Synthesis of Axially Chiral 4,4′‐Bipyridines and Their Remarkably Selective Self‐Assembly into Chiral Metallo‐Supramolecular Squares

A preferred choice: Prochiral 3,3′,5,5′-tetramethyl-4,4′-bipyridine can be converted into two types of axially chiral 4,4′-bipyridine compounds, separable into enantiomers by chiral HPLC. The obtained enantiopure bipyridines were sufficiently stable in solution to be used in the self-assembly of chiral metallo-supramolecular squares, which reveal a remarkable preference for one of ten possible structures (shown here).