Construction of Discrete Pentanuclear Platinum(II) Stacks with Extended Metal-Metal Interactions by Using Phosphorescent Platinum(II) Tweezers.

Discrete pentanuclear Pt stacks were prepared by the host-guest adduct formation between multinuclear tweezer-type Pt complexes. The formation of the Pt stacks in solution was accompanied by color changes and the turning on of near-infrared emission resulting from Pt⋅⋅⋅Pt and π-π interactions. The X-ray crystal structure revealed the formation of a discrete 1:1 adduct, in which a linear stack of five Pt centers with extended Pt⋅⋅⋅Pt interactions was observed. Additional binding affinity and stability have been achieved through a multinuclear host-guest system. The binding behaviors can be fine-tuned by varying the spacer between the two Pt moieties in the guests. This work provides important insights for the construction of discrete higher-order supramolecular metal-ligand aggregates using a tweezer-directed approach.