New three- and four-armed flexible bridging ligands for use in metallosupramolecular chemistry: syntheses and X-ray structures

Preparations are described of twelve new tritopic and tetratopic ligands by coupling of two phenolic precursors with a range of heterocyclic units. X-ray crystal structures of four representative examples revealed the conformations in the solid state with the nitrogen donor atoms separated by distances ranging from 10.9 to 18.2 Å.