Thermochromic properties of low-melting ionic uranyl isothiocyanate complexes

Aoyagi, Noboru; Shimojo, Kojiro; Brooks, Neil R.; Nagaishi, Ryuji; Naganawa, Hirochika; Hecke, Kristof Van; Meervelt, Luc Van; Binnemans, Koen; Kimura, Takaumi

doi:10.1039/c0cc05550f

Cited by 49 publications

(50 citation statements)

References 21 publications

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“…1,[9][10][11][12] While ionic liquid systems with thermochromism related to changes in coordination of the metal centre have previously been reported, this has either been in the presence of additives or molecular solvents, or the magnetic properties were not investigated. [13][14][15][16][17] Here, we report on solutions of cobalt(II)isothiocyanate in thiocyanate ILs that show reversible switching of the cobalt(II) speciation from tetrahedral [Co(NCS)4] 2at room temperature to octahedral [Co(NCS)6] 4at temperatures around 233 K. These temperature-dependent changes in the co-ordination environment are accompanied by reversible changes in colour (blue to red) and by significant changes of the effective magnetic moment of these fluids. The IL acts as a reservoir for the thiocyanate anions, enabling a reversible equilibrium, which in turn results in a reversible temperature-dependent switching of the coordination environment; hence a reversible switching of the magnetic moment.…”

Section: Temperature-dependent Switching Of Paramagnetism Of a Cobaltmentioning

confidence: 99%

Thermochromism and switchable paramagnetism of cobalt(ii) in thiocyanate ionic liquids

et al. 2015

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Temperature-dependent switching of paramagnetism of a cobalt(II) complex is observed in an ionic liquid solution. Paramagnetic and thermochromic switching occur simultaneously due to a reversible change in coordination. This reversible switching is possible in the ionic liquid solution, which enables mobility of thiocyanate anions by remaining mobile at low temperatures and acts as an anion reservoir.

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Section: Temperature-dependent Switching Of Paramagnetism Of a Cobaltmentioning

confidence: 99%

Thermochromism and switchable paramagnetism of cobalt(ii) in thiocyanate ionic liquids

et al. 2015

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“…A further interesting photophysical property of certain uranyl compounds are thermochromic effects. Thus the compound [C 4 mim] 3 [UO 2 (NCS) 5 ] (C 4 mim = 1-butyl-3-methylimidazolium) is thermochromic in ionic liquids [10] but in organic solvents [Et 4 N] 3 [UO 2 (NCS) 5 ] is not [11]. We have reported on the latter compound recently and now extend our study to the selenocyanate [ …”

Section: Introductionmentioning

confidence: 90%

A Structural and Spectroscopic Study of the First Uranyl Selenocyanate, [Et4N]3[UO2(NCSe)5]

et al. 2016

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“…57 In solution studies on uranyl complexes, in addition to powerful optical spectroscopy, crystal structure analyses can supply partial evidence. 28 24 Hence, the successful crystallization of compound 2 herein through our novel synthetic method has …”

Section: Crystal Growth and Designmentioning

confidence: 99%

Crystallization in Ionic Liquids: Synthesis, Properties, and Polymorphs of Uranyl Salts

Liu

2014

Crystal Growth & Design

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Crystallizations in uranyl-containing ionic liquids yielding crystals {X} a {[UO 2 ] b [Y] c } with selected anions and cations (X = [Bmim] + for Y = Cl − , NO 3 − , and SCN − ; Y = Cl − for X = [Emim] + , [Emmim] + , [Bmim] + , and [Bmmim] + ;Emim = l-ethyl-3-methyl-imidazolium, Emmim = l-ethyl-2,3-dimethylimidazolium, Bmim = l-butyl-3-methylimidazolium, and Bmmim = l-butyl-2,3-dimethylimidazolium) were performed herein. Through standard crystallographic analyses, Hirshfeld surface analyses, and multiple characterization techniques, compounds with common cations/anions were investigated. For compounds [Bmim] 2 [(UO 2 ) 2 (μ-OH) 2 (NO 3 ) 4 ] (1), [Bmim] 3 [UO 2 (NCS) 5 ] (2), and [Bmim] 2 [UO 2 Cl 4 ] (3TT and 3TG), common [Bmim] + cations with different conformations were studied with respect to packing and interactions (for 1). The coordinated [(UO 2 ) 2 (μ-OH) 2 (NO 3 ) 4 ] 2− , [UO 2 (NCS) 5 ] 3− , and [UO 2 Cl 4 ] 2− anions that have historically been related to nuclear fuel cycles were demonstrated with respect to geometry and distortion. For compounds with common [UO 2 Cl 4 ] 2− anions [Emim] 2 [UO 2 Cl 4 ] (4), [Emmim] 2 [UO 2 Cl 4 ] (5), [Bmmim] 2 [UO 2 Cl 4 ] (6), 3TT, and 3TG, observed interionic interactions that have been previously impeded by limited structural information were discussed fully in relation to different cations and temperatures. Moreover, multistep phase transformations of 2, which have been undefined in solution studies, have been identified through differential scanning calorimetry analyses and polarizing optical microscopy. The polymorph transformations between 3TT and 3TG in solution, as controlled by uranyl concentration, were studied using optical microscopy and powder X-ray diffraction. The thermal stability, IR/Raman, and UV−vis/luminescence spectra of these compounds were also investigated. ■ INTRODUCTIONIonic liquids (ILs) are attractive to investigators due to their unique physical and chemical properties and have thus been widely examined in many areas. 1,2 Among their usages, crystallization in ILs is a complex and fascinating field of research. 3−5 Both the unique coordination features that cannot generally be observed using molecular solvents and the interaction specifics that are difficult to obtain in the liquid state of ILs can be investigated. 6,7 However, the crystallography data that have immensely promoted our understanding of intermolecular interactions 8 have not been fully explored regarding the crystallographic potential in IL systems.A special interest in f metal-containing ILs has recently arisen in various fields, resulting in many high-quality investigations involving crystallographic studies. 9−12 Specifically, promising applications of ILs in nuclear fuel cycles 13−17 have encouraged extensive studies on uranium-based IL systems, including the relatively common crystallization of uranium salts in ILs and novel explorations of crystallization methods in such complex systems. [3][4][5][6]13,18,19 Using the widely studied uranyl-imidazolium structures as...

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Thermochromic properties of low-melting ionic uranyl isothiocyanate complexes

Cited by 49 publications

References 21 publications

Thermochromism and switchable paramagnetism of cobalt(ii) in thiocyanate ionic liquids

Thermochromism and switchable paramagnetism of cobalt(ii) in thiocyanate ionic liquids

A Structural and Spectroscopic Study of the First Uranyl Selenocyanate, [Et4N]3[UO2(NCSe)5]

Crystallization in Ionic Liquids: Synthesis, Properties, and Polymorphs of Uranyl Salts

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