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@article{2371497,
author = {Kejík, Martin and Brus, Jiri and Jeremias, Lukas and Šimoníková, Lucie and Moravec, Zdeněk and Kobera, Libor and Stýskalík, Aleš and Barnes, Craig E. and Pinkas, Jiří},
article_number = {5},
doi = {http://dx.doi.org/10.1021/acs.inorgchem.3c04035},
keywords = {Aromatic compounds; Condensation; Ligands; Materials; Nuclear magnetic resonance spectroscopy},
language = {eng},
issn = {0020-1669},
journal = {Inorganic Chemistry},
title = {Lewis Acidic Aluminosilicates: Synthesis, 27Al MQ/MAS NMR, and DFT-Calculated 27Al NMR Parameters},
url = {https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c04035},
volume = {63},
year = {2024}
}
TY - JOUR
ID - 2371497
AU - Kejík, Martin - Brus, Jiri - Jeremias, Lukas - Šimoníková, Lucie - Moravec, Zdeněk - Kobera, Libor - Stýskalík, Aleš - Barnes, Craig E. - Pinkas, Jiří
PY - 2024
TI - Lewis Acidic Aluminosilicates: Synthesis, 27Al MQ/MAS NMR, and DFT-Calculated 27Al NMR Parameters
JF - Inorganic Chemistry
VL - 63
IS - 5
SP - 2679-2694
EP - 2679-2694
PB - American Chemical Society
SN - 00201669
KW - Aromatic compounds
KW - Condensation
KW - Ligands
KW - Materials
KW - Nuclear magnetic resonance spectroscopy
UR - https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c04035
N2 - Porous aluminosilicates are functional materials of paramount importance as Lewis acid catalysts in the synthetic industry, yet the participating aluminum species remain poorly studied. Herein, a series of model aluminosilicate networks containing [L–AlO3] (L = THF, Et3N, pyridine, triethylphosphine oxide (TEPO)) and [AlO4]− centers were prepared through nonhydrolytic sol–gel condensation reactions of the spherosilicate building block (Me3Sn)8Si8O20 with L–AlX3 (X = Cl, Me, Et) and [Me4N] [AlCl4] compounds in THF or toluene. The substoichiometric dosage of the Al precursors ensured complete condensation and uniform incorporation, with the bulky spherosilicate forcing a separation between neighboring aluminum centers. The materials were characterized by 1H, 13C, 27Al, 29Si, and 31P MAS NMR and FTIR spectroscopies, ICP-OES, gravimetry, and N2 adsorption porosimetry. The resulting aluminum centers were resolved by 27Al TQ/MAS NMR techniques and assigned based on their spectroscopic parameters obtained by peak fitting (δiso, CQ, η) and their correspondence to the values calculated on model structures by DFT methods. A clear correlation between the decrease in the symmetry of the Al centers and the increase of the observed CQ was established with values spanning from 4.4 MHz for distorted [AlO4]− to 15.1 MHz for [THF–AlO3]. Products containing exclusively [TEPO–AlO3] or [AlO4]− centers could be obtained (single-site materials). For L = THF, Et3N, and pyridine, the [AlO4]− centers were formed together with the expected [L–AlO3] species, and a viable mechanism for the unexpected emergence of [AlO4]− was proposed.
ER -
KEJÍK, Martin, Jiri BRUS, Lukas JEREMIAS, Lucie ŠIMONÍKOVÁ, Zdeněk MORAVEC, Libor KOBERA, Aleš STÝSKALÍK, Craig E. BARNES a Jiří PINKAS. Lewis Acidic Aluminosilicates: Synthesis, 27Al MQ/MAS NMR, and DFT-Calculated 27Al NMR Parameters. \textit{Inorganic Chemistry}. American Chemical Society, 2024, roč.~63, č.~5, s.~2679-2694. ISSN~0020-1669. Dostupné z: https://dx.doi.org/10.1021/acs.inorgchem.3c04035.
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