Hydrolysis to the first dumbbell-like high-nuclearity bismuth-oxo cluster [Bi12(μ3-OH)4(μ2-OH)2(μ3-O)8(μ4-O)2(NO3)6]4+: Synthesis, structure and spectroscopic characterizations

The first dumbbell-like high-nuclearity bismuth-oxo cluster [Bi12(μ3-OH)4(μ2-OH)2(μ3-O)8(μ4-O)2(NO3)6](NO3)4 · 6H2O was obtained by diffusing ethanol into the hydrolysate of Bi(NO3)3 aqueous solution. The dumbbell consists of two Bi–O bonds as the handle and two [Bi6(μ3-OH)2(μ2-OH)(μ3-O)4(μ4-O)] subunits as the bells. The bell can be regarded as a piercing bracelet-like ring consisted of six edge-sharing tetragons with one cross section enveloped by one μ3-O linking three Bi(III) atoms and the other connected by one μ2-O as a open cover. The structure is further stabilized by the interactions of Bi⋯Bi, Bi⋯O and hydrogen bondings. The optical gap of 2.85 eV suggests that the title compound behaves as semiconductors. The title compound features a blue fluorescence at 441 nm, which is assigned to 1P1–1S0 and 3P–1S0 transitions from the s2 electron of Bi3+ cation.