| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1405920 | Journal of Molecular Structure | 2012 | 11 Pages |
A systematic investigation of the conformational structure was performed for the series of symmetrical and unsymmetrical mono-, tri-, pentamethine cyanines, and styryl dyes bearing 2-azaazulenium terminal group. The rotation energy barriers of terminal groups were determined via the dynamic variable temperature NMR experiments. The conformational transformation energy was calculated by quantum chemical methods (B3LYP and M05-2X) both for the cases of considering the solvent influence and not tacking it into account. Based on the comparison of theoretical and experimental data, relative electron-donating abilities and geometrical features of the heterocyclic terminal groups in 2-azaazulenium dyes were estimated. The arrangement of certain heterocyclic nuclei in order of basicity by considering the results of the dynamic NMR investigations was proposed. Influence of the conjugated chain length and the solvent nature on the conformational lability of the investigated dye molecules was discussed.
► Conformational study of 2-azaazulenium and other dyes by DNMR and DFT methods. ► Rotation energy barriers of terminal groups were determined via DNMR experiments. ► Isomerization energies in different solvents were investigated experimentally. ► Medium influence on dye molecules conformational behavior was studied by DFT PCCM. ► Scale of heterocyclic end-groups in order of basicity basing on DNMR was proposed.
