A Modular Synthetic Strategy toward Fast-Growing Poly(amide-carbosilane) Dendrimers Based on Click Chemistry and Organic Solvent Nanofiltration

Dendrimers, constituting a prominent class of monodisperse and multivalent macromolecular compounds with outstanding properties, are characterized by regular and highly branched three-dimensional architectures and well-defined chemical structures. Within each structural type, the skeletal diversity is typically limited to the range of generations. Here, we introduce a novel modular synthetic strategy enabling an increase in the diversity of the dendrimer interior while maintaining its chemical nature. Resulting poly-(amide-carbosilane) (PAMCAS) dendrimers can be fine-tuned within one generation in terms of size, number, and density of end groups, as well as interior free volume. Using a tetravalent core and two building blocksdendritic wedges with branching degrees 3 and 6we demonstrate the potency of this strategy by producing a family of dendrimers through a controlled iterative process that combines highly chemoselective amidic coupling and thiol-ene click reaction (TEC). Within three generations, we prepared 14 structural analogs of PAMCAS dendrimers, systematically varying the order of building blocks and thus their structural profile. The solution properties of the obtained materials were studied by DLS, A4F, diffusion NMR, and molecular modeling. When using exclusively the AB₆ module, the dendritic growth is accelerated and allows straightforward access to structures with extremely high valency in a given generation. As the modular synthetic strategy poses a considerable purification challenge, we implemented organic solvent nanofiltration (OSN) as the main separation tool. Herein, we demonstrate proof-of-principle experiments to evaluate the scope and limits of the use of OSN as an effective separation method in synthetic macromolecular chemistry.