A Series of Metal–Organic Frameworks Based on Different Salicylic Derivatives and 1,1′-(1,4-Butanediyl)bis(imidazole) Ligand: Syntheses, Structures, and Luminescent Properties

Thirteen new metal–organic frameworks (MOFs), namely, [Zn2(L1)2(biim-4)(H2O)] (1), [Cd(HL1)2(biim-4)] (2), [Cd(HL2)2(biim-4)] (3), [Cd(HL3)2(biim-4)] (4), [Zn2(L4)2(biim-4)(H2O)] (5), [Cd(HL4)2(biim-4)] (6), [Zn2(L5)2(biim-4)(H2O)] (7), [Cd(HL5)2(biim-4)1.5]·H2O (8), [Zn2(L6)2(biim-4)(H2O)] (9), [Cd(HL6)2(biim-4)] (10), [Zn2(L7)2(biim-4)2]·H2O (11), [Cd2(L7)2(biim-4)2(H2O)]·H2O (12), and [Zn(HL8)(biim-4)]·0.5H2O (13), where H2L1 = salicylic acid, H2L2 = 3-methylsalicylic acid, H2L3 = 4-methylsalicylic acid, H2L4 = 4-chlorosalicylic acid, H2L5 = 5-chlorosalicylic acid, H2L6 = 5-bromosalicylic acid, H2L7 = 5-nitrosalicylic acid, H3L8 = 5-sulfosalicylic acid, and biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole), have been synthesized under hydrothermal conditions. Compounds 1 and 5 are isomorphous, and show the same 3-connected 103-ths net. Compound 2 possesses a meso-helical chain structure. Compound 3 shows a zero-dimensional (0D) dimeric molecular structure, which is linked by π–π interactions into a two-dimensional (2D) supramolecular assembly. Compounds 4 and 6 exhibit similar one-dimensional (1D) chains, which are extended into different 2D supramolecular layers via C–H···O and C–H···Cl hydrogen-bonding interactions, respectively. Compound 9 is isomorphous with 7 and displays a typical 3D diamond framework. Compound 8 shows an unusual 2D → 3D polythreading array. Compound 10 furnishes a 2D supramolecular (44)-sql network formed by C–H···Br hydrogen-bonding interactions. Compounds 11 and 12 exhibit binodal (4,4)-connected 3D frameworks with (4.53.72)(4.52.83) and (42.62.82)(42.6.82.10) topologies, respectively. Compound 13 has a 3D 4-fold interpenetrating diamond framework. The TGA and luminescent properties of 1–13 have also been investigated in detail.