Chiral Branched Inorganic−Organic Nanocages
Hsien Cheng Huang, Chase Chrenka, Yiming Zhang, Valeriia Poliukhova, Yurii Koliada, Oleksandr Striutskyi, Mariana Gumenna, Valery V. Shevchenko, Vladimir V. TsukrukAbstract
We demonstrated how ionic pairing of sulfonated polyhedral oligomeric silsesquioxane (POSS-SO3H) nanocages with protonated amino acid, l-tryptophan, can yield chiroptically active hybrid inorganic−organic nanostructures. We discovered that preferential complementary Coulombic interactions at the silsesquioxane nanocage vertices drive molecular organization into chain-like supramolecular assemblies of modified nanocage clusters with distinctive nanofibrillar and globular morphologies. The resulting POSS-SO3−−TRP+ hybrid exhibits pH-resilient chiroptical activity, improved electrokinetic activity in comparison to free l-tryptophan, and a higher glass transition temperature upon ionic complexation. These results suggest that ionic inorganic nanocages act as a viable scaffold for stabilizing molecular chirality under mild aqueous conditions, opening a facile route to optically active organic−inorganic assembled chains with tunable robust chiroptical properties of inorganic nanostructures.