[Co(2,2'-bipy) 3 ]Ag 3 I 6 with a hole structure facilitates dye adsorption and photocatalytic reduction.

We synthesized a new iodoargentate [Co(2,2'-bipy) 3 ]Ag 3 I 6 (1) (2,2'-bipy = 2,2'-bipyridine) via the reaction of AgI, KI, 2,2'-bipy and Co(NO 3 ) 2 in dimethylformamide (DMF) solvent at room temperature. The [Co(2,2'-bipy) 3 ] 3+ complex cation directs the formation of the 0 D cluster [Ag 3 I 6 ] 3- anion that features an irregular double-level gear wheel with a maximum diameter of 5.512 Å. The iodoargentate possesses the characteristics of semiconductors with a band gap of 2.03 eV. It exhibits excellent ion-exchange behavior for adsorbing crystal violet (CV) and methylene blue (MB), and it can function as a promising photocatalyst for degrading rhodamine B (RhB). The improved photocatalytic activity can be ascribed to the hole structure in the anions of iodoargentates.