Lewis Lecture 2: Exploiting Isotopic Enrichment to Understand Disorder and Chemical Reactivity in Porous Solids Using NMR Spectroscopy

Speaker: Prof. Sharon Ashbrook, University of St Andrews
Series: Materials Chemistry Research Interest Group

NMR spectroscopy provides an element-specific, sensitive probe of the local environment, enabling detailed structural information to be extracted. Its sensitivity to the atomic scale, without the need for long-range order, makes it a useful tool to study the compositional, positional and temporal disorder present in microporous materials.1 However, many nuclei of interest have low natural abundance, such as 2H (0.01%), 13C (1.1%), 15N (0.36%), 17O (0.04%) and 29Si (4.7%), which can require isotopic enrichment to improve sensitivity and aid spectral assignment, or to enable multidimensional experiments or in situ experiments to be employed on a reasonable timescale. Selective enrichment can also provide information on chemical reactivity, allowing the mechanism of a reaction to be determined.

In this talk I will discuss two different aspects of our work using isotopic enrichment to investigate porous and novel hybrid solids. First, I will show how we have used 17O NMR spectroscopy to characterise compositional disorder in mixed-metal MOFs, including (Al,Ga,Sc)-MIL-53 and (Zr,Hf)-MOF-801.2-4 I will then discuss using 29Si and 17O enrichment for in situ and ex situ NMR experiments to probe the mechanism of the Assembly, Disassembly, Organization, Reassembly (ADOR) method,5-6 and the exploration of the room-temperature lability of bonds in aluminosilicate and silicate zeolite frameworks using 17O enrichment.7-8

1. R. F. Moran et al. Int. Rev. Phys. Chem. 36, 39 (2017). 2. C. M. Rice et al. Phys. Chem. Chem. Phys. 22, 14514 (2020). 3. Z. H. Davis et al. Phys. Chem. Chem. Phys. 25, 20267 (2023). 4. E. A. L. Borthwick et al. Micropor. Mesopor. Mater. 25, 20267 (2026). 5. N. L. Kelly et al. Chem. Sci. 16, 4245 (2025). 6. N. L. Kelly et al. J. Am. Chem. Soc. 148, 1478 (2026). 7. S. M. Pugh et al. J. Am. Chem. Soc. 142, 900 (2020). 8. N. L. Kelly et al. J. Am. Chem. Soc. 148, 13257 (2026).