A Pseudorotaxane System Containing γ-Cyclodextrin Formed via Chiral Recognition with an AuI6AgI3CuII3 Molecular Cap

Solvent-mediated crystal-to-crystal transformations of [Au 6 Ag 3 Cu 3 (H 2 O) 3 ( d -pen) 6 (tdme) 2 ] 3+ ( d -[ 1 (H 2 O) 3 ] 3+ ; pen 2- = penicillaminate, tdme = 1,1,1-tris(diphenylphosphinomethyl)ethane) to form unique supramolecular species are reported. Soaking crystals of d -[ 1 (H 2 O) 3 ] 3+ in aqueous Na 2 bdc (bdc 2- = 1,4-benzenedicarboxylate) yielded crystals containing d -[ 1 (bdc)(H 2 O) 2 ] + due to the replacement of a terminal aqua ligand in d -[ 1 (H 2 O) 3 ] 3+ by a monodentate bdc 2- ligand. When γ-cyclodextrin (γ-CD) was added to aqueous Na 2 bdc, d -[ 1 (H 2 O) 3 ] 3+ was transformed to d -[ 1 (bdc@γ-CD)(H 2 O) 2 ] + , where a γ-CD ring was threaded by a bdc 2- molecule to construct a pseudorotaxane structure. While the use of dicarboxylates with an aliphatic carbon chain instead of bdc 2- afforded analogous pseudorotaxanes, such pseudorotaxane species were not formed when crystals of [Au 6 Ag 3 Cu 3 (H 2 O) 3 ( l -pen) 6 (tdme) 2 ] 3+ ( l -[ 1 (H 2 O) 3 ] 3+ ) enantiomeric to d -[ 1 (H 2 O) 3 ] 3+ were soaked in aqueous Na 2 bdc and γ-CD, affording only crystals containing l -[ 1 (bdc)(H 2 O) 2 ] + .