Transformation, molecular

Molecular transformation calculations can be used for computing differ-enr.es in binding free, energy for two ligands by a well-established scheme... 

The problems that occur when one tries to estimate affinity in terms of component terms do not arise when perturbation methods are used with simulations in order to compute potentials of mean force or free energies for molecular transformations simulations use a simple physical force field and thereby implicitly include all component terms discussed earlier. We have used the molecular transformation approach to compute binding affinities from these first principles [14]. The basic approach had been introduced in early work, in which we studied the affinity of xenon for myoglobin [11]. The procedure was to gradually decrease the interactions between xenon atom and protein, and compute the free energy change by standard perturbation methods, cf. (10). An (issential component is to impose a restraint on the... 

The 3D MoRSE code is closely related to the molecular transform. The molecular transform is a generalized scattering function. It can be used to predict the intensity of the scattered radiation i for a known molecular structure in X-ray and electron diffraction experiments. The general molecular transform is given by Eq. (22), where i(s) is the intensity of the scattered radiation caused by a collection of N atoms located at points r. ... 

According to the free-radical theory of molecular transformation, thermal crac "". ... 

R] KOnig, B. Product Class 9 Furans. In Science of Synthesis Houben-Weyl Methods of Molecular Transformations, Maas, G., Ed. Georg Thieme Verlag New York, 2001 Cat. 2, Vol. 9, 183-278. 

Another agent of this general type is nalmefene (47) Despite their useful characteristics, opiates display tolerance, addiction, abuse, and some toxic side effects Antagonists combat some of these effects, most notably respiratory depression and addiction Nalmefene reputedly has significant oral activity as a narcotic antagonist The synthesis of nalmefine concludes by Wittig olefination of naltrexone (46) to nalmefene (47) This molecular transformation resulted in a significant increase in oral potency as well (141... 

The capacity to construct a representation in any appropriate mode and submode for a given purpose. For example, being able to represent the working of an oil refinery in terms of a diagram of its component parts to an explanation of what takes place in terms of molecular transformations and the chemical equations for these ... 

Ab initio methods allow the nature of active sites to be elucidated and the influence of supports or solvents on the catalytic kinetics to be predicted. Neurock and coworkers have successfully coupled theory with atomic-scale simulations and have tracked the molecular transformations that occur over different surfaces to assess their catalytic activity and selectivity [95-98]. Relevant examples are the Pt-catalyzed NO decomposition and methanol oxidation. In case of NO decomposition, density functional theory calculations and kinetic Monte Carlo simulations substantially helped to optimize the composition of the nanocatalyst by alloying Pt with Au and creating a specific structure of the PtgAu7 particles. In catalytic methanol decomposition the elementary pathways were identified... 

Raevsky, O. A., Trepalin, S. V., Rasdolsky, A. N. The program package MOLTRA (MOLecular Transform Analysis). Registration by Russian State Patent Agency N 990092 of 26 February 1999. 

Oxidations an epoxide is often part of a more extensive molecular transformation.109 In many... 

Bansal RK, Gupta N (2004) In Storr RC, Gilchrist TL (eds) Science synthesis methods of molecular transformations (Houben-Weyl), vol 13. Thieme, Stuttgart, p 689... 

Polymer crystallization is usually divided into two separate processes primary nucleation and crystal growth [1]. The primary nucleation typically occurs in three-dimensional (3D) homogeneous disordered phases such as the melt or solution. The elementary process involved is a molecular transformation from a random-coil to a compact chain-folded crystallite induced by the changes in ambient temperature, pH, etc. Many uncertainties (the presence of various contaminations) and experimental difficulties have long hindered quantitative investigation of the primary nucleation. However, there are many works in the literature on the early events of crystallization by var-... 

Schmidbaur, H. Schier, A. Science of Synthesis, Hoeben—Weyl Methods of Molecular Transformations O Neil, I., Ed. Thieme Stuttgart, 2003 Vol. 3, p 691. 

K. Hemming Houben-Weyl Methods of Molecular Transformations Science of Synthesis , Georg Thieme, Verlag, Stuttgart, 2004 vol. 13, Chap. 13.6, pp. 127-184. 

D. J. Wilkins and P. A. Bradley Product Glass 9 1,2,3-Thiadiazoles. in Science of Synthesis Houben-Weyl Methods of Molecular Transformations , R. C. Storr and T. L. Gilchrist, Eds. Georg Thieme Verlag, Stuttgart, 2004, vol. 13, p. 253. 

It is seen that this difference ranges from 137 to 204 kJ mol-1, which is very significant. The high chemical reactivity of free atoms and radicals in various chemical reactions is one of the reasons for which the radical chain reactions occur much more rapidly than the direct molecular transformation of reactants into products. Although the radical formation is an endothermic reaction but, when appearing in the system, radicals rapidly enter into the reaction, and each radical induces the chain of transformations. 

A comprehensive survey of the chemistry of natural resins relevant to art historical and archaeological contexts is given in Mills and White (1994 95-128) and is not repeated here. Rather, those aspects of structure and chemistry relating to molecular transformation and to the composition of aged resins encountered in archaeological contexts will be emphasized. 

This work was supported by JSPS (Nos. 16109001 and 17689001). M. A. expresses her thanks to the Grant-in-Aid for Scientific Research on Priority Areas, Advanced Molecular Transformation of Carbon Resources from MEXT (No. 18037005). 

Balaban, T. S. Balaban, A. T. Science of Synthesis. Hetarenes and Related Ring Systems. Six-Membered Hetarenes with One Chalcogen, Houben-Weyl Methods of Molecular Transformations 14 Georg Thieme Verlag Stuttgart, 2003 pp 11-200. 

The asymmetric reduction of prochiral ketones to their corresponding enantiomerically enriched alcohols is one of the most important molecular transformations in synthetic chemistry (20,21). The products are versatile intermediates for the synthesis of pharmaceuticals, biologically active compounds and fine chemicals (22,23). The racemic reversible reduction of carbonyls to carbinols with superstoichiometric amounts of aluminium alkoxides in alcohols was independently discovered by Meerwein, Ponndorf and Verley (MPV) in 1925 (21—26). Only in the early 1990s, first successful versions of catalytic... 

On the other hand, some compounds which are Included may not be true Gossypium secondary metabolites. Not only are the sources mentioned above possible contributors of exogenous compounds which have been Included in the accompanying Tables (I - X), but also it is quite possible that methods of isolation and analysis caused molecular transformation which created Isomers of true metabolites or even caused more drastic alterations. The diversity of structures which are plausible natural products is so great that it is not reasonable to exclude many of those reported simply on the basis of structure assignment. For this reason, it can be expected that some errors of inclusion have been made. 

Each molecular transformation applied by Leatherface is specified by a SMARTS definition followed by a series of instructions that specify how the substructure matched by the SMARTS is to be modified. The first example shows how neutral carboxylic acids are converted to their more physiologically relevant anionic forms. The Pit instruction indicates that a single proton is to be removed (—1) from the atom matching the third atom in the SMARTS. 

Besides, the structure, nature and reactivity of the chemisorbed molecule could not be unambiguously identified because the physical tools used could not lead easily to a complete understanding of the quasi molecular character of surface chemisorbed species and move precisely to the definition of the elementary steps occurring during the molecular transformations taking place on the surfaces. 

Schuur, J. H., Selzer, P., and Gasteiger, J. (1996) The coding of the three-dimensional structure of molecules by molecular transforms and its application to structure-spectra correlations and studies of biological activity. J. Chem. Inf. Comput. Sci. 36, 334-344. 

Epoxides are useful synthetic intermediates, and the conversion of an alkene to an epoxide is often part of a more extensive molecular transformation.85 In many instances, advantage is taken of the high reactivity of the epoxide ring to introduce additional functionality. Because epoxide ring opening is usually stereospecific, such reactions can be used to establish stereochemical relationships between adjacent substituents. Such two- or three-step operations can accomplish specific oxidative transformations of an alkene that may not easily be accomplished in a single step. Scheme 12.13 provides a preview of the type of reactivity to be discussed. 

Kobayashi S, Manabe K, Ishitani H, Matsuo J (2002) Science of synthesis, Houben-Weyl methods of molecular transformation, vol 4. Thieme, Stuttgart... 

All 60 C-atoms of Cjq are incorporated in the CgoHjo polycyclic aromatic hydrocarbon (PAH) 6, for which an efficient synthesis was developed [153], Laser irradiation of 6 at 337 nm induces hydrogen loss and the formation of CgQ, as detected by mass spectrometry (Scheme 1.6). Control experiments with C-labeled material and with the C48H24 homologue of 6 verified that the C50 is formed by a molecular transformation directly from the C50H30 PAH and not by fragmentation and recombination in the gas phase. 

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