Efficient one-pot synthesis of [3]catenanes based on Pt(II) metallacycles with a flexible building block

Two quadrilateral metallacycles were prepared by coordination-driven self-assembly of a 90° platinum(II) receptor 6 with a flexible donor 1,3-bis(4,4′-bipyridinium)propane 1a or 1,1-bis(4,4′-bipyridinium)methane 1b, respectively. Three [3]catenanes (3, 4 and 5) were further prepared by in situ addition of crown ethers (DB24C8 or DB30C10) to the yielded metallacycles. By comparing the crystal structures of 1a and 4, it was found that the bite angle change of the flexible bidentate donor 1a (111.0° to 112.3°) is much smaller than that of rigid platinum(II) receptor 6 (90.0° to 83.2°) during metalla-cyclization. The multicomponent [3]catenanes were stabilized by multiple supramolecular interactions, including metal coordination, π–π stacking, charge transfer, and hydrogen bonding.