Enthalpies of sublimation and formation of polycyclic aromatic hydrocarbons (PAHs) derived from comparative molecular field analysis (CoMFA): Application of moment of inertia for molecular alignment

William J. Welsh, Weida Tong, Elizabeth R. Collantes, James S. Chickos, Sergei G. Gagarin

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24 Scopus citations

Abstract

A Quantitative Structure-Property Relationship (QSPR) is developed from the 3D-QSAR method CoMFA to estimate the sublimation enthalpy (ΔsubHOm (298.15 K)) and formation enthalpy (Δf HOm (298.15 K)) of a series of polycyclic aromatic hydrocarbons (PAHs). A unique feature of the present analysis is the application of moment of inertia as the basis for aligning the PAH molecules in the data set, which included nonplanar structures. Partial least-squares (PLS) regression with cross validation was employed to correlate each of the two thermodynamic properties with the steric and electrostatic fields surrounding each PAH molecule. The resulting CoMFA model for ΔsubHOm (298.15 K) yielded r2 values of 0.817 (cross-validated) and 0.948 (conventional) using a training set of 30 PAHs, while that for ΔfHOm (298.15 K) yielded r2 values of 0.617 (cross-validated) and 0.998 (conventional) using a training set of 16 PAHs. CoMFA-predicted values of ΔsubHOm (298.15 K) for a test set of 5 PAHs agreed within an average 5% of the corresponding experimental values. Contributions to the CoMFA models from the 3D steric and electrostatic fields were 93% steric and 7% electrostatic for ΔsubHOm (298.15 K) and 66% steric and 34% electrostatic for ΔfHOm (298.15 K), reflecting the strong correlation between steric bulk as encoded in the CoMFA steric fields and both of these thermodynamic properties. The present CoMFA models were used to predict the ΔsubHOm (298.15 K) and ΔfHOm (298.15 K) values of several PAHs for which the corresponding experimental values are unavailable.

Original languageEnglish (US)
Pages (from-to)55-64
Number of pages10
JournalThermochimica Acta
Volume290
Issue number1
DOIs
StatePublished - Jan 3 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Instrumentation
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

Keywords

  • CoMFA
  • Formation enthalpy
  • Moment of inertia
  • Polycyclic aromatic hydrocarbons (PAHs)
  • Sublimation enthalpy

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