Metallosupramolecules of Pillar[5]arene with Two Flexible Thiopyridyl Arms: A Heterochiral Cyclic Dimer and Organic Guest-Assisted Homochiral Poly-Pseudo-Rotaxanes

The formation of a cyclic dimer complex (1) and a poly-pseudo-rotaxane (2) of a racemic A1/A2-thiopyridyl pillar[5]arene (rac-L) with different chirality is reported. A one-pot reaction of rac-L with HgCl2 afforded a heterochiral cyclic dimer complex, [Hg-2(pR-L)(pS-L)Cl-4]center dot 8CH(2)Cl(2) (1), in which two Hg2+ atoms and one (pR-L)/(pS-L) enantiomeric pair form a [2:2] metallacycle via a metal coordination-based cyclization. Interestingly, the same reaction in the presence of the linear dinitrile guest, CN(CH2) 8CN (G), yielded a one-dimensional poly-pseudorotaxane, {[Hg(G@pR-L)Cl-2][Hg(G@pS-L)Cl-2]}(n) (2), probably due to the rigidified ligand structure resulting from the dinitrile guest (G) threading. In 2, pR-L and pS-L generate two separated homochiral poly-pseudo-rotaxanes in a crystal. Both products are new members of the pillararene-derivative family. This study improves our understanding of self-assembly in nature and leads to this approach being an engineering tool for the construction of mechanically interlocked supramolecules.