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ISSN: 2056-9890

Norpsilocin: freebase and fumarate salt

aCaaMTech, LLC, 58 East Sunset Way, Suite 209, Issaquah, WA 98027, USA, and bUniversity of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
*Correspondence e-mail: andrew@caam.tech

Edited by S. Parkin, University of Kentucky, USA (Received 17 March 2020; accepted 23 March 2020; online 27 March 2020)

The solid-state structures of the naturally occurring psychoactive tryptamine norpsilocin {4-hy­droxy-N-methyl­tryptamine (4-HO-NMT); systematic name: 3-[2-(methyl­amino)­eth­yl]-1H-indol-4-ol}, C11H14N2O, and its fumarate salt (4-hy­droxy-N-methyl­tryptammonium fumarate; systematic name: bis­{[2-(4-hy­droxy-1H-indol-3-yl)eth­yl]methyl­aza­nium} but-2-enedioate), C11H15N2O+·0.5C4H2O42−, are reported. The freebase of 4-HO-NMT has a single mol­ecule in the asymmetric unit joined together by N—H⋯O and O—H⋯O hydrogen bonds in a two-dimensional network parallel to the (100) plane. The ethyl­amine arm of the tryptamine is modeled as a two-component disorder with a 0.895 (3) to 0.105 (3) occupancy ratio. The fumarate salt of 4-HO-NMT crystallizes with a tryptammonium cation and one half of a fumarate dianion in the asymmetric unit. The ions are joined together by N—H⋯O and O—H⋯O hydrogen bonds to form a three-dimensional framework, as well as ππ stacking between the six-membered rings of inversion-related indoles (symmetry operation: 2 − x, 1 − y, 2 – z).

1. Chemical context

Psychoactive tryptamines, particularly psilocybin and psilocin, have recently garnered a great deal of inter­est because of their potential to treat disorders including anxiety, addiction, and depression (Johnson & Griffiths, 2017[Johnson, M. W. & Griffiths, R. R. (2017). Neurotherapeutics 14, 734-740.]; Carhart-Harris & Goodwin, 2017[Carhart-Harris, R. L. & Goodwin, G. M. (2017). Neuropsychopharmacology, 42, 2105-2113.]). Of note, psilocybin was recently granted the `breakthrough therapy' designation by the US Food and Drug Administration (Feltman, 2019[Feltman, R. (2019). Popular Science. https://popsci. com/story/health/psilocybin-magic-mushroom-fda-breakthrough-depression/]). To this point, the focus of research on psychedelics in therapy has largely been on psilocybin and psilocin. Despite this focus, there are more than 200 species of `magic mushrooms' containing many different psychoactive tryptamines and combinations of the same (Stamets, 1996[Stamets, P. (1996). Psilocybin mushrooms of the world: An identification guide. Berkeley, CA: Ten Speed Press.]).

The clinical effects observed for extracts of `magic mushrooms' differ from those observed for pure psilocybin (Zhuk, et al. 2015[Zhuk, O., Jasicka-Misiak, I., Poliwoda, A., Kazakova, A., Godovan, V. V., Halama, M. & Wieczorek, P. (2015). Toxins, 7, 1018-1029.]). This indicates that the minor components of `magic mushrooms' have psychoactive properties that are important, or that they work in conjunction with psilocybin as part of an entourage effect (Russo, 2011[Russo, E. B. (2011). Br. J. Pharmacol. 163, 1344-1364.]). To have a better understanding of `magic mushroom' pharmacology, it is necessary to understand the properties of the minor active components. This could lead to formulations that maximize the desired activity while minimizing negative effects, optimizing the clinical experience.

Baeocystin, the monomethyl analog of psilocybin, is the second most abundant naturally occurring tryptamine found in `magic mushrooms'. It was first isolated from the mushroom Psilocybe baeocystis in 1968 (Leung & Paul, 1968[Leung, A. Y. & Paul, A. G. (1968). J. Pharm. Sci. 57, 1667-1671.]), and subsequently identified in other species, approaching one third of the total tryptamine concentration. Like psilocybin, baeocystin acts as a prodrug when consumed by humans, undergoing rapid hydrolysis of the phosphate ester to afford its active metabolite – the 4-hy­droxy analog.

The prodrug psilocybin hydrolyses to the active 4-hy­droxy-N,N-di­methyl­tryptamine (4-HO-DMT), aka psilocin, and the prodrug baeocystin hydrolyses to the active 4-hy­droxy-N-methyl­tryptamine (4-HO-NMT), aka norpsilocin. Norpsilocin was first identified as a natural product of `magic mushrooms' in 2017, and isolated as an amorphous, colorless solid (Lenz et al., 2017[Lenz, C., Wick, J. & Hoffmeister, D. (2017). J. Nat. Prod. 80, 2835-2838.]). In 2020, norpsilocin was synthesized and isolated as a white solid in 98% purity. When tested as an agonist at the human seratonin 2a receptor, synthetic norpsilocin was as potent, if not more so, compared to psilocin (Sherwood et al., 2020[Sherwood, A. M., Halberstadt, A. L., Klein, A. K., McCorvy, J. D., Kaylo, K. W., Kargbo, R. B. & Meisenheimer, P. (2020). J. Nat. Prod. 83, 461-467.]).

[Scheme 1]

Despite rapidly growing evidence supporting psilocin/psilocybin's potential for treating mood disorders, very little work has been done to investigate the properties of other structurally similar compounds found in magic mushrooms, e.g. norpsilocin/baeocystin. Although these compounds have substantial potential as drug candidates, they have undergone limited investigation because of their lack of availability in pure form and the difficulty of their purification. Crystalline solids are the most convenient and reliable chemical forms for studying, handling, and administering pure compounds. There was an unmet need for the structural characterization of norpsilocin, which is important in examining the structure–activity relationship of the psychedelic tryptamine. Herein, we report the first crystal structure of norpsilocin (I)[link], and the first salt of norpsilocin (II)[link] and its solid-state structure.

2. Structural commentary

The mol­ecular structure of the freebase of norpsilocin, 4-HO-NMT, is shown in Fig. 1[link]. The asymmetric unit contains one full 4-hy­droxy-N-methyl­tryptamine (C11H14N2O) mol­ecule. The ethyl­amine arm (C9–C10–N2–C11) of the tryptamine is modeled as a two-component disorder with a 0.895 (3) to 0.105 (3) occupancy ratio. The rest of the discussion is restricted to the major component. The indole ring system of the tryptamine is near planar with an r.m.s. deviation from planarity of 0.015 Å. The ethyl­amine arm of the tryptamine is slightly turned, with a C7—C8—C9—C10 torsion angle of 29.3 (3)°. The C10—N2—C11 angle about the amine nitro­gen is 113.51 (15)°.

[Figure 1]
Figure 1
The mol­ecular structure of 4-hy­droxy-N-methyl­tryptamine, showing the atom labeling. Displacement ellipsoids are drawn at the 50% probability level. Dashed bonds indicate the minor occupancy disordered component in the structure.

The mol­ecular structure of the fumarate salt of norpsilocin is shown in Fig. 2[link]. The asymmetric unit contains one full 4-hy­droxy-N-methyl­tryptammonium (C11H15N2O+) cation and one half of a fumarate (C4H2O42–) dianion, with the other half generated by inversion. The indole ring system of the tryptamine is near planar with an r.m.s. deviation from planarity of 0.009 Å. Unlike the freebase, the ethyl ammonium arm resides in the same plane as the indole. The planarity of all of the non-hydrogen atoms of the tryptamine is demonstrated with an r.m.s. deviation from planarity of only 0.043 Å. The C10—N2—C11 angle about the ammonium nitro­gen is 114.20 (14)°. The fumarate itself is also near planar, with an r.m.s. deviation from planarity of 0.050 Å. The carboxyl­ate unit of the fumarate is delocalized, with C—O distances of 1.2488 (18) and 1.2553 (18) Å.

[Figure 2]
Figure 2
The mol­ecular structure of bis­(4-hy­droxy-N-methyl­tryptammonium)­fumarate, showing the atom labeling. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines. Symmetry code: (i) 1 − x, −y, 2 − z.

3. Supra­molecular features

The tryptamine mol­ecules of the freebase of norpsilocin are held in an infinite two-dimensional network parallel to the (100) plane through a series of N—H⋯O and O—H⋯N hydrogen bonds (Table 1[link]). The phenol O—H hydrogen bonds with the nitro­gen of the methyl­amine of an inversion-related tryptamine mol­ecule (symmetry operation: −x + 1, −y + 1, −z + 1) to form a dimer. The indole N—H shows an inter­molecular hydrogen bond with the phenol oxygen of another tryptamine mol­ecule (symmetry operation: x, −y + [{3\over 2}], z − [{1\over 2}]), joining the dimers into two-dimensional sheets. The packing of 4-HO-NMT is shown in Fig. 4[link]a.

Table 1
Hydrogen-bond geometry (Å, °) for (I)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1⋯N2i 0.86 (1) 1.80 (1) 2.6501 (16) 169 (2)
N1—H1A⋯O1ii 0.88 (1) 2.04 (1) 2.9092 (15) 175 (2)
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) [x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}].
[Figure 4]
Figure 4
The crystal packing of (a) 4-HO-NMT, and of (b) bis­(4-HO-NMT) fumarate, both shown along the a axis. The hydrogen bonds (Tables 1[link] and 2[link]) are shown as dashed lines. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms not involved in hydrogen bonding are omitted for clarity. For (a) only one component of the disorder is shown.

The tryptammonium cations and the fumarate dianions of the fumarate salt of norpsilocin are held together in an infinite three-dimensional framework through a series of N—H⋯O and O—H⋯O hydrogen bonds (Table 2[link]). The indole N—H, methyl­ammonium N—H, and phenol O—H groups all hydrogen bond with the oxygen atoms of the fumarate dianion (Fig. 3[link]). The six-membered rings of inversion-related indoles stack with parallel slipped ππ inter­actions [inter­centroid distance = 3.6465 (15) Å, inter­planar distance = 3.4781 (16) Å, and slippage = 1.095 (3) Å]. The packing of bis­(4-HO-NMT) fumarate is shown in Fig. 4[link]b.

Table 2
Hydrogen-bond geometry (Å, °) for (II)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
O1—H1⋯O3 0.87 (1) 1.89 (1) 2.7399 (16) 163 (2)
N1—H1A⋯O2i 0.86 (1) 2.07 (1) 2.8854 (18) 157 (2)
N2—H2A⋯O3ii 0.89 (1) 1.90 (1) 2.7349 (18) 155 (2)
N2—H2B⋯O2iii 0.89 (1) 1.91 (1) 2.7715 (19) 164 (2)
Symmetry codes: (i) x+1, y+1, z; (ii) x+1, y, z; (iii) -x+1, -y, -z+1.
[Figure 3]
Figure 3
The hydrogen bonding (Table 2[link]) of a fumarate ion in the structure of bis­(4-hy­droxy-N-methyl­tryptammonium)­fumarate, with hydrogen bonds shown as dashed lines. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms not involved in hydrogen bonding are omitted for clarity. Symmetry codes: (i) 1 − x, −y, 2 − z; (ii) 2 − x, 1 − y, 2 − z; (iii) 1 − x, −y, 1 − z; (iv) 2 − x, −y, 2 − z; (v) x, y, 1 + z; (vi) −1 + x, y, z; (vii) −1 + x, −1 + y, z.

4. Database survey

The most significant comparison to the structure of freebase norpsilocin is psilocin [CSD (Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) refcode PSILIN: Petcher & Weber, 1974[Petcher, T. J. & Weber, H. P. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 946-948.]). In the case of psilocin, the mol­ecule dimerizes through O—H⋯N hydrogen bonds, and does not form an extended network because of the lack of N—H⋯O hydrogen bonds. The other free-base tryptamines whose structures are known include natural products such as psilocybin (PSILOC: Weber & Petcher, 1974[Weber, H. P. & Petcher, T. J. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 942-946.]), DMT – N,N-di­methyl­tryptamine (DMTRYP: Falkenberg, 1972b[Falkenberg, G. (1972b). Acta Cryst. B28, 3219-3228.]) and bufotenine (BUFTEN: Falkenberg, 1972a[Falkenberg, G. (1972a). Acta Cryst. B28, 3075-3083.]), as well as synthetic tryptamines such as N-methyl-N-propyl­tryptamine (WOHYAW: Chadeayne, Golen & Manke, 2019b[Chadeayne, A. R., Golen, J. A. & Manke, D. R. (2019b). IUCrData, 4, x190962.]).

The fumarate salt of norpsilocin crystallizes as a two-to-one tryptammonium-to-fumarate salt. This ratio has also been observed in salts of 4-acet­oxy-N,N-di­methyl­tryptammonium (XOFDOO: Chadeayne, Golen & Manke, 2019a[Chadeayne, A. R., Golen, J. A. & Manke, D. R. (2019a). Acta Cryst. E75, 900-902.]), 4-hy­droxy-N,N-di­propyl­tryptammonium (CCDC 1962339: Chadeayne, Pham et al., 2019b[Chadeayne, A. R., Pham, D. N. K., Golen, J. A. & Manke, D. R. (2019b). IUCrData, 4, x191469.]), and 4-hy­droxy-N-isopropyl-N-methyl­tryptammonium (CCDC 1987588: Chadeayne et al., 2020[Chadeayne, A. R., Pham, D. N. K., Golen, J. A. & Manke, D. R. (2020). Acta Cryst. E76, 514-517.]). One-to-one tryptammonium-to-hydro­fumarate salts have been observed for 4-acet­oxy-N,N-di­methyl­tryptammonium (HOCJUH: Chadeayne et al., 2019c[Chadeayne, A. R., Golen, J. A. & Manke, D. R. (2019c). Psychedelic Science Review. https://psychedelicreview.com/the-crystal-structure-of-4-aco-dmt-fumarate/]), 4-hy­droxy-N-isopropyl-N-methyl­tryptammonium and N-isopropyl-N-methyl­typt­ammonium (RONSUL and RONSOF: Chadeayne, Pham et al., 2019a[Chadeayne, A. R., Pham, D. N. K., Golen, J. A. & Manke, D. R. (2019a). Acta Cryst. E75, 1316-1320.]).

5. Synthesis and crystallization

Single crystals suitable for X-ray analysis were obtained from the slow evaporation of an acetone solution of a commercial sample of 4-hy­droxy-N-methyl­tryptamine (Angene).

The fumarate salt was synthesized starting with 101 mg of 4-hy­droxy-N-methyl­tryptamine, which was dissolved in 10 mL of methanol. 62 mg of fumaric acid was added to the solution and it was stirred overnight under reflux. Solvent was removed in vacuo to yield a dark-blue powder. The powder was triturated with diethyl ether and then recrystallized in acetone to yield colorless crystals suitable for X-ray analysis. 1H NMR (400 MHz, D2O): δ 7.12 (s, 1 H, ArH), 7.10–7.07 (m, 2 H, ArH), 6.66 (s, 2 H, CH), 6.56 (dd, J = 5.5, 2.8 Hz, 1 H, ArH), 3.41 (t, J = 6.8 Hz, 2 H, CH2), 3.26 (t, J = 6.8 Hz, CH2), 2.70 (s, 3 H, CH3); 13C NMR (100 MHz, D2O): δ 171.0 (COOH), 149.7 (ArC), 138.5 (ArC), 134.2 (CH), 123.0 (ArC), 122.8 (ArC), 115.6 (ArC), 108.4 (ArC), 104.2 (ArC), 103.4 (ArC), 50.3 (CH2), 32.4 (CH2), 22.7 (CH3).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3[link]. Hydrogen atoms H1, H1A, and H2 were found from a difference-Fourier map and were refined isotropically, using DFIX restraints with N—H distances of 0.87 (1) Å and an O—H distance of 0.88 (1) Å. Isotropic displacement parameters were set to 1.2Ueq of the parent nitro­gen atom and 1.5Ueq of the parent oxygen atom. All other hydrogen atoms were placed in calculated positions (C—H = 0.93–0.97 Å). Isotropic displacement parameters were set to 1.2Ueq(C) or 1.5Ueq(C-meth­yl).

Table 3
Experimental details

  (I) (II)
Crystal data
Chemical formula C11H14N2O C11H15N2O+·0.5C4H2O42−
Mr 190.24 248.28
Crystal system, space group Monoclinic, P21/c Triclinic, P[\overline{1}]
Temperature (K) 297 297
a, b, c (Å) 9.4060 (16), 8.8436 (15), 12.144 (2) 7.7363 (10), 9.7146 (12), 9.7854 (13)
α, β, γ (°) 90, 100.601 (7), 90 105.524 (4), 110.554 (4), 97.167 (4)
V3) 993.0 (3) 643.69 (14)
Z 4 2
Radiation type Mo Kα Mo Kα
μ (mm−1) 0.08 0.09
Crystal size (mm) 0.35 × 0.2 × 0.1 0.24 × 0.19 × 0.03
 
Data collection
Diffractometer Bruker D8 Venture CMOS Bruker D8 Venture CMOS
Absorption correction Multi-scan (SADABS; Bruker, 2018[Bruker (2018). APEX3, SAINT, and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Multi-scan (SADABS; Bruker, 2018[Bruker (2018). APEX3, SAINT, and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.716, 0.745 0.685, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections 35681, 1955, 1687 14395, 2365, 1774
Rint 0.031 0.046
(sin θ/λ)max−1) 0.620 0.605
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.105, 1.09 0.039, 0.098, 1.11
No. of reflections 1955 2365
No. of parameters 171 181
No. of restraints 105 4
H-atom treatment H atoms treated by a mixture of independent and constrained refinement H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.20, −0.14 0.15, −0.15
Computer programs: APEX3 and SAINT (Bruker, 2018[Bruker (2018). APEX3, SAINT, and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2014 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2018 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), 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.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Computing details top

For both structures, data collection: APEX3 (Bruker, 2018); cell refinement: SAINT (Bruker, 2018); data reduction: SAINT (Bruker, 2018); program(s) used to solve structure: SHELXT2014 (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: publCIF (Westrip, 2010).

3-[2-(Methylamino)ethyl]-1H-indol-4-ol (I) top
Crystal data top
C11H14N2OF(000) = 408
Mr = 190.24Dx = 1.273 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 9.4060 (16) ÅCell parameters from 9944 reflections
b = 8.8436 (15) Åθ = 2.9–26.0°
c = 12.144 (2) ŵ = 0.08 mm1
β = 100.601 (7)°T = 297 K
V = 993.0 (3) Å3BLOCK, colourless
Z = 40.35 × 0.2 × 0.1 mm
Data collection top
Bruker D8 Venture CMOS
diffractometer
1687 reflections with I > 2σ(I)
φ and ω scansRint = 0.031
Absorption correction: multi-scan
(SADABS; Bruker, 2018)
θmax = 26.1°, θmin = 3.2°
Tmin = 0.716, Tmax = 0.745h = 1111
35681 measured reflectionsk = 1010
1955 independent reflectionsl = 1415
Refinement top
Refinement on F2105 restraints
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.038H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.105 w = 1/[σ2(Fo2) + (0.050P)2 + 0.2586P]
where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max < 0.001
1955 reflectionsΔρmax = 0.20 e Å3
171 parametersΔρmin = 0.14 e Å3
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*/UeqOcc. (<1)
O10.72180 (10)0.50889 (10)0.48264 (7)0.0392 (3)
H10.7503 (17)0.4189 (12)0.5019 (14)0.059*
N10.67378 (13)0.84618 (14)0.18771 (10)0.0460 (3)
H1A0.6832 (18)0.8918 (18)0.1255 (10)0.055*
C10.70586 (13)0.68167 (13)0.33046 (10)0.0311 (3)
C20.77773 (13)0.56216 (13)0.39398 (9)0.0313 (3)
C30.90077 (14)0.50210 (15)0.36388 (11)0.0387 (3)
H30.9495340.4241170.4063530.046*
C40.95365 (15)0.55642 (17)0.27050 (12)0.0451 (3)
H41.0363690.5131980.2521500.054*
C50.88612 (15)0.67154 (16)0.20592 (12)0.0441 (3)
H50.9208700.7070540.1438240.053*
C60.76258 (14)0.73365 (14)0.23720 (10)0.0364 (3)
C70.56146 (15)0.86403 (16)0.24481 (12)0.0440 (3)
H70.4860860.9326980.2256400.053*
C80.57603 (14)0.76694 (14)0.33354 (11)0.0356 (3)
C90.4767 (3)0.7551 (3)0.4179 (3)0.0401 (6)0.895 (3)
H9A0.5126320.8204790.4810670.048*0.895 (3)
H9B0.4783890.6520790.4454790.048*0.895 (3)
C100.32164 (18)0.7988 (2)0.36920 (16)0.0426 (4)0.895 (3)
H10A0.3185670.9048130.3485400.051*0.895 (3)
H10B0.2888740.7403780.3016800.051*0.895 (3)
N20.22260 (16)0.77279 (16)0.44818 (14)0.0414 (4)0.895 (3)
H20.1338 (10)0.778 (2)0.4114 (8)0.050*0.895 (3)
C110.2400 (3)0.8822 (2)0.54022 (17)0.0644 (6)0.895 (3)
H11A0.2338570.9829200.5102610.097*0.895 (3)
H11B0.3325320.8679820.5876820.097*0.895 (3)
H11C0.1648660.8673600.5830320.097*0.895 (3)
C9'0.477 (3)0.724 (3)0.410 (3)0.0401 (6)0.105 (3)
H9'A0.5336380.7064740.4841190.048*0.105 (3)
H9'B0.4306840.6285650.3843300.048*0.105 (3)
C10'0.3608 (18)0.8382 (19)0.4191 (15)0.050 (2)0.105 (3)
H10C0.4052480.9366420.4353460.060*0.105 (3)
H10D0.2948870.8449270.3478240.060*0.105 (3)
N2'0.2784 (14)0.7990 (17)0.5074 (13)0.053 (3)0.105 (3)
H2'0.256 (4)0.703 (2)0.500 (4)0.063*0.105 (3)
C11'0.143 (2)0.884 (3)0.507 (2)0.083 (6)0.105 (3)
H11D0.0987340.8498650.5676050.125*0.105 (3)
H11E0.1650250.9900580.5162720.125*0.105 (3)
H11F0.0784920.8681850.4372550.125*0.105 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0534 (6)0.0345 (5)0.0337 (5)0.0108 (4)0.0185 (4)0.0063 (4)
N10.0523 (7)0.0466 (7)0.0415 (6)0.0002 (5)0.0151 (5)0.0174 (5)
C10.0332 (6)0.0300 (6)0.0311 (6)0.0049 (5)0.0081 (5)0.0009 (4)
C20.0354 (6)0.0311 (6)0.0279 (6)0.0023 (5)0.0074 (4)0.0021 (4)
C30.0362 (7)0.0393 (7)0.0407 (7)0.0042 (5)0.0074 (5)0.0000 (5)
C40.0368 (7)0.0494 (8)0.0536 (8)0.0024 (6)0.0199 (6)0.0049 (6)
C50.0448 (7)0.0475 (8)0.0451 (7)0.0096 (6)0.0218 (6)0.0017 (6)
C60.0385 (7)0.0359 (6)0.0357 (6)0.0072 (5)0.0097 (5)0.0025 (5)
C70.0448 (7)0.0419 (7)0.0463 (7)0.0058 (6)0.0109 (6)0.0132 (6)
C80.0372 (6)0.0334 (6)0.0374 (6)0.0012 (5)0.0097 (5)0.0051 (5)
C90.0448 (7)0.0372 (15)0.0414 (10)0.0089 (9)0.0160 (6)0.0076 (10)
C100.0412 (9)0.0473 (10)0.0411 (9)0.0100 (7)0.0124 (7)0.0124 (7)
N20.0383 (7)0.0431 (8)0.0450 (8)0.0085 (6)0.0132 (6)0.0071 (6)
C110.0799 (15)0.0521 (11)0.0699 (13)0.0053 (11)0.0368 (11)0.0077 (10)
C9'0.0448 (7)0.0372 (15)0.0414 (10)0.0089 (9)0.0160 (6)0.0076 (10)
C10'0.053 (5)0.046 (4)0.053 (5)0.007 (4)0.015 (4)0.005 (4)
N2'0.059 (5)0.046 (5)0.059 (6)0.007 (5)0.026 (5)0.001 (5)
C11'0.066 (10)0.078 (11)0.112 (13)0.024 (9)0.038 (9)0.027 (10)
Geometric parameters (Å, º) top
O1—H10.858 (9)C9—C101.520 (3)
O1—C21.3662 (14)C10—H10A0.9700
N1—H1A0.875 (9)C10—H10B0.9700
N1—C61.3655 (18)C10—N21.4729 (19)
N1—C71.3753 (18)N2—H20.873 (9)
C1—C21.4061 (17)N2—C111.464 (2)
C1—C61.4147 (17)C11—H11A0.9600
C1—C81.4416 (17)C11—H11B0.9600
C2—C31.3823 (18)C11—H11C0.9600
C3—H30.9300C9'—H9'A0.9700
C3—C41.4042 (19)C9'—H9'B0.9700
C4—H40.9300C9'—C10'1.509 (10)
C4—C51.368 (2)C10'—H10C0.9700
C5—H50.9300C10'—H10D0.9700
C5—C61.3995 (19)C10'—N2'1.476 (9)
C7—H70.9300N2'—H2'0.876 (14)
C7—C81.3649 (18)N2'—C11'1.476 (10)
C8—C91.512 (3)C11'—H11D0.9600
C8—C9'1.48 (3)C11'—H11E0.9600
C9—H9A0.9700C11'—H11F0.9600
C9—H9B0.9700
C2—O1—H1112.8 (11)C9—C10—H10A109.1
C6—N1—H1A124.4 (12)C9—C10—H10B109.1
C6—N1—C7109.04 (11)H10A—C10—H10B107.8
C7—N1—H1A126.3 (11)N2—C10—C9112.57 (17)
C2—C1—C6118.00 (11)N2—C10—H10A109.1
C2—C1—C8134.67 (11)N2—C10—H10B109.1
C6—C1—C8107.27 (11)C10—N2—H2108.6 (7)
O1—C2—C1118.40 (10)C11—N2—C10113.51 (15)
O1—C2—C3122.57 (11)C11—N2—H2108.6 (7)
C3—C2—C1119.03 (11)N2—C11—H11A109.5
C2—C3—H3119.3N2—C11—H11B109.5
C2—C3—C4121.35 (13)N2—C11—H11C109.5
C4—C3—H3119.3H11A—C11—H11B109.5
C3—C4—H4119.3H11A—C11—H11C109.5
C5—C4—C3121.43 (13)H11B—C11—H11C109.5
C5—C4—H4119.3C8—C9'—H9'A108.6
C4—C5—H5121.4C8—C9'—H9'B108.6
C4—C5—C6117.23 (12)C8—C9'—C10'115 (2)
C6—C5—H5121.4H9'A—C9'—H9'B107.6
N1—C6—C1107.40 (11)C10'—C9'—H9'A108.6
N1—C6—C5129.63 (12)C10'—C9'—H9'B108.6
C5—C6—C1122.96 (12)C9'—C10'—H10C109.1
N1—C7—H7124.7C9'—C10'—H10D109.1
C8—C7—N1110.55 (12)H10C—C10'—H10D107.9
C8—C7—H7124.7N2'—C10'—C9'112.3 (16)
C1—C8—C9127.83 (14)N2'—C10'—H10C109.1
C1—C8—C9'120.9 (8)N2'—C10'—H10D109.1
C7—C8—C1105.73 (11)C10'—N2'—H2'107.7 (14)
C7—C8—C9126.43 (15)C10'—N2'—C11'116.4 (13)
C7—C8—C9'132.4 (9)C11'—N2'—H2'107.6 (14)
C8—C9—H9A109.0N2'—C11'—H11D109.5
C8—C9—H9B109.0N2'—C11'—H11E109.5
C8—C9—C10112.8 (2)N2'—C11'—H11F109.5
H9A—C9—H9B107.8H11D—C11'—H11E109.5
C10—C9—H9A109.0H11D—C11'—H11F109.5
C10—C9—H9B109.0H11E—C11'—H11F109.5
O1—C2—C3—C4178.26 (11)C6—C1—C2—O1178.50 (10)
N1—C7—C8—C10.66 (16)C6—C1—C2—C30.80 (17)
N1—C7—C8—C9178.33 (19)C6—C1—C8—C70.28 (14)
N1—C7—C8—C9'169 (2)C6—C1—C8—C9179.24 (18)
C1—C2—C3—C41.01 (19)C6—C1—C8—C9'169.9 (18)
C1—C8—C9—C10151.89 (16)C7—N1—C6—C11.52 (15)
C1—C8—C9'—C10'169.5 (18)C7—N1—C6—C5176.94 (14)
C2—C1—C6—N1178.58 (11)C7—C8—C9—C1029.3 (3)
C2—C1—C6—C50.01 (19)C7—C8—C9'—C10'23 (4)
C2—C1—C8—C7177.14 (14)C8—C1—C2—O11.9 (2)
C2—C1—C8—C93.9 (3)C8—C1—C2—C3177.41 (13)
C2—C1—C8—C9'7.0 (18)C8—C1—C6—N11.11 (14)
C2—C3—C4—C50.4 (2)C8—C1—C6—C5177.48 (12)
C3—C4—C5—C60.4 (2)C8—C9—C10—N2174.34 (15)
C4—C5—C6—N1178.84 (14)C8—C9'—C10'—N2'172 (2)
C4—C5—C6—C10.6 (2)C9—C10—N2—C1173.1 (2)
C6—N1—C7—C81.39 (17)C9'—C10'—N2'—C11'167 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N2i0.86 (1)1.80 (1)2.6501 (16)169 (2)
N1—H1A···O1ii0.88 (1)2.04 (1)2.9092 (15)175 (2)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x, y+3/2, z1/2.
Bis{[2-(4-hydroxy-1H-indol-3-yl)ethyl]methylazanium} but-2-enedioate (II) top
Crystal data top
C11H15N2O+·0.5C4H2O42Z = 2
Mr = 248.28F(000) = 264
Triclinic, P1Dx = 1.281 Mg m3
a = 7.7363 (10) ÅMo Kα radiation, λ = 0.71073 Å
b = 9.7146 (12) ÅCell parameters from 3848 reflections
c = 9.7854 (13) Åθ = 2.7–25.5°
α = 105.524 (4)°µ = 0.09 mm1
β = 110.554 (4)°T = 297 K
γ = 97.167 (4)°BLOCK, colourless
V = 643.69 (14) Å30.24 × 0.19 × 0.03 mm
Data collection top
Bruker D8 Venture CMOS
diffractometer
1774 reflections with I > 2σ(I)
φ and ω scansRint = 0.046
Absorption correction: multi-scan
(SADABS; Bruker, 2018)
θmax = 25.5°, θmin = 2.7°
Tmin = 0.685, Tmax = 0.745h = 99
14395 measured reflectionsk = 1111
2365 independent reflectionsl = 1111
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.039 w = 1/[σ2(Fo2) + (0.0428P)2 + 0.1031P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.098(Δ/σ)max < 0.001
S = 1.11Δρmax = 0.15 e Å3
2365 reflectionsΔρmin = 0.15 e Å3
181 parametersExtinction correction: SHELXL2018 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
4 restraintsExtinction coefficient: 0.035 (8)
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
O10.71021 (18)0.24171 (13)0.73074 (16)0.0516 (4)
N11.1025 (2)0.68290 (16)0.82025 (18)0.0458 (4)
N21.1755 (2)0.13836 (16)0.45820 (17)0.0390 (4)
C10.9034 (2)0.47406 (17)0.77976 (18)0.0351 (4)
C20.7537 (2)0.39203 (18)0.79685 (19)0.0391 (4)
C30.6597 (3)0.4650 (2)0.8775 (2)0.0492 (5)
H30.5598230.4113330.8881310.059*
C40.7117 (3)0.6188 (2)0.9441 (2)0.0532 (5)
H40.6445800.6649640.9973280.064*
C50.8583 (3)0.7030 (2)0.9328 (2)0.0480 (5)
H50.8934520.8049370.9782510.058*
C60.9524 (2)0.62851 (18)0.85004 (19)0.0391 (4)
C71.1455 (3)0.56779 (19)0.7313 (2)0.0444 (4)
H71.2407460.5776630.6948580.053*
C81.0291 (2)0.43736 (18)0.70422 (19)0.0379 (4)
C91.0327 (3)0.28658 (18)0.6159 (2)0.0434 (4)
H9A0.9064590.2363670.5364180.052*
H9B1.0661690.2305810.6857610.052*
C101.1729 (2)0.29082 (18)0.5407 (2)0.0398 (4)
H10A1.1375040.3435940.4677960.048*
H10B1.2990280.3428090.6192950.048*
C111.3055 (3)0.1317 (2)0.3774 (2)0.0561 (5)
H11A1.2935630.0308050.3218180.084*
H11B1.4341830.1748790.4519830.084*
H11C1.2730490.1849760.3060860.084*
C120.3434 (2)0.02114 (16)0.80503 (17)0.0311 (4)
C130.5073 (2)0.01566 (17)0.94080 (18)0.0344 (4)
H130.6281660.0359740.9410970.041*
O20.17836 (15)0.03196 (13)0.78734 (13)0.0423 (3)
O30.38449 (16)0.07932 (13)0.71675 (14)0.0461 (3)
H10.613 (2)0.203 (2)0.745 (3)0.074 (7)*
H1A1.141 (3)0.7760 (12)0.839 (2)0.069 (7)*
H2A1.216 (3)0.0955 (19)0.5298 (18)0.054 (6)*
H2B1.0586 (16)0.0926 (19)0.3889 (18)0.054 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0481 (8)0.0429 (7)0.0624 (9)0.0009 (6)0.0278 (7)0.0135 (6)
N10.0510 (9)0.0347 (8)0.0500 (9)0.0033 (7)0.0194 (8)0.0161 (7)
N20.0369 (8)0.0476 (9)0.0337 (8)0.0135 (7)0.0111 (7)0.0178 (7)
C10.0342 (9)0.0385 (9)0.0306 (9)0.0070 (7)0.0094 (7)0.0145 (7)
C20.0376 (9)0.0407 (9)0.0353 (9)0.0049 (7)0.0115 (8)0.0133 (7)
C30.0429 (10)0.0626 (12)0.0477 (11)0.0107 (9)0.0233 (9)0.0212 (9)
C40.0609 (12)0.0589 (12)0.0486 (12)0.0230 (10)0.0304 (10)0.0167 (9)
C50.0625 (12)0.0408 (10)0.0409 (10)0.0169 (9)0.0199 (9)0.0130 (8)
C60.0419 (9)0.0393 (9)0.0348 (9)0.0079 (7)0.0114 (8)0.0166 (7)
C70.0433 (10)0.0475 (10)0.0468 (11)0.0067 (8)0.0217 (9)0.0199 (8)
C80.0369 (9)0.0417 (9)0.0363 (9)0.0085 (7)0.0139 (8)0.0162 (7)
C90.0430 (10)0.0425 (10)0.0457 (10)0.0084 (8)0.0201 (9)0.0144 (8)
C100.0387 (9)0.0421 (9)0.0389 (10)0.0102 (7)0.0132 (8)0.0170 (7)
C110.0576 (12)0.0740 (14)0.0527 (12)0.0281 (10)0.0307 (10)0.0291 (10)
C120.0330 (9)0.0272 (8)0.0294 (8)0.0041 (6)0.0086 (7)0.0106 (6)
C130.0287 (8)0.0385 (9)0.0343 (9)0.0043 (7)0.0097 (7)0.0154 (7)
O20.0297 (6)0.0494 (7)0.0429 (7)0.0014 (5)0.0060 (5)0.0233 (6)
O30.0399 (7)0.0606 (8)0.0412 (7)0.0057 (6)0.0114 (6)0.0322 (6)
Geometric parameters (Å, º) top
O1—C21.372 (2)C5—C61.393 (3)
O1—H10.870 (10)C7—H70.9300
N1—C61.372 (2)C7—C81.362 (2)
N1—C71.376 (2)C8—C91.498 (2)
N1—H1A0.863 (10)C9—H9A0.9700
N2—C101.492 (2)C9—H9B0.9700
N2—C111.479 (2)C9—C101.511 (2)
N2—H2A0.892 (9)C10—H10A0.9700
N2—H2B0.885 (9)C10—H10B0.9700
C1—C21.408 (2)C11—H11A0.9600
C1—C61.411 (2)C11—H11B0.9600
C1—C81.438 (2)C11—H11C0.9600
C2—C31.373 (3)C12—C131.499 (2)
C3—H30.9300C12—O21.2488 (18)
C3—C41.402 (3)C12—O31.2553 (18)
C4—H40.9300C13—C13i1.311 (3)
C4—C51.368 (3)C13—H130.9300
C5—H50.9300
C2—O1—H1109.6 (15)C8—C7—N1110.51 (15)
C6—N1—C7108.98 (14)C8—C7—H7124.7
C6—N1—H1A121.5 (15)C1—C8—C9127.04 (14)
C7—N1—H1A128.2 (15)C7—C8—C1105.81 (15)
C10—N2—H2A106.9 (13)C7—C8—C9127.14 (16)
C10—N2—H2B107.9 (13)C8—C9—H9A109.1
C11—N2—C10114.20 (14)C8—C9—H9B109.1
C11—N2—H2A107.5 (13)C8—C9—C10112.38 (13)
C11—N2—H2B108.4 (13)H9A—C9—H9B107.9
H2A—N2—H2B112.1 (18)C10—C9—H9A109.1
C2—C1—C6117.87 (15)C10—C9—H9B109.1
C2—C1—C8134.53 (15)N2—C10—C9110.39 (13)
C6—C1—C8107.60 (14)N2—C10—H10A109.6
O1—C2—C1117.25 (15)N2—C10—H10B109.6
O1—C2—C3123.67 (15)C9—C10—H10A109.6
C3—C2—C1119.08 (16)C9—C10—H10B109.6
C2—C3—H3119.4H10A—C10—H10B108.1
C2—C3—C4121.20 (17)N2—C11—H11A109.5
C4—C3—H3119.4N2—C11—H11B109.5
C3—C4—H4119.1N2—C11—H11C109.5
C5—C4—C3121.82 (18)H11A—C11—H11B109.5
C5—C4—H4119.1H11A—C11—H11C109.5
C4—C5—H5121.6H11B—C11—H11C109.5
C4—C5—C6116.76 (17)O2—C12—C13118.55 (13)
C6—C5—H5121.6O2—C12—O3124.96 (14)
N1—C6—C1107.08 (15)O3—C12—C13116.49 (14)
N1—C6—C5129.66 (16)C12—C13—H13117.6
C5—C6—C1123.26 (16)C13i—C13—C12124.77 (19)
N1—C7—H7124.7C13i—C13—H13117.6
O1—C2—C3—C4179.30 (17)C6—C1—C2—C31.4 (2)
N1—C7—C8—C10.79 (19)C6—C1—C8—C70.02 (18)
N1—C7—C8—C9178.45 (16)C6—C1—C8—C9179.22 (16)
C1—C2—C3—C40.7 (3)C7—N1—C6—C11.23 (18)
C1—C8—C9—C10175.12 (15)C7—N1—C6—C5179.00 (18)
C2—C1—C6—N1178.79 (14)C7—C8—C9—C105.8 (3)
C2—C1—C6—C51.0 (2)C8—C1—C2—O10.7 (3)
C2—C1—C8—C7179.45 (18)C8—C1—C2—C3179.26 (18)
C2—C1—C8—C90.2 (3)C8—C1—C6—N10.74 (18)
C2—C3—C4—C50.5 (3)C8—C1—C6—C5179.47 (16)
C3—C4—C5—C60.8 (3)C8—C9—C10—N2178.34 (14)
C4—C5—C6—N1179.84 (17)C11—N2—C10—C9178.49 (15)
C4—C5—C6—C10.1 (3)O2—C12—C13—C13i13.3 (3)
C6—N1—C7—C81.3 (2)O3—C12—C13—C13i167.0 (2)
C6—C1—C2—O1178.63 (14)
Symmetry code: (i) x+1, y, z+2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O30.87 (1)1.89 (1)2.7399 (16)163 (2)
N1—H1A···O2ii0.86 (1)2.07 (1)2.8854 (18)157 (2)
N2—H2A···O3iii0.89 (1)1.90 (1)2.7349 (18)155 (2)
N2—H2B···O2iv0.89 (1)1.91 (1)2.7715 (19)164 (2)
Symmetry codes: (ii) x+1, y+1, z; (iii) x+1, y, z; (iv) x+1, y, z+1.
 

Acknowledgements

Financial statements and conflict of inter­est: This study was funded by CaaMTech, Inc. ARC reports an ownership inter­est in CaaMTech, Inc., which owns US and worldwide patent applications, covering new tryptamine compounds, compositions, formulations, novel crystalline forms, and methods of making and using the same.

Funding information

Funding for this research was provided by: National Science Foundation, Directorate for Mathematical and Physical Sciences (grant No. CHE-1429086).

References

First citationBruker (2018). APEX3, SAINT, and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCarhart-Harris, R. L. & Goodwin, G. M. (2017). Neuropsychopharmacology, 42, 2105–2113.  Web of Science CAS PubMed Google Scholar
First citationChadeayne, A. R., Golen, J. A. & Manke, D. R. (2019a). Acta Cryst. E75, 900–902.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationChadeayne, A. R., Golen, J. A. & Manke, D. R. (2019b). IUCrData, 4, x190962.  Google Scholar
First citationChadeayne, A. R., Golen, J. A. & Manke, D. R. (2019c). Psychedelic Science Review. https://psychedelicreview.com/the-crystal-structure-of-4-aco-dmt-fumarate/  Google Scholar
First citationChadeayne, A. R., Pham, D. N. K., Golen, J. A. & Manke, D. R. (2019a). Acta Cryst. E75, 1316–1320.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationChadeayne, A. R., Pham, D. N. K., Golen, J. A. & Manke, D. R. (2019b). IUCrData, 4, x191469.  Google Scholar
First citationChadeayne, A. R., Pham, D. N. K., Golen, J. A. & Manke, D. R. (2020). Acta Cryst. E76, 514–517.  CSD CrossRef IUCr Journals 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 citationFalkenberg, G. (1972a). Acta Cryst. B28, 3075–3083.  CSD CrossRef IUCr Journals Web of Science Google Scholar
First citationFalkenberg, G. (1972b). Acta Cryst. B28, 3219–3228.  CSD CrossRef IUCr Journals Web of Science Google Scholar
First citationFeltman, R. (2019). Popular Science. https://popsci. com/story/health/psilocybin-magic-mushroom-fda-breakthrough-depression/  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 citationJohnson, M. W. & Griffiths, R. R. (2017). Neurotherapeutics 14, 734-740.  Web of Science CrossRef CAS PubMed Google Scholar
First citationLenz, C., Wick, J. & Hoffmeister, D. (2017). J. Nat. Prod. 80, 2835–2838.  Web of Science CrossRef CAS PubMed Google Scholar
First citationLeung, A. Y. & Paul, A. G. (1968). J. Pharm. Sci. 57, 1667–1671.  CrossRef CAS PubMed Google Scholar
First citationPetcher, T. J. & Weber, H. P. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 946–948.  CSD CrossRef Web of Science Google Scholar
First citationRusso, E. B. (2011). Br. J. Pharmacol. 163, 1344–1364.  CrossRef CAS PubMed 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 citationSherwood, A. M., Halberstadt, A. L., Klein, A. K., McCorvy, J. D., Kaylo, K. W., Kargbo, R. B. & Meisenheimer, P. (2020). J. Nat. Prod. 83, 461–467.  CrossRef CAS PubMed Google Scholar
First citationStamets, P. (1996). Psilocybin mushrooms of the world: An identification guide. Berkeley, CA: Ten Speed Press.  Google Scholar
First citationWeber, H. P. & Petcher, T. J. (1974). J. Chem. Soc. Perkin Trans. 2, pp. 942–946.  CSD CrossRef Web of Science Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationZhuk, O., Jasicka-Misiak, I., Poliwoda, A., Kazakova, A., Godovan, V. V., Halama, M. & Wieczorek, P. (2015). Toxins, 7, 1018–1029.  CrossRef CAS PubMed Google Scholar

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