The internal barriers of rotation for the 209 polychlorinated biphenyls
1997 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 4, no 2, 75-81 p.Article in journal (Refereed) Published
The internal barrier of rotation (Erot) was calculated for all 209 polychlorinated biphenyls (PCBs) by using a semi-empirical method, viz. the Austin Model 1 (AM1) Hamiltonian. The difference in total energy between a forced planar state and an optimised twisted structure was defined as Erot. The Erot values were in the range of 8.33 to 483 kJ/mol, and were significantly influenced by the number of chlorine atoms in ortho position. An additional structural characteristic of the PCBs influencing Erot of ortho substituted congeners was substitution by chlorine atoms in vicinal meta positions, which is assumed to prevent outward bending of ortho substituents. This so-called buttressing effect contributed with 4 to 31 kJ/mol per added chlorine atom. In conclusion, the internal barrier of rotation, calculated for all 209 PCBs, provides an important structure dependent physico-chemical parameter for multivariate modelling of future quantitative structure-activity and structure-property relationships (QSARs/QSPRs).
Place, publisher, year, edition, pages
1997. Vol. 4, no 2, 75-81 p.
PCBs, physico-chemical properties, semi-empirical calculations, AM1, substitution pattern, ortho-chlorines, dihedral angle, rotational barrier, buttressing effect, QSAR, QSPR
IdentifiersURN: urn:nbn:se:umu:diva-3297DOI: 10.1007/BF02986283ISI: A1997XJ06700005OAI: oai:DiVA.org:umu-3297DiVA: diva2:141849