Imidazolium-based dicationic cyclophanes.: Solid-state aggregates with unconventional (C-H)+•••Cl- hydrogen bonding revealed by X-ray diffraction

The first single-crystal X-ray crystallographic diffraction analysis of a dicationic heterophane showed a non-classic (C-H)(+)center dot center dot center dot Cl- hydrogen bond between the imidazolium rings and halide anions and the formation of unconventional charged assisted hydrogen bonds, which were the non-covalent forces driving the anion interactions shown by the dications 4 center dot 2X. Here is reported the halide-templated controlled synthesis and chemical response in basic media of 4 center dot 2X. Their structural properties were examined at the gas phase by electrospray ionization mass spectrometry in the negative-ion mode and in the solid-state by X-ray crystallography. Thus, the negative-ion ESP MS response showed that the formation of non-covalent self-aggregates of macrocyclic dications is a consequence of hydrogen-bonded complexes with halide anions. Notably, X-ray diffraction of dication 4a center dot 2Cl center dot 2H(2)O provides evidence for the H-bonding network, which has a crucial role in crystal packing. The solid-state aggregates showed that chloride anions and water molecules formed channels among dications 4a(+).