Multidimensional Metal−Organic Frameworks Constructed from Flexible Bis(imidazole) Ligands

Abstract

Two structurally related flexible bis(imidazole) ligands, N,N'-(1,1-methyl)bis(imidazole) (L1) and N,N'-(1,4-butanediyl)bis(imidazole) (L2) reacted with AgI, CuII, ZnII, and CdII salts under hydrothermal conditions (except for 2 at room temperature), resulted in the formation of eight novel metal−organic coordination architectures, from one-dimensional (1D) chain to three-dimensional (3D) network structures: {[Ag(L1)2]ClO4}n (1), {[Cu(L1)2(H2O)2]Cl2(H2O)0.5(acetone)}n (2), {[Cu(L1)2](BF4)2}n (3), {[Cu(L1)2](ClO4)2}n (4), {[Zn(L1)3](ClO4)2}n (5), {[Cd(L1)3](ClO4)2}n (6), {[Cd(L1)2](N3)2}n (7), and {[Zn(L2)2](ClO4)2}n (8). All complexes have been structurally characterized by X-ray diffraction analysis. In 1, the AgI centers are two-coordinate with linear geometry and L1 ligands bridge the AgI centers to form 1D single helical chains. 2 and 7 have 1D double chain structures with the central metal ions being six-coordinated by four discrete L1 and two apical ligands (water molecules for 2 and N3- for 7). 3 and 4 are isostructural two-dimensional (2D) (4,4) networks with square planar CuII centers. 5 and 6 also are isostructural with CdSO4-like 3D framework structures. In 8, the ZnII ions are tetrahedral, and each L2 ligand links two ZnII ions to form a 1D double chain.