New Al-MOFs Based on Sulfonyldibenzoate Ions: A Rare Example of Intralayer Porosity

Abstract

A new sulfone-functionalized metal-organic framework [Al(OH)(SDBA)]·0.25DMF, denoted CAU-11, was synthesized using a V-shaped linker molecule 4,4'-sulfonyldibenzoic acid (H2SDBA). The crystal structure was solved from synchrotron X-ray powder diffraction data. Chains of trans corner-sharing AlO6 octahedra are interconnected by the carboxylate groups to form layers (ABAB stacking). Within the layers, hydrophobic lozenge-shaped pores with a diameter of 6.4 × 7.1 Å(2) are present inducing permanent porosity (aBET = 350 m(2) g(-1) and Vmicro = 0.17 cm(3) g(-1)). With the application of HT-methods (HT = high throughput), the isoreticular carboxylate functionalized compound [Al(OH)(H2DPSTC)]·0.5H2O (CAU-11-COOH) was synthesized using the linker molecule 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DPSDA), which hydrolyzes under the reaction conditions. Due to the additional noncoordinating carboxylic acid groups the pores are hydrophilic. Changing the molar ratio of Al(3+) to linker lead to the discovery of a second new compound [Al2(OH)2(DPSTC)(H2O)2]·0.5H2O (CAU-12). In CAU-12 the linker molecule is fully deprotonated which leads to different connectivity compared to the structure of CAU-11-COOH. Thermal activation of CAU-12 leads to dehydration and transformation of the structure to [Al2(OH)2(DPSTC)]·nH2O (CAU-12-dehy). Coordinated water molecules were removed, and the coordination site is replaced by the previously noncoordinating O atom of the adjacent carboxylate group. The SO2-groups point into the pores resulting in a highly hydrophobic three-dimensional framework. The compounds exhibit high thermal stability in air at least up to 420 °C. Synthesis of CAU-11 can be easily scaled up in very high yields (98%).

Synthesis and Characterization of a Layered Scandium MOF Containing a Sulfone‐Functionalized V‐Shaped Linker Molecule

“…Sc‐CAU‐11 exhibits a specific surface area of a BET = 460 m 2 g –1 and a micropore volume of V m = 0.17 cm 3 g –1 (a BET(theor) = 490 m 2 g –1 calculated with Materials Studio) and the Connolly surface was modeled (Figure S7). In comparison, Al‐CAU‐11, which shows also intralayer porosity, has a specific surface area of 350 m 2 g –1 and a micropore volume of 0.17 cm 3 g –1 . The large specific surface in the title compound is due to the larger ionic radius of Sc 3+ .…”

“…The asymmetric unit of Sc‐CAU‐11 consists of one crystallographic independent Sc 3+ ion, one SDBA 2– ligand and one bridging µ ‐OH group (Figure ). Sc‐CAU‐11 is isostructural to Al‐CAU‐11 and crystallizes in the orthorhombic space group Pnma with the unit cell parameters a = 7.2324(4), b = 13.0422(10), c = 20.4561(14) Å. The structure consists of trans corner‐sharing ScO 6 octahedra, which form chains (Figure and S2).…”

“…The asymmetric unit of Sc-CAU-11 consists of one crystallographic independent Sc 3+ ion, one SDBA 2ligand and one bridging μ-OH group (Figure 1). Sc-CAU-11 is isostructural to Al-CAU-11 [20] and crystallizes in the orthorhombic space group Pnma with the unit cell parameters a = 7.2324(4), b = 13.0422(10), c = 20.4561(14) Å. The structure consists of trans corner-sharing ScO 6 octahedra, which form chains (Figure 2 The layers show an ABAB stacking along the c-axis and the sulfone groups do not point into the pores, but to the adjacent layer, where they are probably involved in H-bonds to the hydroxide groups of the inorganic building unit (Figure 2 and S4).…”

Syntheses, structures and properties of four metal-organic frameworks from chlorophenyl imidazole dicarboxylates

“…Ligands containing N-or O-donors have been prepared [6][7][8][9][10][11][12][13]. In this context, the N-heterocyclic dicarboxylate ligands have been widely used to construct MOFs owing to various coordination modes, such as monodentate, bidentate chelating, monodentate and bidentate bridging [14][15][16][17]. Imidazole-4,5-dicarboxylic acid (H 3 IDC) having the above mentioned advantages has been explored to assemble MOFs [18][19][20][21][22][23], possessing six potential oxygen and nitrogen donors.…”

Synthesis, Structure, and Selected Properties of Aluminum-, Gallium-, and Indium-Based Metal-Organic Frameworks

“…The crystal structure determination for Al-and Ga-MOFs is usually carried out from powder X-ray diffraction data since the growth of crystals of suitable size is often not possible. Here computer-assisted modeling (force field and DFT calculations) in combination with Rietveld refinements have been shown to be an invaluable tool [54,73,74]. Alternatively, state-of-the-art microdiffraction methods on crystals of 0.5-2 μm in diameter have been shown to be useful for the structure determination of Al-MIL-100 [49].…”