| Abstract
| - The (Ge,Si)7O17F2 heptameric clusters are connected through vertex-sharing to form a silicogermanate containing circular 24-rings. The template, 1-aminopropane, is H-bonded to the framework. The H-bonding is critical for stabilizing the framework structure.
- A new silicogermanate, SU-12, |(CH3CH2CH2NH3)3(H2O)2.5|[(Ge6.44Si0.56)O14.5F2], with 24-ring channelsystems was synthesized under hydro/solvothermal conditions, and its structure was determined by single-crystal X-ray diffraction. It is the first silicogermanate with extra-large 24-rings templated by a primarymonoamine. Crystallographic data: tetragonal, space group I4̄2m, unit cell parameters a = 27.6460(22)Å and c = 17.0885(14) Å, V = 13060.8(17) Å3, Z = 16, ρcalcd = 1.797 g/cm3, R1 = 0.0512 [5471observed reflections with I > 2σ(I)], wR2 = 0.1487, S (goodness-of-fit on F2) = 1.08. SU-12 has astructure topology similar to that of the pure germanate ASU-16. However, the symmetry of SU-12 ishigher than that of ASU-16, and the 24-rings become more circular than those in ASU-16. The interactionbetween the templates and framework is compared for ASU-16 and SU-12, and their thermal stabilitiesare studied. The orthorhombic ASU-16 is thermally less stable than the tetragonal SU-12 and transformedto SU-12 by heating. The ion-exchange property of SU-12 is also studied.
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