Trans-cis isomerization of 4-(2-(9-anthryl)vinyl) pyridine. Molecular structures and H-1 NMR kinetic studies

Both cis- and trans-isomers of 4-(2-(9-anthryl) vinyl) pyridine were isolat ed and their molecular structures established by X-ray crystallographic met hod. Variable temperature H-1 NMR spectroscopy was used to study the trans to cis isomerization of the title compound. The kinetic study of the reacti on was based on the ratio of the NMR integration heights in toluene-d(g) of the double doublet due to the cip-isomer at delta 8.51 to that of the mult iplet at delta 8.15 which was kept constant during the whole experiment. Th e isomerization process was found to be first order and the Arrhenius activ ation parameters E-s, ln A, Delta H-not equal and Delta S-not equal were ca lculated as 27.84 kJ/mol, 6.71, 25.23 kJ/mol and - 197.89 J/(K.mol), respec tively. Besides, conformational analyses of both compounds based on molecul ar modelling were carried out and the results were used to compare with the experimental data.