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Lewis acidic aluminosilicates: synthesis, 27 Al MQ/MAS NMR, and DFT-calculated 27 Al NMR parameters
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SYSNO ASEP 0583043 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Lewis acidic aluminosilicates: synthesis, 27 Al MQ/MAS NMR, and DFT-calculated 27 Al NMR parameters Tvůrce(i) Kejik, M. (CZ)
Brus, Jiří (UMCH-V) RID, ORCID
Jeremias, L. (CZ)
Šimoníková, L. (CZ)
Moravec, Z. (CZ)
Kobera, Libor (UMCH-V) RID, ORCID
Stýskalík, A. (CZ)
Barnes, C. E. (US)
Pinkas, J. (CZ)Zdroj.dok. Inorganic Chemistry. - : American Chemical Society - ISSN 0020-1669
Roč. 63, č. 5 (2024), s. 2679-2694Poč.str. 16 s. Jazyk dok. eng - angličtina Země vyd. US - Spojené státy americké Klíč. slova Lewis acidic ; aluminosilicates ; 27 Al ssNMR Vědní obor RIV CD - Makromolekulární chemie Obor OECD Polymer science Způsob publikování Open access Institucionální podpora UMCH-V - RVO:61389013 UT WOS 001158206500001 EID SCOPUS 85184001568 DOI 10.1021/acs.inorgchem.3c04035 Anotace 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. Pracoviště Ústav makromolekulární chemie Kontakt Eva Čechová, cechova@imc.cas.cz ; Tel.: 296 809 358 Rok sběru 2025 Elektronická adresa https://pubs.acs.org/doi/10.1021/acs.inorgchem.3c04035
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