Physical Chemistry/Solid State NMR, Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
Magn Reson Chem. 2007 Dec;45 Suppl 1:S231-46. doi: 10.1002/mrc.2159.
We used solid-state NMR spectroscopy to gain detailed information about the proton positions, proximities and the hydrogen-bonding network in the environmentally friendly flame retardant melamine orthophosphate (MP). High-resolution proton one- and two-dimensional solid-state NMR spectra were obtained at high external magnetic field in combination with fast magic angle spinning of the sample. Furthermore, we recorded homo- and heteronuclear correlation spectra of types (15)N–(15)N, (1)H–(13)C, (1)H–(15)N and (1)H–(31)P. In addition, we determined the geometry of the NH and NH(2) groups in MP by (15)N–(1)H heteronuclear recoupling experiments.We were able to completely assign the different isotropic chemical shifts in MP. Furthermore, we could identify the protonation of the melamine and orthophosphate moieties. The experimental results are discussed in connection with the structural model obtained by powder X-ray diffraction together with a combined molecular modeling-Rietveld refinement approach (De Ridder et al. Helv. Chim. Acta 2004; 87: 1894). We show that the geometry of the NH2 groups can only be successfully estimated by solid-state NMR.
我们使用固态 NMR 光谱学来获取有关环保型阻燃剂三聚氰胺正磷酸盐 (MP)中质子位置、邻近性和氢键网络的详细信息。在高外磁场下结合样品的快速魔角旋转，获得了高分辨率的质子一维和二维固态 NMR 光谱。此外，我们还记录了同核和异核相关谱，类型为 (15)N–(15)N、(1)H–(13)C、(1)H–(15)N 和 (1)H–(31)P。此外，我们通过 (15)N–(1)H 异核重耦实验确定了 MP 中 NH 和 NH2 基团的几何形状。我们能够完全分配 MP 中不同的各向同性化学位移。此外，我们还可以识别三聚氰胺和正磷酸盐部分的质子化。实验结果与粉末 X 射线衍射获得的结构模型以及结合分子建模-Rietveld 精修方法（De Ridder 等人，Helv. Chim. Acta 2004；87:1894）一起进行了讨论。我们表明，只有通过固态 NMR 才能成功估计 NH2 基团的几何形状。
