Second Generation Self-Assembling Dendrimer Combining Supramolecular and Dynamic Covalent Chemistry

A monodisperse second generation self-assembled dendrimer has been obtained combining supramolecular chemistry and dynamic covalent chemistry as orthogonal binding moieties. A branching unit 18 and a core 5 were connected via a heteroleptic terpyridine zinc complex exploiting the sterical hindrance of mesitylene units in the 6,6''-position of one of the terpyridines as the distinction between the ligands. Solubility problems could be solved by introduction of an ethylhexyl ether. The final sphere of the dendrimer was connected via imines, hydrazones and oximes, whereby the oxime made from O-methylhydroxylamine (22) led to a complete turnover of all aldehyde functions. Furthermore, no amine signal was left and also no signals for a diffusion constant of the hydroxylamine 22 were observed. The successful formation of the dendrimers was analyzed by H-1 NMR and DOSY NMR spectroscopy. Furthermore both, the first and second generation dendrimers could be detected by ESI HRMS.

Automated summary

A monodisperse second generation self-assembled dendrimer was synthesized by combining supramolecular chemistry and dynamic covalent chemistry. The ligands were differentiated using a mesitylene unit in the 6,6''-position of one of the terpyridines. Solubility issues were solved by introducing an ethylhexyl ether. The successful formation of the dendrimers was confirmed by H-1 NMR and DOSY NMR spectroscopy, and both first and second generation dendrimers were detected using ESI HRMS.