Chromate Incarceration by Nanojars and Its Removal from Water by Liquid-Liquid Extraction.

The unprecedented liquid-liquid extraction of the dinegative chromate ion (CrO) from neutral aqueous solutions into aliphatic hydrocarbon solvents using nanojars as extraction agents is demonstrated. Transferring chromate from water into an organic solvent is extremely challenging due to its large hydration energy (Δ° = -950 kJ/mol) and strong oxidizing ability. Owing to their highly hydrophilic anion binding pockets lined by a multitude of hydrogen bond donor OH groups, neutral nanojars of the formula [-Cu(μ-OH)(μ-4-Rpz)] ( = 27-33; pz = pyrazolate anion; R = H or -octyl) strongly bind the CrO ion and efficiently transfer it from water into -heptane or C - C isoalkanes (when R = -octyl).

Mapping the Intricate Reactivity of Nanojars toward Molecules of Varying Acidity and Their Conjugate Bases Leading To Exchange of Pyrazolate Ligands.

A comprehensive reactivity study of nanojars toward 18 different acidic compounds with varying pK, including 12 different carboxylic acids (both aliphatic and aromatic mono- and dicarboxylic acids), p-toluenesulfonic acid, hydrogen sulfate, hydrogen carbonate, carbonic acid, 1-decanethiol, and methanol, as well as four different conjugate bases (formate, acetate, benzoate, 2-bromoethanesulfonate) is carried out with the aid of electrospray-ionization mass spectrometry. Thus, the effect on nanojar substitution and breakdown pattern of a number of variables, such as concentration of reagent (acid or conjugate base), acidity of reagent (pK), effect of acid vs conjugate base, steric effects, aromaticity, incarcerated anion and size of the nanojar, is evaluated. Of the substitution and breakdown products identified by mass spectrometry, acetate-substituted nanojars (BuN)[CO⊂{Cu(μ-OH)(μ-pz)(μ-CHCOO)}] (x = 1 and 2), as well as dimeric complexes (BuN)[Cu(μ-pz)A] (A = CO and SO) have been isolated and characterized by single-crystal X-ray diffraction.

Sulfate-Incarcerating Nanojars: Solution and Solid-State Studies, Sulfate Extraction from Water, and Anion Exchange with Carbonate.

A series of 9 homologous sulfate-incarcerating nanojars [SO⊂{Cu(OH)(pz)}] (Cu; n = 27-33; pz = pyrazolate), based on combinations of three [Cu(OH)(pz)] rings (x = 6-14, except 11)-namely, 6 + 12 + 9 (Cu), 6 + 12 + 10 (Cu), 8 + 13 + 8 (Cu), 7 + 13 + 9 (Cu), 8 + 14 + 8 (Cu), 7 + 14 + 9 (Cu), 8 + 14 + 9 (Cu), 8 + 14 + 10 (Cu), and 9 + 14 + 10 (Cu)-has been obtained and characterized by electrospray-ionization mass spectrometry (ESI-MS), variable-temperature H NMR spectroscopy, and thermogravimetry. The X-ray crystal structure of Cu (8 + 13 + 8) is described. Cu and Cu, which are the largest nanojars in this series, are observed for the first time.