SU-75: a disordered Ge10 germanate with pcu topology

Abstract

A disordered open-framework germanate, denoted as SU-75, was synthesized under hydrothermal conditions using diethylenetriamine (dien) or alternatively 1,4-diaminobutane (dab) as the structure directing agent (SDA). SU-75 crystallizes in a tetragonal space group I42d (No. 122) with a = 18.145(3) Å and c = 41.701(9) Å. The three-dimensional (3D) framework is built from Ge(10)(O,OH)(28) (Ge(10)) clusters that are connected following the pcu (primitive cubic) net topology. SU-75 has 10-, 11- and 12-ring channels along the a- and b-axes and channels with alternating 8-, 10-, 12-, 10-ring openings along the c-axis. The framework exhibits a serious disorder, resulted from two possible connectivities between the units of four Ge(10) clusters (4Ge(10) unit). The chemical formula of SU-75 is |(H(2)SDA)(2)(H(2)O)(n)|[Ge(10)O(21)(OH)(2)] (SDA = dien or dab, n = 5-6), determined by combining single crystal synchrotron X-ray diffraction, thermogravimetric analysis (TGA) and CHN elemental analysis. A superoctahedron is introduced to simplify the description of the connectivity of the Ge(10) clusters and to illustrate the disorder. This is also used to compare the structure of SU-75 with those of related Ge(10) germanates.

Disorder in Extra-Large Pore Zeolite ITQ-33 Revealed by Single Crystal XRD

“…In fact, the occupancy of 13% reflects the probability of changing heights for the columns but not the real occupancy of one domain. This phenomenon also happens in other disordered structures we have studied previously. , We propose the size of the disordered domain to be the reason. On one hand, when the domain is as small as a few unit cells, the proportion of two parts should be equal after refinement.…”

“…This phenomenon also happens in other disordered structures we have studied previously. 14,15 We propose the size of the disordered domain to be the reason. On one hand, when the domain is as small as a few unit cells, the proportion of two parts should be equal after refinement.…”

Solving complex open-framework structures from X-ray powder diffraction by direct-space methods using composite building units

“…The octahedra are edge sharing, and this influences the vibrational modes corresponding to linkages between polyhedra. The IR spectra of six Ge 10 phases, Ge pharmacosiderite (Nowotny & Wittmann, 1954), ASU-21 (Bonneau et al, 2009), SU-62 (Inge, Peskov et al, 2012), SU-74 (Inge, Huang et al, 2012), SU-75 (Huang et al, 2012) and SU-M (Zou et al, 2005), all had a number of overlapping bands between 400 and 500 cm À1 (Fig. S6).…”

Three-Dimensional Open-Framework Germanate Built from a Novel Ge13 Cluster and Containing Two Types of Chiral Layers

“…Crystalline inorganic open frameworks constructed from TO x (T = framework element; x = 4, 5, 6, ...) polyhedral building units are of great interest due to their wide applications in gas adsorption, ion-exchange, and catalysis. − As a relatively new member of open-framework materials, germanates have attracted great attention in the past two decades. − In contrast to the TO 4 (T = Si, Al) tetrahedra building unit in zeolite frameworks, germanium can have various oxygen coordination forming GeO 4 tetrahedron, GeO 5 trigonal bipyramid, and GeO 6 octahedron. Normally, these polyhedral units were further linked into even larger clusters, such as Ge 7 (O,OH,F) 19 (Ge 7 ) cluster, − Ge 8 (O,OH,F) 20 (Ge 8 ) cluster, − Ge 9 (O,OH,F) 25–26 (Ge 9 ) cluster, − and Ge 10 (O,OH) 27–28 (Ge 10 ) cluster. − Different connections of these clusters lead to numerous types of frameworks, which is the origin of the structural diversity of germanate frameworks. For example, Ge 7 clusters have been found in zero (0D)-, one (1D)-, two (2D)-, and three-dimensional (3D) frameworks .…”