Synthesis and characterization of a mixed-valence hexadecavanadate cluster with half-open framework

A new mixed-valence hexadecavanadate cluster compound, (Me2NH2)4[H6V16O42(SO4)] · 8H2O (1), has been synthesized via an efficient method in organic media. The hollow cluster shell of 1, with a sulfate ion locating in its centre, exhibits four large eight-membered –O–V–O–V– rings on its surface, which makes the cluster into a half-open structure distinguished from the common hollow clusters built up with closed surfaces. The intense blue luminescence of 1 in solution state is scarcely reported for the polyoxometalate clusters.