Host-guest interactions in a series of self-assembled As2L2Cl2 macrocycles

The reaction of AsCl3 with H2L (where L = a rigid dithiolate) results in the self-assembly of As2L2Cl2 supramolecular macrocycles. For ligands 4,4'-bis(mercaptomethyl)biphenyl (H2), 4,4'-bis(mercaptomethyl)-trans-stilbene (H2), and 1,4-dimethoxy-2,5-bis(mercaptomethyl)benzene (H2), the macrocyclic cavities of the resulting assemblies are large enough to host aromatic solvent molecules, as revealed by single crystal X-ray structures of the inclusion complexes. As2L2Cl(2) macrocycles form in solution as a mixture of diastereomers, but the diastereomers can be selectively crystallized and separated. Crystallization of syn- or anti-As(2)3(2)Cl2 can be controlled using host-guest interactions by the prudent choice of crystallization solvents. anti-As(2)3(2)Cl2 crystallizes exclusively from chloroform and benzene, while a [(syn-As(2)(2)Cl(2))(2).p-xylene] dimer crystallizes from p-xylene and a mixture of [(syn-As(2)3(2)Cl(2))(anti-As(2)3(2)Cl2) x toluene] and [(syn-As(2)3(2)Cl2)2 x toluene] dimers crystallize from toluene.