Photocontrolled On-Surface Pseudorotaxane Formation with Well-Ordered Macrocycle Multilayers
F.B. Schwarz, T. Heinrich, J.O. Kaufmann, A. Lippitz, R. Puttreddy, K. Rissanen, W.E.S. Unger, C.A. Schalley – 2016
The photoinduced pseudorotaxane formation between a photoresponsive axle and a tetralactam macrocycle was investigated in solution and on glass surfaces with immobilized multilayers of macrocycles. In the course of this reaction, a novel photoswitchable binding station with azobenzene as the photoswitchable unit and diketopiperazine as the binding station was synthesized and studied by NMR and UV-Vis spectroscopy. Glass surfaces have been functionalized with pyridine-terminated SAMs and subsequently with multilayers of macrocycles through layer-by-layer self assembly. A preferred orientation of the macrocycles could be confirmed by NEXAFS spectroscopy. The photocontrolled deposition of the axle into the surface-bound macrocycle-multilayers was monitored by UV Vis spectroscopy and led to an increase of the molecular order, as indicated by more substantial linear dichroism effects in angle-resolved NEXAFS spectra.