Redetermined structure of gossypol (P3 polymorph)

Muhabbat Honkeldieva; Rishad Kunafiev; Hayrullo I Hamidov

doi:10.1107/S205698901500941X

. 2015 Jun 3;71(Pt 7):o442–o443. doi: 10.1107/S205698901500941X

Redetermined structure of gossypol (P3 polymorph)

Muhabbat Honkeldieva ^a,^*, Rishad Kunafiev ^a, Hayrullo I Hamidov ^a

PMCID: PMC4518924 PMID: 26279897

Abstract

An improved crystal structure of the title compound, C₃₀H₃₀O₈ (systematic name: 1,1′,6,6′,7,7′-hexahydroxy-5,5′-diisopropyl-3,3′-dimethyl[2,2′-binaphthalene]-8,8′-dicarbaldehyde), was determined based on modern CCD data. Compared to the previous structure [Talipov et al. (1985). Khim. Prirod. Soedin. (Chem. Nat. Prod.), 6, 20–24], geometrical precision has been improved (typical C—C bond-distance s.u. = 0.002 Å in the present structure compared to 0.005 Å in the previous structure) and the locations of several H atoms have been corrected. The gossypol molecules are in the aldehyde tautomeric form and the dihedral angle between the naphthyl fragments is 80.42 (4)°. Four intramolecular O—H⋯O hydrogen bonds are formed. In the crystal, inversion dimers with graph-set motif R ₂ ²(20) are formed by pairs of O—H⋯O hydrogen bonds; another pair of O—H⋯O hydrogen bonds with the same graph-set motif links the dimers into [001] chains. The packing of such chains in the crystal leads to the formation of channels (diameter = 5–8 Å) propagating in the [101] direction. The channels presumably contain highly disordered solvent molecules; their contribution to the scattering was removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9–18] routine in PLATON and the stated molecular mass, density etc., do not take them into account.

Keywords: crystal structure, redetermination, gossypol, polymorph, hydrogen bonding

Related literature

For the previous structure determination of gossypol P3 polymorph, see: Talipov et al., (1985 ▸). For details of the extraction and synthesis of gossypol and its derivatives, see: Adams et al. (1960 ▸). For its synthesis and biological activities, see: Baram & Ismailov (1993 ▸); Polsky et al. (1989 ▸); Radloff et al. (1985 ▸). For information on crystalline inclusion compounds, see: Ibragimov & Talipov (1999 ▸, 2004 ▸); Ibragimov et al. (1997 ▸); Gdaniec et al. (1996 ▸); Talipov et al. (1988 ▸). For the use of SQUEEZE, see: Spek (2015 ▸). graphic file with name e-71-0o442-scheme1.jpg

Experimental

Crystal data

C₃₀H₃₀O₈
M _r = 518.54
Monoclinic,
a = 21.2196 (4) Å
b = 19.0886 (2) Å
c = 15.2564 (2) Å
β = 113.262 (2)°
V = 5677.29 (16) Å³
Z = 8
Cu Kα radiation
μ = 0.73 mm⁻¹
T = 293 K
0.30 × 0.30 × 0.30 mm

Data collection

Oxford Diffraction Xcalibur Ruby diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 ▸) T _min = 0.730, T _max = 1.000
13408 measured reflections
5810 independent reflections
4382 reflections with I > 2σ(I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.047
wR(F ²) = 0.161
S = 1.11
5810 reflections
374 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.44 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 ▸); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015 ▸); molecular graphics: OLEX2 (Dolomanov et al., 2009 ▸); software used to prepare material for publication: OLEX2.

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S205698901500941X/hb7412sup1.cif

e-71-0o442-sup1.cif^{(303.5KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S205698901500941X/hb7412Isup2.hkl

e-71-0o442-Isup2.hkl^{(318.5KB, hkl)}

Click here for additional data file.^{(3.8KB, cml)}

Supporting information file. DOI: 10.1107/S205698901500941X/hb7412Isup3.cml

Click here for additional data file.^{(1.3MB, tif)}

. DOI: 10.1107/S205698901500941X/hb7412fig1.tif

The molecular structure of title compound, with displacement ellipsoids shown at the 50% probability level.

Click here for additional data file.^{(3.1MB, tif)}

. DOI: 10.1107/S205698901500941X/hb7412fig2.tif

A packing diagram for title compound.

CCDC reference: 1401388

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

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
O1H1O6ⁱ	0.90(2)	2.16(2)	2.9692(17)	150(2)
O3H3O2	0.90(3)	1.59(3)	2.454(2)	160(3)
O5H5O3ⁱⁱ	0.83(2)	2.30(2)	2.9546(17)	136(2)
O4H4AO3	0.98(4)	1.88(4)	2.601(2)	128(3)
O4H4AO5ⁱⁱ	0.98(4)	2.46(4)	3.278(2)	141(3)
O7H7O6	0.92(3)	1.63(3)	2.479(2)	152(3)
O8H8O7	0.87(4)	2.02(4)	2.575(2)	120(3)
C22H22O1	0.93	2.12	2.721(2)	121
C26H26BO8ⁱⁱⁱ	0.96	2.55	3.483(2)	165
C27H27O4^iv	0.93	2.31	3.138(2)	148
C27H27O5	0.93	2.07	2.727(2)	127

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

We thank the Academy of Sciencesof the Republic of Uzbekistan for supporting this study (F7-T048).

supplementary crystallographic information

S1. Experimental

S1.1. Synthesis and crystallization

Preparative details of the material

S1.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1.

S2. Results and discussion

Comment

Gossypol, a phenolic pigment extracted from cotton seeds [Adams et al., 1960], demonstrates a wide range of biological activity [Baram et al., 1993; Polsky et al., 1989: Radloff et al.,1985] and versatile host properties [Ibragimov, Talipov. 1999; 2004; Gdaniec et al., 1996]. Unique ability as a host compound to form crystalline inclusion compounds with many organic solvents makes gossypol an interesting object of solid supramolecular chemistry. Gossypol has also been found to form pseudopolymorphic structures with same guest molecule, e.g., clathrates formed with dichloromethane [Ibragimov et al., 1997] and diethyl ether [Talipov et al., 1988]. Unsolvated polymorphs of the compound are also known [Gdaniec et al., 1996]. In the crystal of the title compound, gossypol (1,1',6,6',7,7'-hexahydroxy -5,5'diisopropyl - 3,3'dimethyl[2,2' - binaphthalene] - 8,8'- dicarboxaldehyde), C₃₀H₃₀O₈, is one independent molecule in the asymmetric part of the unit cell. The crystals of the title compound were obtained after decomposition of gossypol clathrate with dichloromethane, where the single crystals are not destroyed and their cell volumes are only reduced by ~4%. In the title compound gossypol molecules are in the aldehyde tautomeric form (Fig. 1). H-bonds O4—H···O3 (O8—H···O7) and O3—H···O2 (O7—H···O6) form five- and six-membered rings. Naphthyl fragments C(1)—C(10) (C7 0.07A) and C(11)—C(20) (C12 0.04 A) are planar and dihedral angle between their planes are equal to 80.42 (4)°. One of the most commonly found associations is a centrosymmetric dimer that is linked by two pairs O5–H···O3 and O4–H···O5 hydrogen bonds and hydrophobic stacking interactions between two of the naphthalene rings [Gdaniec et al., 1996]. In the title crystal centrosymmetric dimers are formed as above, these assemble into extended serpentine chains by other pair of hydrogen bonds O1—H···O6 directed along the c axis through a twofold rotation axis with direction [0 1 0]. The packing of such chains in the crystal leads to the formation of broadly rough channels (Fig. 2) (where diameter varied 5-7 A), parallel to the ac diagonal.