The Use of Dipyrromethene Ligands in Supramolecular Chemistry
Zhang, Y., Thompson, A., Rettig, S., and David Dolphin
J. Am. Chem. Soc.
Novel helical Co(II) and Zn(II) complexes and a trimeric Zn(II) complex are prepared which serve as an entry point for the use of dipyrromethenes in self-assembly and supramolecular chemistry. These metal complexes of polypyrromethenes are uncharged with no counterions present, thus providing facile isolation, via chromatography if necessary. The crystal structures of helical complexes L2Zn2 where L = dianionic polypyrromethene I (n = 0, R = R2 = R4 = Me, R3 = Et) and L2Co2 where L = I (n = 1, R1 = R3 = R4 = Et, R
= Me) were determined by single-crystal x-ray diffraction. Reaction of a ligand comprising two dipyrromethenes linked at the α position afforded a 3:3 ligand:metal complex L'3Zn3.