Metal-coordination-driven mixed ligand binding in supramolecular bisporphyrin tweezers

Abstract

Mg(II)bisporphyrin has been used as an efficient host for the selective binding of guest ligands. In the presence of heterogeneous guest pairs, 2-aminopyrimidine/pyrazine and 2-aminopyrimidine/1,4-dioxane, 2-aminopyrimidine is bound selectively inside the bisporphyrin cavity whereas pyrazine/1,4-dioxane is bound outside to produce 1D mixed ligand polymers. UV-vis, 1H NMR spectra and X-ray structure confirm such a selective and orthogonal binding of the guest ligands. The mixed ligand polymer has been synthesized just by mixing the host and guests in one pot and easily isolated as a solid in nearly quantitative yield due to its high stability.