NMR of Metal Centers and Doped Metals in MOFs and COFs

Abstract

There have been tremendous advances in the fields of metal–organic frameworks (MOFs) and covalent-organic frameworks (COFs) over the past two decades. The rapidly expanding number of MOFs and COFs, along with their various associated properties, has highlighted the need for effective structural characterization routes in order to elucidate structure–property relationships. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy provides unique insights that are helpful for understanding and rationalizing the local structure of various materials. In this chapter, we summarize the significant number of studies from the last 15 years which have used SSNMR to examine incorporated metal centers and dopant metals in MOFs and COFs, with targets ranging from spin-1/2 nuclei such as 111Cd and 207Pb to challenging quadrupolar nuclei including 25Mg, 47/49Ti, 43Ca, 67Zn and 115In. Examples of the detailed information available from metal SSNMR are provided, illustrating how this technique can shed light on the local structure around the target metal, investigate host–guest interactions, and monitor changes in the MOF structure. General acquisition strategies for metal SSNMR spectra of MOFs and COFs are also discussed.