A Germanate with a Collapsible Open-Framework

Abstract

A novel open-framework germanate, |NC2H8∥N2C6H18|[Ge7O14.5F2]·4H2O denoted SU-65 (SU = Stockholm University), with 24-ring channels and a very low framework density of 8.9 Ge atoms per 1000 Å3 was synthesized under hydro-solvothermal conditions. The framework of SU-65 is built of 5-connected Ge7 clusters decorating the fee net and is a framework orientation isomer to ASU-16. Half of the 8- and 12-rings in ASU-16 are instead 10-rings in SU-65 due to the different orientations of half of the clusters in the crystal structure. Flexibility of the frameworks is also influenced by the orientation of the clusters. The unique unit cell angle in SU-65 changes upon heating, unlike ASU-16 which only undergoes changes in unit cell lengths. SU-65 undergoes significant structural changes at 180 °C in a vacuum, forming SU-65ht. The crystal structure of SU-65ht was investigated by rotation electron diffraction, X-ray powder diffraction, and infrared spectroscopy. Through these techniques it was deduced that SU-65ht has similar clusters, symmetry, and topology as SU-65, but one of the unit cell lengths is shortened by approximately 5 Å. This corresponds to a 22% decrease in unit cell volume.

Synthesis of Organosilyl‐Functionalized Cage‐Type Germanoxanes Containing Fluoride Ions

“…The matrix‐assisted laser desorption ionization time of flight (MALDI‐TOF) mass spectrum shows the peaks assigned to the cage germanoxanes containing a fluoride ion, indicating the successful synthesis of 1 [Figure a and d (left)]. The Fourier transform infrared (FTIR) spectrum of 1 shows a strong band at 932 cm −1 (Figure S2 a, Supporting Information), which is assigned to Ge−O−Ge stretching . Due to the insolubility of 1 in typical organic solvents, silylation reactions were conducted by dispersing the solid 1 into a solution containing silylating agents.…”