The Structure of a Complex Open-Framework Germanate Obtained by Combining Powder Charge-Flipping and Simulated Annealing

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• 作者：A. Ken Inge ; Shiliang Huang ; Hong Chen ; Francisca Moraga ; Junliang Sun ; Xiaodong Zou
• 刊名：Crystal Growth & Design
• 出版年：2012
• 出版时间：October 3, 2012
• 年：2012
• 卷：12
• 期：10
• 页码：4853-4860
• 全文大小：591K
• 年卷期：v.12,no.10(October 3, 2012)
• ISSN：1528-7505

文摘

A novel open-framework germanate, denoted as SU-74-MPMD, was prepared by hydrothermal synthesis using 2-methylpentamethylenediamine (MPMD) as the organic structure directing agent (SDA). The structure of SU-74-MPMD was determined from synchrotron X-ray powder diffraction (XRPD) data using the charge-flipping algorithm, and is one of the most complicated germanates solved from X-ray powder diffraction. The structure is built of layers of Ge₁₀O₂₆(OH)₂ (Ge₁₀) clusters that are connected by additional GeO₄ tetrahedra to form a three-dimensional (3D) framework with 10- and 12-rings. The organic structure directing agent MPMD in the pores was located by simulated annealing. SU-74-MPMD: space group P2₁/c, a = 12.62726(4) 脜, b = 17.35186 (5) 脜, c = 16.17343(5) 脜, 尾 = 115.5509(2)掳 and Z = 4. SU-74 was later synthesized using 1-(2-aminoethyl)piperazine (AEP) as the SDA (denoted as SU-74-AEP), and its structure was solved by single crystal synchrotron X-ray diffraction. The framework structure of SU-74-AEP is the same as that of SU-74-MPMD. The locations of the organic SDAs in the pores are different for SU-74-MPMD and SU-74-AEP, suggesting a space-filling role of the SDAs. The Ge₁₀ clusters follow the fcu-11-P2₁/c net. The underlying topology of SU-74 is compared to those of other Ge₁₀ structures containing additional GeO₄ tetrahedra. The presence of additional tetrahedra can significantly affect the framework topology through the addition of edges between the Ge₁₀ nodes.