title: Cis-trans isomerisation of azobenzenes studied by laser-coupled NMR spectroscopy and DFT calculations.
abstract: In a combined experimental and computational study of a group of para-substituted azobenzenes, the effects of substituents and solvent on the kinetics of thermal cis-to-trans isomerisation have been examined and the success of DFT calculations in predicting kinetic parameters assessed. Mono-substituted species are predicted to isomerise by inversion in both non-polar and polar solvent, whereas for push-pull azobenzenes the mechanism is predicted to change from inversion to rotation on going from non-polar to polar solvent. Computed free energies of activation qualitatively reproduce experimental trends but do not quantitatively predict the kinetics of cis-trans isomerisation. The polarisable continuum model of solvation fails to predict the experimentally observed influence of solvent on the entropy of activation.
authors.affiliation: School of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh, UKEH9 3JJ.
authors.forename: Nuha A
authors.initials: NA
authors.lastname: Wazzan
authors.forename: Patricia R
authors.initials: PR
authors.lastname: Richardson
authors.forename: Anita C
authors.initials: AC
authors.lastname: Jones