Molecular rectangles from metallomacrocycles: development of dibenzofuran ligands

Two new ligands 4,6-bis(4-pyridylsulfide)dibenzofuran L1 and 4,6-bis(methylsulfanylmethyl)dibenzofuran L2, based on dibenzofuran with exodentate thio-pyridine arms were prepared. The crystal structures of three metallomacrocycles were determined. Reaction of L1 with AgClO4 in a 1 : 1 metal-to-ligand ratio gave a ClO4– clamped metallomacrocycle, 1. The analogous reaction with CuCl2 gave a metallomacrocycle, 2, in which bridging chloride ions bisected the macrocycle. Both metallomacrocycles were rectangular in shape but their cavities were occluded by bridging interactions. Reaction of L2 with CuI in a 1 : 2 metal-to-ligand ratio gave a metallomacrocycle, 3, in which Cu2I2 moieties were incorporated into the edge of the macrocycle. This allowed for clearly defined cavities, which formed channels containing MeCN molecules in the overall threedimensional honeycomb array.