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

Abstract

Thirteen new metal–organic frameworks (MOFs), namely, [Zn 2 (L1) 2 (biim-4)(H 2 O)] ( 1 ), [Cd(HL1) 2 (biim-4)] ( 2 ), [Cd(HL2) 2 (biim-4)] ( 3 ), [Cd(HL3) 2 (biim-4)] ( 4 ), [Zn 2 (L4) 2 (biim-4)(H 2 O)] ( 5 ), [Cd(HL4) 2 (biim-4)] ( 6 ), [Zn 2 (L5) 2 (biim-4)(H 2 O)] ( 7 ), [Cd(HL5) 2 (biim-4) 1.5 ]·H 2 O ( 8 ), [Zn 2 (L6) 2 (biim-4)(H 2 O)] ( 9 ), [Cd(HL6) 2 (biim-4)] ( 10 ), [Zn 2 (L7) 2 (biim-4) 2 ]·H 2 O ( 11 ), [Cd 2 (L7) 2 (biim-4) 2 (H 2 O)]·H 2 O ( 12 ), and [Zn(HL8)(biim-4)]·0.5H 2 O ( 13 ), where H 2 L1 = salicylic acid, H 2 L2 = 3-methylsalicylic acid, H 2 L3 = 4-methylsalicylic acid, H 2 L4 = 4-chlorosalicylic acid, H 2 L5 = 5-chlorosalicylic acid, H 2 L6 = 5-bromosalicylic acid, H 2 L7 = 5-nitrosalicylic acid, H 3 L8 = 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 10 3 - 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 (4 4 )- sql network formed by C–H···Br hydrogen-bonding interactions. Compounds 11 and 12 exhibit binodal (4,4)-connected 3D frameworks with (4.5 3 .7 2 )(4.5 2 .8 3 ) and (4 2 .6 2 .8 2 )(4 2 .6.8 2 .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.