Supramolecular Entrapping and Extraction of Selenate, Molybdate and Tungstate Ions from Water by Nanojars.

The supramolecular binding exclusively by H-bonds of SeO(4)(2-), MoO(4)(2-) and WO(4)(2-) ions to form nanojars of the formula [EO(4)(2-)⊂{cis-Cu(II)(μ-OH)(μ-pz)}(n)](2-) (Cu(n)EO(4); E = Se, Mo, W; n = 28-34; pz = pyrazolate) was studied in solution by electrospray ionization mass spectrometry, variable temperature, paramagnetic (1)H NMR and UV-vis spectroscopy, and in the solid state by single-crystal X-ray crystallography. These large anions allow for the observation of a record nanojar size, Cu(34)EO(4) (E = Mo, W). Six crystal structures are described of nanojars of varying sizes with either SeO(4)(2-), MoO(4)(2-) or WO(4)(2-) entrapped ions, including the first example of a cocrystal of two different nanojars in crystallographically unique positions, Cu(31)MoO(4) and Cu(32)MoO(4). The latter provides unprecedented structural information about the Cu(8)+Cu(14)+Cu(10) ring combination of a nanojar with an entrapped tetrahedral anion. Also, the first crystal structure of a supramolecular host-guest complex with an entrapped WO(4)(2-) ion, Cu(31)WO(4) is reported in this work. The relative strength of binding of SeO(4)(2-), MoO(4)(2-) and WO(4)(2-) ions by nanojars of different sizes was assessed by reactivity studies toward Ba(2+) ions and NH(3). Thermal stability studies of the various Cu(n)EO(4) nanojars were conducted in DMSO-d(6) solutions over a 22-150 °C range. Furthermore, liquid-liquid extraction of SeO(4)(2-), MoO(4)(2-) and WO(4)(2-) ions from water into an organic solvent by nanojars was investigated.