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2. Tailoring Redox Active Ligands for Probing the Reactivity of Actinides

Author

Miliordos, Evangelos, primary, Black, Clayton, additional, Ducilon, John, additional, Forbes, Madeleine, additional, Gardner, Dylan, additional, Gorden, Anne, additional, Grundhoefer, John, additional, Hiti, Ethan, additional, Hoang, Tessa, additional, Hollingsworth, William, additional, Hunter, Katharine, additional, Mayhugh, Jacob, additional, Niklas, Julie, additional, Stilley, Avery, additional, Williamson, Justin, additional, Ariyarathna, Isuru, additional, Jackson, Benjamin, additional, Lu, Zhongyuan, additional, Stinson, Jared, additional, Paz, Holden, additional, Farnum, Byron, additional, DeBettencourt‐Dias, Ana, additional, Monteiro, Jorge, additional, and Gorden, John, additional

Published
2022
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6. Trapping an Unexpected/Unprecedented Hexanuclear Ce(III) Hydrolysis Product with Neutral 4-Amino-1,2,4-triazole

Author

Wineinger, Hannah, Smetana, Volodymyr, Hiti, Ethan, Baryshnikov, Glib, Qu, Fengrui, Agren, Hans, Mudring, Anja-Verena, Rogers, Robin D., Wineinger, Hannah, Smetana, Volodymyr, Hiti, Ethan, Baryshnikov, Glib, Qu, Fengrui, Agren, Hans, Mudring, Anja-Verena, and Rogers, Robin D.

Abstract

Using Ce(III) as both a representative lanthanide and actinide analog, the ability of mixtures of acidic and basic azoles to allow direct access to homoleptic N-donor f-element complexes in one pot reactions from hydrated salts as starting materials was examined by reacting mixtures of 4-amino-1,2,4-triazole (4-NH2-1,2,4-Triaz), 5-amino-tetrazole (5-NH2-HTetaz), and 1,2,3-triazole (1,2,3-HTriaz) in 1:1 and 1:3 ratios with CeCl3 center dot 7H(2)O, [C(2)mim](3)[CeCl6] ([C(2)mim](+) = 1-ethyl-2-methylimidazolium), and Ce(NO3)(3)center dot 6H(2)O. Although unsuccessful in our goal, structural analysis revealed that neutral 4-NH2-1,2,4-Triaz is structure directing via eta(2)mu(2)kappa(2) bridging, with the formation of the dinuclear complexes [Ce2Cl2(mu(2)-4-NH2-1,2,4-Triaz)(4)(H2O)(8)]Cl-4 center dot 4H(2)O, [Ce-2(mu(2)-4-NH2-1,2,4-Triaz)(4)(4-NH2-1,2,4-Triaz)(2)(Cl)(6)], and [4-NH2-1,2,4-HTriaz][Ce-2(mu(2)-4-NH2-1,2,4-Triaz)(2)(mu(2)-NO3)(NO3)(6)(H2O)(2)]. When the synthetic conditions favored hydrolysis, the hexanuclear Ce(III) complex [Ce-6(mu(3)-O)(4)(mu(3)-OH)(2)(mu(3)-Cl)(2)(Cl)(6)(mu(2)-4-NH2-1,2,4-Triaz)(12)]center dot 7H(2)O was isolated. This unexpected hydrolysis product represents the first example of a high nuclearity lanthanide complex where all Ln atoms are pairwise connected through 12 N-donor ligands or 12 neutral bridging ligands of any type, a rare example of incorporation of non-oxo coordinating anions in the M6X8 core, and the first reported Ce(III) hexanuclear complex of this type.

Published
2023
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7. CO2 capture from ambient air via crystallization with tetraalkylammonium hydroxides

Author

Mishra, Manish Kumar, Smetana, Volodymyr, Hiti, Ethan A., Wineinger, Hannah B., Qu, Fengrui, Mudring, Anja-Verena, Rogers, Robin D., Mishra, Manish Kumar, Smetana, Volodymyr, Hiti, Ethan A., Wineinger, Hannah B., Qu, Fengrui, Mudring, Anja-Verena, and Rogers, Robin D.

Abstract

Aqueous solutions of a series of short carbon chain tetra(n-alkyl)ammonium hydroxides, [Nnnnn][OH] with n = 2: n-ethyl, 3: n-propyl, 4: n-butyl, have been serendipitously found to be potential candidates for direct air carbon capture (DAC) when being used as reagents in more complicated reactions. Aqueous solutions of [N3333][OH], [N2222][OH], or [N3333][OH] with UO2SO4·3H2O and 1,4-diamidoximylbenzene, and [N4444][OH] with cytosine (HCyt) directly absorb CO2 from the atmosphere upon mild heating in the open atmosphere crystallizing in complexes reaching up to 2 : 1 CO2/[Nnnnn]OH ratio. [N2222][HCO3]·3H2O (1), [N2222]2[H(HCO3)3]·5H2O (2), [N3333][HCO3]·0.5H2O (3), [N3333][H(HCO3)2] (4), [N3333]2[(tpa)(H2CO3)2] (5; tpa = terephthalate), [N4444][H(Cyt)(HCO3)]·H2O (6) and [N4444][H2(Cyt)2(HCO3)]·H2O (7) have been isolated in crystalline form and structurally characterized by single crystal X-ray diffraction. The compounds are characterized by complex polyanionic formations from bicarbonate dimers ([(HCO3)2·(H2O)]24−) or chains ([H(HCO3)2]nn− or [H2(tpa)(HCO3)2]n2n−) to water-bicarbonate associates ([(HCO3)2·6H2O]2− and [(H2CO3·(HCO3)2)2·6H2O·2H2O]2−) and three-component anionic layers ([H(Cyt)(HCO3)·H2O]nn− and [H2(Cyt)2(HCO3)·H2O]nn−) frequently showing proton sharing. While some hydroxides themselves can maintain a high CO2/[Nnnnn][OH] ratio, particularly 2 and 4, the presence of secondary hydrogen bond donors/acceptors may increase the sorption efficiency through decreased solubility and enhanced crystallization.

Published
2022
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9. CO2 capture from ambient air via crystallization with tetraalkylammonium hydroxides.

Author

Mishra, Manish Kumar, Smetana, Volodymyr, Hiti, Ethan A., Wineinger, Hannah B., Qu, Fengrui, Mudring, Anja-Verena, and Rogers, Robin D.

Subjects
TETRAALKYLAMMONIUM, CRYSTALLIZATION, HYDROXIDES, AQUEOUS solutions, SINGLE crystals, AMMONIUM hydroxide, AMMONIA
Abstract

Aqueous solutions of a series of short carbon chain tetra(n-alkyl)ammonium hydroxides, [Nnnnn][OH] with n = 2: n-ethyl, 3: n-propyl, 4: n-butyl, have been serendipitously found to be potential candidates for direct air carbon capture (DAC) when being used as reagents in more complicated reactions. Aqueous solutions of [N3333][OH], [N2222][OH], or [N3333][OH] with UO2SO4·3H2O and 1,4-diamidoximylbenzene, and [N4444][OH] with cytosine (HCyt) directly absorb CO2 from the atmosphere upon mild heating in the open atmosphere crystallizing in complexes reaching up to 2 : 1 CO2/[Nnnnn]OH ratio. [N2222][HCO3]·3H2O (1), [N2222]2[H(HCO3)3]·5H2O (2), [N3333][HCO3]·0.5H2O (3), [N3333][H(HCO3)2] (4), [N3333]2[(tpa)(H2CO3)2] (5; tpa = terephthalate), [N4444][H(Cyt)(HCO3)]·H2O (6) and [N4444][H2(Cyt)2(HCO3)]·H2O (7) have been isolated in crystalline form and structurally characterized by single crystal X-ray diffraction. The compounds are characterized by complex polyanionic formations from bicarbonate dimers ([(HCO3)2·(H2O)]24−) or chains ([H(HCO3)2]nn− or [H2(tpa)(HCO3)2]n2n−) to water-bicarbonate associates ([(HCO3)2·6H2O]2− and [(H2CO3·(HCO3)2)2·6H2O·2H2O]2−) and three-component anionic layers ([H(Cyt)(HCO3)·H2O]nn− and [H2(Cyt)2(HCO3)·H2O]nn−) frequently showing proton sharing. While some hydroxides themselves can maintain a high CO2/[Nnnnn][OH] ratio, particularly 2 and 4, the presence of secondary hydrogen bond donors/acceptors may increase the sorption efficiency through decreased solubility and enhanced crystallization. [ABSTRACT FROM AUTHOR]

Published
2022
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11. Uranyl Naphthylsalophen and Pyrasal Complexes: Oxo Ligands Acting as Hydrogen Bond Acceptors in the Solid State

Author

Tharp Eralie, Dylan M., Hiti, Ethan A., Bhakta, Dev T., Williamson, Justin A., Gorden, John D., Vasylevskyi, Serhii, and Gorden, Anne E.V.

Abstract

Uranium is most stable when it is exposed to oxygen or water in its +6 oxidation state as the uranyl (UO22+) ion. This ion is subsequently particularly stable and very resistant to functionalization due to the inverse trans effect. Uranyl oxo ligands are typically not considered good hydrogen bond acceptors due to their weak Lewis basicity; however, the ligands bound in the equatorial plane greatly affect the strength of the oxo ligands’ hydrogen bonding. In this work, new naphthylsalophen and pyrasal complexes of uranium were synthesized and crystallized for characterization in the solid state. The bond lengths and angles of the uranyl ion and the ligand conformation are compared. In the solid state, one of the pyrasal complexes showed a hydrogen bond directly from a water molecule to the uranyl oxo ligand, which resulted in an asymmetric lengthening of the U–Oylbonds from 1.789 to 1.862 Å and 1.784 to 1.844 Å.

Published
2024
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12. Emission Properties of Coordination Complexes: The Impact of Mixed Donors on f-Block Elements

Author

Hiti, Ethan

Subjects
Chemistry and Biochemistry
Abstract

There is a growing need to understand the fundamental aspects of chemistry concerning f-elements. Whether it be through the use of softer donor systems to try and selectively coordinate actinide ions in solution which could be useful in the event of a spill or contamination event, using mixed donor systems to take advantage of the distinct photophysical properties of Ln (III) ions for new emissions agents for biological imaging compounds. The 4f or 5f orbitals play a pivotal role in their unique chemistry, emission, and optical properties, accessible to these elements. Here, we look at three different aspects of f-element chemistry that allow us to look at the nature of the f-orbitals while looking at how this affects their emissive properties. The highly conjugated salimidizine ligand and 3 derivatives are examined for the electronic properties of the ligand and how these can be altered both for selective coordination of metal ions and somewhat tunable emissions. These properties would enable it to be potentially be used in colorimetric or fluorescence sensors for uranyl detection in solution. Examination of these organic frameworks is examined in the presence of copper (II) ions which are considered to be a common “false positive” metal ion due to similar charge to ionic size ratios. Overall, these organic frameworks are able to distinguish via fluorescence intensity the binding of uranyl versus copper. Further details and explanation for this is given through computational modeling of the complexes. Next, the ability of cyano substituted naphthylsalophens were examined as sensitizers or antennae with Ln (III) ions for 2 photon up-conversion processes. This Schiff base type (-2) ligand forms 3:2 ligand to lanthanide sandwich-type complexes that display characteristic metal centered emission for Nd (III), Er (III), and Yb (III). Upon excitation at 980 nm, in mixed lanthanide complexes and Er (III) complexes, Er-centered up-conversion emission is observed at 543 nm and 656 nm respectively. This is achieved with power densities as low as 2.18 W cm-2. Lastly, the naphthylpyrasal ligand in metal complexes was examined. These complexes were characterized through UV-vis spectroscopy, electrochemical analysis, and single crystal X-ray diffraction. This framework shows the ability in solid state to form N-oxide species in the solid state which is not commonly seen with actinides. Three distinct crystallographic species are formed showing a solvent dependance on crystallization solvent mixtures to produce different solid-state morphologies. This species seems to be formed through the presence of peroxides in the crystallization solvents. Through further examination of the solid state, we see that two of these structures produce close to a 5° bend from linearity in the typically linear -yl oxygen bonds.

Published
2021

13. CO 2 capture from ambient air via crystallization with tetraalkylammonium hydroxides.

Author

Mishra MK, Smetana V, Hiti EA, Wineinger HB, Qu F, Mudring AV, and Rogers RD

Subjects
Crystallization, Hydroxides, Water, Protons, Carbon, Bicarbonates, Carbon Dioxide chemistry
Abstract

Aqueous solutions of a series of short carbon chain tetra( n -alkyl)ammonium hydroxides, [N nnnn ][OH] with n = 2: n -ethyl, 3: n -propyl, 4: n -butyl, have been serendipitously found to be potential candidates for direct air carbon capture (DAC) when being used as reagents in more complicated reactions. Aqueous solutions of [N 3333 ][OH], [N 2222 ][OH], or [N 3333 ][OH] with UO 2 SO 4 ·3H 2 O and 1,4-diamidoximylbenzene, and [N 4444 ][OH] with cytosine (HCyt) directly absorb CO 2 from the atmosphere upon mild heating in the open atmosphere crystallizing in complexes reaching up to 2 : 1 CO 2 /[N nnnn ]OH ratio. [N 2222 ][HCO 3 ]·3H 2 O (1), [N 2222 ] 2 [H(HCO 3 ) 3 ]·5H 2 O (2), [N 3333 ][HCO 3 ]·0.5H 2 O (3), [N 3333 ][H(HCO 3 ) 2 ] (4), [N 3333 ] 2 [(tpa)(H 2 CO 3 ) 2 ] (5; tpa = terephthalate), [N 4444 ][H(Cyt)(HCO 3 )]·H 2 O (6) and [N 4444 ][H 2 (Cyt) 2 (HCO 3 )]·H 2 O (7) have been isolated in crystalline form and structurally characterized by single crystal X-ray diffraction. The compounds are characterized by complex polyanionic formations from bicarbonate dimers ([(HCO 3 ) 2 ·(H 2 O)] 2 4- ) or chains ([H(HCO 3 ) 2 ] n n - or [H 2 (tpa)(HCO 3 ) 2 ] n 2 n - ) to water-bicarbonate associates ([(HCO 3 ) 2 ·6H 2 O] 2- and [(H 2 CO 3 ·(HCO 3 ) 2 ) 2 ·6H 2 O·2H 2 O] 2- ) and three-component anionic layers ([H(Cyt)(HCO 3 )·H 2 O] n n - and [H 2 (Cyt) 2 (HCO 3 )·H 2 O] n n - ) frequently showing proton sharing. While some hydroxides themselves can maintain a high CO 2 /[N nnnn ][OH] ratio, particularly 2 and 4, the presence of secondary hydrogen bond donors/acceptors may increase the sorption efficiency through decreased solubility and enhanced crystallization.

Published
2022
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