Multiatomic fragments

Medicinal chemists have numerous fast in sUico tools to evaluate the log Poet of NCEs prior to synthesis. These different methods can be divided in two main classes according to the level of description of molecular structure, namely 2D fragmental methods which cut the molecule in typical atomic or multiatomic fragments possessing their own lipophilicity coefficients and 3D global methods which code explicitly the principal intermolecular interactions potential of a 3D molecule. This section presents only an outline of the principal in silica methods since this subject was recently reviewed in detail [33, 34]. 

These methods model the log P by adding the specific contributions of elementary building blocks of a molecule, that is, the chemical monoatomic or multiatomic fragments. The geometrical and topological effects that operate in such a case mean that several correction factors have to be added to the additivity scheme. 

ClogP This method developed by Leo and Hansch presents some similarities with the method of Rekker, since the log P of a molecule is calculated by adding lipophUicity values attributed to multiatomic fragments and numerous corrections factors which take into account not only geometrical and topological effects but also electronic and steric effects (Equation 5.3) [39-41]. 

With sputtering, a target of coating metal is bombarded with argon ions in order to produce multiatomic fragments, which are then deposited on a substrate. Sputtering rates are generally less than that of ordinary PVD. 

Multiatomic fundamental fragments-, any combination of nonisolating carbons, with or without hydrogens and/or heteroatoms... 

Multiatomic derived fragments any combination of single atomic fragments or multiatomic fundamental fragments... 

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