Laboratory of Crystallography, ETH Zurich, CH-8093 Zurich, Switzerland.
J Am Chem Soc. 2011 Dec 21;133(50):20604-10. doi: 10.1021/ja209220a. Epub 2011 Nov 30.
The structure of the calcined borosilicate zeolite catalyst SSZ-82 ([Si(61.3)B(4.7)O(132)], Pmmn, a = 24.2783(4), b = 11.4665(2), and c = 14.1127(3) Å) has been solved from X-ray powder diffraction (XPD) data using the recently developed 2D-XPD charge flipping approach. The electron density maps generated with the more conventional powder charge flipping (pCF) algorithm could not be interpreted easily, so this new method, which begins by phasing low-resolution, 2D subsets of the data, was applied. Crystallographic phases were derived for the three main projections ([100], [010], and [001]) by using just the corresponding subsets of reflections (0kl, h0l, and hk0, respectively) from the full set of 3039 extracted intensities. These phases were then imposed on the (otherwise random) starting phases in the application of the pCF algorithm to the full data set. The framework structure, with 11 Si/B atoms in the asymmetric unit and a novel 12-/10-ring 2D channel system, could be seen clearly in the resulting electron density map. This is the first application of the 2D-XPD method to data collected on a material of unknown structure. Rietveld refinement of the structure revealed the positions of the B atoms in the framework and indicated that some water had been readsorbed in the pores.
煅烧硼硅酸盐沸石 SSZ-82（[Si(61.3)B(4.7)O(132)]，Pmmn，a = 24.2783(4)，b = 11.4665(2)，c = 14.1127(3)Å）的结构已通过 X 射线粉末衍射（XPD）数据利用最近开发的 2D-XPD 电荷翻转方法解决。使用更传统的粉末电荷翻转（pCF）算法生成的电子密度图不易解释，因此应用了这种新方法，该方法首先对低分辨率的 2D 数据子集进行相，然后使用从提取的 3039 个强度的完整数据集的相应子集（分别为 0kl、h0l 和 hk0）获得三个主要投影（[100]、[010]和[001]）的晶相。然后将这些相位施加到（否则随机）pCF 算法应用于完整数据集的起始相位上。在得到的电子密度图中，可以清楚地看到具有 11 个 Si/B 原子的不对称单元的骨架结构和新颖的 12-/10-环二维通道系统。这是首次将 2D-XPD 方法应用于未知结构材料收集的数据。结构的 Rietveld 精修揭示了骨架中 B 原子的位置，并表明一些水已重新吸附在孔中。
