Date of Award
Chemistry and Biochemistry
Coordination cage, Molecular machine, Molecular polygon, Rotaxane
The interest in molecular machinery has exploded in recent years, as highlighted by the Nobel Prize in chemistry in 2016 “for the design and synthesis of molecular machines.” Rotaxanes, specifically molecular shuttles, are a potential component for the creation of viable molecular machines. Metal-organic frameworks (MOFs) provide a way to aggregate individual component parts, but their properties are not easily studied. A coordination cage can mimic the individual pores of a MOF, and would provide a platform to study a potential molecular machine component. Taking inspiration from Fujita and Stang’s success by using pyridine and benzonitrile-based ligands with Pd(II) and Pt(II)-based metal corners to create molecular polygons, as well as our research group’s success with using rotaxanes as linkers in MOFs, the -rotaxane ligands [2⸦24C8] and [3⸦24C8] were designed, synthesized, and characterized. [1⸦24C8] was created by retrosynthetic analysis to be a molecular shuttle that could easily be converted into a symmetrical “H-shaped” ligand via replacement of its terminal Br groups. The creation of the coordination cage [Pd8(dppp)8[3⸦24C8]4][OTf]16 was strongly supported by 1D, and 2D NMR experiments and was estimated by modeling to have a hydrodynamic radius of 21.0 Å. Two other molecular cubes, [Pd8(en)8[2⸦24C8]4][NO3]16 and [Pt8(dppp)8[2⸦24C8]4][OTf]16 were attempted to be synthesized, but characterization methods were unable to conclusively determine if assembly was successful.
Rowsell, Peter Alexander, "Rotaxane Incorporated Coordination Cages" (2018). Electronic Theses and Dissertations. 7480.