Category Archives: MOF

Dynamic Nuclear Polarization of Metal–Organic Frameworks Using Photoexcited Triplet Electrons #DNPNMR

Fujiwara, Saiya, Masanori Hosoyamada, Kenichiro Tateishi, Tomohiro Uesaka, Keiko Ideta, Nobuo Kimizuka, and Nobuhiro Yanai. “Dynamic Nuclear Polarization of Metal–Organic Frameworks Using Photoexcited Triplet Electrons.” Journal of the American Chemical Society 140, no. 46 (November 21, 2018): 15606–10.

https://doi.org/10.1021/jacs.8b10121.

While dynamic nuclear polarization based on photoexcited triplet electrons (triplet-DNP) has the potential to hyperpolarize nuclear spins of target substrates in the low magnetic field at room temperature, there has been no triplet-DNP system offering structural rigidity and substrate accessibility. Here, we report the first example of triplet-DNP of nanoporous metal−organic frameworks. Accommodation of a carboxylate-modified pentacene derivative in a partially deuterated ZIF-8 (DZIF-8) results in a clear 1H NMR signal enhancement over thermal equilibrium.

Selective Host-Guest Interaction between Metal Ions and Metal-Organic Frameworks using Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy

Guo, Z., et al., Selective Host-Guest Interaction between Metal Ions and Metal-Organic Frameworks using Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy. Chemistry, 2014: p. n/a-n/a.

http://www.ncbi.nlm.nih.gov/pubmed/25297002

The host-guest interaction between metal ions (Pt2+ and Cu2+ ) and a zirconium metal-organic framework (UiO-66-NH2 ) was explored using dynamic nuclear polarization-enhanced 15 N{1 H} CPMAS NMR spectroscopy supported by X-ray absorption spectroscopy and density functional calculations. The combined experimental results conclude that each Pt2+ coordinates with two NH2 groups from the MOF and two Cl- from the metal precursor, whereas Cu2+ do not form chemical bonds with the NH2 groups of the MOF framework. Density functional calculations reveal that Pt2+ prefers a square-planar structure with the four ligands and resides in the octahedral cage of the MOF in either cis or trans configurations.

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