Porous structures and adsorption phenomena in rare-earth element phosphates and bridged resorcinarene cages elucidated by combined experimental and computational ¹³P and ¹²⁹Xe NMR

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>The aim of the present thesis is to unravel the structure and adsorption properties of essential materials that have a broad range of applications from environmental science to technology. Studied materials are rare-earth element phosphates and resorcinarene cages. Using NMR spectroscopic techniques, we probed the structures and micro/nano scale pores of these materials. DFT computational methods were applied to interpret experimental results, as well as to provide molecular-level understanding of the investigated systems.</p><p>Firstly, we determined the configuration of water molecules in rare earth element phosphates and characterized the surface and pore structures of the samples. Rare-earth element phosphate samples included lanthanum, samarium, lutetium and ytterbium phosphates. Here, for the first time we studied rare-earth element phosphates applying ¹²⁹Xe NMR, a technique which is highly sensitive to the chemical environment and which can provide detailed information on the structures of porous materials. ¹²⁹Xe NMR analysis was complemented by ¹³P solid-state NMR to provide additional information on the local structures and the coordination of water molecules on surfaces. Complementary information from quantum chemical calculations enabled the identification of several surface structures and confirmed the experimentally observed bulk phases. Additional structural characterization of these materials was obtained by PXRD, TGA, LDS, FTIR and FESEM methods.</p><p>Secondly, we investigated supramolecular cage molecules based on bridged resorcinarene macrocycles, which are new, promising and affordable potential cages for ¹²⁹Xe NMR biosensor applications. Computational modelling predicted unique chemical shifts of ¹²⁹Xe in the cages, and chemical exchange saturation transfer and relaxation experiments revealed fast xenon exchange dynamics, which is favorable for biosensor applications.</p></div>

<div lang="en" class="abs"><p class="abs_header">Original papers</p><p>Original papers are not included in the electronic version of the dissertation.</p><ol type="I"><li><p>Khalili, R., Larsson, A.-C., Telkki, V.-V., Lantto, P., & Kantola, A. M. (2022). Local structures of rare earth phosphate minerals by NMR. Journal of Solid State Chemistry, 311, 123097. <a href="https://doi.org/10.1016/j.jssc.2022.123097">https://doi.org/10.1016/j.jssc.2022.123097</a></p><p><a href="https://urn.fi/urn:nbn:fi-fe2022092259887">Self-archived version</a></p></li><li><p>Khalili, R., Kantola, A. M., Komulainen, S., Selent, A., Selent, M., Vaara, J., Larsson, A.-C., Lantto, P., & Telkki, V.-V. (2022). 129Xe NMR analysis of pore structures and adsorption phenomena in rare-earth element phosphates. Microporous and Mesoporous Materials, 344, 112209. <a href="https://doi.org/10.1016/j.micromeso.2022.112209">https://doi.org/10.1016/j.micromeso.2022.112209</a></p><p><a href="https://urn.fi/urn:nbn:fi-fe2022102563242">Self-archived version</a></p></li><li><p>Komulainen, S., Ferando, P. U. A. I., Mareš, J., Selent, A., Khalili, R., Cesana, P. T., Ebeling, A., Kantola, A. M., Beyeh, N. K., Rissanen, K., DeBoef, B., Lantto, P., & Telkki, V.-V. (2023). Resorcinarene cages: a new class of potential 129Xe biosensors with unique chemical shift and exchange dynamics. Manuscript submitted for publication.</p></li></ol></div>

<div lang="fi" class="abs"><p class="abs_header">Osajulkaisut</p><p>Osajulkaisut eivät sisälly väitöskirjan elektroniseen versioon.</p><ol type="I"><li><p>Khalili, R., Larsson, A.-C., Telkki, V.-V., Lantto, P., & Kantola, A. M. (2022). Local structures of rare earth phosphate minerals by NMR. Journal of Solid State Chemistry, 311, 123097. <a href="https://doi.org/10.1016/j.jssc.2022.123097">https://doi.org/10.1016/j.jssc.2022.123097</a></p><p><a href="https://urn.fi/urn:nbn:fi-fe2022092259887">Rinnakkaistallennettu versio</a></p></li><li><p>Khalili, R., Kantola, A. M., Komulainen, S., Selent, A., Selent, M., Vaara, J., Larsson, A.-C., Lantto, P., & Telkki, V.-V. (2022). 129Xe NMR analysis of pore structures and adsorption phenomena in rare-earth element phosphates. Microporous and Mesoporous Materials, 344, 112209. <a href="https://doi.org/10.1016/j.micromeso.2022.112209">https://doi.org/10.1016/j.micromeso.2022.112209</a></p><p><a href="https://urn.fi/urn:nbn:fi-fe2022102563242">Rinnakkaistallennettu versio</a></p></li><li><p>Komulainen, S., Ferando, P. U. A. I., Mareš, J., Selent, A., Khalili, R., Cesana, P. T., Ebeling, A., Kantola, A. M., Beyeh, N. K., Rissanen, K., DeBoef, B., Lantto, P., & Telkki, V.-V. (2023). Resorcinarene cages: a new class of potential 129Xe biosensors with unique chemical shift and exchange dynamics. Manuscript submitted for publication.</p></li></ol></div>