Inorganic-organic hybrid materials with different dimensions constructed from copper-fluconazole metal-organic units and Keggin polyanion clusters

Inorganic-organic hybrid materials based on Keggin polyoxometalate building blocks combined with Cu-II/Cu-I and flexible fluconazole ligand [1-(2,4-difluorophenyl)-1,1-bis[(1H-1,2,4-triazol-1-yl)-methyl]methanol] (Hfcz) have been obtained by hydrothermal methods, namely, [Cu-2(II)(Hfcz)(4)(SiW12O40)center dot 3H(2)O (1), [Cu-4(II)(fcz)(4)(H2O)(4)(SiMo40)]center dot 6H(2)O (2), [Cu-2(II)(fcz)(2)][Cu-4(II)(fcz)(4)(SiW12O40)][Cu-2(II)(fcz)(2)(H2O)(2)(SiW12O40)]center dot 6H(2)O (3), (Et3NH)(2)[Cu-2(I)(Hfcz)(2)(SiW12O40)]center dot 2H(2)O (4), (Et3NH)(2)[Cu-2(I)(Hfcz)(2)(SiW12O40)]center dot H2O (5) and [Cu-4(I)(Hfcz)(4)(SiMo12O40)] (6). Their structures have been determined by single-crystal X-ray diffraction analyses, and the compounds are further characterized by elemental analyses, IR spectra and thermogravimetric (TG) analyses. In 1, Cu(II) cations are bridged by fluconazole ligands to form a 3D lvt coordination polymeric network, which is connected by (SiW12O40)(4-) anions to form a complicated 3D (4,6)-connected framework with the topology of (4(2.)6(4))(4(6.)6(7.)8(2))(2). In 2, two fcz(-) anions chelate two Cu2+ cations to form a [Cu(fcz)(2)(2+) dimer, which is bridged by (SiW12O40)(4-) polyanions to generate a 2D (4,4) grid. Compound 3 is formed by three types of co-crystallizing subunits including a dimer [Cu(fcz)](2)(2+), a dumbbell molecule [Cu-4(fcz)(4)(SiW12O40)] and an infinite chain {[Cu-2(fcz)(2)(H2O)(2)(SiW12O40)](2-)}(infinity). In compounds 4 and 5, Hfcz ligands link Cu+ cations to generate 1D coordination polymeric units, and (SiW12O40)(4-) polyanions connect these metal-organic units to form two types of (6(3)) sheets which are topological isomerism. In compound 6, (siMo(12)O(40))(4-) polyanions fixed in Cu-I-Hfcz square rings are further extended into a 2D sheet via linking Cu-I atoms of different rings. By carefully inspection of the structures of 1-6, it is believed that various transition-metal organic units and Keggin polyanions with different coordination modes are important for the formation of the different structures. In addition, electrochemical behaviors of compounds 1, 2, 5 and 6 have been investigated.