Topology-enforced synthesis of atomically precise silver nanoclusters in 3D DNA lattices.

DNA nanotechnology leverages the molecular design resolution of the DNA double helix to fold and tile matter into designer architectures. Recent advances in bioinorganic chemistry have exploited DNA/Ag+ affinity to carry out the templated reduction of silver nanoclusters. Here, we develop a unified method that leverages the topology of DNA triangles with embedded silver base pairs to nucleate controlled cluster growth in a mesoporous 3D lattice. Use of confocal fluorescence microscopy allows for the direct observation of reaction kinetics and reconstruction of the optical bandgap. These crystals yield molecular structures of Ag4 and Ag6 by x-ray diffraction in varying pyrimidine:pyrimidine pairs. Intercluster distances of less than 2 nanometers show observable electronic coupling, with red shifting observed relative to literature standards. A thorough computational investigation establishes a theoretical basis for our observed behavior and establishes the interplay between cluster size, charge, geometry, and resonance. We anticipate that these results will yield advances in materials synthesis, DNA-based plasmonic crystals, and optically active nanoelectronics.