Sequential synthesis of rigid multi-bipyridine ligands bearing diethynyl/phenyl solubilizing fragments

Reliable and practical synthetic routes for the construction of multitopic bipyridine ligands are presented. The first series contains the chelating fragments connected via an ethynyl function and the second series is built from an alternation of ethynyl/phenyl/bipyridine modules. The synthetic protocol is based on sequential Pd-promoted cross-coupling reactions between selected bis-bpy or ethynyl/phenyl/bpy intermediates of increasing size. The ligands bearing functionalized 1,4-diethynyl-2,5-di(dodecyloxy)benzene subunits are soluble in chlorinated solvents.