ERA NanoSci - Nanoscale Optical-toMechanical Energy Conversion: Coupling Nano-Object with Light Powered Molecular Lifters
Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
Final Report Abstract
In spite of the large amount of work performed by the majority of the partners, the initial objective of the international project has been only partially fulfilled. Since the beginning, the Ferrara and Rehovot groups have faced a main problem concerning the detection by UV-Vis spectroscopy of the self-assembled monolayers (SAMs) of azobenzene’s compound I formed on Au nanostructured surfaces. This problem has slowed down and partially hindered the progress towards the original objective. Our colleagues (Ferrara, Rehovot) have tried to solve this problem by using additional, different techniques. Without changing the overall aim of the programme, and in the attempt to solve the unexpected problem, we addressed in parallel new research challenges. Our group in Karlsruhe has synthesized several types of new, rigid azobenzenes compounds (AZOs); in particular the I-VI compounds meant to form self-assemble monolayers (SAMs) on the surface of metals. To prevent oxidation processes, all azobenzene’s derivatives are terminated with labile thioacetyl group, which can be easily cleaved in situ just before or during the formation of SAMs. The synthesis of the designed AZO compounds I-VI has been completed. The targeted structures have been assembled in a new modular approach. Metal catalyzed cross-coupling reactions provide terminally sulphur and/or nitrogen functionalized building blocks which will be interlinked by azo-forming coupling reactions. Unsubstituted AZO compound I was prepared using an improved protocol. More soluble AZO derivative II having tert-butyl head group has been prepared. Extended AZO compound III with anthracene unit was prepared, for better packing on the surface via π-π stacking. Hydrophilic AZO compounds IV, VI bearing long brush-like hydrophilic chains have been prepared. These compounds should alter surface hydrophilicity of SAMs upon photoisomerization. AZO compound V bearing long fluorophilic chains has been prepared. All compounds are terminated with labile thioacetate group, which is easily cleaved in situ just before or during the formation of SAMs. The synthetic methodology provides versatile synthetic pathways to azobenzene derivatives that might be used as potential photo-responsive nanoscale devices. The new azobenzene’s derivatives were prepared, fully characterized, and sent to both Ferrara and Rehovot groups for surface measurements. Finally, all groups of researchers have already agreed to continue collaboration on this promising research project.
Publications
- Langmuir, 2010, 26, 10822-10826
Dreas-Wlodarczak, A.; Müllneritsch, M.; Juffmann, T.; Cioffi, C.; Arndt, M.; Mayor, M.
- Beilstein J. Nanotechnol. 2011, 2, 834-844
Tirosh, E.; Benassi, E.; Pipolo, S.; Mayor, M.; Valášek, M.; Frydman, V.; Corni, S.; Cohen, S. R.
- Theor. Chem. Acc. 2012, 131, 1-14
Pipolo, S.; Benassi, E.; Brancolini, G.; Valášek, M.; Mayor, M.; Corni, S.
- „Synthesis of new AZO compounds in order to vary surface properties“, 4th European Chemistry Congress, Prague, Czech Republic, August 26-30, 2012
Valášek, M.; Mayor. M.
