Nanoscaled Bismuth Oxido Clusters: Probing Factors of Structure Formation and Photocatalytic Activity†

Hydrolysis of bismuth(III) nitrate in the presence of sodium benzoate (NaOBz) in dimethyl sulfoxide (DMSO) gave the bismuth oxido cluster [{Bi38O45(NO3)20(OBz)4(DMSO)24}·4DMSO][{Bi38O45(NO3)24(DMSO)26}·4DMSO] (1), which crystallizes in the monoclinic space group P21/c with cell parameters of a = 35.8728(12) A, b = 20.2750(5) A, c = 34.8624(11) A, and β = 111.797(4)°. The asymmetric unit contains two crystallographically independent bismuth oxido clusters of different composition. Because of the distinct structural relationship of this type of bismuth oxido clusters with the photocatalytically active polymorph β-Bi2O3, colloidal suspensions of nanoscaled 1 as well as colloids composed of the recently reported clusters [Bi6O4(OH)4(NO3)6]·H2O (2), [{Bi38O45(NO3)24(DMSO)26}·2DMSO][{Bi38O45(NO3)24(DMSO)24}·0.5DMSO] (3), and [Bi38O45(OMc)24(DMSO)9]·2DMSO·7H2O (4) were probed for their photocatalytic activity. The bismuth oxido cluster 3 decomposes more than 85 % of a 1 × 10–5 M aqueous solution of rhodamine B (RhB) under visible-light irradiation within 150 min. Colloids of such clusters might serve as model compounds for indirect photodegradation processes of organic contaminants at the metal oxide surface.