Dipolar Molecular Rotors in Surface-Anchored Metal Organic Frameworks

Abstract

The functionalization of surfaces with molecular machines is highly interesting due to the vast field of applications. Transferring the function of individual molecules to a macroscopic scale by bringing a multitude of them to act collectively is essential for materializing new technologies. For this purpose, dipolar rotors can be put into a supra molecular structure to switch the light transmission of a material by changing their orientation. A high three-dimensional order can be achieved by using rotors as linkers in surface-anchored metal organic frameworks (SURMOFs).1-3 Crafted SURMOF thin films allow the alignment of the dipolar rotors in an external electric field.4 Making use of this behaviour, the transmission of light can be modulated with the application of the field and be investigated towards its uses in optical technologies. In this project, different organic linker molecules with permanent dipole moments are synthesized and used in SURMOF fabrication. Dielectric loss spectroscopy of the SURMOF thin films gives information about the dipole-dipole interaction within the layers and the alignment of rotors along the applied electric field.5 Devices are being constructed with a transparent top electrode for electric field application. Information gathered from the behaviour of first generation linker molecules will refine the molecule designs for the next generation so that the optical and electronic properties of the material can be tuned as desired. Shekhah, H. Wang, S. Kowarik, F. Schreiber, M. Paulus, M. Tolan, C. Sternemann, F. Evers, D. Zacher, R. A. Fischer, C. Woll, J. Am. Chem. Soc. 2007, 129, 15118-15119.-G. Gu, A. Pfriem, S. Hamsch, H. Breitwieser, J. Wohlgemuth, L. Heinke, H. Gliemann, C. Wöll, Microporous and Mesoporous Materials 2015, 211, 82-87.L. Zhuang, A. Terfort, C. Wöll, Coordination Chemistry Reviews 2016, 307, 391-424.Zheng, M. E. Mulcahy, D. Horinek, F. Galeotti, T. F. Magnera, J. Michl, J. Am. Chem. Soc. 2004, 126, 4540.D. Horansky, L. I. Clarke, J. C. Price, T.-A. V. Khuong, P. D. Jarowski, M. A. Garcia-Garibay, Physical Review B 2005, 72, 014302. Figure 1