Kobayashi Takeshi, Perras Frédéric A, Goh Tian Wei, Metz Tanner L, Huang Wenyu, Pruski Marek
Ames Laboratory, U.S. Department of Energy , Ames, Iowa 50011, United States.
Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
J Phys Chem Lett. 2016 Jul 7;7(13):2322-7. doi: 10.1021/acs.jpclett.6b00860. Epub 2016 Jun 9.
Ultrawideline dynamic nuclear polarization (DNP)-enhanced (195)Pt solid-state NMR (SSNMR) spectroscopy and theoretical calculations are used to determine the coordination of atomic Pt species supported within the pores of metal-organic frameworks (MOFs). The (195)Pt SSNMR spectra, with breadths reaching 10 000 ppm, were obtained by combining DNP with broadbanded cross-polarization and CPMG acquisition. Although the DNP enhancements in static samples are lower than those typically observed under magic-angle spinning conditions, the presented measurements would be very challenging using the conventional SSNMR methods. The DNP-enhanced ultrawideline NMR spectra served to separate signals from cis- and trans-coordinated atomic Pt(2+) species supported on the UiO-66-NH2 MOF. Additionally, the data revealed a dominance of kinetic effects in the formation of Pt(2+) complexes and the thermodynamic effects in their reduction to nanoparticles. A single cis-coordinated Pt(2+) complex was confirmed in MOF-253.
超宽带动态核极化（DNP）增强的¹⁹⁵Pt固态核磁共振（SSNMR）光谱和理论计算被用于确定负载在金属有机框架（MOF）孔内的原子态Pt物种的配位情况。通过将DNP与宽带交叉极化和CPMG采集相结合，获得了宽度达10000 ppm的¹⁹⁵Pt SSNMR光谱。尽管静态样品中的DNP增强低于通常在魔角旋转条件下观察到的增强，但使用传统的SSNMR方法进行本文所述的测量将极具挑战性。DNP增强的超宽带NMR光谱用于分离负载在UiO-66-NH₂ MOF上的顺式和反式配位原子态Pt²⁺物种的信号。此外，数据揭示了在Pt²⁺配合物形成过程中动力学效应的主导作用以及它们还原为纳米颗粒过程中的热力学效应。在MOF-253中确认了一种单一的顺式配位Pt²⁺配合物。
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