The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals
We report a facile co-precipitation method of synthesizing orthorhombic phase CsNd2F7 and hexagonal phase K2NdF5 nanocrystals, which avoids the use of relatively harsh conditions (e.g., high temperatures and long reaction times in hydrothermal synthesis). By reacting MF (M = Cs and K), Nd(CH3CO2)3,...
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sg-ntu-dr.10356-1608322022-08-03T06:22:04Z The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals Wu, Xiangyang Tham, Jing Yang Chacko, Ann-Marie Yeow, Edwin Kok Lee School of Physical and Mathematical Sciences Science::Chemistry Transmission Electron Microscopy Mixtures We report a facile co-precipitation method of synthesizing orthorhombic phase CsNd2F7 and hexagonal phase K2NdF5 nanocrystals, which avoids the use of relatively harsh conditions (e.g., high temperatures and long reaction times in hydrothermal synthesis). By reacting MF (M = Cs and K), Nd(CH3CO2)3, oleic acid (OA), and 1-octadecene in the presence of sufficient amounts of oleylamine ligands (OAm) to ensure a non-acidic environment, CsNd2F7 and K2NdF5 nanocrystals are formed for reaction temperatures (Tr) ranging between 150 and 300 °C. When OAm is in excess of OA and Tr = 300 °C, uniformly distributed CsNd2F7 nanodiscs (∼20 nm in diameter) and sub-10 nm K2NdF5 nanodiscs with an average thickness of 2-3 unit cell layers are formed. When OAm is removed, the acidic mixture produces CsNd2F7 nanocrystals at low Tr (150-200 °C); however, a mixture of NdF3 and Cs-oleate is observed instead when Tr is increased. Similarly, in an acidic enviroment, K2NdF5 nanocrystals rapidly decompose into a mixture of K0.156Nd0.142-yF0.702-3y and y(NdF3) (y < 0.142) at low Tr (150-200 °C), while orthorhombic KNdF4 nanocrystals are synthesized at higher Tr (>200 °C). Therefore, the penta- and heptafluoride nanocrystals are thermodynamically stable only in a basic medium when OA is consumed, in part by its condensation reaction with OAm. We further demonstrate that the CsNd2F7 and K2NdF5 nanocrystals display good light-to-heat conversion efficiencies (16-27%) and computed tomography (CT) attenuation, making them promising theranostic photothermal imaging/therapy and CT contrast agents. Ministry of Education (MOE) We acknowledge financial support from the Singapore Ministry of Education MoE Tier 1 grants (RG89/20 and RG6/18) and Duke-NUS Block Grant. 2022-08-03T06:22:04Z 2022-08-03T06:22:04Z 2021 Journal Article Wu, X., Tham, J. Y., Chacko, A. & Yeow, E. K. L. (2021). The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals. Chemistry of Materials, 33(21), 8367-8377. https://dx.doi.org/10.1021/acs.chemmater.1c02736 0897-4756 https://hdl.handle.net/10356/160832 10.1021/acs.chemmater.1c02736 2-s2.0-85118762220 21 33 8367 8377 en RG89/20 RG6/18 Chemistry of Materials © 2021 American Chemical Society. All rights reserved. |
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Science::Chemistry Transmission Electron Microscopy Mixtures Wu, Xiangyang Tham, Jing Yang Chacko, Ann-Marie Yeow, Edwin Kok Lee The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals |
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We report a facile co-precipitation method of synthesizing orthorhombic phase CsNd2F7 and hexagonal phase K2NdF5 nanocrystals, which avoids the use of relatively harsh conditions (e.g., high temperatures and long reaction times in hydrothermal synthesis). By reacting MF (M = Cs and K), Nd(CH3CO2)3, oleic acid (OA), and 1-octadecene in the presence of sufficient amounts of oleylamine ligands (OAm) to ensure a non-acidic environment, CsNd2F7 and K2NdF5 nanocrystals are formed for reaction temperatures (Tr) ranging between 150 and 300 °C. When OAm is in excess of OA and Tr = 300 °C, uniformly distributed CsNd2F7 nanodiscs (∼20 nm in diameter) and sub-10 nm K2NdF5 nanodiscs with an average thickness of 2-3 unit cell layers are formed. When OAm is removed, the acidic mixture produces CsNd2F7 nanocrystals at low Tr (150-200 °C); however, a mixture of NdF3 and Cs-oleate is observed instead when Tr is increased. Similarly, in an acidic enviroment, K2NdF5 nanocrystals rapidly decompose into a mixture of K0.156Nd0.142-yF0.702-3y and y(NdF3) (y < 0.142) at low Tr (150-200 °C), while orthorhombic KNdF4 nanocrystals are synthesized at higher Tr (>200 °C). Therefore, the penta- and heptafluoride nanocrystals are thermodynamically stable only in a basic medium when OA is consumed, in part by its condensation reaction with OAm. We further demonstrate that the CsNd2F7 and K2NdF5 nanocrystals display good light-to-heat conversion efficiencies (16-27%) and computed tomography (CT) attenuation, making them promising theranostic photothermal imaging/therapy and CT contrast agents. |
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School of Physical and Mathematical Sciences |
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School of Physical and Mathematical Sciences Wu, Xiangyang Tham, Jing Yang Chacko, Ann-Marie Yeow, Edwin Kok Lee |
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Article |
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Wu, Xiangyang Tham, Jing Yang Chacko, Ann-Marie Yeow, Edwin Kok Lee |
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Wu, Xiangyang |
title |
The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals |
title_short |
The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals |
title_full |
The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals |
title_fullStr |
The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals |
title_full_unstemmed |
The role of ligand acid-base reaction in the facile synthesis of Alkali Metal Neodymium Penta- And Heptafluoride Nanocrystals |
title_sort |
role of ligand acid-base reaction in the facile synthesis of alkali metal neodymium penta- and heptafluoride nanocrystals |
publishDate |
2022 |
url |
https://hdl.handle.net/10356/160832 |
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1743119589378621440 |