INDEX structural properties

Chi indices for the various isomers of hexane. (Figure adapted in part from Hall L H and L B Kier 1991. The ir Connectivity Chi Indexes and Kappa Shape Indexes in Structure-property Modeling. In Lipkowitz K B and id (Editors) Reviews in Computational Chemistiy Volume 2. New York, VCH Publishers, pp. 367-422.)... 

LH Hall, LB Kier. The molecular connectivity chi indexes and kappa shape indexes in structure-property modeling. In KB Lipkowitz, DB Boyd, eds. Reviews in Computational Chemistry, Vol. 2. New York VCH, 1991, pp 367-422. 

Lowell H. Hall and Lemont B. Kier, The Molecular Connectivity Chi Indexes and Kappa Shape Indexes in Structure-Property Modeling. 

Recent developments and prospects of these methods have been discussed in a chapter by Schneider et al. (2001). It was underlined that these methods are widely applied for the characterization of crystalline materials (phase identification, quantitative analysis, determination of structure imperfections, crystal structure determination and analysis of 3D microstructural properties). Phase identification was traditionally based on a comparison of observed data with interplanar spacings and relative intensities (d and T) listed for crystalline materials. More recent search-match procedures, based on digitized patterns, and Powder Diffraction File (International Centre for Diffraction Data, USA.) containing powder data for hundreds of thousands substances may result in a fast efficient qualitative analysis. The determination of the amounts of different phases present in a multi-component sample (quantitative analysis) is based on the so-called Rietveld method. Procedures for pattern indexing, structure solution and refinement of structure model are based on the same method. 

The first subgroup best describes global molecular properties such as size, surface, volume, while the second subgroup describes more and more (as the order of index increases) local structural properties and possibly long-range interactions. 

The second structural property described by the 4ypc index is the substitution pattern on the benzene ring. The value of the 4ypc index increases sharply with the degree of substitution, while in the isomeric classes of substituted benzenes it increases with the proximity of substituents. Thus, this structural parameter has also been found to be very useful in describing activities and properties of polysubstituted benzenes [103], chlorinated benzenes [279], and polychlorinated biphenyls [286]. 

Structure-property rules in this book are presented in boxes along with an identifier of the form R-c.s.i, where c is the chapter number, s is the section number, and i is an index in that section. In some instances, similar structure-property relationships can be expressed quantitatively. In these cases, the difference in a property value, AP, for structural differences are indicated. 

Pantelides [27, 28], in his work with Sargent, defined the index in a manner that exposes its potential to cause problems in initialization as well as in the integration error. They too showed that the index problem can be eliminated by differentiation. Noting that only some of the equations need to be differentiated, they use a method based on the structural properties of the equations to discover these equations. They cite several examples in which the index problem is almost certain to occur in setting up and solving dynamic simulation models, e.g., calculations of flash dynamics and problems in which the trajectory of a state variable is specified. 

L. B. Kier and L. H. Hall, Molecular Connectivity in Chemistry and Drug Research, Academic Press, New York, 1976. L. H. Hall and L. B. Kier, in Reviews in Computational Chemistry, K. B. Lipkowitz and D. B. Boyd, Eds., VCH Publishers, New York, 1991, pp. 367-422. The Molecular Connectivity Chi Indexes and Kappa Shape Indexes in Structure-Property Modeling. 

The aforementioned macroscopic physical constants of solvents have usually been determined experimentally. However, various attempts have been made to calculate bulk properties of Hquids from pure theory. By means of quantum chemical methods, it is possible to calculate some thermodynamic properties e.g. molar heat capacities and viscosities) of simple molecular Hquids without specific solvent/solvent interactions [207]. A quantitative structure-property relationship treatment of normal boiling points, using the so-called CODESS A technique i.e. comprehensive descriptors for structural and statistical analysis), leads to a four-parameter equation with physically significant molecular descriptors, allowing rather accurate predictions of the normal boiling points of structurally diverse organic liquids [208]. Based solely on the molecular structure of solvent molecules, a non-empirical solvent polarity index, called the first-order valence molecular connectivity index, has been proposed [137]. These purely calculated solvent polarity parameters correlate fairly well with some corresponding physical properties of the solvents [137]. 

The second appendix, by Dr. Donald B. Boyd, is an updated compendium of software for molecular modeling, computational chemistry, de novo molecular design, quantitative structure-property relationships, synthesis planning, and other facets of computers helping molecular science. This is one of the most current and most complete compilations anywhere. Appendix 2 provides addresses, telephone numbers, and electronic mailing addresses of suppliers of software. Combined with the subject index of this volume, it is possible to... 

Martorell, C. Calpena, A.C. Escribano, E. Poblet, J.M. Freixas, J. Influence of the chromatographic capacity factor (log L) as an index of lipophilicity in the antibacterial activity of a series of 6-fluoroquinolones. Relationship between physico-chemical and structural properties and their hydrophobicity. J. Chromatogr., A 1993, 655, 177-184. 

Although several molecular quantities were defined from the beginiming of quantum chemistry and graph theory, the term molecular descriptor has become popular with the development of structure-property correlation models. The - Platt number [Platt, 1947] and - Wiener index [Wiener, 1947c], defined in 1947, are sometimes referred to as the first molecular descriptors. 

Baskin, I.I., Gordeeva, E.V., Devdariani, R.Q., Zefirov, N.S., Palyulin, V.A. and Stankevitch, I.V. (1989). Solving the Inverse Problem of Structure-Property Relations for the Case of Topological Indexes. Dokl.Akad.Nauk.SSSR, 307,613-617. 

Cao, C.Z. (1996). Distance-Edge Topological Index for Research on Structure-Property Relationships of Alkanes. Acta Chim.Sin.,54, 533-538. 

Katritzky, A.R., Sild, S. and Karelson, M. (1998b). General Quantitative Structure-Property Relationship Treatment of the Refractive Index of Organic Compoxmds. J.Chem.lnf.Comput.ScL, 38,840-844. 

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