3-D metal-organic frameworks based on s -block metal ions

Probing Calcium‐Based Metal‐Organic Frameworks via Natural Abundance 43Ca Solid‐State NMR Spectroscopy

“…We have performed a natural abundance 43 Ca magic‐angle spinning (MAS) NMR study on four Ca based MOFs of varying composition and topology: CaBDC (H 2 BDC=terephthalic acid), CaPDC (H 2 PDC=2,5‐pyridinedicarboxylic acid), CaSDB, and CaBTC (H 3 BTC=trimesic acid). The advent of high magnetic fields has resulted in sensitivity enhancements for low‐ γ unreceptive quadrupolar nuclei, including 43 Ca .…”

“…Activated CaSDB yields similar parameters, with ar esonance at d iso = À12.3(9) ppm that corresponds to a C Q ( 43 Ca) of 3.18 (14) MHz and a h Q value of 0.90(7).T he similarity in all three NMR parameters indicates that the local Ca environment is essentially preserved from as-made to activated CaSDB. [18] Therei sa lso an on-coordinated lattice water molecule present. Calculationsc orrectly predict that activated CaSDBi sm ore chemically shiftedt han as-made CaSDB, with the predicted shifto f2 .15 ppm slightly overestimating the experimental difference of 0.6 ppm (Table2).…”

“…300 ppm within inorganic Ca-based materials. [9a, 14] These challenges raise the question:c an 43 Ca NMR spectra of MOFs be obtained with sufficient quality to provide direct information on Ca metal centers?We have performed an atural abundance 43 Ca magic-angle spinning( MAS) NMR study on four Ca based MOFs of varying composition and topology:C aBDC (H 2 BDC = terephthalic acid), [15] CaPDC [16] (H 2 PDC = 2,5-pyridinedicarboxylic acid), CaSDB, [17] and CaBTC [18] (H 3 BTC = trimesic acid). The advent of high magnetic fields has resulted in sensitivity enhancements for low-g unreceptiveq uadrupolar nuclei, including 43 Ca.…”

“…Figure S9). [18] Therei sa lso an on-coordinated lattice water molecule present. In accordance with the crystal structure, only one resonance was observed in the as-made CaBTC 43 Ca MAS NMR spectrum.T he lattice water can be removed by activation,y ielding activated CaBTC ( Figure S10), which remains eight-coordinate and bound to as ingle water molecule.…”

Milestone Report - M4FT-15OR03120218 - A Literature Search on the Effects of the Decay of ⁸⁵Kr to ⁸⁵Rb on Long-term Storage Options

“…There are two types of Rb-bearing MOFs -one in which the Rb is used as a linker to produce the MOF structure and one in which the Rb is contained within the MOF cage, usually from ion exchange. Several MOF materials in which the Rb was part of the structure were located in the literature search (Gassensmith et al 2011;Gassensmith et al 2014;Kim et al 2010;Morris et al 2007;Xue et al 2014;Yan et al 2014;Zhang et al 2013). Rubidium generated through decay of Kr would not be expected to become part of the MOF structure, but located in the cage originally occupied by the Kr, making ion exchange studies more relevant to the topic of this study.…”