Programming Dimensional Transitions in DNA Brick Crystals via Interfacial Connectivity

The precise control of assembly dimensionality and macroscopic structural parameters remains a fundamental challenge in molecular self‐assembly. Here, we introduce a programmable strategy to govern the 1D‐to‐2D dimensional transition and structural width of DNA brick crystals by engineering their connecting interfaces. Using the number of interface connecting strands ( N x ) as a quantitative design parameter, we discover a sharp dimensional threshold that is preserved across both honeycomb and square lattices. At N x ≤ 8, the assembly is strictly confined to one‐dimensional nanoribbons; whereas at N x ≥ 12, lateral coupling activates extended two‐dimensional arrays whose structural width increases monotonically with N x . Thermal and thermodynamic analyses reveal that this sharp threshold behavior is lattice‐independent and originates from the size‐dependent thermal stability of the laterally connected domains. Our work establishes interfacial connectivity as a predictive handle for the on‐demand engineering of self‐assembled nanostructures with programmable dimensionality and prescribed widths.