Improved strategies for DNP-enhanced 2D 1H-X heteronuclear correlation spectroscopy of surfaces

Takeshi Kobayashi, Ames Laboratory
Frederic Perras, Ames Laboratory
Umesh Chaudhary, Ames Laboratory
Igor I. Slowing, Iowa State University and Ames Laboratory
Wenyu Huang, Ames Laboratory
Aaron D. Sadow, Iowa State University and Ames Laboratory
Marek Pruski, Iowa State University and Ames Laboratory

Abstract

We demonstrate that the dynamic nuclear polarization (DNP)-enhanced 1H-X heteronuclear correlation (HETCOR) measurements of surface species are better accomplished by using proton-free solvents. This approach notably prevents HETCOR spectra from being obfuscated by the solvent-derived signals otherwise present in DNP measurements. Additionally, in the hydrogen-rich materials studied here, which included functionalized mesoporous silica nanoparticles and metal organic frameworks, the use of proton-free solvents afforded higher sensitivity gains than the commonly used solvents containing protons. We also explored the possibility of using a solvent-free sample formulation and the feasibility of indirect detection in DNP-enhanced HETCOR experiments.