Molecular and Crystal Structure of Two Anthracene Derivatives and their 1,4-Endoperoxides. Influence of the Aromatic Ring Distortion upon the Steric Acceleration of the 1,4-Addition of Singlet Oxygen

1999 ◽  
Vol 52 (3) ◽  
pp. 213
Author(s):  
Nacer Lahrahar ◽  
Henri Bouas-Laurent ◽  
Jean-Pierre Desvergne ◽  
Pierre Marsau ◽  
Jean Rigaudy
Keyword(s):  
Crystal Structure ◽  
Singlet Oxygen ◽  
Aromatic Ring ◽  
Structure Determination ◽  
Molecular Structures ◽  
X Ray ◽  
Anthracene Derivatives ◽  
Oxygen Addition ◽  
Ring Distortion

The X-ray structure determination of two anthracene derivatives, namely 1,2,3,4-tetramethylanthracene (TMA) and 1,2,3,4-tetramethyl-9,10-diphenylanthracene (TMDPA), and of their endoperoxides, 1,2,3,4- tetramethyl-1,4-dihydro-1,4-epidioxyanthracene (TMAPO) and 1,2,3,4-tetramethyl-9,10-diphenyl-1,4-dihy- dro-1,4-epidioxyanthracene (TMDPAPO), has been performed. The compared analysis of the conformations of the four molecular structures strongly suggests that the steric acceleration observed for singlet oxygen addition to TMDPA should be attributed to the important distortion of the anthracene nucleus.

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.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

Crystal structure determination of solar cell materials: Cu2ZnSnS4 thin films using X-ray anomalous dispersion

2012 ◽  
Vol 524 ◽  
pp. 22-25 ◽  
Author(s):  
Hiroshi Nozaki ◽  
Tatsuo Fukano ◽  
Shingo Ohta ◽  
Yoshiki Seno ◽  
Hironori Katagiri ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Solar Cell ◽  
Structure Determination ◽  
Anomalous Dispersion ◽  
Crystal Structure Determination ◽  
X Ray

scholarly journals 3P-094 High resolution and precise X-ray crystal structure determination of Cyctochrome c Oxidase(The 46th Annual Meeting of the Biophysical Society of Japan)

2008 ◽  
Vol 48 (supplement) ◽  
pp. S142
Author(s):  
Michihiro Suga ◽  
Kyoko Ito-Shinzawa ◽  
Hiroshi Aoyama ◽  
Kazumasa Muramoto ◽  
Eiki Yamashita ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Annual Meeting ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
X Ray ◽  
Biophysical Society

ChemInform Abstract: NMR, MS and X-Ray Crystal Structure Determination of the Bixin Family of Apocarotenoids.

ChemInform ◽  
2010 ◽  
Vol 28 (5) ◽  
pp. no-no
Author(s):  
D. R. KELLY ◽  
A. A. EDWARDS ◽  
J. A. PARKINSON ◽  
G. OLOVSSON ◽  
J. TROTTER ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
X Ray
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