Berlin 2015 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 86: Nanostructure at Surfaces: Molecular Assembly
O 86.9: Vortrag
Donnerstag, 19. März 2015, 17:15–17:30, HE 101
Reversible photoisomerization within monolayers of a π-expanded oligothiophene 8-mer: A photosensitive molecular cargo nanoarchitecture — •Jose D. Cojal1, Masahiko Iyoda2, and Jürgen P. Rabe1 — 1Department of Physics & IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany — 2Department of Chemistry, Tokyo Metropolitan University, Tokyo, Japan
A π-expanded oligoethynylene-thiophene macrocycle has been optically switched between its E,E- and Z,Z-conformers in different solutions. Here, we report a self-assembled monolayer of Z,Z-8mer (E,E-8mer) between its octanoic acid solution and HOPG, which upon illumination at 365nm (550nm) with an intensity of ∼ 1mW/cm2, photoisomerizes to the of E,E-8mer (Z,Z-8mer). The switching process was followed using STM imaging while irradiating with the corresponding wavelength. The 2D-hexagonal network of the Z,Z-8mer displayed an average unit cell of a=(2.76± 0.01)nm, b=(2.86± 0.03)nm, θ=(60.8± 0.8)∘, while the E,E-8mer exhibited a different average unit cell a=(2.89± 0.02)nm, b=(2.95± 0.03)nm, θ=(60.3± 0.8)∘ with a 95% of confidence level. To validate the reversible switching, emission spectra were recorded starting with a monolayer of Z,Z-8mer, which isomerizes to the E,E form after 15 minutes of illumination at 365nm with an intensity of 700mW/cm2, and returns to the original spectrum after 15 additional minutes of illumination at 550nm with an intensity of 500mW/cm2. Combining the photoswitchable properties of the monolayers of the macrocycle with its host-guest capabilities we envisage a photosensitive molecular cargo system.