A Redox-active Cyclometalated Platinum Ring Enables Synthetic Post-processing of a [2]Rotaxane.

Post-synthetic modification of mechanically interlocked molecules (MIMs) is an attractive avenue to add complexity to already intricate systems. This remains an important, challenging topic that is under-developed. In this paper, we report the synthesis and characterization of a [2]rotaxane molecule featuring a ring appended to an emissive cyclometalated Pt unit. Modulation of the oxidation state at the metal center can transform the interlocked molecule into a new Pt [2]rotaxane or a Pt [3]rotaxane held together by an intermetallic Pt-Pt bond - a first of its kind. These molecules display distinct structural and photophysical properties, as well as shuttling dynamics. This approach for post-synthetic modification could be used to construct more complex MIMs and inorganic supramolecular assemblies with redox properties.