The Minor Iridoid Glucosides of Barleria lupulina: Isolation, Crystal Structure and Plant Growth-Inhibiting Properties of 6-O-Acetylshanzhiside Methyl Ester

1987 ◽  
Vol 40 (5) ◽  
pp. 785 ◽  
Author(s):  
LT Byrne ◽  
JM Sasse ◽  
BW Skelton ◽  
A Suksamrarn ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Methyl Ester ◽  
Plant Growth ◽  
Structure Determination ◽  
Chemical Methods ◽  
X Ray ◽  
Aerial Parts ◽  
Iridoid Glucosides ◽  
Wheat Embryos ◽  
Growth Inhibiting

The minor iridoid glucosides present in the aerial parts of Barleria lupulina Lindl. ( Acanthaceae ) have been identified as ipolamiidoside (7) and the new compound 6-O-acetylshanzhiside methyl ester (3). The structure of (3) was determined by spectroscopic and chemical methods, and was confirmed by a single-crystal X-ray structure determination. Crystals of (3) are orthorhombic P212121, a 43.75(1), b 8.151(3), c 5.695(2) �, Z 4. The crystal structure was determined at 295 K from diffractometer data [I528 reflections with I > 3σ(I)] and refined to a residual of 0.043. Shanzhiside methyl ester (1) and its 6-Oacetyl (3), 8-Oacetyl (2) and 6,8-O,O-diacetyl (4) derivatives, all of which occur in Barleria lupulina, have been found to inhibit the growth of wheat embryos.

Pigments of Fungi. XLVIII Clavorubin from Two Australasian Toadstools of the Genus Cortinarius and the X-Ray Crystal Structure of the Methyl Ester of 6-O-Methylclavorubin

1998 ◽  
Vol 51 (5) ◽  
pp. 347 ◽  
Author(s):  
Melvyn Gill ◽  
Malcolm S. Buchanan ◽  
Peter J. Steel ◽  
Nives M. Milanovic ◽  
Somphone Phonh-Axa
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Single Crystal ◽  
Natural Product ◽  
Structure Analysis ◽  
Claviceps Purpurea ◽  
Chemical Methods ◽  
X Ray ◽  
First Time

Clavorubin (1,5,6,8-tetrahydroxy-3-methyl-9,10-dioxoanthracene-2-carboxylic acid) (1), previously known only from the ascomycetious rye fungus Claviceps purpurea (‘ergot’), has been isolated from the fruit bodies of two Australasian basidiomycetes belonging to the genus Cortinarius and characterized by spectroscopic and chemical methods. A single-crystal X-ray structure analysis of the methyl ester (4) of 6-O-methylclavorubin establishes unequivocally, for the first time, the structure of the natural product.

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

scholarly journals Molekül- und Kristallstruktur von 1.1-Dimethylsilylentitanocendichlorid, (CH3)2Si(C5H4)2TiCl2 / Molecular and Crystal Structure of l,r-Dimethylsilylene Titanocene Dichloride, (CH3)2Si(C5H4)2TiCl2

1981 ◽  
Vol 36 (10) ◽  
pp. 1208-1210 ◽  
Author(s):  
Hartmut Köpf ◽  
Joachim Pickardt
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Structure Determination ◽  
Titanocene Dichloride ◽  
Molecular And Crystal Structure ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Space Group ◽  
X Ray ◽  
Structural Dimensions

Abstract The molecular structure of the bridged [1]-titanocenophane 1,1'-dimethylsilylene titanocene dichloride, (CH3)2Si(C5H4)2TiCl2, has been investigated by an X-ray structure determination. Crystal data: monoclinic, space group C2/c, Z = 4, a = 1332.9(3), 6 = 988.7(3), c = 1068.9(3) pm, β = 113.43(2)°. The results are compared with the structural dimensions of similar compounds: 1,1'-methylene titanocene dichloride, CH2(C5H4)TiCl2, with the unbridged titanocene dichloride, (C5H5)2TiCl2 and the ethylene-bridged compound (CH2)2(C5H4)2TiCl2

Calcium Carbodiimide Compounds Revisited – Syntheses, Single Crystal Structure Determination and Vibrational Spectra of Ca11N6[CN2]2, Ca4N2[CN2] and Ca[CN2]

2008 ◽  
Vol 63 (5) ◽  
pp. 530-536 ◽  
Author(s):  
Olaf Reckeweg ◽  
Francis J. DiSalvo
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Single Crystal ◽  
Single Crystals ◽  
Vibrational Spectra ◽  
Structure Determination ◽  
X Ray ◽  
Characteristic Features ◽  
Reported Data ◽  
Correct Data

Single crystals of Ca11N6[CN2]2 (dark red needles, tetragonal, P42/mnm (no. 136), a = 1456.22(5), and c = 361.86(2) pm, Z = 2), Ca4N2[CN2] (transparent yellow needles, orthorhombic, Pnma (no. 62), a = 1146.51(11), b = 358.33(4), and c = 1385.77(13) pm, Z = 4) and Ca[CN2] (transparent, colorless, triangular plates, rhombohedral, R3̅m (no. 166), a = 369.00(3), and c = 1477.5(3) pm, Z = 3) were obtained by the reaction of Na2[CN2], CaCl2 and Ca3N2 (if demanded by stoichiometry) in arc-welded Ta ampoules at temperatures between 1200 - 1400 K. Their crystal structures were re-determined by means of single crystal X-ray structure analyses. Additionally, the Raman spectra were recorded on these same single crystals, whereas the IR spectra were obtained with the KBr pellet technique. The title compounds exhibit characteristic features for carbodiimide units with D∞h symmetry (d(C-N) = 121.7 - 123.8 pm and ∡ (N-C-N) = 180°). The vibrational frequencies of these units are in the expected range (Ca11N6[CN2]2: νs = 1230, νs = 2008; δ = 673/645/624 cm−1; Ca4N2[CN2]: νs = 1230, νs = 1986; δ = 672/647 cm−1; Ca[CN2]: νs = 1274, νs = 2031, δ = 668 cm−1). The structural results are more precise than the previously reported data, and with the newly attained Raman spectrum of Ca11N6[CN2]2 we correct data reported earlier.

New similarity index for crystal structure determination from X-ray powder diagrams

2005 ◽  
Vol 38 (6) ◽  
pp. 861-866 ◽  
Author(s):  
Detlef Walter Maria Hofmann ◽  
Ludmila Kuleshova
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Structure Prediction ◽  
Similarity Index ◽  
Crystal Structure Determination ◽  
Crystal Structure Prediction ◽  
X Ray ◽  
Organic Pigments ◽  
Structure Solution ◽  
Similarity Indices

A new similarity index for automated comparison of powder diagrams is proposed. In contrast to traditionally used similarity indices, the proposed method is valid in cases of large deviations in the cell constants. The refinement according to this index closes the gap between crystal structure prediction and automated crystal structure determination. The opportunities of the new procedure have been demonstrated by crystal structure solution of un-indexed powder diagrams of some organic pigments (PY111, PR181 and Me-PR170).

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