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

Discrete pentanuclear Pt^II stacks were prepared by the host‐guest adduct formation between multinuclear tweezer‐type Pt^II complexes. The formation of the Pt^II 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^II 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^II 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.     

Solvent‐Induced Cluster‐to‐Cluster Transformation of Homoleptic Gold(I) Thiolates between Catenane and Ring‐in‐Ring Structures

Supramolecular ensembles adopting ring‐in‐ring structures are less developed compared with catenanes featuring interlocked rings. While catenanes with inter‐ring closed‐shell metallophilic interactions, such as d¹⁰–d¹⁰ Au^I–Au^I interactions, have been well‐documented, the ring‐in‐ring complexes featuring such metallophilic interactions remain underdeveloped. Herein is described an unprecedented ring‐in‐ring structure of a Au^I‐thiolate Au₁₂ cluster formed by recrystallization of a Au^I‐thiolate Au₁₀ [2]catenane from alkane solvents such as hexane, with use of a bulky dibutylfluorene‐2‐thiolate ligand. The ring‐in‐ring Au^I‐thiolate Au₁₂ cluster features inter‐ring Au^I–Au^I interactions and underwent cluster core change to form the thermodynamically more stable Au₁₀ [2]catenane structure upon dissolving in, or recrystallization from, other solvents such as CH₂Cl₂, CHCl₃, and CH₂Cl₂/MeCN. The cluster‐to‐cluster transformation process was monitored by ¹H NMR and ESI‐MS measurements. Density functional theory (DFT) calculations were performed to provide insight into the mechanism of the “ring‐in‐ring? [2]catenane” interconversions.