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The Structure of Molecular and Surface Platinum Sites Determined by DNP-SENS and Fast MAS 195Pt Solid-State NMR Spectroscopy
- Source :
- Journal of the American Chemical Society, Vol. 142, No 44 (2020) pp. 18936-18945
- Publication Year :
- 2020
- Publisher :
- American Chemical Society (ACS), 2020.
-
Abstract
- The molecular level characterization of heterogeneous catalysts is challenging due to the low concentration of surface sites and the lack of techniques that can selectively probe the surface of a heterogeneous material. Here, we report the joint application of room temperature proton-detected NMR spectroscopy under fast magic angle spinning (MAS) and dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS), to obtain the 195Pt solid-state NMR spectra of a prototypical example of highly dispersed Pt sites (single site or single atom), here prepared via surface organometallic chemistry, by grafting [(COD)Pt(OSi(OtBu)3)2] (1, COD = 1,5-cyclooctadiene) on partially dehydroxylated silica (1@SiO2). Compound 1@SiO2 has a Pt loading of 3.7 wt %, a surface area of 200 m2/g, and a surface Pt density of around 0.6 Pt site/nm2. Fast MAS 1H{195Pt} dipolar-HMQC and S-REDOR experiments were implemented on both the molecular precursor 1 and on the surface complex 1@SiO2, providing access to 195Pt isotropic shifts and Pt–H distances, respectively. For 1@SiO2, the measured isotropic shift and width of the shift distribution constrain fits of the static wide-line DNP-enhanced 195Pt spectrum, allowing the 195Pt chemical shift tensor parameters to be determined. Overall the NMR data provide evidence for a well-defined, single-site structure of the isolated Pt sites.
- Subjects :
- Analytical chemistry
chemistry.chemical_element
General Chemistry
Nuclear magnetic resonance spectroscopy
010402 general chemistry
01 natural sciences
Biochemistry
Catalysis
0104 chemical sciences
NMR spectra database
chemistry.chemical_compound
Colloid and Surface Chemistry
chemistry
Solid-state nuclear magnetic resonance
ddc:540
Magic angle spinning
Platinum
Spectroscopy
Organometallic chemistry
Subjects
Details
- ISSN :
- 15205126 and 00027863
- Volume :
- 142
- Database :
- OpenAIRE
- Journal :
- Journal of the American Chemical Society
- Accession number :
- edsair.doi.dedup.....782107816436b9eef721a594c5ce7380