Solvent-Dependent Self-Assembly of a Pillar[5]arene-Based Poly-Pseudo-Rotaxane Linked and Threaded by Silver(I) Trifluoroacetate: A Double Role.

In the supramolecule area, the fabrication of a new concept called polyrotaxanes or poly-pseudo-rotaxanes remains challenging. We herein report the formation of a poly-pseudo-rotaxane in which the same salt-type guest serves both linking and threading in the resulting structure. The combination of A1/A2-thiopyridyl pillar[5]arene ( L ) and silver(I) trifluoroacetate in CHCl 3 /CH 3 OH afforded a one-dimensional (1D) poly-pseudo-rotaxane. In this structure, to our surprise, the AgCF 3 CO 2 guest not only links the di-armed L ligands via an infinite - L -Ag- L -Ag- arrangement but also threads into a pillar[5]arene cavity in a dimer form, (AgCF 3 CO 2 ) 2 . In contrast, the same reaction in CH 2 Cl 2 /CH 3 OH yielded a simple 1D coordination polymer because an included CH 2 Cl 2 molecule in the pillar[5]arene cavity prevents the threading of the silver(I) trifluoroacetate guest. Comparative 1 H- and 19 F-NMR studies support the solvent-dependent poly-pseudo-rotaxane formation at a lower concentration of L .