Hydrothermal Synthesis and Structural Characterization of a New Organically Templated Germanate, Ge₁₀O₂₁(OH)·N₄C₆H₂₁

Abstract

A new open-framework germanium oxide Ge(10)O(21)(OH).N(4)C(6)H(21) has been hydrothermally synthesized at 180 degrees C for 6 days by using the tris(2-aminoethyl)amine (tren) molecule as a structure-directing agent. This compound was characterized by means of single-crystal X-ray diffraction and FTIR. It crystallizes in the noncentric monoclinic system Cm (a = 14.0495(2) A, b = 12.8058(3) A, c = 9.2637(2) A, beta = 128.406(1) degrees, Z = 4). Its three-dimensional framework is built up from GeO(4) and GeO(3)(OH) tetrahedra connected by vertexes to GeO(5) trigonal bipyramids and GeO(6) octahedra. A pseudo-cubic building unit ("4-3" subunit) consists of four GeO(4) tetrahedra, two GeO(5) trigonal bipyramids, and one GeO(6) octahedron (Ge(7)). In the "4-3" block, the GeO(5) trigonal bipyramids share a common edge. This Ge(7) entity is linked to three tetrahedral units GeO(3)X (X = O, OH), and this forms an original decameric building unit Ge(10)O(21)(OH) which is new in the germanates crystal chemistry. It results in a relatively dense open framework composed of pear-shape cavities (7(8)6(2)5(2)4(4)3(2)) encapsulating the triprotonated tren molecule. The inorganic network contains small pores delimited by 7-ring channels running along [001].

Germanates of 1D Chains, 2D Layers, and 3D Frameworks Built from Ge–O Clusters by Using Metal‐Complex Templates: Host–Guest Symmetry and Chirality Transfer

“…Similar Ge 7 X 19 cluster units were observed in ASU‐12,8i ASU‐16,8c ASU‐19,8l ASU‐20,8l and Ge 10 O 21 (OH)⋅ N 4 C 6 H 21 8k by using different bases as templates. Seven of the anions in this cluster are singly coordinated and available for linkage when the clusters condense into a framework, but the presence of partly terminal anions can prevent the Ge 7 X 19 clusters from completely connecting, thus generating interrupted structures.…”

“…Furthermore, the layers of ASU‐208l are four‐connected 4 4 nets, which are further connected in pairs by additional isolated GeO 4 linkages to produce the slab structure of ASU‐19 8l. However, in Ge 10 O 21 (OH)⋅N 4 C 6 H 21 ,8k the Ge 7 X 19 clusters are linked to each other by additional isolated GeO 4 tetrahedra to produce a 3D framework with a relatively dense noninterrupted structure in which no terminal anion is present.…”

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.…”

Germanate Frameworks Constructed from Oxo Germanium Cluster Building Units

“…[43] The linkage mode of Ge 7 clusters in ASU-16 is T 4 P, which is the same as that in ASU-12. If every Ge 7 cluster is described as a 5-connectd node in the network, the structure of ASU-16 is formed from a prismatic stacking of planar 4.8 2 [44] This complex cavity has internal dimensions of 10 ϫ 8.3 Å, where the triprotonated TREN molecule is hosted. …”