| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 26292 | Journal of Photochemistry and Photobiology A: Chemistry | 2016 | 13 Pages |
•Photooptical phenomena in films of novel photochromic bent-shaped compounds.•Polarized visible and UV light induces the photoorientation of the chromophores.•High values of photoinduced dichroism which are comparable with other azo-systems.•Photoinduced melting could be served for the optical data recording and storage.
A comparative study of the photo-optical properties and the photo-orientation processes in thin films of the bent-shaped azobenzene-containing compounds with different molecular structure was performed. For this purpose three new compounds were designed and prepared: two of these compounds with a symmetric bent-shaped molecular structure incorporate two azobenzene chromophores with different length of alkyl chains (6 and 8 methylene units), the third bent-shaped compound possesses only one azobenzene fragment. The effect of molecular and supramolecular structure, thermal prehistory of the films, wavelengths of the excitation light on the photo-optical properties, photoorientation processes and films morphology was revealed. It was shown that UV-irradiation leads to E–Z isomerization of azobenzene fragments in both amorphousized and crystalline films of the synthesized substances. This process is partially suppressed in crystalline films, but, nevertheless, UV-irradiation of the bichromophoric compounds results in transition from crystalline to amorphous state and decrease in the surface roughness. Irradiation of amorphousized films with polarized visible and UV-light induces the photoorientation of chromophores in direction perpendicular to the polarization plane of the incident light. Relatively high values of photoinduced dichroism in the bent-shaped compounds (D ∼ 0.60–0.65) are comparable with other azobenzene-containing rod-shaped systems. Photoinduced isothermal melting and photoorientation processes could be served for the photo-optical data recording and storage.
