Point bonding

The carboxylic acid functionality is not involved in any significant interaction with the gold substrate but rather dominates the pairing interaction between enantiomers. This three-point bonding of each molecule, Au—S, Au—N, and O—H—O, drives the self-recognition preference for homochiral pairs [58]. 

Point bonding, 27 474, 476. See also Thermal point bonding Point-contact transistor, 9 730-731 Point of departure, 25 244 Point of incipient precipitatioi,... 

Other models, which have been developed independently, have features in common with the AOM. Kettle and his co-workers (39—42) have discussed molecular geometry using a perturbation treatment which places the relative energies of MO s in terms of squared overlap integrals, and the point bond model of Howald and Keeton (43) is essentially equivalent to the ex model. 

Because of the fractional R-Li bond, clusters and polymers can reversibly form an open cluster, which traps the unsaturated substrate through multiple-point bonding (cf Schemes 10.5 and 10.7). Lithium cations assist the electron flow from the cuprate to the electrophile and, to achieve such cooperative action, a cluster of a particular size may be necessary. Lewis acid metals other than lithium (Zn , for example) will also play similar roles. 

Biochemistry Boiling point Bond or chemical bond Buffer solution... 

Specific interactions between starch and proteins were observed as early as the beginning of the twentieth century. Berczeller996 noted that the surface tension of aqueous soap solutions did not decrease with the addition of protein (egg albumin) alone, but it did decrease when starch and protein were added. This effect was observed to increase with time. Sorption of albumin on starch is inhibited by bi- and trivalent ions and at the isoelectric point. Below the isoelectric point, bonding between starch and albumin is ionic in character, whereas nonionic interactions are expected above the isoelectric point.997 The Terayama hypothesis998 predicts the formation of protein complexes with starch, provided that starch exhibits the properties of a polyelectrolyte. Apart from chemically modified anionic starches (such as starch sulfate, starch phosphate, and various cross-linked starch derivatives bearing ionized functions), potato starch is the only variety that behaves as a polyelectrolyte. Its random phosphate ester moieties permit proteins to form complexes with it. Takeuchi et a/.999-1002 demonstrated such a possibility with various proteins and a 4% gel of potato starch. 

Such analysis can reveal bond paths (lines of maximum ED finking two atoms), exact location of the bond critical points, bond elhpticity (deviation from cylindrical symmetry), and so on. The real atomic boundaries can be found and the effective atomic charges integrated. 

To model the substrate we have used the Dual Site-Bond Model (DSBM) [S], which has proved to be useful to analyze topography effects on several molecular processes on heterogeneous surfaces. DSBM provide a statistical description of the disordered media based on two elements sites, and the corresponding saddle points (bonds) the adsorptive energy surface is described by site and bond probability density functions Fs( s) Fb(Eb)- The distribution functions S and B associated to F and Fb are defined by... 

Bohr Model Boiling point Bond energy Bony fish... 

Cemented carbides are sintered materials consisting of very hard and high melting point metal carbides in a matrix of low melting point bonding metals of the iron group, particularly cobalt. 

Chlorocuprates(II) and bromocuprates(II) were discussed by Howald and Keeton (1966) in terms of the point bond model, which is closely related to the angular overlap model and takes account of both a- and -bonding. They were able to successfully interpret the charge transfer spectra as well as d—d spectra. 

Nonspecific multi-point bonding of inert protein... 

Nonspecific multi-point bonding of isolated enzyme in incorrect orientation (left) and in specific multipoint bonding (right)... 

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