Simple quantitative structure-property relationship (QSPR) modeling of 17O carbonyl chemical shifts in substituted benzaldehydes compared to DFT and empirical approaches.
The geometry of 50 substituted benzaldehydes was optimized at the semiempirical PM3 level, and various electronic and steric descriptors accounting for properties of the benzene ring, aldehyde group, and their connecting carbon-carbon bond were calculated. Quantitative structure-property relationships (QSPR) between (17)O carbonyl chemical shifts and these descriptors were established using partial least-squares regression and principal component regression. These two parsimonious QSPR models were comparable with the literature empirical model and DFT (density functional theory) and capable of predicting (17)O chemical shifts for 10 benzaldehydes. Principal component analysis, hierarchical cluster analysis, and crystal structure data retrieved from the Cambridge Structural Database were additional methods for chemical verification of the regression models. The QSPR models are recommended as being more reliable than and superior to the empirical and DFT models due to the results of all validations, simplicity, and short time that regressions need for (17)O shift prediction.
Instituto de Química, Universidade Estadual de Campinas, Campinas, SP, 13083-970, Brazil. rudolf@iqm.unicamp.br
Rudolf
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Kiralj
Márcia M C
MM
Ferreira