Transition-Metal-Functionalized DNA Double-Crossover Tiles: Enhanced Stability and Chirality Transfer to Metal Centers

The double crossover junction (DX) is a fundamental building block for generating complex and varied structures from DNA. However, its implementation in functional devices is limited to the inherent properties of DNA itself. Here, we developed design strategies to generate the first metal-DX DNA tiles (DX_M ) by site-specifically functionalizing the tile crossovers with tetrahedral binding pockets that coordinate Cu^I . These DX junctions bind two Cu^I ions independently at distinct sites, display greater thermal stability than native DX tiles upon metalation, and melt in a cooperative fashion. In addition, the right-handed helical chirality of DNA is transferred to the metal centers. Our tiles display high metal ion selectivity, such that Cu^II is spontaneously reduced to Cu^I in situ. By modifying our design over three generations of tiles, we elucidated the thermodynamic and geometric requirements for the successful assembly of DX_M tiles, which have direct applicability in developing robust, stable DNA-based materials with electroactive, photoactive, and catalytic properties.