Ligand-Shell Softness Directs Symmetry Transitions in Nanotripod Superstructures

Here, we show that polymer-grafted Gd₂O₃ nanotripods assemble into compact achiral and open chiral nanoporous superstructures. By tuning tripod aspect ratio, polymer ligand length, and ligand shell architecture, we direct phase selection among p2, pmg, pgg, and p6 wallpaper symmetries.

In the p6 phase, planar chirality emerges through arm-to-arm interlocking. Direct ligand exchange generates mixed ligand shells with softer effective interactions, expanding the accessible phase space beyond that obtained by two-step ligand exchange. Coarse-grained simulations incorporating ligand-mediated attractions reproduce the experimental phase behavior and identify competition between translational entropy and polymer–polymer enthalpic interactions as a key driver of phase selection.