Corey-Pauling-Koltun molecular model

Fig. 2. From left to right, Corey-Pauling-Koltun molecular models of cyclohexa-amylose, cycloheptaamylose, and cyclooctaamylose viewed from the secondary hydroxyl side of the torus. 

Fig. 7. Corey-Pauling-Koltun molecular models of cyclohexaamylose complexes with p-f-butylphenyl acetate (top) and wi-t-butylphenyl acetate (bottom).

As measured on Corey-Pauling-Koltun molecular models the smaller value is for the ring of hydrogen atoms bonded to C-5, and the larger value is for the ring of hydrogen atoms bonded to C-3. The depth of the cyclodextrin cavity is 790-800 pm. 

The donor-acceptor distances were estimated using Corey-Pauling-Koltun molecular models. 

CPK Corey-Pauling-Koltun (molecular models) creatine phosphokinase... 

The solution (dichloromethane) spectra of polymers X, XI, and IX can be seen in Fig. 1. Surprisingly, the absorption spectrum of the l.c. p-methoxycinnamate polymer, IX, showed a 10 nm red shift relative to the two non-l.c.-cinnamate polymers, X and XI. We suggest that, in the thermodynamically most stable conformation the p-methoxycinnamate moiety was intramolecularly perturbed by the phenyl ester group. The ester, phenyl p-methoxycinnamate also shows this perturbation, but the alkyl and cycloalkyl esters do not. CPK (Corey-Pauling-Koltun) molecular models sow that the phenyl ester group could assume an orientation that was almost coplanar with the cinnamate moiety which could easily give rise to a 10 nm red shift (see Fig. 2). 

The thorough analysis of these and other data on influence of the structural variations of the host, in conjunction with assembling Corey-Pauling-Koltun molecular models, have led to the following scheme of guest fixation by 18C6 systems ... 

Pedersen prepared Corey-Pauling-Koltun molecular models of his new complexing agents and observed that they bound cations in a manner similar to the crowning of a regal head. He called the compounds crown ethers, inspired by the observation that they crown cations, and in part because their systematic names are impossibly cumbersome. 

These results are consistent with the Corey-Pauling-Koltun molecular model which indicates that the 2-substituted anthracenes can be included by B-and Y-CyDs such that the long axis of the aromatic ring is parallel to the axis of the CyD cavity (axial inclusion), and that the meso-substitution of the bulky and ionic group prevents the aromatic compounds to be effectively incorporated in the CyDs. 

If we model each atom in a molecule as a sphere of radius equal to the van der Waals radius of the atom (for bonded atoms, these spheres overlap, and the spheres of bonded atoms are truncated), the van der Waals surface of a molecule is defined by the outwardfacing surfaces of these atomic spheres. The van der Waals surface is what one sees in the familiar space-filling CPK (R. B. Corey-Pauling-Koltun) molecular models. In discussing intermolecular interactions, the MEPs in the regions on and outside the van der Waals surface are most significant. 

FIGURE 14.2 Molecular dynamics simulation of the diffusion of benzene within a hydrated lipid bilayer membrane. Benzene molecules are shown as Corey-Pauling-Koltun (CPK) models atoms in the phospholipid head groups are shown as ball and stick models and hydrocarbon chains and water molecules as dark and light stick models, respectively. (Reproduced with permission from Bassolino-Klinaas D, Alper HE, Stouch TR. Biochemistry 1993 32 12624-37.)... 

When poly(L-alanine)-grafted silica is applied for separation of PAHs in a reversed phase mode, we can encounter various specific selectivities. For example, 0=10.4 was obtained for a mixture of p- and o-terphenyls, while a= 1.5 in ODS. Both p- and o-terphenyls possess the same numbers in carbon atoms and rr-electrons, but the molecular planarity is entirely different. As indicated in the Corey-Pauling-Koltun (CPK) models of Fig. 7A,p-terphe-nyl is a little twisted (almost planar), but more slender (linear) than o-terphenyl. No similar enhancement of the selectivity is observed in poly(L-leucine)- and poly(L-phenylalanine)-grafted silica. These polypeptides show, rather, similarity to ODS e.g., 0=1.7 in poly(L-leucine)-grafted silica. 

The earliest models of molecules were constructed of wire, wood, or plastic. The most famous of these, the Corey-Pauling-Koltun (CPK) models, were commercially available in plastic and consisted of a large variety of atom types representative of average atoms with, say, sp, sp, and sp hybridization. The models were helpful because they enabled one to see the three-dimensional relations between atoms more accurately than could be portrayed on the printed page. The extent of the utility of the models was just that they helped to convey molecular architecture. With the advent of high speed graphical computing, physical models have been replaced with computerized pictures that enable one to visualize and move molecules in many different ways. 

Fig. 8. Model for the high affinity complex between horse Cc and CcO determined by Roberts and Pique (34). The backbone of horse Cc and CcO subunit II are shown with the side chains of selected lysines and acidic residues colored blue and red, respectively. The residue numbers on subunit II are for R. sphaeroides CcO. Van der Waals surfaces are shown for Cc heme and subunit II Trp143 and Met263. The CuA coppers are represented by green Corey-Pauling-Koltun models. Reprinted with permission from Ref. (18). Copyright 1999, American Society of Biochemistry and Molecular Biology.

To reach a peeper understanding of the role of cavity interactions in photochemical transformations, further study of the evolution of reaction intermediates by time-resolved techniques is needed. The results studies should be added to information on the structure of the complex. In this respect the molecular-modeling computation techniques that have been applied recently appear particularly useful and more reliable than the Corey-Pauling-Koltun models. 

Color raster devices A raster device can map an array stored in memory on to the screen so that the value of each element of the array controls the appearance of the corresponding point on the screen. It is possible to draw each atom as a shaded sphere, or to simulate the appearance of the Corey-Pauling-Koltun (CPK) physical models to maintain most of the famihar color scheme (i.e. C = black, N = blue, O = red, P = Green, and S = yellow). In such representation, atoms are usually opaque, so that only the front layer of atoms is visible. However, clipping with an inner plane or rotation can show the packing in the molecular interior. 

Figure IIB. A space-filling representation of the framework drawing of psilocin depicted in Figure llA. The molecular structures depicted in the figures in this chapter are two-dimensional, line-drawing representations of the molecules that show how the atoms are connected and allow for ready comparison of similarity between molecules. Molecules actually have three-dimensional shapes in which each of the constituent atoms occupies a volume defined by its cloud of electrons. Linus Pauling and two of his colleagues, Robert Corey and Walter Koltun, first developed a form of molecular models to depict the 3-dimensional space-filling aspect of molecules in the way shown in this figure.

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