Germanate with Three-Dimensional 12 × 12 × 11-Ring Channels Solved by X-ray Powder Diffraction with Charge-Flipping Algorithm

Abstract

A new open-framework germanate, denoted as GeO-JU90, was prepared by the hydrothermal synthesis method using 1,5-bis(methylpyrrolidinium)pentane dihydroxide as the organic structure-directing agent (SDA). The structure of GeO-JU90 was determined from synchrotron X-ray powder diffraction (XRPD) data using the charge-flipping algorithm. It revealed a complicated framework structure containing 11 Ge atoms in the asymmetric unit. The framework is built of 7-connected Ge7 clusters and additional tetrahedral GeO3(OH) units forming a new three-dimensional interrupted framework with interesting 12 × 12 × 11-ring intersecting channels. The Ge K-edge extended X-ray absorption fine structure (EXAFS) analysis was performed to provide the local structural information around Ge atoms, giving rise to a first-shell contribution from about 4.2(2) O atoms at the average distance of 1.750(8) Å. The guest species in the channels were subsequently determined by the simulated annealing method from XRPD data combining with other characterization techniques, e.g., (13)C NMR spectroscopy, infrared spectroscopy (FTIR), compositional analyses, and thermogravimetric analysis (TGA). Crystallographic data |(C15N2H32)(NH4)|[Ge11O21.5(OH)4], orthorhombic Ama2 (No. 40), a = 37.82959 Å, b = 15.24373 Å, c = 12.83659 Å, and Z = 8.

A Crystalline Mesoporous Germanate with 48‐Ring Channels for CO2 Separation

“…[4,5,18] Because the Ge 7 and Ge 10 clusters are the most frequently obtained BUsa nd have been found in more than 50 germanate structures,i ti sd esirable to build new "hybrid" germanates with both Ge 7 and Ge 10 clusters to increase the pore size. [18,[20][21][22][23] These imply that it is the replacement of OH terminals by F À , additional GeO 4 tetrahedra, or OR groups in ethanolamine that plays ap rimary role in the formation of Ge 7 clusters. [19] We analyzed the connectivity of Ge 7 cluster,a sp roposed by Yu et al, [38] with respect to the HF content (Supporting Information, Table S1).…”

“…Our findings show that, for the germanates synthesized with HF,t he Ge 7 connectivity is mostly lower than five and F À or OH always act as terminal groups.F or the five germanates synthesized without HF,t he Ge 7 connectivity is equal to or higher than six, owing to the additional GeO 4 tetrahedra or ethanolamine which are connected to Ge 7 cluster as terminal species. [18,[20][21][22][23] These imply that it is the replacement of OH terminals by F À , additional GeO 4 tetrahedra, or OR groups in ethanolamine that plays ap rimary role in the formation of Ge 7 clusters. Thus,w ep ropose that it might be possible to obtain hybrid open frameworks built by both Ge 10 and Ge 7 clusters by choosing other types of guest species instead of HF.H erein, we report an ovel hierarchical meso-and micro-porous germanate PKU-17 containing both Ge 7 and Ge 10 clusters in the framework.…”

Application of X-ray Diffraction and Electron Crystallography for Solving Complex Structure Problems

“…SU-74-MPMD and GeO-JU90, two novel open-framework germanates, were prepared using 2-methylpentamethylenediamine (MPMD) and 1,5-bis­(methylpyrrolidinium) pentane dihydroxide, respectively, as OSDAs. Their frameworks were determined by pCP.…”

A Germanate with a Collapsible Open-Framework

“…Framework isomerism has also been observed in open-framework germanates, a class of oxides that often have interesting structural features, such as extra-large pores. The majority of open-framework germanates are constructed of large composite building units (CBUs), such as the Ge 7 X 19 (X = O, OH, F) cluster − (Ge 7 cluster) as illustrated in Figure . With the availability of large CBUs, open-framework germanates with extra-large pores can be readily constructed via scale chemistry .…”