Survival of the Fittest Nanojar: Stepwise Breakdown of Polydisperse Cu 27 −Cu 31 Nanojar Mixtures into Monodisperse Cu 27 (CO 3 ) and Cu 31 (SO 4 ) Nanojars

Nanojars are emerging as a class of anion sequestration agents of unparalleled efficiency. Dinegative oxoanions (e.g., carbonate, sulfate) template the formation of a series of homologous nanojars [Cu(OH)(pyrazolato)] n ( n =27–31). Pyridine selectively transforms less stable, larger CO 3 2− nanojars ( n =30, 31) into more stable, smaller ones ( n =27, 29), but leaves all SO 4 2− nanojars ( n =27–29, 31) intact. Ammonia, in turn, transforms all less stable nanojars into the most stable one and allows the isolation of pure [CO 3 2− ⊂{Cu(OH)(pz)} 27 ] and [SO 4 2− ⊂{Cu(OH)(pz)} 31 ]. A comprehensive picture of the solution and solid‐state intricacies of nanojars was revealed by a combination of variable temperature NMR spectroscopy, tandem mass spectrometry, and X‐ray crystallography.