A series of metal–organic frameworks based on a semi-rigid bifunctional ligand 5-[(1H-1,2,4-triazol-1-yl)methoxy] isophthalic acid and flexible N-donor bridging ligands

Abstract

Eight metal–organic frameworks, namely, [Co₂(L)₂(biim-4)(H₂O)₂] (1), [Mn₂(L)₂(biim-4)(H₂O)₂] (2), [Mn₂(L)₂(btd)] (3), [Ni₂(L)₂(biim-4)(H₂O)₂]·4H₂O (4), [Cu₂(L)₂(biim-4)(H₂O)]·2H₂O (5), [Cu₂(L)₂(btd)]·4H₂O (6), [Zn₂(L)₂(biim-4)]·4H₂O (7) and [Zn₂(L)₂(biim-4)]·H₂O (8), where H₂L = 5-[(1H-1,2,4-triazol-1-yl)methoxy] isophthalic acid, biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole), and btd = 1,10-bis(1,2,4-triazol-1-yl)decane, have been synthesized and characterized. Compounds 1 and 2 are isostructural and display three-dimensional (3D) (4,5)-connected nets with the same (4²·6⁴)(4²·6⁷·8) topology. Compound 3 possesses a 3D (4,5)-connected framework with (4³·6³)(4³·6⁶·8) topology. Compound 4 shows a two-dimensional (2D) trinodal (3,4)-connected network with a topology of (4·5²)₂(5⁴·8²)(4²·5²·7²) and a vertex symbol of (4·5·5)(5·5·5·5)(4·4·5·5), which is extended by hydrogen bonding interactions into a 3D supramolecular architecture. Compounds 5 and 6 furnish 3D (3,4)-connected nets with (4·6·8)(4·6²·8³) and (4·8²)(4·8²·10³) topologies, respectively. Compounds 7 and 8 were prepared by using the same raw materials at different temperatures. Compound 7 has a 2D → 3D parallel polycatenation formed through bilayers. Compound 8 features a 3D (3,4)-connected net with (6·10²)(6²·10⁴) topology. In addition, photoluminescent properties for compounds 7 and 8 are discussed.