Tuning functional sites and thermal stability of mixed-linker MOFs based on MIL-53(Al)

Abstract

The MIXMOF concept has been applied to the metal-organic framework compound MIL-53(Al). The random incorporation of two different linker molecules (benzene-1,4-dicarboxylate and 2-aminobenzene-1,4-dicarboxylate) in the framework structure and its influence on thermal stability were proven using several complementary techniques (XRD, ATR-IR, MAS-NMR and TG).

Dynamic Nuclear Polarization Enhanced Solid‐State NMR Spectroscopy of Functionalized Metal–Organic Frameworks

“…[20] Under the DNP conditions developed here, a high-resolution 9.4 T 1 H-15 N CPMAS spectrum of 1 with a reasonable signal-to-noise ratio could be acquired within 34 min (for comparison, at room temperature and using standard NMR instrumentation, the acquisition of a spectrum of similar signal-to-noise ratio required 13 h, Figure S8). The 15 N CPMAS spectrum of 1 shows a single broad resonance at a chemical shift of 66 ppm, consistent with a neutral primary amine bound to an aromatic carbon (an aniline). The 15 N CPMAS spectrum of 2 required a longer experimental time (2.3 h) to attain a reasonable S/N, due to the reduction in the number of 15 N spins by a factor of 80 % in comparison to 1.…”

“…The 15 N CPMAS spectrum of 1 shows a single broad resonance at a chemical shift of 66 ppm, consistent with a neutral primary amine bound to an aromatic carbon (an aniline). The 15 N CPMAS spectrum of 2 required a longer experimental time (2.3 h) to attain a reasonable S/N, due to the reduction in the number of 15 N spins by a factor of 80 % in comparison to 1. As expected, the 15 C CPMAS spectra of 1, 2 and 3, respectively, recorded with (black) or without microwave irradiation (red) to induce DNP.…”

“…DNP-enhanced 1 H-15 N CPMAS solid-state NMR spectra of 1-3 are shown in Figure 2. Natural abundance 15 N solidstate NMR experiments represent a considerable challenge due to the low gyromagnetic ratio (n 0 = 40.58 MHz at 9.4 T) and low natural abundance (N.A. = 0.37 %) of 15 N. Grant and co-workers have previously employed DNP to acquire natural abundance 1 H-15 N CPMAS solid-state NMR spectra of carbazole at low field (1.4 T).…”

“…Natural abundance 15 N solidstate NMR experiments represent a considerable challenge due to the low gyromagnetic ratio (n 0 = 40.58 MHz at 9.4 T) and low natural abundance (N.A. = 0.37 %) of 15 N. Grant and co-workers have previously employed DNP to acquire natural abundance 1 H-15 N CPMAS solid-state NMR spectra of carbazole at low field (1.4 T). [20] Under the DNP conditions developed here, a high-resolution 9.4 T 1 H-15 N CPMAS spectrum of 1 with a reasonable signal-to-noise ratio could be acquired within 34 min (for comparison, at room temperature and using standard NMR instrumentation, the acquisition of a spectrum of similar signal-to-noise ratio required 13 h, Figure S8).…”

Synthesis and Characterization of Amine-Functionalized Mixed-Ligand Metal–Organic Frameworks of UiO-66 Topology

“…[22][23][24][25] Furthermore, varying the composition of mixed linkerMOFs can result in systematic alteration of the gas adsorption capacity and selectivity of the material. Such an approach has been previously been adopted on several MOF topologies, namely MOF-5, 26 MIL-53-Al, [27][28] CAU-10, 29 and MIL-101 30 where a mixture of benzene-1,4-dicarboxylic acid (BDC) and its amino-, bromo-, nitro-, methyl-functionalized derivatives were used as linkers. In these studies, various properties of the materials were significantly influenced by the amount and type of functionality introduced in to the framework; namely the surface area (MOF-5), 26 the breathing pressure (MIL-53) 28 and sorption properties (CAU-10) 29 were observed to have been affected.…”