Halogen Bonds Direct the Solid State Architectures of a Multivalent Iodopropargylcalixarene
journal contributionposted on 07.05.2020, 20:29 by Maria Chiara Gullo, Laura Baldini, Alessandro Casnati, Luciano Marchiò
The iodoalkynyl group is a ditopic synthon, able to act as a halogen bond (XB) donor through the iodine atom and as an XB acceptor on the CC triple bond. With the aim of exploring the self-assembly properties via XB of calixarene macrocycles containing this synthon, we synthesized and characterized a tetra(iodopropargyl)calixarene (3). In the solid state, all the iodoalkynyl units of 3 are involved in intermolecular XB interactions as both donors and acceptors, resulting in a two-dimensional network of calixarene double layers. On the contrary, in the cocrystal of 3 with 4,4′-bipyridine, a bidentate XB acceptor, the iodine atoms are halogen bonded to the pyridine nitrogen atoms forming a one-dimensional ribbon of calixarenes alternated by two 4,4′-bipyridine units. These supramolecular architectures are the first example of solid-state networks of calixarene derivatives where the self-assembly is mostly driven by XBs.