Crystal structures molecular overlap

With regard to the molecular structure of CCHn, both cyclohexyl rings having a chair conformation are substituted in the equatorial positions and the alkyl chain is completely extended in the all-trans conformation. The cyclohexyl rings are nearly coplanar. The crystal structures of the investigated CCHn show that various types of molecular overlapping are present in the crystal. The molecular packing in the crystalline state is quite different in all three compounds. 

The three-dimensional crystal structure of Pigment Violet 23 (117) elucidates molecular staples whereby the stables of the single molecular planes are arranged in an almost perpendicular orientation to each other. Interactions of the -ir-orbitals as well as van der Waals forces are responsible for the cohesion of the structure. The degree of overlapping is especially high in the dioxazine part of the molecule [3],... 

Any examination of crystal structures of complexes of a series of ligands binding to a protein (the set of complexes of thermolysin with a variety of inhibitors determined in the Brian Mathews lab, for example see references in DePriest et al. [36]) shows clearly a major limitation of the pharmacophore assumption. Ligands do not optimize overlap of similar chemical functionality in complexes but find a way to maintain correct hydrogenbonding geometry, for example, while accommodating other molecular interactions. 

The determination of the perfect lattice band structure is relatively straightforward. The hole and electron occupy states based respectively upon the highest filled and lowest unfilled molecular orbitals of the parent molecule. The energy levels of these states are broadened into bands by the intermolecular overlap of the molecular orbitals. Knowing the crystal structure and assuming reasonable forms of these orbitals, the band structure may be calculated (Chojnacki, 1968 Le Blanc, 1961, 1962a, b). 

A molecular modeling study shows that the conformation of pseudo-docetaxel 80 overlaps well with that of docetaxel based on the X-ray crystal structure,84 except that the two hydrophobic groups, phenyl at C-3 and rert-butoxycarbonyl group at C3 -N, have exchanged their positions almost perfectly. The ability of pseudo-... 

The relative inactivity of 240, in vitro, in comparison to artemisinin is somewhat surprising in that the geometry of these two molecules are very similar. Molecular mechanics calculations of 240 provide a structure which overlaps nicely with the reported crystal structure of artemisinin l.7,140 That the crystallographic coordinates... 

X-ray structure analysis before and after irradiation revealed that the reaction proceeded via single crystal-to-single crystal transformation without decomposition of the initial crystal structure. A one-dimensional columnar structure is formed, in which two types of molecular overlaps (type 1 and type 2) are repeated alternately (Fig. 5) [116]. Two olefinic groups are aligned nearly in parallel in... 

Earlier chapters in this volume have dealt with the molecular properties and crystal structures of organic metals. The large planar molecules under consideration here are usually stacked face to face in chains sometimes the molecular planes are perpendicular to the stacking axis, as in the case of the Bechgaard salts, or they may be tilted by as much as 30°, as in TTF-TCNQ. Because the overlap of the partially occupied tt orbitals is much better along the stacking axis, their electronic band structures are often quasi-one-dimensional. 

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