Solid-state NMR: An EYE Opener in Surface Chemistry

Abstract

Solid-state NMR plays a critical role in establishing the atomic structure of surface species, obtained by the controlled grafting of organometallic complexes onto amorphous oxide supports, a promising strategy towards molecularly defined heterogeneous catalysts. Using one-dimensional or multi-dimensional NMR analysis allows us to map the structure of organometallic residues on surfaces, in a similar fashion that the structure of homogeneous catalysts can be determined using solution NMR techniques. In addition, chemical shift anisotropy analysis can be used as a tool to obtain detail structures and to determine the dynamics of surface species. In combination with DFT calculations we have also shown that the structure of aluminum species can be determined using high-field and ultrafast (27)Al NMR. Finally, we discussed the latest development in Dynamic Nuclear Polarization, which allows the selective enhancements of the NMR signals of surface species, thus reducing the NMR acquisition time by factors up to 10,000. This makes solid-state NMR an indispensible tool in determining structure-property relationship and in the development of advanced materials including catalysts through more rational approach.

State of the Art and Perspectives in the “Molecular Approach” Towards Well-Defined Heterogeneous Catalysts

“…This field has benefited from the development of advanced spectroscopic techniques [12,13], particularly in the realm of solid-state NMR [14,15]. Detailed studies of molecular surface equivalents provide precursors, and in some cases mechanistic understanding to complement to spectroscopic characterization data.…”