The Water Molecule in Na₆[AlSiO₄]₆ Sodalite

Abstract

The behavior of a water molecule in Na 6 [AlSiO 4 ] 6 sodalite has been investigated using density functional calculations. The lowest energy position of the molecule is near the plane of the 6-ring window which does not contain a Na ion. The molecule is oriented to form hydrogen bonds with two of the framework oxygens and to interact with a Na ion in a nearby window. In this configuration the energy is 0.58 eV below the energy of the isolated water molecule plus that of anhydrous sodalite. Several tests indicate that most of the binding energy is due to the interaction of the oxygen with the Na ion. An analysis of electronic density for the lowest energy position shows that, when the molecule is put in contact with sodalite, charge is transferred from the water molecule to the spaces between the hydrogen atoms and the framework oxygens and between the water molecule oxygen and the nearest Na framework ion. Other bonding sites are above the plane of a 6-ring window occupied by a Na ion and above a 4-ring window. † Part of the special issue "John T. Yates, Jr., Festschrift".

Dehydrated Na6[AlSiO4]6 sodalite as a promising SO2 sorbent material: A first principles thermodynamics prediction

“…Correspondingly, the cell volume shrinks a little by ~0.6%, reflecting the structural flexibility of the Na 6 ‐SOD framework. Such a volume reduction upon adsorption has been also observed for a hydrated Na 6 ‐SOD system …”

“…It should be noted that sites 1 and 2 are not crystallographically identical concerning the β‐cage center at (0.5,0.5,0.5). The three Na + cations in site 3 are located slightly outside of the centered cage, while the other three Na + cations in site 4 are located slightly inside of the centered cage . The ground‐state lattice parameter of the conventional cell was predicted to be 9.120 Å, agreeing very well with the experimental measurement of 9.122 Å .…”

“…D, E, All window sites are labeled in a β‐cage viewed along the [1] and the [11] directions, respectively. The directions are defined with respect to the unit cell center for convenience [Color figure can be viewed at wileyonlinelibrary.com]…”

“…More attractively, Na 6 ‐SOD can be directly synthesized from coal fly ash by hydrothermal treatments . Furthermore, sodalite nano‐cage, as the basic building unit of Na 6 ‐SOD, can be found in many other porous materials such as zeolite X/Y/A, and thus, the knowledge developed for Na 6 ‐SOD will be helpful to understand many other relevant sorbent systems …”

Structure, Vibrational Spectra and 11B-NMR Chemical Shift of Na8[AlSiO4]6(B(OH)4)2: Comparison of Theory and Experiment

“…At the same level of theory Huai et al calculated the structure and different properties of an electron-deficient telluride using the VASP software − and the tight-binding linear muffin-tin orbital atomic sphere approximation (TB-LMTO-ASA) . Shannon and Metiu investigated isolated water molecules within a sodalite cage at GGA DFT level using VASP. − Mikuła et al investigated vibrational spectra (IR and Raman) of sodalites using the CRYSTAL code , at HF level and the Gaussian09 program at DFT level, respectively. There are also many theoretical studies of boron-containing molecules in solids.…”