012). CrystEngComm, 14, 3717-3726.]). The C—C and C—N bond lengths in the pyrimidine ring are characteristic for a delocalized double bond and a typical single bond (QORNAM, Glöckle et al., 2001[Glöckle, M., Hübler, K., Kümmerer, H.-J., Denninger, G. & Kaim, W. (2001). Inorg. Chem. 40, 2263-2269.]).

[Figure 1]
Figure 1
Mol­ecular structure of (I) with displacement ellipsoids drawn at the 50% probability level. Unlabelled atoms are generated by the symmetry operationx, y, 3/2 − z.

3. Supra­molecular features

In the crystal, the H2bmtz mol­ecules are stacked along [010] into columns through ππ inter­actions between the pyrimidine rings [centroid-to-centroid distance = 3.726 (2) Å]. At the same time, the water mol­ecules are connected by O—H⋯O hydrogen bonds (Table 1[link]), resulting in the formation of a zigzag chain. These motifs are then connected together through N—H⋯O hydrogen bonds involving the tetra­zine nitro­gen atoms and the water mol­ecules to form a sheet structure propagating in the ab plane, as shown in Fig. 2[link]. The sheets are further linked into an overall three-dimensional supra­molecular network through N—H⋯N hydrogen bonds with an R22(10) ring motif, Fig. 3[link], which involve the di­hydro nitro­gen atoms and the pyrimidine nitro­gen atoms. A weak C—H⋯O inter­action is also noted (Table 1[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1A⋯O1i 0.88 (1) 1.81 (1) 2.642 (4) 156 (2)
O1—H1B⋯N1 0.86 (1) 2.15 (4) 2.863 (3) 140 (5)
N4—H4⋯N2ii 0.85 (1) 2.57 (1) 3.221 (1) 133 (2)
C2—H2⋯O1iii 0.93 2.43 3.278 (3) 151
Symmetry codes: (i) [-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (ii) -x, -y+1, -z+2; (iii) [x, -y, z+{\script{1\over 2}}].
[Figure 2]
Figure 2
Partial packing diagram of (I), showing the O—H⋯O and O—H⋯N hydrogen bonds (dashed lines) and ππ stacking inter­actions propagating in the ab plane.
[Figure 3]
Figure 3
Partial packing diagram of (I) viewed along the b axis, showing the N—H⋯N hydrogen bonds (dashed lines).

4. Hirshfeld surface analysis

To further qu­antify the nature of the inter­molecular inter­actions present in the crystal structure, Hirshfeld surfaces (McKinnon et al., 2007[McKinnon, J. J., Jayatilaka, D. & Spackman, M. A. (2007). Chem. Commun. pp. 3814-3816.]) and their associated two-dimensional fingerprint plots (Spackman & McKinnon, 2002[Spackman, M. A. & McKinnon, J. J. (2002). CrystEngComm, 4, 378-392.]) were generated using CrystalExplorer17 (Turner et al., 2017[Turner, M. J., Mckinnon, J. J., Wolff, S. K., Grimwood, D. J., Spackman, P. R., Jayatilaka, D. & Spackman, M. A. (2017). CrystalExplorer17. The University of Western Australia.]). The shorter and longer contacts are indicated as red and blue spots, respectively, on the Hirshfeld surfaces, and contacts with distances approximately equal to the sum of the van der Waals radii are represented as white spots. The contribution of inter­atomic contacts to the dnorm surface of the title compound is shown in Fig. 4[link]. Analysis of the two-dimensional fingerprint plots, Fig. 4[link], reveals that H⋯H (36.8%) contacts are the major contributors toward the Hirshfeld surface, whereas H⋯N/N⋯H (26.1%) contacts (i.e. N—H⋯N) make a less significant contribution. The contribution of the H⋯O/O⋯H (9.0%) contacts (i.e. C—H⋯O and O—H⋯O) and other contacts such as C⋯C (7.1%) (i.e. ππ stacking), H⋯C/C⋯H (6.1%) and N⋯N (4.7%) make a small contribution to the entire Hirshfeld surface.

[Figure 4]
Figure 4
Two-dimensional fingerprint plots of the title compound (I), showing (a) all inter­actions, and those delineated into (b) H⋯H, (c) H⋯N/N⋯H, (d) C⋯N/N⋯C, (e) H⋯O/O⋯H, (f) C⋯C, (g) H⋯C/C⋯H, and (h) N⋯N contacts [de and di represent the distances from a point on the Hirshfeld surface to the nearest atoms outside (external) and inside (inter­nal) the surface, respectively].

5. Database survey

A search of the Cambridge Crystallographic Database (CSD version 5.41, November 2019 update; Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) using ConQuest gave 4261 hits, reflecting the large number of pyrimidine-containing heterocyclic compounds that have been characterized. However, searches for compounds related to H2bmtz yielded just two hits for μ2-1,4-di­hydro-3,6-bis­[(2′-pyrimid­yl)-1,2,4,5-tetra­zine]bis­[bis­(tri­phenyl­phosphine)cop­per(I)] bis­(tetra­fluorido­borate) di­chloro­methane solvate (QORNAM, Glöckle et al., 2001[Glöckle, M., Hübler, K., Kümmerer, H.-J., Denninger, G. & Kaim, W. (2001). Inorg. Chem. 40, 2263-2269.]) and catena-[[μ2-3,6-di(pyrimidin-2-yl)-1,4-di­hydro-1,2,4,5-tetra­zine][μ2-(di­cyano­ethen­yl­­idene)amido][(di­cyano­ethenyl­idene)amido]­aceto­nitrile­disilver(I)] (ZASTAQ, Chainok et al., 2012[Chainok, K., Neville, S. M., Forsyth, C. M., Gee, W. J., Murray, K. S. & Batten, S. R. (2012). CrystEngComm, 14, 3717-3726.]).

6. Synthesis and crystallization

All commercially available chemicals and solvents were of reagent grade and were used as received without further purification. H2bmtz was synthesized according to a literature method (Kaim & Fees, 1995[Kaim, W. & Fees, J. (1995). Z. Naturforsch. B, 50, 123-127.]). Single crystals for X-ray structure analysis were obtained by recrystallization from mixed solvents of CH2Cl2/H2O (1:1, v/v).

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. All H atoms were located in difference-Fourier maps: the carbon-bound H atoms were relocated to idealized positions and refined as riding atoms with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C). The 1,4-di­hydro-1,2,4,5-tetra­zine and water H atoms were located in difference-Fourier maps and were constrained to N—H = 0.86 ± 0.01 Å with Uiso(H) = 1.2Ueq(N) and O—H = 0.84 ± 0.01 Å with Uiso(H) = 1.5Ueq(O), respectively.

Table 2
Experimental details

Crystal data
Chemical formula C10H8N8·2H2O
Mr 276.28
Crystal system, space group Monoclinic, C2/c
Temperature (K) 296
a, b, c (Å) 23.4730 (12), 3.7262 (2), 13.9102 (7)
β (°) 95.687 (2)
V3) 1210.67 (11)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.11
Crystal size (mm) 0.32 × 0.2 × 0.2
 
Data collection
Diffractometer Bruker D8 QUEST CMOS PHOTON II
Absorption correction Multi-scan (SADABS; Bruker, 2016[Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.714, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 11339, 1487, 1145
Rint 0.030
(sin θ/λ)max−1) 0.667
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.053, 0.174, 1.05
No. of reflections 1487
No. of parameters 103
No. of restraints 4
H-atom treatment H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.26, −0.39
Computer programs: APEX3 and SAINT (Bruker, 2016[Bruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2018 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

Supporting information


Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

3,6-Bis(pyrimidin-2-yl)-1,4-dihydro-1,2,4,5-tetrazine dihydrate top
Crystal data top
C10H8N8·2H2OF(000) = 576
Mr = 276.28Dx = 1.516 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 23.4730 (12) ÅCell parameters from 4681 reflections
b = 3.7262 (2) Åθ = 3.3–28.1°
c = 13.9102 (7) ŵ = 0.11 mm1
β = 95.687 (2)°T = 296 K
V = 1210.67 (11) Å3Block, orange
Z = 40.32 × 0.2 × 0.2 mm
Data collection top
Bruker D8 QUEST CMOS PHOTON II
diffractometer
1487 independent reflections
Radiation source: sealed x-ray tube1145 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
Detector resolution: 7.39 pixels mm-1θmax = 28.3°, θmin = 2.9°
φ and ω scansh = 3029
Absorption correction: multi-scan
(SADABS; Bruker, 2016)
k = 44
Tmin = 0.714, Tmax = 0.746l = 1818
11339 measured reflections
Refinement top
Refinement on F2Primary atom site location: dual
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.053H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.174 w = 1/[σ2(Fo2) + (0.1061P)2 + 0.7279P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
1487 reflectionsΔρmax = 0.26 e Å3
103 parametersΔρmin = 0.39 e Å3
4 restraints
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.21290 (11)0.4286 (11)0.71824 (16)0.1166 (10)
H1A0.2318 (9)0.594 (5)0.7537 (16)0.060 (8)*
H1B0.1796 (10)0.400 (13)0.738 (3)0.19 (2)*
N10.14093 (6)0.2128 (5)0.86243 (11)0.0426 (4)
N20.07173 (6)0.2495 (4)0.97609 (10)0.0386 (4)
N30.05508 (6)0.4046 (4)0.72282 (9)0.0372 (4)
N40.00726 (6)0.5326 (4)0.83844 (9)0.0381 (4)
H40.0111 (9)0.481 (6)0.8970 (8)0.052 (6)*
C10.17826 (8)0.0798 (6)0.93187 (14)0.0488 (5)
H10.2150050.0242910.9169850.059*
C20.16473 (8)0.0213 (5)1.02458 (14)0.0468 (5)
H20.1909690.0772231.0717680.056*
C30.11048 (8)0.1160 (5)1.04382 (13)0.0441 (5)
H30.1002610.0861891.1062360.053*
C40.08877 (6)0.2840 (4)0.88786 (11)0.0327 (4)
C50.04524 (7)0.4139 (4)0.81150 (11)0.0323 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0846 (16)0.196 (3)0.0734 (14)0.0089 (18)0.0266 (13)0.0020 (18)
N10.0327 (8)0.0553 (9)0.0399 (8)0.0017 (6)0.0047 (6)0.0006 (7)
N20.0387 (8)0.0453 (8)0.0319 (7)0.0027 (6)0.0038 (6)0.0021 (6)
N30.0305 (7)0.0496 (9)0.0316 (7)0.0050 (6)0.0040 (5)0.0019 (6)
N40.0353 (7)0.0527 (9)0.0263 (7)0.0066 (6)0.0039 (5)0.0024 (6)
C10.0348 (9)0.0596 (12)0.0516 (11)0.0081 (8)0.0020 (8)0.0018 (9)
C20.0453 (10)0.0468 (10)0.0460 (10)0.0080 (8)0.0072 (8)0.0021 (8)
C30.0503 (11)0.0476 (10)0.0342 (8)0.0041 (8)0.0034 (7)0.0033 (7)
C40.0316 (8)0.0331 (8)0.0334 (8)0.0012 (6)0.0029 (6)0.0029 (6)
C50.0313 (8)0.0347 (8)0.0312 (8)0.0022 (6)0.0054 (6)0.0014 (6)
Geometric parameters (Å, º) top
O1—H1A0.882 (10)N4—H40.851 (9)
O1—H1B0.860 (10)N4—C51.395 (2)
N1—C11.334 (2)C1—H10.9300
N1—C41.334 (2)C1—C21.376 (3)
N2—C31.339 (2)C2—H20.9300
N2—C41.334 (2)C2—C31.373 (3)
N3—N4i1.423 (2)C3—H30.9300
N3—C51.278 (2)C4—C51.480 (2)
H1A—O1—H1B109 (2)C3—C2—C1116.54 (16)
C1—N1—C4115.86 (15)C3—C2—H2121.7
C4—N2—C3116.00 (15)N2—C3—C2122.46 (16)
C5—N3—N4i111.21 (13)N2—C3—H3118.8
N3i—N4—H4110.2 (15)C2—C3—H3118.8
C5—N4—N3i113.47 (13)N1—C4—C5117.46 (14)
C5—N4—H4111.5 (15)N2—C4—N1126.25 (15)
N1—C1—H1118.6N2—C4—C5116.30 (14)
N1—C1—C2122.79 (17)N3—C5—N4121.13 (14)
C2—C1—H1118.6N3—C5—C4120.39 (14)
C1—C2—H2121.7N4—C5—C4118.44 (13)
N1—C1—C2—C31.6 (3)N4i—N3—C5—C4178.46 (14)
N1—C4—C5—N310.4 (3)C1—N1—C4—N23.1 (3)
N1—C4—C5—N4172.09 (16)C1—N1—C4—C5176.87 (15)
N2—C4—C5—N3169.62 (15)C1—C2—C3—N21.8 (3)
N2—C4—C5—N47.9 (2)C3—N2—C4—N13.0 (3)
N3i—N4—C5—N341.7 (2)C3—N2—C4—C5176.97 (15)
N3i—N4—C5—C4135.76 (15)C4—N1—C1—C20.6 (3)
N4i—N3—C5—N41.0 (2)C4—N2—C3—C20.4 (3)
Symmetry code: (i) x, y, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1A···O1ii0.88 (1)1.81 (1)2.642 (4)156 (2)
O1—H1B···N10.86 (1)2.15 (4)2.863 (3)140 (5)
N4—H4···N2iii0.85 (1)2.57 (1)3.221 (1)133 (2)
C2—H2···O1iv0.932.433.278 (3)151
Symmetry codes: (ii) x+1/2, y+1/2, z+3/2; (iii) x, y+1, z+2; (iv) x, y, z+1/2.
 

Acknowledgements

The authors thank the Faculty of Science and Technology, Thammasat University, for funds to purchase the X-ray diffractometer.

Funding information

Funding for this research was provided by: Faculty of Science and Technology, Thammasat University (contract No. SciGR8/2563 to Kittipong Chainok).

References

First citationAlcaide, A., Marconi, L., Marek, A., Haym, I., Nielsen, B., Møllerud, S., Jensen, M., Conti, P., Pickering, D. S. & Bunch, L. (2016). Med. Chem. Commun. 7, 2136–2144.  Web of Science CrossRef CAS Google Scholar
First citationBruker (2016). APEX3, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationChainok, K., Neville, S. M., Forsyth, C. M., Gee, W. J., Murray, K. S. & Batten, S. R. (2012). CrystEngComm, 14, 3717–3726.  Web of Science CSD CrossRef CAS Google Scholar
First citationDolomanov, 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
First citationGiles, I. D., Chifotides, H. T., Shatruk, M. & Dunbar, K. R. (2011). Chem. Commun. 47, 12604–12606.  Web of Science CSD CrossRef CAS Google Scholar
First citationGlöckle, M., Hübler, K., Kümmerer, H.-J., Denninger, G. & Kaim, W. (2001). Inorg. Chem. 40, 2263–2269.  Web of Science PubMed Google Scholar
First citationGroom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179.  Web of Science CrossRef IUCr Journals Google Scholar
First citationJubeen, F., Iqbal, S. Z., Shafiq, N., Khan, M., Parveen, S., Iqbal, M. & Nazir, A. (2018). Synth. Commun. 48, 601–625.  Web of Science CrossRef CAS Google Scholar
First citationKaim, W. (2002). Coord. Chem. Rev. 230, 127–139.  Web of Science CrossRef CAS Google Scholar
First citationKaim, W. & Fees, J. (1995). Z. Naturforsch. B, 50, 123–127.  CrossRef CAS Google Scholar
First citationMcKinnon, J. J., Jayatilaka, D. & Spackman, M. A. (2007). Chem. Commun. pp. 3814–3816.  Web of Science CrossRef Google Scholar
First citationSheldrick, G. M. (2015a). Acta Cryst. A71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (2015b). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSpackman, M. A. & McKinnon, J. J. (2002). CrystEngComm, 4, 378–392.  Web of Science CrossRef CAS Google Scholar
First citationTurner, M. J., Mckinnon, J. J., Wolff, S. K., Grimwood, D. J., Spackman, P. R., Jayatilaka, D. & Spackman, M. A. (2017). CrystalExplorer17. The University of Western Australia.  Google Scholar
First citationVarano, F., Catarzi, D., Vincenzi, F., Betti, M., Falsini, M., Ravani, A., Borea, P. A., Colotta, V. & Varani, K. (2016). J. Med. Chem. 59, 10564–10576.  Web of Science CrossRef CAS PubMed Google Scholar

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