Hydrogen bonding partitioning

Following the rationale of the previous section, we may write now for the hydrogen bonding partition function ... 

The flic presented contains 11 data items. The header lines arc property names as used by CACTVS [64, 65], and arc sufficiently self-descriptive. For example, E NHDONORS is the number of hydrogen bond donor.s, E SM1LES" is the SMILES string representing the structure of sulfamidc, and E LOGP is the logP value (octanol/water partition coefficient) for this substance. 

Where FCl is the solute gas-liquid partition coefficient, r is the tendency of the solvent to interact through k- and n-electron pairs (Lewis basicity), s the contribution from dipole-dipole and dipole-induced dipole interactions (in molecular solvents), a is the hydrogen bond basicity of the solvent, b is its hydrogen bond acidity and I is how well the solvent will separate members of a homologous series, with contributions from solvent cavity formation and dispersion interactions. 

Separation by adsorption chromatography takes place preferentially as a result of hydrogen bonding or dipole-dipole interactions. Hence, separation of mixtures of substances on silica gel layers by lipophilic solvents primarily takes place according to polarity differences. Further separation within a polarity group can then be achieved either two-dimensionally or off-line by partition chromatography on anotho TLC plate (Fig. 4). 

Partitioning or cell-based methods provide an absolute measure of the chemical space covered by a collection of compounds. They are based on the definition of a low-dimensional chemistry space, for example, one based on a small number of physicochemical properties such as molecular weight, calculated logP, and number of hydrogen bond donors [45]. Each property defines an axis of the chemistry-space. The range of values for each property is divided into a set of bins, and the combinatorial product of all bins then defines the set of cells or partitions that make up the space. 

Polar intermolecular interactions encoded in partition coefficients an indirect estimation of hydrogen-bond parameters of polyfunctional solutes. J. Phys. Chem. 1992, 96,1455-1459. 

Whiting, G. S., Michell, R. C. Hydrogen bonding. 32. An analysis of water-octanol and water-alkane partitioning and logp parameter of Seiler. J. Pharm. Sci. 1994, 83, 1085-1100. 

Reynolds, D., Abraham, M. H. Rapid method for estimating octanol-water partition coefficient (logPocr) from isocratic RP-HPLC and a hydrogen bond acidity term (Aj.J. Liquid Chromatogr. 

Kamlet, M. J., Doherty, R. M., Carr, P., Abraham, M. H., Marcus, Y Taft, R. W. Linear solvation energy relationships. 46. An improved equation for correlation and prediction of octanol-water partition coefficients of organic non-electrolytes (including strong hydrogen bond donor solutes)./. Phys. Chem. 1988, 92, 5244-5255. 

The log octanol-water partition coefficient (log Pq/w) probably is the most frequently used physicochemical parameter in medicinal chemistry [101 104]. Octanol, with a polar head and a flexible, nonpolar tail, has hydrogen-bonding capabilities and amphilicity similar to... 

Glendening, E. D., Streitwieser, A., 1994, Natural Energy Decomposition Analysis An Energy Partitioning Procedure for Molecular Interactions With Apphcation to Weak Hydrogen Bonding, Strong Ionic, and Moderate Donor-Acceptor Interactions , J. Chem. Phys., 100, 2900. 

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