Theoretical linear solvation energy relationships

A variety of different approaches to the prediction of toxicity have been developed under the sponsorship of the Predictive Toxicology Evalnation project of the National Institnte of Environmental Health Sciences. The widespread application of compnta-tional techniqnes to stndies in biology, chemistry, and environmental sciences has led to a qnest for important, characteristic molecnlar parameters that may be directly derived from these compntational methods. Theoretical linear solvation energy relationships combine compntational molecular orbital parameters with the linear solvation energy relationship of Kamlet and Taft to characterize, nnderstand, and predict biological, chemical, and physical properties of chemical componnds (Eamini and Wilson, 1997). 

Theoretical Linear Solvation Energy Relationship (TLSER) With the LSER descriptors of Kamlet and Taft in mind, Famini and Wilson developed QM-derived parameters to model terms in Eq. [18] and dubbed these the TLSER descriptors. Descriptor calculations are done with the MNDO Hamiltonian in MOPAC and AMP AC. MNDO has greater systematic errors than do AMI and PM3, but the errors tend to cancel out better in MNDO-derived correlation equations. A program called MADCAP was developed to facilitate descriptor calculation from MOPAC output files. 

Quantum-chemical descriptors are used in several QSAR approaches, such as, for example, theoretical linear solvation energy relationships (TLSERs), - Mezey 3D shape analysis, - GIPF approach, - CODESSA method, -> ADAPT approach. 

Theoretical Linear Solvation Energy Relationships (TLSERs)... 

TLSER polarizability index theoretical linear solvation energy relationships... 

In analogy with solvatochromic parameters but based on quantum theoretical chemistry, a set of —> quantum-chemical descriptors intended to describe the hydrogen bonding effects of molecules by Theoretical Linear Solvation Energy Relationships (TLSER) were proposed. 

Finally, a multiparameter correlation equation based solely on theoretically determined solvent descriptors, introduced by Famini and Wilson, deserves attention [350], Linear solvation energy relationships (LSERs), such as the KAT equation (7-54) and its successors, can be summarized by the general form shown in Eq. (7-66) ... 

Many attempts to correlate the analyte structure with its HPLC behavior have been made in the past [4-6], The Quantitative structure-retention relationships (QSRR) theory was introduced as a theoretical approach for the prediction of HPLC retention in combination with the Abraham and co-workers adaptation of the linear solvation energy relationship (LSER) theory to chromatographic retention [7,8],... 

Famini, G.R. and Wilson, L.Y. (1994a). Using Theoretical Descriptors in Linear Solvation Energy Relationships. Theor.Comput.Chem., 1, 213-241. 

Murray, J.S., Politzer, P. and Famini, G.R. (1998) Theoretical alternatives to linear solvation energy relationships./. Mol. Struct. (Thcochcm), 454, 299-306. 

In the preceding section, factors that were theoretically connected with ion-transfer processes included ion radius, solvent dielectric constant, and solvent molar volume. Failure to account totally for the standard molar Gibbs transfer energies led to the suggestion that donor-acceptor properties of the solvent could be used to augment the electrostatic approach. In this section, we briefly describe statistical approaches that have been employed to elucidate the major factors governing ion transfer. The approaches that will be treated here rely on linear solvation energy relationships of the form... 

Before analyzing concrete cases, a theoretical introduction with respect to some basic methodological issues will be provided in the next section. The methods to be applied are quantum mechanical calculations, which are different from the use of the linear solvation free energy relationships for predicting the equilibrium constant, as described in Chapter 12 of [1]. It is to be mentioned here that the forthcoming discussion of the theoretical results for the prototropic tautomerism always refers to ground-state processes. 

The solvent accessible surface area (SASA) is often used as a descriptor in quantitative structure-activity relationships (Connolly 1996). For a wide variety of molecules there is an approximate linear relation between solvation free energies and SASA. However, theoretical considerations indicate that the SASA model is incapable of accurately describing non-polar solvation phenomena at length-scales comparable to the size of a water molecule. It is more useful at large length-scales when more extended hydrophobic surfaces are in contact with the solvent. 

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