Highly Accurate Synthesis of Quasi-sub-nanoparticles by Dendron-assembled Supramolecular Templates

Quasi-sub-nanomaterials (1-3 nm) have been predicted to exhibit unique properties originating from the gray structures considered both bulk solids and molecules, while their synthesis is extremely difficult. The present study describes a new template synthesis method for quasi-sub-nanosized materials using a combination of coordination chemistry and polymer chemistry. Utilizing self-assembly of guest basic phenylazomethine dendron units onto host acidic core units with six tritylium cations, the dendron-assembled supramolecules were constructed easily and quantitatively without costly techniques. This huge supramolecular capsule accumulating multiple acidic rhodium salts in its basic ligands enabled a precise synthesis of rhodium particles via formation of multinuclear complexes. The obtained particles (Rh₈₄ , ≈1.5 nm) have particle sizes within 1-3 nm range and were larger than conventional sub-nanoparticles (Rh₁₄ , ≈0.85 nm), therefore the precise template synthesis of quasi-sub-nanoparticles was successfully demonstrated.