Synthesis of metallo-supramolecular materials based on terpyridine functionalized double-decker silsesquioxane with improved complexation efficiency

Silsesquioxane-based transition-metal complexes have come to the forefront due to the ability of silsesquioxane to control nanostructures and properties. However, some difficulties in complete complexation and purification limit the widespread use of transition-metal-based supramolecular coordination complexes comprising silsesquioxane. Herein, 2 different approaches have been proposed for the synthesis of metallo-supramolecular materials on the basis of ruthenium(II)-terpyridine functional double-layer silsesquioxane (DDSQ) (Tpy/Ru-DDSQ) (Routes 1 and 2). In Route 1, complexation was followed by functionalization of DDSQ with the ligand, whereas in Route 2, complexation was performed before the ligand was inserted into the DDSQ. Tpy/Ru-DDSQ obtained from both approaches was characterized by (1)H NMR, X-ray photoelectron spectrometer, and FTIR and found in the same structure. Both methods were fully discussed and their merits were explored. The complexation yield of the routes was similar. However, the results based on NMR and UV-Vis spectroscopy demonstrated that the incorporation rate of DDSQ into the complex was quite high in Route 2. As far as is known, this is the first study based on the effects of complexing Tpy ligands before/after binding to the target compound, particularly to silsesquioxane-based materials.