Supramolecular dendrimer capsules by cooperative binding

Design, Synthesis and Self-Assembly of Functional Amphiphilic Metallodendrimers

A new family of alkynylated, amphiphilic dendrimers consisting of amidoamine linkers connected to 5,5'-functionalized 2,2'-bipyridine cores has been developed and evaluated in the formation of metallodendrimers of different generations and in self-assembly protocols. A convergent synthetic strategy was applied to provide dumbbell-shaped amphiphilic dendrimers, where the 2,2'-bipyridine cores could be coordinated to FeII centers to afford corresponding metallodendrimers. The ability of the metallic- and non-metallic dendritic structures to self-assemble into functional supramolecular aggregates were furthermore evaluated in aqueous solution. Spherical aggregates with sizes of a few hundred nanometers were generally produced, where controlled disassembly of the metallodendrimers through decomplexation could be achieved.

Ion-selective controlled assembly of dendrimer-based functional nanofibers and their ionic-competitive disassembly

The construction of hierarchical materials through controlled self-assembly of molecular building blocks (e.g., dendrimers) represents a unique opportunity to generate functional nanodevices in a convenient way. Transition-metal compounds are known to be able to interact with cationic dendrimers to generate diverse supramolecular structures, such as nanofibers, with interesting collective properties. In this work, molecular dynamics simulation (MD) demonstrates that acetate ions from dissociated Cd(CH(3)COO)(2) selectively generate cationic PPI-dendrimer functional fibers through hydrophobic modification of the dendrimer's surface. The hydrophobic aggregation of dendrimers is triggered by the asymmetric nature of the acetate anions (AcO(-)) rather than by the precise transition metal (Cd). The assembling directionality is also controlled by the concentration of AcO(-) ions in solution. Atomic force (AFM) and transmission electron microscopy (TEM) prove these results. This well-defined directional assembly of cationic dendrimers is absent for different cadmium derivatives (i.e., CdCl(2), CdSO(4)) with symmetric anions. Moreover, since the formation of these nanofibers is controlled exclusively by selected anions, fiber disassembly can be consequently triggered via simple ionic competition by NaCl salt. Ions are here reported as a simple and cost-effective tool to drive and control actively the assembly and the disassembly of such functional nanomaterials based on dendrimers.