Two new Cd^II MOFs of 1,4-bis(1H-benzimidazol-1-yl)butane and flexible dicarboxylate ligands: luminescence sensing towards Fe³⁺

Abstract

Two new CdII MOFs, namely, two-dimensional (2D) poly[[[μ2-1,4-bis(1H-benzimidazol-1-yl)butane](μ2-heptanedioato)cadmium(II)] tetrahydrate], {[Cd(C7H10O4)(C18H18N4)]·4H2O} n or {[Cd(Pim)(bbimb)]·4H2O} n (1), and 2D poly[diaqua[μ2-1,4-bis(1H-benzimidazol-1-yl)butane](μ4-decanedioato)(μ2-decanedioato)dicadmium(II)], [Cd2(C10H16O4)2(C18H18N4)(H2O)2] n or [Cd(Seb)(bbimb)0.5(H2O)] n (2), have been synthesized hydrothermally based on the 1,4-bis(1H-benzimidazol-1-yl)butane (bbimb) and pimelate (Pim2−, heptanedioate) or sebacate (Seb2−, decanedioate) ligands. Both MOFs were structurally characterized by single-crystal X-ray diffraction. In 1, the CdII centres are connected by bbimb and Pim2− ligands to generate a 2D sql layer structure with an octameric (H2O)8 water cluster. The 2D layers are further connected by O—H...O hydrogen bonds, resulting in a three-dimensional (3D) supramolecular structure. In 2, the CdII centres are coordinated by Seb2− ligands to form binuclear Cd2 units which are linked by bbimb and Seb2− ligands into a 2D hxl layer. The 2D layers are further connected by O—H...O hydrogen bonds, leading to an 8-connected 3D hex supramolecular network. IR and UV–Vis spectroscopy, thermogravimetric analysis and solid-state photoluminescence analysis were carried out on both MOFs. Luminescence sensing experiments reveal that both MOFs have good selective sensing towards Fe3+ in aqueous solution.

Two Water-Stable Zn(II) Coordination Polymers as Luminescent Sensors for Detection of Uric Acid in Serum, MnO4–, and Cr(VI) Oxo-Anions in Tap Water

“…27,28 Also, its two sulfonate groups can coordinate to metal centers with various modes (Scheme S1), which can help to generate CPs with diverse structures. In addition, 1,4-bis(2methyl-1H-imidazole-1-yl)butane (Mbimb) and 1,4-bis(1Hbenzimidazol-1-yl)butane (bbimb) are two flexible N-donor ligands containing −(CH 2 ) 4 − with good conformational freedom, 29,30 Luminescence Sensing Experiments. First, the resulting crystals were ground, and then 10 mg of powder samples of 1 and 2 were dispersed in 100 mL of deionized water.…”

“…Recently, the construction of CPs via rigid mixed with flexible ligands has been well documented. − 1,5-Naphthalenedisulfonate (1,5-NDS) is a rigid O-donor ligand with a naphthalene ring as the conjugate system, which has the benefits of construction of CPs with excellent luminescence properties. , Also, its two sulfonate groups can coordinate to metal centers with various modes (Scheme S1), which can help to generate CPs with diverse structures. In addition, 1,4-bis­(2-methyl-1 H -imidazole-1-yl)­butane (Mbimb) and 1,4-bis­(1 H -benzimidazol-1-yl)­butane (bbimb) are two flexible N-donor ligands containing –(CH 2 ) 4 – with good conformational freedom, , thus forming unpredictable intriguing topologies and properties. Also, upon carefully inspection, CPs based on 1,5-NDS mixed with flexible N-donor ligands are still scarce.…”