Can one and two-dimensional solid-state NMR fingerprint zeolite framework topology?

Abstract

In this contribution, we have explored the potential and strength of one-dimensional (1D) 29Si and two-dimensional (2D) 29S–29Si and 29Si–17O NMR as invariants of non-oriented graph for fingerprinting zeolite frameworks. 1D and 2D 29Si NMR can indeed provide indications on the graph vertices, edges and allow the construction of the adjacency matrix, i.e. the set of connections between the graph vertices. From the structural data, hypothetical 1D 29Si and 2D 29Si–29Si NMR signatures for 193 of the zeolite frameworks reported in the Atlas of Zeolite Structures have been generated. Comparison between all signatures shows that thanks to the 1D 29Si NMR data only, almost 20% of the known zeolite frameworks could be distinguished. Further NMR signatures were generated by taking into account 2D 29Si–29Si and 29Si–17O correlations. By sorting and comparison of all the NMR data, up to 80% of the listed zeolites could be unambiguously discriminated. This work indicates that (i) solid-state NMR data indeed represent a rather strong graph invariant for zeolite framework, (ii) despite their difficulties and costs (isotopic labeling is often required, the NMR measurements can be long), 29Si and 17O NMR measurements are worth being investigated in the frame of zeolites structure resolution. This approach could also be generalized to other zeolite-related materials containing NMR-measurable nuclides.