Molecular rectangles from metallomacrocycles: development of dibenzofuranligands

Abstract

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 three-dimensional honeycomb array.