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 (H(2)l), 4,4'-bis(mercaptomethyl)-trans-stilbene (H(2)2), and 1,4-dimethoxy-2,5-bis(mercaptomethyl) benzene (H(2)3), 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. As2L2Cl2 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)Cl(2) can be controlled using host-guest interactions by the prudent choice of crystallization solvents. anti-As(2)3(2)Cl(2) crystallizes exclusively from chloroform and benzene, while a [(syn-As(2)3(2)Cl(2))(2) center dot p-xylene] dimer crystallizes from p-xylene and a mixture of [(syn-As(2)3(2)Cl(2))(anti-As(2)3(2)Cl(2)) center dot toluene] and [(syn-As(2)3(2)Cl(2))(2) center dot toluene] dimers crystallize from toluene.