Supramolecular assemblies of calix[4]arenes organized by feeble forces

X-ray crystallographic investigations have shown that dimeric supramolecular assemblies of water-soluble calix[4]arenes are formed by a combination of hydrophobic effects and either hydrogen bonding or secondary bonding. For Na-4(pyridinium)[calix [4]arene sulfonate]center dot 8H(2)O, a dimeric arrangement based on hydrogen bonding and hydrophobic effects is found. The compound crystallizes in the monoclinic space group P2(1)/n with a = 11.873(3), b = 24.345(6), c = 14.846(3) angstrom, beta 96.78(2)degrees, and D-c = 1.66 g cm(-3) for Z = 4, Refinement based on 3492 observed reflections led to a final R value of 0.051. For [Cu(NC5H5)(H2O)(3)](Na)(3)[calix[4]arene sulfonate]center dot 13 H2O, the dimeric association is based on a secondary bonding interaction between the copper(II) ion and a sulfonate oxygen atom combined with hydrophobic interactions. The compound crystallizes in the monoclinic space group P2(1)/n with a = 14.672(3), b = 25577(5), c = 15.457(3) angstrom, beta = 101.94(4)degrees, and D-c = 1.55 g cm(-3) for Z = 4. Refinement based on 3602 observed reflections afforded a final R value of 0.064.