Crystal spacing

It is often difficult to represent inorganic compounds with the usual structure models because these structures are based on complex crystals space groups), aggregates, or metal lattices. Therefore, these compounds are represented by individual polyhedral coordination of the ligands such as the octahedron or tetrahedron Figure 2-124d). 

Compound Ref. Crystal Space Z Dihedral angle Selected intermolecular... 

X-ray structures of mitochondrial 6ci complexes from three different sources (113, 124, 125) have found the b- and c-type hemes at roughly identical positions, whereas the Rieske protein was seen in different places as a function of crystal space group and presence or absence of inhibitors of the enzyme. This fact was interpreted to suggest a long-range conformational movement of the Rieske protein during turnover of the complex. The range of observed positions of the Rieske protein indicated that the soluble domain can move like a... 

Krieger E, Darden T, Nabuurs SB, Finkelstein A, Vriend G. Making optimal use of empirical energy functions force-field parameterization in crystal space. Proteins 2004 57 678-83. 

Fast methods for evaluating these integrals for the case of gaussian basis functions are known [12], Also, Hall has described how to get the symmetry operators (B) 1SjB, r, for any crystal space group [13]. The parameters account for thermal smearing of the charge density. In this work I use the form recommended by Stewart [14],... 

The changes in reorientation of surface atoms were explained using the dynamic model of the crystal space lattice. It was assumed that during anodic polarization, when the oxidation of adsorbed water is taking place, atoms oscillate mainly in a direction perpendicular to the electrode surface. This process leads to periodic separation of atoms in the first surface layer. Thus, the location of atoms in different orientations is possible. It was stated that various techniques of electrode pretreatment used for... 

The model protein is used to search the crystal space until an approximate location is found. This is, in a simplistic way, analogous to the child s game of blocks of differing shapes and matching holes. Classical molecular replacement does this in two steps. The first step is a rotation search. Simplistically, the orientation of a molecule can be described by the vectors between the points in the molecule this is known as a Patterson function or map. The vector lengths and directions will be unique to a given orientation, and will be independent of physical location. The rotation search tries to match the vectors of the search model to the vectors of the unknown protein. Once the proper orientation is determined, the second step, the translational search, can be carried out. The translation search moves the properly oriented model through all the 3-D space until it finds the proper hole to fit in. 

Species, Crystal Space Group, Resolution A) H2O ID (watxxx) H-Bond Partner— H2O Distance (A)... 

It has been earlier mentioned that the octacoordinated Pr(III) ion in triclinic NH4[Pr(TTA)4] -HaO crystal (space group Z = 2) possesses essentially... 

Table 16.1 Representative crystal space group analysis viruses versus proteins...

The structure of pseudoazurin from A. faecalis strain S-6 was determined in two laboratories (in part, because it crystallizes so readily excellent crystals are formed in a matter of hours ) (Petratos et al., 1987, 1988a Adman et al, 1989). The crystals, space group P6j, have the interesting property that they are intensely blue when viewed along the sixfold axis, but are nearly colorless when viewed normal to this axis. This is assumed to be due to the fact that the plane of the Cu-Sy-C/3 atoms is perpendicular to the sixfold axis, consistent with the fact that the copper— thiolate bond is responsible for the blue color of the protein. 

Knowing that the crystal spacing of the monochromator (303) has an interplanar distance of 0.1356 nm, calculate the limits of the wavelengths within which it is possible to record the spectrum if the angle of incidence varies through 10 to 75. ... 

ATOMIC PLANE. A plane passed through the atoms of a crystal space lattice, in accordance with certain rules relating its position to the crystallographic axes. See also Mineralogy. 

N-(2-acetamido-4-nitropheryl)pyrrolidene (PAN) is dimorphic. The thermodynamically stable form is non-polar (Fig.2), (14). The crystal space group is P21 with two independent molecules per asymmetric unit which are related by a pseudo center of inversion. This crystal does not display measurable frequency doubling generation. 

The regularity of the array of the atoms in ideal crystals permits the subdivision of the crystal space into equal and equally oriented regions of space, the so-called elementary cells. Each cell contains the same complex of atoms with the same orientation in space. Such an elementary cell may contain s atoms. Each atom has three degrees of freedom, one in each of the directions of the three coordinate axes. Therefore a space lattice has 3 s eigenfrequencies or modes. Of these 3 s modes for k = 0 i.e. in the center of BZ 1) three correspond to the translations into the directions of the coordinate axes. These have the frequency to = 0, which corresponds to the frequencies of the acoustical branches according to Eq. (II.7) for k = 0. The 3 s eigenfrequencies of a crystal with s atoms in the elementary cell correspond to 3 s - 3 optical and 3 acoustical branches. 

The crystal structure analysis (by two-dimensional Fourier methods) was facilitated by the fact that the crystal space group requires the molecule to have symmetry 222, the asymmetric crystal unit consisting of one-quarter of the chemical molecule. If there were no distortions from a regular planar model with a trigonal arrangement of bonds... 

The parameter Z is used to denote the number of molecules or formula units in the asymmetric unit of a crystal structure, i.e. the number of molecules that cannot be related to one another by the symmetry operations defined by the crystal space group. Of course, Z is therefore crucially dependent on the somewhat subjective definition of what constitutes the formula unit . Strictly Z is defined as the number of formula units in the unit cell divided by the number of independent general positions. The... 

Crystallisation of racemic 9 from a variety of solvents results in penannular inclusion compounds where two molecules of the host wrap round one of the guest [30], The resulting molecular pens assemble as layers by means of aryl offset face-face (OFF) interactions (Section 3.1.2). The crystal space groups observed are usually P2i/c, and sometimes C2/c. 

---