Stepwise construction of pyrene bridged polytopic ligands carrying acetylenic tethers

Reliable and practical synthetic routes for the construction of polytopic bipyridine or terpyridine frameworks are presented. These ligands are prepared by sequential Pd-promoted cross-coupling reactions between selected ethynyl substituted bipyridine or terpyridine building blocks and 1,6-dibromopyrene. A convergent synthetic route for the preparation of Ru complexes bearing peripheral uncomplexed fragments has been established starting from preorganized building blocks carrying a bromide function. This protocol highlights the use of metallo-synthons in Sonogashira cross-coupling reactions and allows the synthesis of very soluble complexes.