Supramolecular self-assembly of dinuclear alkynylplatinum(II) complexes into highly ordered crystalline hexagonal bipyramid superstructures

We demonstrate the formation of highly symmetric crystalline hexagonal bipyramid-shaped superstructures in the self-assembly of dinuclear Pt(II) terpyridine complexes and show that it proceeds via a nonclassical crystallization (NCC) growth mechanism, which has not been reported in the supramolecular self-assembly of metal-organic complexes previously. Instead of identifying the classical hexagonal-shaped nuclei, we observed the intermediates of nanorods and pseudo-hexagonal shapes, establishing a previously unreported growth pattern of crystallization with direct experimental evidence for the NCC mechanism, which is the first of its kind in organic/organometallic supramolecular self-assembly. In addition, the crystal structures of the hexagonal bipyramids were found to be constructed from a weaving-like trimeric motif that elongates into a 2D hexagonal network by Pt···Pt, π-π, and hydrophobic interactions. It is envisaged that the current molecular packing strategy and the discovery of this NCC pathway will provide new insights into the rational design of geometric-shaped crystalline materials via supramolecular self-assembly.