Synthesis and Structure of Macrocyclic Tetraimidazolium Salt Containing Propylene and m-Phenylene Linkers

Macrocyclic tetraimidazolium salts 2 and 3 containing propylene and m-phenylene linkers were synthesized from diimidazole derivative 1 and 1,3-diiodopropane. The molecular structure of 3 was determined by single-crystal X-ray diffraction analysis, revealing an almost planar macrocyclic framework. DFT calculations identified three low-energy conformers of the tetracation in 3, suggesting conformational flexibility in solution.