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

The supramolecular binding exclusively by H-bonds of SeO4 2-, MoO4 2- and WO4 2- ions to form nanojars of the formula [EO4 2-subset of{cis-CuII(mu-OH)(mu-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 1H 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 SeO4 2-, MoO4 2- or WO4 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 Cu8+Cu14+Cu10 ring combination of a nanojar with an entrapped tetrahedral anion. Also, the first crystal structure of a supramolecular host-guest complex with an entrapped WO4 2- ion, Cu 31 WO 4 is reported in this work. The relative strength of binding of SeO4 2-, MoO4 2- and WO4 2- ions by nanojars of different sizes was assessed by reactivity studies toward Ba2+ ions and NH3. Thermal stability studies of the various Cu n EO 4 nanojars were conducted in DMSO-d 6 solutions over a 22-150 degrees C range. Furthermore, liquid-liquid extraction of SeO4 2-, MoO4 2- and WO4 2- ions from water into an organic solvent by nanojars was investigated.