A 3D all-inorganic architecture based on the [H2W12O42]10− building block with different alkaline-earth metal linkers: crystal structures, surface photovoltage and photoluminescent properties

Abstract

Three-dimensional (3D) all-inorganic polyoxometalate compounds, Ca2Na6[H2W12O42]·30H2O (1), Sr4H2[H2W12O42]·26H2O (2), Sr4Na2[H2W12O42]·30H2O (3) and Ba4Na2[H2W12O42]·29.5H2O (4) have been synthesized and their structures consist of [H2W12O42]10− building units and alkaline-earth metal cations (Ca2+, Sr2+ and Ba2+) as linkers. The most interesting feature is that compound 2 represents the first example of a 3D all-inorganic framework in which the paradodecatungstate-B anions [H2W12O42]10− were linked by pure alkaline-earth metal cations. Moreover, each [H2W12O42]10− building unit in compound 2 acts as a decadentate ligand coordinated with ten Sr2+ ions, which represents the highest coordination number of [H2W12O42]10− with alkaline-earth metal cations so far. Another interesting feature is that compounds 1–4 exhibit a clear response to surface photovoltage and electric field-induced surface photovoltage, which is indicative of the semiconductor property and suggests these compounds have potential applications as photocatalysts and light-to-electricity conversion materials.