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Application of quantum topological molecular similarity descriptors in QSPR study of the O‐methylation of substituted phenols
Author(s) -
Hemmateenejad Bahram,
Mohajeri Afshan
Publication year - 2007
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20787
Subject(s) - quantitative structure–activity relationship , similarity (geometry) , phenols , computational chemistry , quantum chemical , molecular descriptor , chemistry , quantum chemistry , methylation , quantum , topology (electrical circuits) , stereochemistry , organic chemistry , mathematics , computer science , molecule , artificial intelligence , physics , quantum mechanics , gene , biochemistry , combinatorics , image (mathematics) , supramolecular chemistry
The usefulness of a novel type of electronic descriptors called quantum topological molecular similarity (QTMS) indices for describing the quantitative effects of molecular electronic environments on the O‐methylation kinetic of substituted phenols has been investigated. QTMS theory produces for each molecule a matrix of descriptors, containing bond (or structure) information in one dimension and electronic effects in another dimension, instead of other methods producing a vector of descriptors for each molecule. A collection of chemometrics tools including principal component analysis (PCA), partial least squares (PLS), and genetic algorithms (GA) were used to model the structure‐kinetic data. PCA separated the bond and descriptor effects, and PLS modeled the effects of these parameters on the rate constant data, and GA selected the most relevant subset of variables. The model performances were validated by both cross‐validation and external validation. The results indicated that the proposed models could explain about 95% of variances in the rate constant data. The significant effects of variables on the reaction kinetic were identified by calculating variable important in projection (VIP). It was found that the rate constant of esterification of phenols is highly influenced by the electronic properties of the C2C1OH fragment of the parent molecule. Indeed, the C2X and C4X bonds (corresponding to ortho and para substituents) were found as highly influential parameters. All of the eight calculated QTMS indices were found significant however, λ 1 , λ 2 , λ 3 , ϵ, and K ( r ) were detected as highly influential parameters. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008