Gossypol clathrates: Structure and thermal behavior of gossypol solvates with two picoline isomers

Gossypol forms stable solvates with 4- and 2-picolines at room temperature. The solvates are investigated by single crystal X-ray diffraction and thermal analysis. Solvate crystals of gossypol with 4-picoline (1) have the 1:3 composition (gossypol:4-picoline) and crystallize in the P2₁/c space group. This substance is isostructural to a trisolvate of gossypol with pyridine. Solvate crystals of gossypol with 2-picoline (2) have the 1:4 composition (gossypol:2-picoline) and crystallize in the P-1 space group. The unit cell parameters for the investigated structures are as follows: 1 monoclinic crystals, C₃₀H₃₀O₈·3C₆H₇N, a = 10.7530(1) ?, b = 20.7834(3) ?, c = 19.1166(2) ?, β = 95.537(1)°, V = 4252.32(9) ?³, M = 797.92, Z = 4, d _x = 1.246 g/cm³, and R = 0.0489 for 4102 reflections; 2 triclinic crystals, C₃₀H₃₀O₈·4C₆H₇N, a = 11.467(1) ? b = 14.962(2) ?, c = 15.570(3) ?, α = 75.62(1)°, β = 69.83(1)°, γ = 79.58(1)°, V = 2414.6(7) ?³, M = 891.04, Z = 2, d _x = 1.226 g/cm³, and R = 0.0528 for 3779 reflections. The results of the single crystal XRD and thermal analysis confirm that gossypol with 4-picoline forms a trisolvat, and a tetrasolvate with 2-picoline. The transition from 4-picoline to 2-picoline proves to change the type of the host-guest association from one-dimensional to zero-dimensional, i.e., to lead to a new crystal structure. Desolvation of compound 2 begins at a lower temperature than that for compound 1, which is explained by their different crystal structures. Keywords: gossypol, 4-picoline, 2-picoline, clathrate formation, crystal structure.     

Inclusion complexes of the natural product gossypol. Recognition by gossypol of halogeno methanes. Structure of the dichloromethane complex of gossypol and single crystal conservation after decomposition

The structures of gossypol complexes are extremely sensitive to the halogenomethane present as the guest; e.g. changing the number of Cl atoms in chloromethane derivatives changes the structure of the gossypol complex. The crystals of C₃₀H₃₀O₈·CH₂Cl₂ are monoclinic, space groupC2/c,a=21.320(4),b=19.199(6),c=15.765(2)Å, =113.05(2)^o,V=5916(2)ų,Z=8,D _x=1.35 g/cm³,T=295 K. The structure has been solved by direct methods and refined to the finalR value of 0.084 for 1828 reflections. In the structure H-bonded gossypol molecules form columns, generating channels in the structure which are filled by guest molecules. After decomposition (desolvation) monocrystals of the complexes are conserved without destruction, in which there are rather wide and empty channels though slightly smaller than in the complex. An attempt is made to explain some peculiarities of the behavior of the gossypol polymorph formed on the basis of its structure with empty channels. Supplementary data relevant to this article have been deposited with the British Library Publication No. SUP 82165 (17 pages).     

Investigation of the complex thermal behavior of fats

The thermal behavior of three ural fats (displaying very different composition), cocoa butter (CB)², lard, and a stearin obtained from anhydrous milk-fat (AMF) fractionation, were studied by both DSC and X-ray diffraction as a function of temperature (XRDT). To perform temperature explorations between –30C and +80C, at rates identical to those used for DSC and ranging from 0.1 K min^–1 to 10 K min^–1, a new set of X-ray sample-holders, temperature-controlled by Peltier effect, has been developed. It is shown that the three more stable polymorphic forms of CB were easily characterized by either X-ray diffraction or DSC, and existence of two -3L forms was confirmed. On the contrary, the more complex polymorphism of lard and AMF required combined examination by DSC and XRDT and the brightness of the synchrotron source for studies at the highest heating rates. Quantitative analysis of the long spacings of XRDT recordings is invaluable for interpretation of thermal events. For instance, it was found that the simultaneous formation of two polymorphic forms, of apparent long spacing of 34 and 42 å, at the onset of lard crystallization might explain the difficulty of its fractionation.Special thanks to Courtney P. Mudd (NIH, Bethesda) for his pertinent advice on the mounting and use of thermoelectric devices. The study of lard crystallization was initiated by Valerie Portalier and suggested by Jean-Luc Vendeuvre of CTSCCV (Maisons-Alfort). For the AMF part of this study, stearin was fractionated by ADRIA Normandie, while characterization of its thermal properties was performed as part of a research program funded by ARILAIT Recherches and the French Ministry of Research and Technology.     

Gossypol Clathrates. Structure of a Gossypol Complex with Isobutylacetate

The natural compound gossypol forms stable clathrates with isobutylacetate. The clathrates were investigated by X-ray diffractometry. The crystallographic parameters of single crystals were determined and refined using 15 reflections on a Syntex P2₁ four-circle automatic diffractometer. The crystals are monoclinic, C₃₀H₃₀O₈·0.5C₆H₁₂O₂, a = 11.444(2), b = 30.724(5), c = 16.521(3) , = 88.17°, V = 5805.9(17) ³, M = 1153.24, Z = 4, d _calc = 1.32 g/cm³, space group , R = 0.047 for 4686 reflections. The clathrates are not isostructural to any of the previously prepared guest–host complexes, although there are many common features between the structure of the given solvate and the gossypol clathrate and the unbranched analog of isobutylacetate.     

Structure of gossypol arylimines

A number of new Schiff's bases of gossypol with aromatic amines and sulfanilamide compounds has been obtained. It has been shown by UV and PMR spectroscopy and x-ray structural analysis that in some solvents they exist predominantly in the quinoid form. For dianilinegossypol (in the solid state) the quinoid structure has been demonstrated and two polymorphic modifications have been revealed by x-ray structural analysis.A. S. Sadykov Institute of Bioorganic Chemistry, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 650–654, September–October, 1988.     

Determinations of the inclusion complex between gossypol and beta-cyclodextrin

Features of the inclusion complex between gossypol (Gos) and beta-cyclodextrin (CD), such as its aqueous solubility, association constant, characteristics in the solid state and crystalline morphology, as well as the stoichiometry of this complex have been determined. The phase-solubility diagram drawn using UV detections belongs to an AN-type. Fluorescence detection and calculation with the modified Benesi-Hidebrond equation provide an 1:2 stoichiometry for the complex. Its apparent stability constant has been determined to be 3,203 M(-1) by fluorescence technique and confirmed by the calculation from UV spectroscopy. X-ray powder diffractions (XRD) and Scanning Electron Microscopy (SEM) observations showed a clear difference in the crystal morphology of the complex from those of both Gos and beta-CD.     

Inclusion complexes of the natural product gossypol. Crystal structure of the 2:1 complex of gossypol withm-Xylene

The crystal structure of a 2: 1 inclusion complex of gossypol withm-xylene has been determined by X-ray structure analysis. The crystals of C₃₀H₃₀O₈·0.5C₈ H₁₀ are triclinic, space groupPl^–,a = 8.478(1),b = 14.087(2),c = 14.411(2) Å, = 115,39(1), = 75.11(1), = 86.80(1)°,V = 1475.2(4) ų,Z = 2,D _x = 1.29 g cm^–3,T = 295 K, (CuK ) = 7.01 cm^–1. The structure has been solved by direct methods and refined to the finalR value of 0.079 for 3910 observed reflections. The gossypol molecules are linked by intermolecular hydrogen bonds and form bimolecular layers parallel to the ab plane. Disorderedm-xylene molecules occupy cavities between these layers. All polar groups of the gossypol molecule are packed in the interior of the bilayer while non-polar groups are directed outwards. An analysis of the crystal packing of other inclusion complexes of gossypol shows that such bilayers are formed in four complexes and three of those structures are generically related to each other.Deceased.     

Xanthenol clathrates: structure, thermal stability, guest exchange and kinetics of desolvation

A series of clathrates comprising the xanthenol host, 9-(4-methoxyphenyl)-9H-xanthen-9-ol, with a variety of aromatic guests displays similar structures in the space group P(-1). We have elucidated the structures of the inclusion compounds H x 1/2G, where H is 9-(4-methoxyphenyl)-9H-xanthen-9-ol and G is benzene, o-, m- and p-xylene. The structures are isostructural with respect to the host and display consistent (Host)-OH...O-(Host) hydrogen bonding. The guests lie on a centre of inversion and with the exception of the symmetrical guests, benzene and p-xylene, are disordered. An interesting case arises with m-xylene, which is ordered at low temperature (113 K) with both the host and guest molecules in general positions. At a higher temperature (283 K) the inclusion compound with m-xylene fits the series. We have correlated the structures with their thermal stabilities, guest exchange and kinetics of desolvation.     

Structure and thermal behavior of a layered silver hydroxyalkanecarboxylate

The structure and thermal behavior of silver 16-hydroxyhexadecanoate (Ag-HHDA) have been investigated by using various analytical tools. The X-ray diffraction pattern was composed of a series of peaks that could be indexed to (0k0) reflections of a layered structure. Diffuse reflectance infrared Fourier transform spectroscopy revealed that the alkyl chains in Ag-HHDA as prepared were in an all-trans conformational state. Upon heating the sample, noticeable structural changes took place particularly in two temperature regions. The first structural change occurring at approximately 380 K was a partially irreversible one in which the binding state of carboxylate to silver converted from bridging into unidentate. A second dramatic structural change occurring at approximately 480 K was a totally irreversible process that could be associated with the decomposition of Ag-HHDA. All of these thermal characteristics of Ag-HHDA are comparable to those of silver stearate (Ag-STA). Separately, we have endeavored without success to intercalate polar molecules into the OH-group terminated layers in Ag-HHDA; the exfoliation of Ag-HHDA in various polar solvents was also unsuccessful. This is indicative of the presence of a rather stronger H-bond in Ag-HHDA, but the comparable thermal characteristics of Ag-HHDA and Ag-STA dictate that the thermal behavior of silver alkanoate is determined exclusively by the silver-to-carboxylate group interaction. This is in sharp contrast to the case of two-dimensional self-assembled monolayers for which the terminal functionalities play a crucial role in determining the structure and thermal stability of entire monolayers.     

Inclusion complexes of the natural product gossypol. Crystal structure of the 1 : 1 complex of gossypol with isovaleric acid

The crystal structure of the 1 : 1 lattice inclusion complex of gossypol with isovaleric acid has been determined by X-ray structure analysis. The crystals of C₃₀H₃₀O₈C₅H₁₀O₂ are monoclinic, space groupC2/c,a=28.835(7),b=9.063(2),c=26.880(4)Å, =109.66(1)°,V=6615(2) ų,Z=8,D _x = 1.25 g cm^–3, (CuK) = 7.14 cm^–1,T = 295 K. The structure was solved by direct methods and refined with isotropic thermal parameters to the finalR value of 0.132 for 1114 observed reflections. Hydrogen bonded gossypol molecules form columns along the [1 0 1] direction. These columns pack into layers parallel to the (101) plane. The layers of gossypol molecules are separated by the layers of isovaleric acid. The acid molecules are connectedvia a pair of O-H...O hydrogen bonds forming centrosymmetric dimers. There is no hydrogen bond interaction between the carboxylic acid dimers and gossypol molecules.     

Inclusion complexes of the natural product gossypol. Crystal structure of the 2:1 complex of gossypol with amyl acrylate

The crystal structure of the 2: 1 inclusion complex of gossypol with amyl acrylate has been determined by X-ray structure analysis. The crystals of (C₃₀H₃₀O₈)₂C₈H₁₄O₂ are triclinic, space group P ,a = 14.425(2),b = 15.519(1),c = 16.409(2) Å, =97.89(1), = 117.80(1), =67.01(1)° (reduced cell:a = 14.425(2),b = 15.519(2),c = 16.017(2)Å, = 92.19(1), = 115.01(l), =67.01(1)°],V = 2986.7(5) ų,Z = 2,D _x = 1.31 g cm^–3, (CuK ) = 7.40 cm^–1,T = 292 K. The structure has been solved by direct methods and refined to the final R value of 0.059 for 5155 observed reflections. The gossypol molecules bonded via several hydrogen bonds form centrosymmetric tetramers. The two independent gossypol molecules, A and B, are related within the tetramer by a local noncrystallographic 2-fold axis. The host molecules in the crystal form cavities in which two guest molecules are placed. The ester molecule interacts via a pair of C-...H-O hydrogen bonds with two gossypol molecules of the same chirality and belonging to the same tetramer unit. The amyloxy group of the ester molecule shows a very large thermal motion. It adopts a non-extended conformation in which it can be fitted into the cavity formed by the host molecules.     

The thermal behaviour of some clathrates based upon Dianin's Compound

Clathrates based upon Dianin's Compound (4-p-hydroxyphenyl-2,2,4-trimethylchroman) exhibit shape and size selectivity towards included guest molecules in a manner similar to that shown by some commercially important zeolites. Clathrates derived from Dianin's Compound and a wide range of guest solvents were heated to their melting points and beyond, and their behaviour observed.

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Zusammenfassung Auf Dianin's Verbindung (4-p-Hydroxyphenyl-2,2,4-trimethylchroman) basierende Klathrate weisen gegenüber eingeschlossenen Gastmolekülen eine ähnliche Form- und Grössenselektivität auf wie einige wichtige kommerzielle Zeolithe. Von Dianin's Verbindung und einer Reihe von Lösungsmitteln erhaltene Klathrate wurden bis zum Schmelzpunkt und darüber hinaus erhitzt und dabei ihr Verhalten beobachtet.

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—4-- -2,2,4- — , , . , , , .

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The assistance of Mr Carl Garland and Miss Marianne McCusker in the early stages and Miss Cathy Kennedy in the later stages of this work is acknowledged with thanks. Instruction in the use of the Thermal Analyser and interpretation of several of the calorimetric analyses were generously provided by Dr Geoff Irvine.     

X-ray structural investigation of gossypol and its derivatives XX. Structure of the solvate of gossypol with pyridine

The structure of the solvate of gossypol with pyridine has been determined by x-ray structural analysis. The crystalline solvate is a H-clathrate with the channel type of structure in which there are three pyridine molecules to each host molecule. On the desolvation of gossypol tripyridine, a new polymorph is formed.Communications (XI–XIX) are represented by the publications given in the Literature Cited under Nos. 1–9.Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 186–191, March–April, 1992.     

X-ray structural investigation of gossypol and its derivatives XXII. Structure of the H-clathrate of gossypol with dimethyl sulfoxide

In crystals obtained from solutions in DMSO, gossypol molecules are again present in the aldehyde tautomeric form. These crystals are H-clathrates with the channel type of structure which has much in common with the structure of the complexes of gossypol with methanol and with formic acid.Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 330–334, May–August, 1992.     

X-ray structural investigation of gossypol and its derivatives XXV. Structure of the clathrate of gossypol with isopropyl alcohol

With isopropyl alcohol, gossypol forms a clathrate isostructural with the complexes of gossypol formed by ketones (acetone), aldehydes (butyraldehyde),or alcohols (propyl alcohol). The hydroxy group of isopropyl alcohol acts as the proton acceptor in a hydrogen bond of the host-guest type.A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 62 70 71. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 220–225, March-April, 1995. Original article submitted September 6, 1994.