Structure-enthalpy relationships in polycyclic cata-condensed aromatic hydrocarbons

Abstract

Translation of the Bible or any other text unavoidably involves a determination about its meaning. There have been different views of meaning from ancient times up to the present, and a particularly Enlightenment and Modernist view is that the meaning of a text amounts to whatever the original author of the text intended it to be. This article analyzes the authorial-intent view of meaning in comparison with other models of literary and legal interpretation. Texts are anchors to interpretation but are subject to individualized interpretations. It is texts that are translated, not intentions. The challenge to the translator is to negotiate the meaning of a text and try to choose the most salient and appropriate interpretation as a basis for bringing the text to a new audience through translation.

First-Principles Prediction of Enthalpies of Formation for Polycyclic Aromatic Hydrocarbons and Derivatives

“…Herndon and co-workers have extensively used group additivity approaches in conjunction with quantum chemical methods. They used the semiempirical AM1 method, the DFT method B3LYP, , and the ab initio MP2 theory to determine enthalpies of formation for many common PAHs. ,, Marsh and Wornat used the semiempirical AM1 method to compute thermochemical functions for a number of PAHs (indene, fluoranthene, pyrene, coronone, fluorene) and their cyclopenta-fused derivatives. Pope and Howard employed group additivity in conjunction with the molecular mechanics method MM3 and the semiempirical MOPAC methods MNDO, AM1, and PM3 to study the stability of common PAHs, as well as the fullerenes.…”

The Hückel total π-electron energy puzzle

“…In the work 12 the experimental standard gas-phase enthalpies of formation of the twelve C 22 H 14 benzenoid isomers were compared with the results of three different computational methods: the simple HMO theory, the highly parametrized semi-empirical MNDO molecular orbital model, 13 and the advanced MMX/PI version of the molecular mechanics model. 14 The HMO results were far better than those obtained by the MNDO and MMX/PI approaches. The respective correlation coefficients were 0.966 (for HMO), 0.797 (for MNDO), and 0.780 (for MMX/PI).…”

Nonplanarity Index for Fused Benzenoid Hydrocarbons

“…While the data from Sander and Wise (1) totally agreed with the data from Herndon and coworkers (4) in Figure 1 123, 3.889 b ) suggest that it is planar with a thickness of ∼3.9Å whereas the Herndon and coworkers claim it to be slightly nonplanar because of (3T +3S 3 ) strain. In their initial 1990 article, Herndon et al (6), from their original PCM-MM calculations, concluded that benzo[b]triphenylene had planar geometry, but with the newly defined T interaction recalculation showed that the formerly obtained planar geometry was identified as a local minimum and the slightly nonplanar geometry was subsequently determine to be the global MM minimum (of order of <1 kcal lower). Based on the thickness numbers by Sander and Wise (1), the first 8 catacondensed C 22 H 14 listed in Figure 2 are planar and only for benzo [b]triphenylene is there disagreement.…”

“…(4) In regard to the perylene and its related members, quaterrylene is experimentally known to be planar (5). It is not clear why the zigzag (6) for those catacondensed systems containing the newly defined T interaction have all been recalculated (compounds 8, 16, 17, 27, 32-37). In every case, the formerly obtained planar geometry is now identified as a local minimum, and a slightly nonplanar geometry at a slightly lower energy (<1 kcal) is determined to be the global MM minimum."…”