Adjustable chiral self-sorting and self-discriminating behaviour between diamond-like Tröger's base-linked cryptands

Two isomers of Tröger's base-linked cryptands 5a and 5b were synthesized, and both of them have two chiral N-centers, exhibiting rare diamond-like scaffolds. Particularly, when growing from the solution of rac-5a, a single enantiomer RNRN-5a was found in the crystal cell, revealing chiral self-sorting behaviour. However, when adding CF3COOH to protonate Tröger's base in the solution of rac-5a, two enantiomers were both formed in pairs in the crystal cell, exhibiting chiral self-discriminating behaviour.