Crystal structure of ITQ-1p, the pure-silica precursor to the zeolite ITQ-1 (MWW framework type)
6 affiliations
- 1Department of Chemical Engineering
- 2University of California
- 3Chemical Engineering, School for Engineering of Matter, Transport and Energy
- 4Arizona State University
- 5Department of Materials
- 6ETH Zurich
Abstract
The synergy between solid-state NMR, a probe of local structure, and X-ray powder diffraction, a probe of long-range order, has been exploited to untangle the details of the structure of ITQ-1p, the layered precursor to the pure silica zeolite ITQ-1 (MWW framework type). Rietveld refinement of the structure using synchrotron powder diffraction data was guided by the results from a variety of solid-state NMR techniques, including two-dimensional (2D) 29 Si– 29 Si correlation spectra that resolve all eight Si sites, 2D 29 Si{ 1 H} and 13 C{ 1 H} correlation spectra that show a complicated distribution of hydrogen-bonded environments in the interlayer space, and a 1D 23 Na spectrum that indicates a nearly symmetrical environment around the Na + ions. The main features of the resulting structure are: MWW silicate layers with silanol nests at the interlayer surface, hexamethyleneimine (HMI) molecules in the intralayer channel and in the interlayer space, trimethylaminoadamantane ions (TMAda + ) in the "pockets" at the surface of the layer with the trimethylamino group pointing towards the interlayer space, and a Na + ion surrounded by a puckered ring of 3 water molecules and 3 OH – groups at the origin between the two TMAda+ ions in adjacent layers. This well-defined TMAda + -Na + (OH – ) 3 (H 2 O) 3 -TMAda + complex may well be the key to the unusually high crystallinity of ITQ-1p. Indeed, these structural details give considerable insight into the synthetic process, and provide a foundation for tailoring interlayer chemistry to realize specific catalytic features.
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BibTeX
@misc{berkson2026crystal,
title = {{Crystal structure of ITQ-1p, the pure-silica precursor to the zeolite ITQ-1 (MWW framework type)}},
author = {Zachariah J. Berkson and Alyssa McNarney and Hardik K. Balsaraf and Bradley F. Chmelka and Christian Baerlocher and Lynne B. McCusker},
howpublished = {ChemRxiv},
year = {2026},
month = aug,
doi = {10.26434/chemrxiv.15008091/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008091/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Crystal structure of ITQ-1p, the pure-silica precursor to the zeolite ITQ-1 (MWW framework type)
AU - Zachariah J. Berkson
AU - Alyssa McNarney
AU - Hardik K. Balsaraf
AU - Bradley F. Chmelka
AU - Christian Baerlocher
AU - Lynne B. McCusker
PY - 2026
DA - 2026/08/31
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008091/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008091/v1
AB - The synergy between solid-state NMR, a probe of local structure, and X-ray powder diffraction, a probe of long-range order, has been exploited to untangle the details of the structure of ITQ-1p, the layered precursor to the pure silica zeolite ITQ-1 (MWW framework type). Rietveld refinement of the structure using synchrotron powder diffraction data was guided by the results from a variety of solid-state NMR techniques, including two-dimensional (2D) 29 Si– 29 Si correlation spectra that resolve all eight Si sites, 2D 29 Si{ 1 H} and 13 C{ 1 H} correlation spectra that show a complicated distribution of hydrogen-bonded environments in the interlayer space, and a 1D 23 Na spectrum that indicates a nearly symmetrical environment around the Na + ions. The main features of the resulting structure are: MWW silicate layers with silanol nests at the interlayer surface, hexamethyleneimine (HMI) molecules in the intralayer channel and in the interlayer space, trimethylaminoadamantane ions (TMAda + ) in the "pockets" at the surface of the layer with the trimethylamino group pointing towards the interlayer space, and a Na + ion surrounded by a puckered ring of 3 water molecules and 3 OH – groups at the origin between the two TMAda+ ions in adjacent layers. This well-defined TMAda + -Na + (OH – ) 3 (H 2 O) 3 -TMAda + complex may well be the key to the unusually high crystallinity of ITQ-1p. Indeed, these structural details give considerable insight into the synthetic process, and provide a foundation for tailoring interlayer chemistry to realize specific catalytic features.
ER -