Crown ethers as pre-organised exo-receptors in the divergent recognition of α,ω-diiodoperfluoroalkanes

Abstract

Both the nitrogen atoms of Kryptofix^® 2.2. 1 act as electron-donors to the iodine atoms of α,ω-diiodoperfluoroalkanes 2a,b giving rise to infinite 1D chains 3a,b as white crystalline solids which are stable in air at room temperature. The structural features of these non-covalent co-polymers have been studied using various techniques (IR, ¹H NMR, ¹⁹F NMR, X-ray diffraction) and it has been established that when Kryptofix^® 2.2. is halogen bonded to iodides 2, it adopts the same conformation as when in the pure form, namely the exo–exo topology. The co-existence of halogen-bonding and hydrogen-bonding in supramolecular architectures 3 suggests pre-organisation of the interacting partners as a new strategy in the rational design of divergent self-assembly processes.