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 HgCl 2 afforded a heterochiral cyclic dimer complex, [Hg 2 ( pR - L )( pS - L )Cl 4 ]·8CH 2 Cl 2 ( 1 ), in which two Hg 2+ 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(CH 2 ) 8 CN ( G ), yielded a one-dimensional poly-pseudo-rotaxane, {[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.