Assembly of inorganic [Mo(2)S(2)O(2)](2+) panels connected by selenite anions to nanoscale chalcogenide–polyoxometalate clusters

We describe how supramolecular assembly, mediated by control of the ratio of the hetero-atoms in the units [Mo(2)S(2)O(2)](2+) and SeO(3)(2–) leads to the formation of new types of building blocks, [(Mo(2)O(2)S(2))(3)(OH)(4)(H(2)O)(6)(SeO(3))] = {Mo(6)} and [(Mo(2)O(2)S(2))(2)(OH)(2)(H(2)O)(4)(SeO(3))] = {Mo(4)} which are linked in an type of inorganic ‘panelling’ to the assembly of a range of new clusters 1–3 with the general formula {(Mo(2)O(2)S(2))(x)(OH)(y)(SeO(3))(z)(H(2)O)(w)}(n–), where x, y, z, w, n = [8, 0, 20, 8, 24] for 1, [14, 14, 17, 8, 20] for 2 and [8, 8, 8, 0, 8] for 3. Cluster 1, a rare example of inorganic cryptand, exhibits an elliptical “endo” motif defining an anisotropic ellipse with the dimensions 1.7 × 1.0 nm, with pores ranging from 5.3 to 6.4 Å and site selective cation recognition properties; cluster 2 exhibits an “exo” structural motif constructed by 3 × {Mo(6)} and 2 × {Mo(4)} panels spanning a cross shape 2.4 × 2.0 nm and cluster 3 a ring shaped structure of a 1.5 nm in diameter. The control of endo vs. exo topology as a function of the Se : Mo ratio is reflected to the difference in surface area of ca. 500 Å(2) between clusters 1 and 2 intermolecular interactions and proton conduction properties, and this work shows that very simple synthetic parameters can critically change the structure and properties of all-inorganic nanoscale chalcogenide–polyoxometalates.