Extended organic-inorganic hybrids based on Dawson and double-Dawson-type polyoxometalates

The reaction between K-12[H2P2W12O48] and CuCl2 in a NaCl aqueous solution assisted with organoamines (1,2-ethylenediamine (en), 1, 6-hexamethylene diamine (hn), or both) leads to the isolation of three compounds: K4Na10[alpha(1)-CuP2W17O60(OH)](2) center dot similar to 58H(2)O (1), Na-2[H(2)en][H(2)hn](0.5)[Cu(en)(2)](4.5)[alpha(1)-CuP2W17O6O(OH)](2) center dot similar to 43H(2)O (2), and Na-3[H(2)hn](2.5)[(alpha(1)-P2W17O60Cu(OH)(2)] center dot similar to 14H(2)O (3). The polyoxoanion [alpha 1-CuP2W17O60(OH)](2)(14-) in 1 and 2 exhibits a double-Dawson-type polyoxoanion that consists of two alpha(1)-type mono-Cu-substituted Wells-Dawson anions, which can be synthesized by both the conventional aqueous solution method and the hydrothermal technique. Furthermore, the double-Dawson-type polyoxoanions in 2 are linked by the [Cu(en)(2)](2+) bridges to form 2-D networks, which are further packed into a 3-D supramolecular porous framework via extensive hydrogen bonding interactions, exhibiting two types of tunnels (A and B), Compound 3 possesses a 3-D supramolecular framework with 1-D tunnels constructed from the alpha(1)-type mono-Cu-substituted Wells-Dawson anion. The magnetic studies of compounds 1 and 2 indicate that weak antiferromagnetic interactions exist in these two compounds.