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

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., 13C 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.