Halonium ions are particularly strong halogen bond donors, and are accordingly valuable tools for a variety of fields, such as supramolecular and synthetic organic chemistry.

Self-assembly of pre-organized subunits with a concave overall shape is an effective strategy for the synthesis of supramolecular capsules. We report the synthesis of a cavitand-based hexameric capsule held together solely by 12 robust [N,,,I + ,,,N] halogen bonds and its characterization in solution and in the gas phase via 1 H NMR spectroscopy, diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY), and electrospray ionization mass spectrometry. The [N,,,I + ,,,N] halogen-bonded hexameric capsule was efficiently synthesized from the isolobal metallosupramolecular Ag + capsule by application of the [N

Two [N⋅⋅⋅I ⋅⋅⋅N] halogen-bonded dimeric capsules using tetrakis(3-pyridyl)ethylene cavitands with different lower rim alkyl chains are synthesized and analyzed in solution and the gas phase. These first examples of symmetrical dimeric capsules making use of the iodonium ion (I ) as the main connecting module are characterized by H NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), electrospray ionization mass spectrometry (ESI-MS), and ion mobility-mass spectrometry (TW-IMS) experiments. The synthesis and effective halogen-bonded dimerization proceeds through analogous dimeric capsules with [N⋅⋅⋅Ag ⋅⋅⋅N] binding motifs as the intermediates as evidenced by the X-ray structures of (CH Cl ) @[3 a ⋅Ag ⋅(H O) ⋅OTs ] and (CH Cl ) @[3 a ⋅Ag ⋅(H O) ⋅OTs ], two structurally different capsules.

Tripodal N-donor ligands are used to form halogen-bonded assemblies via structurally analogous Ag -complexes. Selective formation of discrete tetrameric I L and dimeric I L halonium cages, wherein multiple [N⋅⋅⋅I ⋅⋅⋅N] halogen bonds are used in concert, can be achieved by using sterically rigidified cationic tris(1-methyl-1-azonia-4-azabicyclo[2.2.2]octane)-mesitylene ligand, L1(PF ) , and flexible ligand 1,3,5-tris(imidazole-1-ylmethyl)-2,4,6-trimethylbenzene, L2, respectively. The iodonium cages, I L1 (PF ) and I L2 (PF ) , were obtained through the [N⋅⋅⋅Ag ⋅⋅⋅N]→ [N⋅⋅⋅I ⋅⋅⋅N] cation exchange reaction between the corresponding Ag L1 (PF ) and Ag L2 (PF ) coordination cages, prepared as intermediates, and I . The synthesized metallo- and halonium cages were studied in solution by NMR, in gas phase by ESI-MS and in the solid-state by single crystal X-ray diffraction.

Ion-mobility mass spectrometry and DFT calculations reveal the surprisingly solvent-dependent formation of large pentameric [N···I+···N] halogen-bonded capsules.