Metallic Open Channel Colloidal Superlattices

Porous crystals are promising materials for many applications including absorption, storage, separation, chemical sensing, optics, and catalysis. Composition, pore size, and geometry are three important parameters that dictate the properties of porous crystals. However, it is challenging to synthetically control metallic crystals with continuous shape-defined pores smaller than 1 µm. Herein, a universal approach for synthesizing metallic open channel superlattices with 10 to 1000 nm pores from DNA-modified hollow colloidal nanoparticles is reported. By tuning nanoparticle geometry and DNA design, we show crystal channel size tunability. We further show that the assembly of hollow nanoparticles is driven by edge-to-edge rather than face-to-face DNA-DNA interactions. Four design rules describing this assembly regime are presented and then used to synthesize 12 open channel superlattices with control over their symmetry, channel topology, and porosity. The open channels can be filled with guests of the appropriate size and complementary DNA. Moreover, calculations and experimental measurements reveal that the resulting metallic open channel superlattices have promising optical properties, including negative refractivity in a wide wavelength range (776-2000 nm) and broadband absorption in the optical range (400-800 nm). This work addresses a synthetic gap in porous crystal design and represents a new direction for the field of colloidal crystal engineering with important implications in catalysis, plasmonics, electronics, biology, and medicine.