Tetramine Aspect Ratio and Flexibility Determine Framework Symmetry for Zn 8 L 6 Self‐Assembled Structures

Abstract

We derive design principles for the assembly of rectangular tetramines into Zn 8 L 6 pseudo‐cubic coordination cages. Because of the rectangular, as opposed to square, geometry of the ligand panels, and the possibility of either Δ or Λ handedness of each metal center at the eight corners of the pseudo‐cube, many different cage diastereomers are possible. Each of the six tetra‐aniline subcomponents investigated in this work assembled with zinc(II) and 2‐formylpyridine in acetonitrile into a single Zn 8 L 6 pseudo‐cube diastereomer, however. Each product corresponded to one of four diastereomeric configurations, with T , T h , S 6 or D 3 symmetry. The preferred diastereomer for a given tetra‐aniline subcomponent was shown to be dependent on its aspect ratio and conformational flexibility. Analysis of computationally modeled individual faces or whole pseudo‐cubes provided insight as to why the observed diastereomers were favored.