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In Situ X‐ray Diffraction Investigation of the Crystallisation of Perfluorinated Ce IV ‐Based Metal–Organic Frameworks with UiO‐66 and MIL‐140 Architectures **
Author(s) -
Shearan Stephen J. I.,
Jacobsen Jannick,
Costantino Ferdinando,
D'Amato Roberto,
Novikov Dmitri,
Stock Norbert,
Andreoli Enrico,
Taddei Marco
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202005085
Subject(s) - cerium , reagent , crystallization , metal organic framework , nucleation , yield (engineering) , nitric acid , chemistry , protonation , acetic acid , aqueous solution , inorganic chemistry , materials science , crystallography , organic chemistry , ion , adsorption , metallurgy
We report on the results of an in situ synchrotron powder X‐ray diffraction study of the crystallisation in aqueous medium of two recently discovered perfluorinated Ce IV ‐based metal–organic frameworks (MOFs), analogues of the already well investigated Zr IV ‐based UiO‐66 and MIL‐140A, namely, F4_UiO‐66(Ce) and F4_MIL‐140A(Ce). The two MOFs were originally obtained in pure form in similar conditions, using ammonium cerium nitrate and tetrafluoroterephthalic acid as reagents, and small variations of the reaction parameters were found to yield mixed phases. Here, we investigate the crystallisation of these compounds, varying parameters such as temperature, amount of the protonation modulator nitric acid and amount of the coordination modulator acetic acid. When only HNO 3 is present in the reaction environment, only F4_MIL‐140A(Ce) is obtained. Heating preferentially accelerates nucleation, which becomes rate determining below 57 °C. Upon addition of AcOH to the system, alongside HNO 3 , mixed‐phased products are obtained. F4_UiO‐66(Ce) is always formed faster, and no interconversion between the two phases occurs. In the case of F4_UiO‐66(Ce), crystal growth is always the rate‐determining step. A higher amount of HNO 3 favours the formation of F4_MIL‐140A(Ce), whereas increasing the amount of AcOH favours the formation of F4_UiO‐66(Ce). Based on the in situ results, a new optimised route to achieving a pure, high‐quality F4_MIL‐140A(Ce) phase in mild conditions (60 °C, 1 h) is also identified.