Molecular 378 INDEX

Sicbaldi, F., Finizio, A. (1993) KqW estimation by combination of RP-HPLC and molecular indexes for a heterogeneous set of pesticide. In Proceedings IX Symposium Pesticide Chemistry, Mobility and Degradation of Xenobiotics. 11-13, Oct 1993, Piacenza, Italy. 

Ishigaki S, Niwa J, Ando Y, Yoshihara T, Sawada K, Doyu M, et al. Differentially expressed genes in sporadic amyotrophic lateral sclerosis spinal cords—screening by molecular indexing and subsequent cDNA microarray analysis. FEBS Lett 2002 531(2) 354-358. 

CiM index Chemically Intuitive Molecular index -> eigenvalue-based descriptors (O Burden eigenvalues)... 

A combined molecular index called the detour/Wieuer index w/W (or MmPS topological index) is defined as the sum of the longest and shortest paths between any two vertices in the molecular graph ... 

Molecular index defined as -> total information content based on the number of conformations of a molecule (usually below a cut-off energy value) [Bonchev, 1983] ... 

Burden, F.R. (1997). A Chemically Intuitive Molecular Index Based on the Eigenvalues of a Modified Adjacency Matrix. Quant.Struct.-Act.Relat., 16,309-314. 

Degree of esterification is an important molecular index for pectin classification that describes the extent to which carboxyl groups in pectin molecules exist as the methyl ester. Depending on the methods used for determination, DE can be expressed either by the ratio of methylated carboxyl groups to a total of carboxyl groups or by the percentage of methoxyl content. The theoretical maximum value for each expression is 100% for the former and 16.3% for the latter (Doessburg, 1965). 

Computational Chemistry Module Computes quantum-chemical and other atomic and molecular indexes in addition, performs clustering of conform-ers for flexible compounds. 

Burden, F.R. (1997) A chemically intuitive molecular index based on the eigenvalues of a modified adjacency matrix. Quant. Struct. -Act. Relat., 16, 309-314. 

Finally, there is one particular topological descriptor that should be mentioned because it has found considerable utility in a number of studies. This property, originally called a chemically intuitive molecular index by its inventor, Frank Burden, is based on a modified molecular adjacency matrix. The approach was extended by Pearlman " to take account of atomic charge, polarisability and hydrogen bonding ability, properties which are termed BCUT descriptors. BCUTs are available in a number of software packages and in addition to their utility in QSAR modelling, they have been shown to be useful measures of chemical similarity. 

It is possible to define a molecular index P for the induction term to be used in combination with the MEP Va to get a detailed description of the spatial propensity of the molecule to develop electrostatic interactions of classical type. Both functions are used under the form of an interaction with a unit point charge q placed at position r. In the case of Va this means a simple multiplication in the case of Pa there is the need of making additional calculations (to polarize the charge distribution of A). There are fast methods to do it, both at the variational level and at the PT level. The analysis of Pa has not yet extensively been used to model IND contributions to AE, and it shall not be used here. This remark has been added to signal that when one needs to develop interactions potentials for molecular not yet studied interactions including, e.g., complex solutes, the use of this approach could be of considerable help. 

The links with the underlying theory become feeble. The computers arc omnivorous observables or other statutory quantities attract their interest as well as molecular indexes or other interpretative tools, these last often considered at the same degree of "realism" as the physical observables. The selection of the level of the theory and of the method is basal on the criterion of "continuity", i.e. by looking at the methods used by other computers and trying to do something better. A criterion to decide what is better is simply the cost of the method ab initio methods are better that the semiempirical ones which m turn are better than the semiclassical ones. A larger basis set is better than a smaller one, and so on. 

The molecular index based on the vertex-distance/detour matrix is called the Wiener-sum index (Randid, 1994b) ... 

The molecular index based on the resistance-distance/vertex-distance matrix is called the Kirchhoff-sum index (Babic et al 2002). Matrices D/Q and QAD have been used to study the graph cyclicity (Klein and Ivanciuc, 2002) ... 

This deformation has nothing to do with the polarization effects due to the second partner. Clearly this interpretation of a partial CP correction to Ees (a contribution in our terminology) makes impossible the use of as a molecular index of reactivity. It is not compulsory to use in an interpretation of the interaction act, but the introduction of CP correction to Ees deprives the researcher of a tool, without doing anything in exchange, the being intuitively and physically more... 

It is not a fixed molecular index its magnitude varies from property to property and from regression to regression. 

In a recent paper Eisenschitz and the present author have shown that between the spherical symmetric H atoms at large distances there are attractive forces of which the potential is inversely proportional to the sixth power in the distance and which for that reason are at large distances in general more important than the forces discussed previously, which exist only with the assumption of polarisable quadrupole molecules (with a potential inversely proportional to the eighth power in the distance). It now appears that these interactions, which can hardly be calculated even for the most simple molecules, can easily be estimated from spectroscopic data and the knowledge of the molecular [index of] refraction and that these forces reflect, with the accuracy with which they have themselves been determined, the van der Waals attraction not only for spherically symmetric noble gases, but also form an essential part of the attraction for two-atomic non-polar gases and even weakly polar molecules. 

Prom (10) we obtain an estimate of the sum 5, if the polarisability is assumed to be known — for instance by extrapolation of the molecular [index of] refraction for long wavelengths ... 

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