Dendrimer-metallomacrocycle composites: Nanofiber formation by multi-ion pairing

The ion-promoted, automorphogenic, and stoichiometric self-assembly of nanoscale composite fibers using a structurally rigid hexameric macrocycle was reported. The related 3rd generation dendrimer was treated with [(1 ¹²⁺)(PF_-612] to afford a neutral, sphere-like motif. The G1 dendrimer was prepared by hydrolysis of the corresponding 12-tert-butyl ester with formic acid to possess a hydrodynamic diameter at basic pH, as determined by 2D diffusion ordered spectroscopy (DOSY). Characterization of the dendrimer/hexamer fibrous composite began with analysis of the clear and colorless filtrate, which confirmed the presence of the PF_-6 counterions. Additional evidence for the formation of [(2^12-)(1 ¹²⁺) was obtained using TEM. The UV-vis absorption spectrum showed strong π-π* transitions in the range of 288 to 313 nm with a shoulder at 330 nm in addition to a metal to ligand charge transfer (MLCT).