Bright Fluorescence and Host-Guest Sensing with a Nanoscale M4L6 Tetrahedron Accessed by Self-Assembly of Zinc-Imine Chelate Vertices and Perylene Bisimide Edges

A highly luminescent Zn4L6 tetrahedron is reported with 3.8 nm perylene bisimide edges and hexadentate Zn-II-imine chelate vertices. Replacing Fe-II and monoamines commonly utilized in subcomponent self-assembly with Zn-II and tris(2-aminoethyl) amine provides access to a metallosupramolecular host with the rare combination of structural integrity at concentrations <10(-7) mol L-1 and an exceptionally high fluorescence quantum yield of Phi(em)=0.67. Encapsulation of multiple perylene or coronene guest molecules is accompanied by strong luminescence quenching. We anticipate this self-assembly strategy may be generalized to improve access to brightly fluorescent coordination cages tailored for host-guest light-harvesting, photocatalysis, and sensing.