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Activation enthalpies and entropies of the atropisomerization of substituted butyl-bridged biphenyls
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
 
ID 3378915
Author(s) Bihlmeier, Angela; Rotzler, Jürgen; Rickhaus, Michel; Mayor, Marcel; Klopper, Wim
Author(s) at UniBasel Mayor, Marcel
Year 2015
Title Activation enthalpies and entropies of the atropisomerization of substituted butyl-bridged biphenyls
Journal Physical Chemistry Chemical Physics
Volume 17
Number 17
Pages / Article-Number 11165-73
Abstract A combined quantum chemical and experimental study of the atropisomerization energies of di-para-substituted butyl-bridged biphenyl cyclophanes is presented. We studied the influence of electron donor and electron acceptor substituents on the height of the enantiomerization barrier and examined the enthalpic and entropic contributions. The reaction pathway with minimum and transition state structures was established using density functional theory calculations. The Gibbs free activation energies derived from this pathway correspond well to the ones determined by temperature dependent high performance liquid chromatography (HPLC) measurements. Surprisingly, large discrepancies were found for the contributions of enthalpy and entropy. Thermodynamic data derived from circular dichroism (CD) measurements support the quantum chemical calculations for the distribution of enthalpy and entropy, contrary to the HPLC measurements. Rationalizations for this are given.
Publisher ROYAL SOC CHEMISTRY
ISSN/ISBN 1463-9084
edoc-URL http://edoc.unibas.ch/40736/
Full Text on edoc No
Digital Object Identifier DOI 10.1039/C4CP06009A
PubMed ID http://www.ncbi.nlm.nih.gov/pubmed/25712635
ISI-Number WOS:000353338800006
Document type (ISI) Journal Article
 
   

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