New microporous copper(II) coordination polymers based upon bifunctional 1,2,4-triazole/tetrazolate bridges

Abstract

A series of Cu(II) coordination polymers, [Cu(μ2-L1)3]PO3F (1), [Cu2(μ2-L1)4(μ4-L1)](NO3)4·2H2O (2), [Cu(μ2-L1)2(μ2-X)]X·12H2O (X = Cl, 3; Br, 4), [Cu4(μ2-OH)2(μ4-L1)3(μ2-L1)2(H2O)2](CF3SO3)6·10H2O (5), [Cu3(μ2-OH)2(μ4-L1)(H2O)2(μ3-SO4)2] (6), [Cu(μ4-L1)(μ2-SO4)]·6H2O (7), [Cu2(μ4-L2)3]Cl·12H2O (8) involving new bifunctional p-phenylene bridged bi(1,2,4-triazole) and mixed 1,2,4-triazole-tetrazolate based ligands (L1= 1,4-phenylene-4,4′-bi(1,2,4-triazole), HL2= 5-(4-[1,2,4]triazol-4-yl-phenyl)-1H-tetrazole) has been prepared under hydrothermal conditions and their structures have been established by means of X-ray diffraction. In crystal structures 1–8, the organic ligands, utilizing two neighboring nitrogen atoms (N1, N2 in triazole (trz) and N2, N3 in tetrazolate), behave either in μ2 or in μ2 + μ4 manner binding the adjacent metal centers or Cu3(μ2-OH)2 clusters into 1D columns (1, 3, 4), 2D zigzag layers (2) and 3D frameworks (5–8). The mutual coplanarity between uncoordinated trz moiety and p-phenylene spacer as well as its radial disposition around the “propeller-like” [Cu2(η2-trz)3] subunits is a crucial factor, which specifically mediates multiple π–π interactions through intercalation of the neighboring Cu(η2-trz)n (n = 2,3) axles, and as a consequence, affording one-dimensional channels with trigonal (1, 2) or rhombic geometry (3, 4). Large rectangular channels have been realized in neutral [Cu(μ4-L1)(μ2-SO4)]n (7) and cationic [Cu2(μ4-L2)3]nn+ (8) frameworks, in which the remaining void space is filled by water molecules and counter anions (Cl−).