Oligomers crystal structure

The refinement methodology has, likewise, been furthered by the study of crystalline amyloses. For example, we now know that given only minimally adequate diffraction data, but having on hand detailed information from monomer and oligomer crystal structures, and having the capability to refine models with complete stereochemical flexibility, structures can be solved with... 

Essen L., Siegert R, Lehmann WD, Oesterhelt D (1998) Lipid patches in membrane protein oligomers crystal structure of the bacteriorhodopsin-lipid complex. Proc. Natl. Acad. Sci. USA 95(20) 11673-11678... 

Essen, L., Siegert, R., Lehmann, W.D., Oesterhelt, D. 1998. Lipid patches in membrane protein oligomers crystal structure of the bacteriorhodopsin-Iipid complex. Proc. Natl. Acad. Sci. USA 95 11673-11678. Ferguson, A.D., Welte, W., Hofmann, E., Lindner, B., Holst, O., Coulton, J.W., et al. 2000. A conserved structural motif for lipopolysaccharide recognition by procaryotic and eucaryotic proteins. Structure Fold. Des. 8 585-592. 

Fig. 2.3 Model of the 2i- and 3i-helical structures proposed for PHB chains with ideal torsion angle values. The 2i-helix was determined by fiber X-ray diffraction of PHB [49-51] while the 3i-helical fold was constructed by using preferred dihedral angles found along the backbone in crystal structures of cyclic oligomers 9 ( oligolides ) [37, 43, 45]...

The zinc complex of 1,1,1,5,5,5-hexafluoroacetylacetonate forms coordination polymers in reaction with either 2,5-bis(4-ethynylpyridyl)furan or l,2-bis(4-ethynylpyridyl)benzene. The X-ray crystal structures demonstrate an isotactic helical structure for the former and a syndio-tactic structure for the latter in the solid state. Low-temperature 1H and 19F NMR studies gave information on the solution structures of oligomers. Chiral polymers were prepared from L2Zn where L = 3-((trifluoromethyl)hydroxymethylene)-(+)-camphorate. Reaction with 2,5-bis(4-ethy-nylpyridyl)furan gave a linear zigzag structure and reaction with tris(4-pyridyl)methanol a homo-chiral helical polymer.479... 

Unfortunately, the ethylene oligomers produced by the Ph-substituted catalyst are a complex mixture of 1-alkenes, 2-alkyl-1-alkenes, and 2-alkenes (Scheme 25). In contrast, the OEt-substituted catalyst selectively affords 1-alkenes (average number of inserted ethylene units 7), due to its relative reluctance to react with olefins other than ethylene 44 An X-ray crystal structure of the OEt-substituted... 

The synthesis and crystal structure of the peptide nucleic acid (PNA) monomer 25 having cyanuric acid as nucleobase have been described. Monomer 25 can be directly used for the solid phase synthesis of PNA oligomers . 

We first describe the crystal structure and magnetic properties of some examples of SCO oligomers that can be considered as model systems for the polymers. 

The removal of side products such as EG, A A, CO2, water and oligomers is controlled by the physics of mass transport in the solid state. This mechanism correlates with particle size, density, crystallinity, crystal structure and perfection, and surface conditions, as well as the desorption of the reaction products from... 

Figure 1 shows schematically the skeletal structures of hydroxo-bridged oligomers which have been observed in X-ray crystal structures, including a few speculative but relevant structures (4b, 7b, and 7c). 

Fig. 1. The di-, tri-, and tetranuclear structures observed in X-ray crystal structures of hydroxo-bridged oligomers of cobalt(III), rhodium(III), iridium(III), or chromium(III) structures 4b, 7b, and 7c have never been observed, but the last two have been mentioned as possible structures for two of the known isomers of Cj4(OH)66+...

---