A Pseudorotaxane System Containing γ-Cyclodextrin Formed via Chiral Recognition with an Au Ag Cu Molecular Cap.

Solvent-mediated crystal-to-crystal transformations of [Au Ag Cu (H O) (d-pen) (tdme) ] (d-[1(H O) ] ; pen =penicillaminate, tdme=1,1,1-tris(diphenylphosphinomethyl)ethane) to form unique supramolecular species are reported. Soaking crystals of d-[1(H O) ] in aqueous Na bdc (bdc =1,4-benzenedicarboxylate) yielded crystals containing d-[1(bdc)(H O) ] due to the replacement of a terminal aqua ligand in d-[1(H O) ] by a monodentate bdc ligand. When γ-cyclodextrin (γ-CD) was added to aqueous Na bdc, d-[1(H O) ] was transformed to d-[1(bdc@γ-CD)(H O) ] , where a γ-CD ring was threaded by a bdc molecule to construct a pseudorotaxane structure. While the use of dicarboxylates with an aliphatic carbon chain instead of bdc afforded analogous pseudorotaxanes, such pseudorotaxane species were not formed when crystals of [Au Ag Cu (H O) (l-pen) (tdme) ] (l-[1(H O) ] ) enantiomeric to d-[1(H O) ] were soaked in aqueous Na bdc and γ-CD, affording only crystals containing l-[1(bdc)(H O) ] .