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Updated: Mar 6, 2026

Synthesis of Zeolites Using the ADOR Assembly-Disassembly-Organization-Reassembly Route
Published on: April 3, 2016
Intermolecular interactions in AST zeolites through 14N NMR and DFT calculations
Eddy Dib1, Mélanie Freire2, Valérie Pralong2
1ICGM-MACS, Institut Charles Gerhardt de Montpellier, UMR5253 CNRS-ENSCM-UM, 8 rue de l'école normale, Montpellier Cedex 5, 34296, France.
Abstract:
The structure of the silica AST zeolites (octadecasil) synthesized in fluoride medium using tetramethylammonium (TMA) as the organic structure-directing agent has been reinvestigated using 14N NMR quadrupolar parameters and DFT calculations. The value of the experimental 14N quadrupolar coupling constant (CQ = 27 kHz) is larger than expected for a TMA cation possessing a high degree of motion. The analysis of a DFT-optimized octadecasil cluster along with the comparison between measured and calculated 14N NMR parameters demonstrate the presence of weak C-H...O hydrogen bonds between the TMA in the [46612] cages and the silica skeleton. These intermolecular interactions can be related to the presence of Si...F tetrel bonds within the [46] cages. These new results provide additional information with regard to the formation mechanisms and structure of the octadecasil zeolites.
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