Scandium(III) Coordination Polymers Containing Capsules Based on Two p-Sulfonatocalix[4]arenes

Reactions of sodium p‐sulfonatocalix[4]arene and scandium(III) tris‐triflate in the presence, and absence, of [18]crown‐6 give the crystalline complexes [Sc2(μ‐OH)2(H2O)10]{Na4(H2O)8[calix[4]arene(SO3)4]2}⋅13 H2O and {[Sc2(μ‐OH)2(H2O)8][Sc(H2O)4]2[calix[4]arene(SO3)4‐H+]2([18]crown‐6)}⋅16 H2O. Both complexes involve novel coordination polymers with calixarene units linked through sodium or scandium centers and also feature capsule assemblies through to the head‐to‐head association of calixarenes. A linear array of capsules associated with an infinite chain of aquo‐bridged sodium ions, and an aquated hydroxy‐bridged scandium(III) dimer, [Sc2(μ‐OH)2(H2O)10]4+, are found in the absence of the crown ether. In the presence of [18]crown‐6 both hydrated scandium monomers and dimers bridge between calixarenes in a two‐dimensional coordination network. The crown ethers reside in cavities created by two calixarenes from adjacent polymeric sheets via a variety of supramolecular interactions(hydrogen‐bonding, shape complementarity), and effectively add a third dimension to the network. The extended structure of both of these polymers is highly porous, and resembles a bilayer. A chain of calixarene capsules encapsulating aquo‐bridged sodium atoms characterizes the anion (see picture) of a crystalline supramolecular complex formed by reaction of sodium p‐sulfonatocalix[4]arene and scandium(III) tris‐triflate. In the presence of [18]crown‐6 a two‐dimensional coordination polymer is formed through ScIII–calixarene interactions, with host–guest interactions between the calixarenes and crown ether molecules effectively imparting a third dimension to the network.