4,4'-Biphenyldisulfonic acid induced coordination polymers of symmetrical tetramethyl cucurbit[6] uril with alkaline-earth metals for detection of antibiotics

Three new coordination polymers based on macrocyclic symmetrical tetramethyl cucurbit[6]uril (TMeQ[6]) with formulae {[Ca-2(C40H44N24O12)(H2O)(10)](C12H8O6S2)(2)}center dot 13H(2)O (1), {[Sr(C40H44N24O12)(H2O)(4)](C12H8O6S2)}center dot 13H(2)O (2), and {[Ba-2(C40H44N24O12)(C12H8O6S2)](C12H8O6S2)(H2O)(7)}center dot 12H(2)O (3) have been obtained by the self-assembly of TMeQ[6] with the corresponding alkaline-earth metal salts in the presence of 4,4 '-biphenyldisulfonic acid (H2BPDS). Single crystal X-ray diffraction analysis of these three coordination polymers reveals that the deprotonated 4,4 '-biphenyldisulfonic acid (H2BPDS2-) plays an important role in the self-assembly of these coordination polymers. In complexes 1 and 2, only the TMeQ[6] is involved in coordination with the Ca2+ and Sr2+ ions. The BPDS2- is involved in "outer-surface interactions " with the TMeQ[6]. Meanwhile, in complex 3, the BPDS2- is also coordinated with the Ba2+ ion. These coordination polymers provide a new strategy to design and construct Q[n]-based poly-dimensional coordination polymers, which can be built by one-dimensional Q[n]-metal coordination chains via outer-surface interactions. Furthermore, complex 1 can detect NFX (norfloxacin) molecules with high selectivity.