| 1. |
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| 2. |
- Abdelhamid, Hani Nasser, et al.
(author)
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Luminescence properties of a family of lanthanide metal-organic frameworks
- 2019
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In: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 279, s. 400-406
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Journal article (peer-reviewed)abstract
- Two isostructural series of lanthanide metal-organic frameworks denoted as SUMOF-7II (Ln) and SUMOF-7IIB (Ln) (Ln = La, Ce, Pr, Nd, Sm, Eu, and Gd) were synthesized using4,4',4 ''-(pyridine-2,4,6-triyl)tris(benzoic acid) (H(3)L2) and a mixture of H(3)L2 and 4,4',4 ''-(benzene-1,3,5-triyl)tris(benzoic acid) (H3BTB) as linkers, respectively. Both series were characterized using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal analysis (TGA), and photoluminescence spectroscopy. Photoluminescence measurements show that Eu-MOFs demonstrate a red emission while Pr- and Nd-MOFs display an emission in the near-infrared (NIR) range. On the other hand, La-, Ce-, Sm- and Gd-MOFs exhibit only a ligand-centered emission. The average luminescence lifetimes in the SUMOF-7IIB series are 1.3-1.4-fold longer than the corresponding ones in the SUMOF-7II series. SUMOF-7IIs show a good photo- and thermal stability. Altogether, the properties of SUMOF-7II and SUMOF-7IIB render them promising materials for applications including sensing, biosensing, and telecommunications.
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| 3. |
- Adranno, Brando, et al.
(author)
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Broadband white-light-emitting electrochemical cells
- 2023
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In: Advanced Photonics Research. - : John Wiley & Sons. - 2699-9293. ; 4:5
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Journal article (peer-reviewed)abstract
- Emerging organic light-emitting devices, such as light-emitting electrochemical cells (LECs), offer a multitude of advantages but currently suffer from that most efficient phosphorescent emitters are based on expensive and rare metals. Herein, it is demonstrated that a rare metal-free salt, bis(benzyltriphenylphosphonium)tetrabromidomanganate(II) ([Ph3PBn]2[MnBr4]), can function as the phosphorescent emitter in an LEC, and that a careful device design results in the fact that such a rare metal-free phosphorescent LEC delivers broadband white emission with a high color rendering index (CRI) of 89. It is further shown that broadband emission is effectuated by an electric-field-driven structural transformation of the original green-light emitter structure into a red-emitting structure.
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| 4. |
- Adranno, Brando, et al.
(author)
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Enhanced stability and complex phase behaviour of organic-inorganic green-emitting ionic manganese halides
- 2023
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 52:19, s. 6515-6526
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Journal article (peer-reviewed)abstract
- Light-emitting materials based on earth-abundant metals, such as manganese hold great promise as emitters for organic lighting devices. In order to apply such emitter materials and, in particular, to overcome the problem of self-quenching due to cross-relaxation, we investigated a series of tetrabromidomanganate ([MnBr4]2−) salts with bulky tetraalkylphosphonium counter cations [Pnnn]+, namely [Pnnnn]2[MnBr4] (n = 4 (1), 6 (2) and 8 (3)), which can be obtained by a straightforward reaction of the respective phosphonium bromide and MnBr2. Variation of the cation size allows control of the properties of the resulting ionic materials. 1 and 3 qualify as ionic liquids (ILs), where 1 features a melting point of 68 °C, and 3 is liquid at room temperature and even at very low temperatures. Furthermore, 1 and 2 show the formation of higher-ordered thermotropic mesophases. For 1 a transition to a thermodynamically metastable smectic liquid crystalline phase can be observed at room temperature upon reheating from the metastable glassy state; 2 appears to form a plastic crystalline phase at ∼63 °C, which persists up to the melting point of 235 °C. The photoemission is greatly affected by phase behaviour and ion dynamics. A photoluminescence quantum yield of 61% could be achieved, by balancing the increase in Mn2+-Mn2+ separation and reducing self-quenching through increasingly large organic cations which leads to adverse increased vibrational quenching. Compared to analogous ammonium compounds, which have been promoted as @#x0308;inorganic hybrid perovskite, the phosphonium salts show superior performance, with respect to photoluminescent quantum yield and thermal and air/humidity stability. As the presented compounds are not sensitive to the atmosphere, in particular moisture, and show strong visible electroluminescence in the green region of light, they are important emitter materials for use in organic light-emitting devices.
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| 5. |
- Adranno, Brando, 1993-
(author)
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In Light of Ionic Materials : A short exploration of ionic materials for light-related applications
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Ionic liquids (ILs) have been one of the most attractive classes of materials of the last decades. The reason behind this is their peculiar set of properties, which enable their possible application in several research fields. ILs are salts that exhibit a very low melting point, which has been arbitrarily defined to be below 100 °C. Due to their ionic nature, ILs have little to no vapor pressure and they often demonstrate good electrical conductivity and high thermal and electrochemical stability. In this work, the focus is directed toward the exploitation of ILs for the engineering of materials that can have a primary role in light-emitting or light-absorbing devices. Materials belonging to the first type are explored in Papers I-III, while the ones belonging to the second are tackled in Papers IV and V.There has always been a struggle to find a balance between costs and the efficiency of emitting materials for application in dedicated devices. In Papers I-III, two strategies are taken into account to address this issue. Finding inspiration from ionic complexes of Mn(II), newly designed ionic materials and ILs emitting green light are proposed as an alternative to the more expensive heavy metals-based ones such as Ir(III) and Pt(II). Coming closer to an ideal compromise of cost and performance, fully organic and extremely cheap low-melting salts based on the 8-hydroxyquinoline unit were prepared. These compounds revealed efficient fluorescence in the blue region of the spectrum for such simple molecules, paving the way for the preparation of possibly inexpensive light-emitting devices.In Paper IV, direct absorption of light is taken into consideration with photoresponsive ionic liquids, which undergo cis-trans isomerization. Due to this feature and their ionic nature, these materials could be adopted into photoswitches. Additionally, the effect of functional groups on the isomerization of the ILs and on the ability of the materials to undergo mesophase formation was studied.One of the key components of dye-sensitized solar cells is the electrolytic mediator sandwiched between two electrodes. This has been a matter of intense study due to issues regarding its stability, which impair the device's performance. ILs can be adopted in devices to solve this issue. In Paper V, triazolium ILs allowed the manufacturing of devices with higher efficiencies and longer lifetimes than the ones realized with imidazolium relatives. These materials allowed for the stability of the ionic couple I-/I3- and moisture resistance due to their non-hygroscopic nature.
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| 6. |
- Adranno, Brando, et al.
(author)
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The 8-hydroxyquinolinium cation as a lead structure for efficient color-tunable ionic small molecule emitting materials
- 2023
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In: Advanced Photonics Research. - : John Wiley & Sons. - 2699-9293. ; 4:3
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Journal article (peer-reviewed)abstract
- Albeit tris(8-hydroxyquinolinato) aluminum (Alq3) and its derivatives are prominent emitter materials for organic lighting devices, and the optical transitions occur among ligand-centered states, the use of metal-free 8-hydroxyquinoline is impractical as it suffers from strong nonradiative quenching, mainly through fast proton transfer. Herein, it is shown that the problem of rapid proton exchange and vibration quenching of light emission can be overcome not only by complexation, but also by organization of the 8-hydroxyquinolinium cations into a solid rigid network with appropriate counter-anions (here bis(trifluoromethanesulfonyl)imide). The resulting structure is stiffened by secondary bonding interactions such as pi-stacking and hydrogen bonds, which efficiently block rapid proton transfer quenching and reduce vibrational deactivation. Additionally, the optical properties are tuned through methyl substitution from deep blue (455 nm) to blue-green (488 nm). Time-dependent density functional theory (TDFT) calculations reveal the emission to occur from which an unexpectedly long-lived S-1 level, unusual for organic fluorophores. All compounds show comparable, even superior photoluminescence compared to Alq3 and related materials, both as solids and thin films with quantum yields (QYs) up to 40-50%. In addition, all compounds show appreciable thermal stability with decomposition temperatures above 310 °C.
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| 7. |
- Alammar, Tarek, et al.
(author)
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Ionic-Liquid-Assisted Microwave Synthesis of Solid Solutions of Sr1-xBaxSnO3 Perovskite for Photocatalytic Applications
- 2017
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 10:17, s. 3387-3401
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Journal article (peer-reviewed)abstract
- Nanocrystalline Sr1-xBaxSnO3 (x=0, 0.2, 0.4, 0.8, 1) perovskite photocatalysts were prepared by microwave synthesis in an ionic liquid (IL) and subsequent heat-treatment. The influence of the Sr/Ba substitution on the structure, crystallization, morphology, and photocatalytic efficiency was investigated and the samples were fully characterized. On the basis of X-ray diffraction results, as the Ba content in the SrSnO3 lattice increases, a symmetry increase was observed from the orthorhombic perovskite structure for SrSnO3 to the cubic BaSnO3 structure. The analysis of the sample morphology by SEM reveals that the Sr1-xBaxSnO3 samples favor the formation of nanorods (500nm-5m in diameter and several micrometers long). The photophysical properties were examined by UV/Vis diffuse reflectance spectroscopy. The band gap decreases from 3.85 to 3.19eV with increasing Ba2+ content. Furthermore, the photocatalytic properties were evaluated for the hydroxylation of terephthalic acid (TA). The order of the activities for TA hydroxylation was Sr0.8Ba0.2SnO3>SrSnO3>BaSnO3>Sr0.6Ba0.4SnO3>Sr0.2Ba0.8SnO3. The highest photocatalytic activity was observed for Sr0.8Ba0.2SnO3, and this can be attributed to the synergistic impacts of the modification of the crystal structure and morphology, the relatively large surface area associated with the small crystallite size, and the suitable band gap and band-edge position.
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| 8. |
- Alammar, Tarek, et al.
(author)
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Luminescence properties of mechanochemically synthesized lanthanide containing MIL-78 MOFs
- 2018
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In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 47:22, s. 7594-7601
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Journal article (peer-reviewed)abstract
- Three metal-organic framework (MOF) compounds, Ln(0.6) Gd-0.(6) {C6H (COO)(3)); Ln = Eu, Tb, and Dy with a MIL-78 structure, have been synthesized by a solvent-free mechanochemical method from stoichiometric mixtures of benzene 1,3,5-tricarboxylic acid, C6H3 (COOH)(3), also known as trimesic acid, and the respective lanthanide carbonates, Ln(2)(CO3)(3)center dot xH(2)O, Ln = Eu, Gd, Tb and Dy. MIL-78 (Ln(0.5)Gd(0.)(6)) shows the characteristic red, green, and yellow luminescence of Eu3+, Tb3+, and Dy3+, respectively. Efficient intramolecular energy transfer from the ligand triplet state to the excited states of Ln(3+) ions can be observed. The lifetimes and quantum yields of these compounds are studied and discussed in detail. Among the three compounds, the Tb3+ containing compound shows the longest lifetime and highest quantum yield due to a smaller contribution from non-radiative decay pathways and better matching of the lowest triplet energy level of the benzenetricarboxylate ligand and the resonance level of Tb3+.
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| 9. |
- Alammar, Tarek, et al.
(author)
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Mechanochemical synthesis, luminescent and magnetic properties of lanthanide benzene-1,4-dicarboxylate coordination polymers (Ln(0.5)Gd(0.5))(2) (1,4-BDC)(3)(H2O)(4); Ln = Sm, Eu, Tb
- 2020
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In: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1144-0546 .- 1369-9261. ; 44:3, s. 1054-1062
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Journal article (peer-reviewed)abstract
- Mechanochemical reactions of benzene-1,4-dicarboxylate (BDC2-) and lanthanide carbonates, Ln(2)(CO3)(3)center dot xH(2)O (Ln = Sm, Eu, Gd, Tb) yield phase pure lanthanide coordination polymers, (Ln(0.5)Gd(0.5))(2)(1,4-BDC)(3)(H2O)(4) with Ln = Sm, Eu, Tb, which are isostructural with Tb-2(1,4-BDC)(3)(H2O)(4) as confirmed by powder X-ray diffraction and vibrational spectroscopy. Upon excitation with UV light all three compounds display strong emissions, characteristic for the respective optically active lanthanide ion, namely, red for Eu3+, green for Tb3+ and orange-red for Sm3+. In case of the Tb3+-containing compound, the energy difference between the triplet energy level of benzene-1,4-dicarboxylate ligand (BDC2-) allows for the most efficient BDC2--Tb3+ energy transfer. As a consequence, an intense green luminescence with rather long lifetime (0.81 ms) and high quantum yield (22%) is observed after allowed excitation of the BDC2- ligand. The compounds are paramagnetic with no onset of long range magnetic ordering down to liquid He temperatures.
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| 10. |
- Alammar, Tarek, et al.
(author)
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Microwave-Assisted Synthesis of Perovskite SrSnO3 Nanocrystals in Ionic Liquids for Photocatalytic Applications
- 2017
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 56:12, s. 6920-6932
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Journal article (peer-reviewed)abstract
- Nanosized SrSnO3 photocatalysts have been successfully synthesized by microwave synthesis in various ionic liquids (ILs) followed by a heat treatment process to optimize the materials' crystallinity. The influence of the ILs with various cations such as 1-butyl-3-methylimidazolium ([C(4)mim](+)), 6-bis(3-methylimidazolium-1-yl)hexane ([C-6(mim)(2)](2+)), butylpyridinium ([C4Py](+)), and tetradecyltrihexylphosphonium ([P-66614](+)) and bis(trifluoromethanesulfonyl)amide ([Tf2N](-)) as the anion on the structure, crystallization, and morphology of the products was investigated. The samples were characterized by X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), surface area analysis by gas adsorption, X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV vis spectroscopy, and Raman and IR spectroscopy. According to structure characterization by XRD and Raman spectroscopy all samples wcrystallized phase-pure in the orthorhombic GdFeO3 perovskite structure type. SEM reveals that, on the basis of the IL, th(e) obtained SrSnO3 nanoparticles exhibit different morphologies and sizes. Rod-shaped particles are formed in [C(4)minn][Tf2N], [C-6(mim)(2)][Tf2N](2), and p [P-66614][Tf2N]. However, the particle dimensions and size distribution vary depending on the IL and range from quite thin and long needlelike partinles with a narrow size distribution obtained in [P-66614] [TfA to relatively larger particles with a broader size distribution obtained in [C-6(mim)(2)][Tf2N](2). In contrast, in [C4Py][Tf2N] nanospheres with a diameter of about 50 nm form. For these particles the highest photocatalytic activity was observed. Our investigations indicate that the improved photocatalytic activity of this material results from the synergistic effect of the relatively large surface area associated with nanosize and an appropriate energy band structure.
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| 11. |
- Alammar, Tarek, et al.
(author)
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Synthesis and exploration of Barium Stannate-Zirconate BaSn1-xZrxO3 (0 ≤ X ≤ 1) solid solutions as photocatalysts
- 2024
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 63:14, s. 6132-6140
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Journal article (peer-reviewed)abstract
- Employing ionic liquid-assisted microwave synthesis and moderate heat treatment allows for the preparation of otherwise difficult-to-obtain perovskite-type BaSn1-xZrxO3 solid solutions (0 ≤ x ≤ 1). The impact of substituting Sn for the crystal structure, crystallinity, morphology, and photocatalytic performance was investigated. The obtained materials are characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Raman and IR spectroscopy. SEM images show that the morphology of the samples varies from rods for x = 0, 0.2 to spherical for x = 0.5, 0.8, 1. Upon Zr for Sn substitution, the band gap changes from 3.1 to 5.0 eV as the valence and conduction bands move to lower and higher energies. The photocatalytic activities of the BaSn1-xZrxO3 samples in the hydroxylation of terephthalic acid (TA) follow the order BaSn0.5Zr0.5O3> BaSn0.8Zr0.2O3> BaSnO3> BaSn0.2Zr0.8O3> BaZrO3. The superior photocatalytic activity of BaSn0.5Zr0.5O3 can be attributed to the synergistically favorable combination of a suitable band structure, band gap size, and increased surface area-to-volume ratio, resulting in a diminished crystalline particle size unattainable from samples prepared via traditional synthetic routes or without ionic liquid.
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| 12. |
- Alammar, Tarek, et al.
(author)
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The Power of Ionic Liquids : Crystal Facet Engineering of SrTiO3 Nanoparticles for Tailored Photocatalytic Applications
- 2021
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In: Advanced Sustainable Systems. - : Wiley. - 2366-7486. ; 5:2
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Journal article (peer-reviewed)abstract
- Sonochemical synthesis of nano-sized SrTiO3 carried out at close to room temperature, in ionic liquids (ILs) allows the tuning of particle size and particle morphology, that is, tracht and habitus, as well as particle aggregation via the choice of the ionic liquids (ILs) as the reaction medium. The nanoparticles demonstrate high performance for photocatalytic water splitting and photodecomposition of organic material. To this end bis(trifluoromethanesulfonyl)amide ([Tf2N](-))-based ILs with cations of different properties with respect to specific interactions with the target material are investigated. Isolated, 15 +/- 1 nm sized nano-spheres of SrTiO3 are observed to form in [C(3)mimOH][Tf2N] ([C(3)mimOH](+) = 1-(3-hydroxypropyl)-3-methylimidazolium). Aggregation of small sized nanoparticles are observed to around 250 +/- 100 nm large cube-like formations in [C(4)mim][Tf2N] ([C(4)mim](+) = 1-butyl-3-methylimidazolium), raspberry-like in [C4Py][Tf2N] ([C4Py](+) butylpyridinium), and ball-like in [P-66614][Tf2N] ([P-66614](+) tetradecyltrihexyl phosphonium). Importantly, the different materials show different performance as photocatalysts. SrTiO3 prepared in [C(4)mim][Tf2N] shows the highest photocatalytic activity for H-2 evolution (1115.4 mu mol h(-1)) when using 0.025 wt% Rh as the co-catalyst, whereas the material prepared in [C(3)mimOH][Tf2N] shows the highest activity for the photocatalytic degradation of methylene blue (88%) under UV irradiation. The different photocatalytic activities can be correlated with the different crystal surface facets expressed in the respective nanosized SrTiO3 material, {110} for material obtained from [C(4)mim][Tf2N], and {100} for material from [C(3)mimOH][Tf2N]. First-principles density functional theory (DFT) calculations are used to support the experimental findings.
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| 13. |
- Babizhetskyy, Volodymyr, et al.
(author)
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Crystal and electronic structures of the new ternary gallide Zr12Pd40−xGa31+y (x = 0–1.5, y = 0–0.5)
- 2023
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In: Journal of Solid State Chemistry. - 0022-4596 .- 1095-726X. ; 327
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Journal article (peer-reviewed)abstract
- Zr12Pd40Ga31 was prepared from the elements by arc melting under argon and subsequent annealing at 870 K for 720 h. Single-crystal X-ray diffraction reveals that Zr12Pd40Ga31 crystallizes in a new hexagonal structure type: Pearson symbol (PS) hP166, space group P6/mmm, a = 18.7670(6) Ǻ, c = 8.6634(6) Ǻ). The crystal structure consists of three types of atomic layers – two flat sheets at z = 0 (layer A) and z = 0.5 (C) and one corrugated at z = 0.25 and z = 0.75 (B), which stack in the sequence … ABCB … along the [001] direction. The structure shows close vicinity to a series of hexagonal structures with PS hP164–hP171. These compounds show peculiar structural variability expressed in the different atomic occupations of the Wyckoff positions along and around the 3-fold and 6-fold axes. Homogeneity range and lattice parameters of new ternary compound Zr12Pd40−xGa31+y (x = 0–1.5, y = 0–0.5) have been refined from EDX and powder XRD data. Electronic structure calculations and bonding analysis have been performed for an idealized model revealing domination of the Pd–Ga and Ga–Ga interactions.
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| 14. |
- Babizhetskyy, V., et al.
(author)
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Investigation in the ternary Ta-Ni-P system : Solid state phase equilibria at T=1070 K, crystal and electronic structures of new ternary phosphides
- 2021
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In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 864
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Journal article (peer-reviewed)abstract
- The solid state phase diagram for the ternary Ta-Ni-P system was established at T=1070 K in the region of up to 67 at% of P by means of X-ray powder diffraction methods (PXRD). Six ternary compounds, namely Ta4NiP (Nb4CoSi-type), Ta1.10-0.82Ni0.90-1.18P (TiNiSi-type), TaNiP2 (NbNiP2-type), Ta(5.00-4.81)Ni(4.00-4.19)P4 (Nb5Cu4Si4-type), TaNi2P (own structure type) and Ta1-0.08(1)Ni0.08(1)P2 (OsGe2-type) have been confirmed to exist. Rather minor Ta/Ni homogeneity ranges have been found for alpha-Ta3-xNixP (x=0.2) (Ti3P-type), Ta1-xNixP (x=0.18) (NbAs-type), Ni3-xTaxP (x=0.2) (Ni3P-type) and Ni2-xTaxP (x=0.25) (Fe2P-type). The crystal structure of Ta4.811(9)Ni4.189(9)P4 has been refined from single crystal X-ray diffraction data (Nb5Cu4Si4-type, space group I4/m, a =9.8474(17), c=3.5182(7) angstrom, R1=0.0283, wR2=0.0470), while that of the new TaNi2P compound was determined by means of PXRD. This phosphide crystalizes in its own structure type (space group Pnma, a=8.3588(3), b=3.5208(1), c=6.7051(3) angstrom, R-I=0.044, R-P=0.161). A new isostructural Fe-compound, TaFe2P (a=8.358(2), b=3.5194(7), c=6.703(1) angstrom), was also synthetized. The electronic structures of Ta5Ni4P4 and TaNi2P were analyzed using the tight-binding linear muffin-tin orbital (TB-LMTO) and extended Huckel methods.
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| 15. |
- Babizhetskyy, Volodymyr, et al.
(author)
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New cation-disordered quaternary selenides Tl(2)Ga(2)TtSe(6) (Tt = Ge, Sn)
- 2020
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In: Zeitschrift für Naturforschung. B, A journal of chemical sciences. - : Walter de Gruyter GmbH. - 0932-0776 .- 1865-7117. ; 75:1-2, s. 135-142
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Journal article (peer-reviewed)abstract
- Two new quaternary selenides of the alpha-TlSe structure type have been synthesized and characterized. Single crystal X-ray diffraction analysis has revealed that Tl2Ga2SnSe6 crystallizes with space group I4/mmc, a =8.095(1), c=6.402(1) angstrom, with a refined composition of Tl1-xGa1-ySny Se-2 (x= y=0.345(5)), Z=4, R1=0.028; wR2= 0.066. The crystal structure of the isostructural compound Tl2Ga2GeSe6 has been determined by means of powder X-ray diffraction: space group I4/mmc, Z= 4, a= 8.0770(4 ), c= 6.2572(5) angstrom, refined composition Tl1-xGa1-ySny Se-2, x=0343(5), y=0.35(2), (R-B(I) = 0.084; R-p = 0.041; R-PW= 0.058). According to their optical absorption spectra all compounds are semiconductors with relatively narrow direct band gaps of 2.15(3) and 2.05(5) eV for the Ge and Sn phase, respectively.
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| 16. |
- Babizhetskyy, Volodymyr, et al.
(author)
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New intermetallics R1+xZr1−xNi (R = Er–Tm, x ~ 0.5) with the TiNiSi type of structure
- 2021
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In: Intermetallics (Barking). - : Elsevier BV. - 0966-9795 .- 1879-0216. ; 137
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Journal article (peer-reviewed)abstract
- A new series of isostructural rare earth compounds R1+xZr1−xNi (R = Er, Tm, Lu; x ~ 0.5) was synthesized from the elements by arc melting and subsequent annealing at 870 K for 1400 h. The crystal structures of the intermetallic compounds were investigated by means of single-crystal X-ray diffraction. They all crystallize in the TiNiSi structure type (space group Pnma, No. 62, oP12). In R1+xZr1−xNi, the R/Zr statistical mixture leading to nonequiatomic compositions occupies the position corresponding to the nickel site of the TiNiSi structure type. The calculated shortest interatomic distances are close to the sums of the single-bond covalent radii of respective elements. Electronic structure calculations performed with the tight-binding LMTO method revealed the non-zero density of states at the Fermi level and suggest metallic character. R1+xZr1−xNi (R = Er, Tm, Lu; x ~ 0.5) undergoes no long-range magnetic ordering down to 2 K.
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| 17. |
- Bell, Thomas, et al.
(author)
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Binary Intermetallics in the 70 atom % R Region of Two R-Pd Systems (R = Tb and Er) : Hidden, Obscured, or Nonexistent?
- 2020
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:15, s. 10802-10812
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Journal article (peer-reviewed)abstract
- Although rare-earth-metal-transition-metal (R/T) phase diagrams have been explored extensively, our recent studies have uncovered new previously nonexistent binary intermetallics. These compounds belong to a narrow region between 70 and 71.4 atom % of the rare-earth metal but represent four different structure types. The binaries Tb7Pd3 and Er17Pd7 are compositionally approaching (less than 1 atom % difference) the previously reported R2.16Pd0.89 (R = Tb and Er), and apparently form by peritectoid transformation, thus, being hard to detect by fast cooling. Tb7Pd3 (1) crystallizes in the Th7Fe3 structure type (hP20, P6(3)mc, a = 9.8846(4) angstrom, c = 6.2316(3) angstrom, Z = 2) while Er17Pd7 (2) belongs to the Pr17Co7 type being its second reported representative (cP96, P2(1)3, a = 13.365(2) degrees, Z = 4). Er17Pd7 (2) is overlapping with the cubic F-centered Er2.11Pd0.89 (3b, Fd (3) over barm, a = 13.361(1) angstrom, Z = 32) with practically identical unit cell parameters but a significantly different structure. Electronic structure calculations confirm that heteroatomic R-T bonding strongly dominates in all structures; T-T bonding interactions are individually strong but do not play a significant role in the total bonding.
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| 18. |
- Bell, Thomas, et al.
(author)
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Tb3Pd2, Er3Pd2 and Er6Co5-x : structural variations and bonding in rare-earth-richer binary intermetallics
- 2018
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In: Acta crystallographica. Section C, Structural chemistry. - 2053-2296. ; 74:9, s. 991-996
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Journal article (peer-reviewed)abstract
- The three binary Tb/Er-rich transition metal compounds Tb3Pd2 (triterbium dipalladium), Er3Pd2 (trierbium dipalladium) and Er6Co5-x (hexaerbium pentacobalt) crystallize in the space groups Pbam (Pearson symbol oP20), P4/mbm (tP10) and P6(3)/m (hP22), respectively. Single crystals of Tb3Pd2 and Er6Co5-x suitable for X-ray structure analysis were obtained using rare-earth halides as a flux. Tb3Pd2 adopts its own structure type, which can be described as a superstructural derivative of the U3Si2 type, which is the type adopted by Er3Pd2. Compound Er6Co5-x belongs to the Ce6Co2-xSi3 family. All three compounds feature fused tricapped {TR6} (R = rare-earth metal and T = transition metal) trigonal prismatic heterometallic clusters. R3Pd2 is reported to crystallize in the U3Si2 type; however, our more detailed structure analysis reveals that deviations occur with heavier R elements. Similarly, Er6Co5-x was assumed to be stoichiometric Er4Co3 = Er6Co4.5. Our studies reveal that it has a single defective transition-metal site leading to the composition Er6Co4.72(2). LMTO (linear muffin-tin orbital)-based electronic structure calculations suggest the strong domination of heteroatomic bonding in all three structures.
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| 19. |
- Bousrez, Guillaume, et al.
(author)
-
Ionic Liquid-Based Dye-Sensitized Solar Cells-Insights into Electrolyte and Redox Mediator Design
- 2021
-
In: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 9:24, s. 8107-8114
-
Journal article (peer-reviewed)abstract
- A series of asymmetric and symmetric 1,3-dialkyltriazolium iodides were studied with hindsight to their application as electrolytes and redox mediators in dye-sensitized solar cells (DSSCs). Compounds with an alkyl chain length from C4 to C10 present the characteristics of ionic liquids (ILs), whilst those with longer chains exhibit liquid crystallinity. All compounds show an appreciable chemical and thermal stability with decomposition temperatures around 185–195 °C. Testing these compounds as electrolytes and redox mediators in DSSCs reveals significant changes in the properties of the electrolyte upon addition of the redox couple. Addition of iodine generally leads to a depression of the melting point and an enhancement of conductivity. These changes in the electrolyte, which are significant, have so far been largely overlooked in DSSC optimization. Furthermore, in comparison to frequently employed imidazolium iodides, 1-alkyl-3-methyltriazolium iodides show both an improved superior efficiency and an extended cell lifetime. This is attributed to the fact that, unlike the imidazolium salts, the triazolium counterparts are not hygroscopic. The nonhygroscopic nature of the salts also renders device fabrication easier. In addition, electrode passivation, which is commonly observed with imidazolium iodides, could not be noticed for the triazolium analogues, making these materials overall extremely attractive.
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| 20. |
- Bousrez, Guillaume, et al.
(author)
-
Magnetic, Photo- and Electroluminescent : Multifunctional Ionic Tb Complexes
- 2021
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 60:23, s. 17487-17497
-
Journal article (peer-reviewed)abstract
- In the search for new multifunctional materials, particularly for application in solid-state lighting, a set of terbium salicylato (Sal) complexes of general composition [Cat][Tb(Sal)4] with the commonly ionic liquid-forming (IL) cations [Cat] = (2-hydroxyethyl)trimethylammonium (choline) (Chol+), diallyldimethylammonium (DADMA+), 1-ethyl-3-methylimidazolium (C2C1Im+), 1-butyl-3-methylimidazolium (C4C1Im+), 1-ethyl-3-vinylimidazolium (C2Vim+), and tetrabutylphosphonium (P4444+) were synthesized. All Tb compounds exhibit strong green photoluminescence of high color purity by energy transfer from the ligand in comparison with what the analogous La compounds show, and quantum yields can reach up to 63% upon ligand excitation. When excited with an HF generator, the compounds show strong green electroluminescence with the same features of mission. The findings promise a high potential of application as emitter materials in solid-state lighting. As an additional feature, the Tb compounds show a strong response to applied external fields, rendering them multifunctional materials.
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| 21. |
- Bousrez, Guillaume, et al.
(author)
-
Ready Access to Anhydrous Anionic Lanthanide Acetates by Using Imidazolium Acetate Ionic Liquids as the Reaction Medium
- 2021
-
In: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 27:52, s. 13181-13189
-
Journal article (peer-reviewed)abstract
- Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C(2)mim](n)[{Ln(2)(OAc)(7)}(n)] and the dimeric [C(2)mim](2)[Ln(2)(OAc)(8)], based on the ion size and the ratio of IL used. A reaction with an IL : Ln-salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy-Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal-acetate coordination modes where eta(2)mu kappa(2) is the most represented in both structure types.
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| 22. |
- Celania, Chris, et al.
(author)
-
Bringing order to large-scale disordered complex metal alloys : Gd2Au15-xSbx and BaAuxGa12-x
- 2018
-
In: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 20:3, s. 348-355
-
Journal article (peer-reviewed)abstract
- Herein, two new tetragonal complex metallic alloys (CMAs) have been discovered and characterized: Gd2Au15-xSbx [x = 3.0-3.6; I4/mmm; tI34; a = 7.31-7.33 angstrom, c = 14.05-14.11 angstrom; V = 750.2-758 angstrom(3)] and BaAuxGa12-x [x = 3.6-4.4; I4/mcm; tI104; a = 8.77-8.78 angstrom, c = 26.06-26.13 angstrom; V = 2006.5-2010 angstrom(3)]. Both structures incorporate significant anionic site mixing and intricate positional disorder. Gd2Au15-xSbx represents a new structure type with in-plane disordered, but strongly geometrically restricted rhombi motifs. These rhombi connect through additional mixed Au/Sb positions along the c axis; this forms octahedral fragments. BaAuxGa12-x finds its place within the extended NaZn13 structural family, displaying cation-centered snub cubes with empty, distorted icosahedra (allowing for the 1 : 12 ratio) and tetrahedral stars. The split positions order due to geometric constraints to form nets of crown cyclooctane-like sheets in two different conformations. Adjacent planes adopt opposite conformations, forming layers of snub cubes with order between layers, but disorder across the greater structure. The substantial degree of mixing in both structures, together with mutual orientation of the ordered and disordered positions, suggests significant importance of heteroatomic bonding, typically found in polar intermetallic compounds.
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| 23. |
- Celania, Chris, et al.
(author)
-
Crystal structures and new perspectives on Y3Au4 and Y(14)Au51
- 2017
-
In: Acta crystallographica. Section C, Structural chemistry. - 2053-2296. ; 73, s. 692-696
-
Journal article (peer-reviewed)abstract
- Y3Au4 (triyttrium tetragold) and Y14Au51 (tetradecayttrium henpentacontagold), two binary representatives of Au-rich rare earth (R) systems crystallize with the space groups R (3) over bar and P6/m, adopting the Pu3Pd4 and Gd14Ag51 structure types, respectively (Pearson symbols hR(42) and hP(65)). Avariety of binary R-Au compounds have been reported, although only a few have been investigated thoroughly. Many reports lack information or misinterpret known compounds reported elsewhere. The Pu3Pd4 type is fairly common for group 10 elements Ni, Pd, and Pt, while Au representatives are restricted to just five examples, i.e. Ca3Au4, Pr3Au4, Nd Au-3(4), Gd3Au4, and Th3Au4. Sm6Au7 is suspected to be Sm3Au4 due to identical symmetry and close unit-cell parameters. The Pu3Pd4 structure type allows for full substitution of the position of the rare earth atom by more electronegative and smaller elements, i.e. Ti and Zr. The Gd14Ag51 type instead is more common for the group 11 metals, while rare representatives of group 12 are known. Y3Au4 can be represented as a tunnel structure with encapsulated cations and anionic chains. Though tunnels are present in Y14Au51, this structure is more complex and is best described in terms of polyhedral 'pinwheels' around the tunnel forming polyhedra along the c axis.
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| 24. |
- Celania, Chris, et al.
(author)
-
R-14(Au, M)(51) (R = Y, La-Nd, Sm-Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In, Sn, Sb, Bi) : Stability Ranges and Site Preference in the Gd14Ag51 Structure Type
- 2018
-
In: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 18:2, s. 993-1001
-
Journal article (peer-reviewed)abstract
- Twenty new ternary representatives of the Gd14Ag51 structure type have been synthesized within the R-Au-M family (R = Y, La-Nd, Sm-Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, Sn, Sb, Bi) using solid state synthesis techniques. The list of post transition metals (M) involved in the formation of this type of structure could be augmented by five new representatives. All compounds crystallize in the hexagonal space group P6/m (#175) with the unit cell ranges of a = 12.3136(2)-12.918(1) angstrom and c = 8.9967(3)-9.385(1) angstrom, and incorporate different degrees of Au/M mixing. The involvement of the post transition element in the structure varies from one to another compound both qualitatively and quantitatively. A rather significant phase width can be expected for the majority of compounds, however, not without exclusions. The distribution of the post transition metals within the structure has been analyzed via single crystal X-ray diffraction. While the positional disorder of one near-origin Au position is expectable for all compounds due to steric reasons, two specimens show an obvious deviation from the others including another Au position split along the c axis. Possible factors affecting this behavior are discussed.
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| 25. |
- Celania, Chris, et al.
(author)
-
Structures, properties, and potential applications of rare earth-noble metal tellurides
- 2019
-
In: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 274, s. 243-258
-
Journal article (peer-reviewed)abstract
- As many nations continue to develop and industrialize, the global energy demands are rising rapidly. With the threat of climate change disaster looming, the search for sustainable, green energy has become of higher priority. Thermoelectric materials add an important facet to the mosaic of future energy plans by allowing the scavenging of (low-quality waste) heat created through other processes and their transformation back into useful electrical energy. Thermoelectrics (similar to other green energy sources like solar cells) have struggled to reach high enough efficiencies to allow their cost-effective widespread implementation. Thus, the search for new thermoelectric materials has gained momentum. This review covers the growing family of rare earth metal (R: Sc, Y, and La-Lu)-noble metal (M: Cu, Ag, Au, Pd and Pt)-tellurides which are an interesting group of materials in the discussed context. Rare earth metal -noble metal tellurides constitute an increasing family of structures, numbering nearly forty unique structure types and including quaternary and quinary compounds. Structures include 1D channel structures, 2D layered slab structures, and complex 3D networks. R-M-Te compounds provide a wide variety of p-type semiconducting materials to choose from. The effectiveness of these structures as thermoelectric materials range in utility, with most showing maximum performance (figure of merit, zT - see below) values in the mid to high temperature ranges. To date, this culminates in the highest zT for this family with TbCuTe2, zT = 1.0 at 750 K, which still has potential for optimization. Albeit most observed compounds have been structurally quite well characterized, for many a thorough investigation of their physical properties, be it transport or magnetism is lacking. This work strives to combine, analyze, and at times untangle the variety of structures and properties reported across the breadth of research on this family.
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| 26. |
- Celania, Chris, et al.
(author)
-
The Prolific Ternary System Pt/Sn/Nd : Insertion of Pt into the Structures of Sn/Nd Intermetallics Yields Structural Complexity and Wealth
- 2023
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 62:24, s. 9369-9378
-
Journal article (peer-reviewed)abstract
- The understanding of structure and bonding in intermetallic phases still lags behind that of molecular compounds. For that reason, exploring intermetallic phases and identifying structural patterns and relationships are particularly important for closing this knowledge gap. In particular, here we report on the addition of increasing amounts of platinum to ∼2:1 mixtures of tin and neodymium, which yields eight ternary Pt/Sn/Nd compounds, four of which have not been reported before. Interestingly, except for PtSnNd (1), all observed ternary phases of the system can be derived from the binary compounds Sn2Nd and Sn5Nd2 by adding Pt to the composition(s), as they lie on or close to two lines: Sn2Nd-Pt (Pt0.21(1)Sn2Nd (2), PtSn2Nd (3), Pt1.33Sn2Nd (4), Pt2-xSn2+xNd (x = 0.27(3), 5), and Pt3Sn2Nd (6)) or Sn5Nd2-Pt (Pt1.5Sn5-xNd2 (x = 0.16(2), 7) and Pt3Sn5Nd2-x (x = 0.161(8), 8)). While the introduction of increasing amounts of Pt to the binaries Sn2Nd and Sn5Nd2 leads to stepwise changes in the coordination environment of Nd, Pt preserves its coordination over the entire system in the form of interpenetrating bipyramidal {PtSn5Nd5} clusters.
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| 27. |
- Chand, Deepak, et al.
(author)
-
Alternative to the Popular Imidazolium Ionic Liquids : 1,2,4-Triazolium Ionic Liquids with Enhanced Thermal and Chemical Stability
- 2019
-
In: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 7:19, s. 15995-16006
-
Journal article (peer-reviewed)abstract
- Direct quaternization of 1-methyl-1,2,4-triazole with n-alkyl methanesulfonates (alkyl = butyl, octyl, dodecyl) showed to be an atom-economic, convenient, mild, solvent- and halide-free way to obtain 1,2,4-triazolium methanesulfonate ionic liquids in high purity and yield. Subsequent metathesis with lithium bis(trifluoromethanesulfonyl)amide (LiTf2N) allows for a much desired, easy access to halide-free, bis(trifluoromethanesulfonyl)amide ionic liquids. Differential scanning calorimetry confirms that all investigated compounds qualify as ionic liquids (ILs). Moreover, it reveals for 1-methyl-4-n-dodecyl-1,2,4-triazolium methanesulfonate a rather complex thermal behavior involving formation of mesophases. Indeed, polarizing optical microscopy shows oily streaky textures that are characteristic for smectic liquid crystalline phases. Single-crystal X-ray diffraction structure analysis confirms formation of a layered structure. All compounds are photoluminescent. The color of fluorescence at room temperature can be tuned from blue to orange through the length of the alkyl side chain of the cation, the aromatic interactions between the cations, and the anion nature. In addition, at low temperatures (77 K) a close to white phosphorescence with average lifetimes in the millisecond time range can be observed for 1-methyl-4-n-butyl-triazolium methanesulfonate and all of the studied bis(trifluoromethanesulfonyl)amide ILs. All ILs show an appreciable liquidus range and thermal (up to 260-350 degrees C) and electrochemical stability. The presented set of ILs overcomes the sometimes problematic acidity and low stability of imidazolium ILs in basic environment and can be obtained easily in high purity without halide contamination. Overcoming two shortcomings of classical imidazolium ILs, they may be good alternatives for a number of applications and even enabling new ones.
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| 28. |
- Di Marcantonio, M., et al.
(author)
-
Green-yellow emitting hybrid light emitting electrochemical cell
- 2017
-
In: Journal of Materials Chemistry C. - : Royal Society of Chemistry (RSC). - 2050-7526 .- 2050-7534. ; 5:46, s. 12062-12068
-
Journal article (peer-reviewed)abstract
- Light-emitting electrochemical cells (LECs) are attractive candidates for future low-cost lighting applications such as light-emitting smart tags, thanks to their simplicity, fully solution-based fabrication and flexibility. However, high brightness and efficiency in combination with satisfactory operation lifetimes need to be achieved for different emission colours bearing future device commercialization in mind. LECs emitting in the yellow-green spectral range, where the human eye is most sensitive are thereby particularly attractive. Here we present an improved hybrid LEC based on an Ir-iTMC, [Ir(4-Fppy)(2)(pbpy)][PF6] (4-Fppy = 2-(4-fluorophenyl) pyridinato, pbpy = 6-phenyl-2,2'-bipyridine) emitting at 557 nm. It features a luminance of 2400 cd m(-2) when driven at a constant voltage of 4 V, and a lifetime of 271 h at a luminance of 1500 cd m(-2) under pulsed current operation. The hybrid LEC shows an enhanced performance compared to a LEC solely based on the Ir-ITMC where operation lifetimes of 165 h at a luminance above 1200 cd m(-2) under pulsed current operation conditions were observed. The performance improvement was achieved by addition of a solution-processed ZnO nanoparticle film on top.
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| 29. |
- Goerigk, Felix C., et al.
(author)
-
Synthesis and Crystal Structure of the Short LnSb(2)O(4)Br Series (Ln = Eu-Tb) and Luminescence Properties of Eu3+-Doped Samples
- 2020
-
In: Crystals. - : MDPI AG. - 2073-4352. ; 10:12
-
Journal article (peer-reviewed)abstract
- Pale yellow crystals of LnSb(2)O(4)Br (Ln = Eu-Tb) were synthesized via high temperature solid-state reactions from antimony sesquioxide, the respective lanthanoid sesquioxides and tribromides. Single-crystal X-ray diffraction studies revealed a layered structure in the monoclinic space group P2(1)/c. In contrast to hitherto reported quaternary lanthanoid(III) halide oxoantimonates(III), in LnSb(2)O(4)Br the lanthanoid(III) cations are exclusively coordinated by oxygen atoms in the form of square hemiprisms. These [LnO(8)](13-) polyhedra form layers parallel to (100) by sharing common edges. All antimony(III) cations are coordinated by three oxygen atoms forming psi(1)-tetrahedral [SbO3](3-) units, which have oxygen atoms in common building up meandering strands along [001] according to {[SbO2/2vO1/1t]-}infinity 1 (v = vertex-sharing, t = terminal). The bromide anions are located between two layers of these parallel running oxoantimonate(III) strands and have no bonding contacts with the Ln(3+) cations. Since Sb3+ is known to be an efficient sensitizer for Ln(3+) emission, photoluminescence studies were carried out to characterize the optical properties and assess their suitability as light phosphors. Indeed, for both, GdSb2O4Br and TbSb2O4Br doped with about 1.0-1.5 at-% Eu3+ efficient sensitization of the Eu3+ emission could be detected. For TbSb2O4Br, in addition, a remarkably high energy transfer from Tb3+ to Eu3+ could be detected that leads to a substantially increased Eu3+ emission intensity, rendering it an efficient red light emitting material.
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| 30. |
- Grilli, Davide, et al.
(author)
-
Lan(n+1)+xNin(n+5)+ySi(n+1)(n+2)–z : A Symmetric Mirror Homologous Series in the La–Ni–Si System
- 2023
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 62:27, s. 10736-10742
-
Journal article (peer-reviewed)abstract
- A series of four homologous silicides have been discovered during systematic explorations in the central part of the La–Ni–Si system at 1000 °C. All compounds La12.5Ni28.0Si18.3 (n = 3; a = 28.8686(8), c = 4.0737(2) Å, Z = 3), La22.1Ni39.0Si27.8 (n = 4; a = 20.9340(6), c = 4.1245(2) Å, Z = 1), La32.9Ni49.8Si39.3 (n = 5; a = 24.946(1), c = 4.1471(5) Å, Z = 1), and La44.8Ni66.1Si53.4 (n = 6; a = 28.995(5), c = 4.158(1) Å, Z = 1) crystallize in the hexagonal space group P63/m and can be generalized according to Lan(n+1)+xNin(n+5)+ySi(n+1)(n+2)–z with n = 3–6. Their crystal structures are based on AlB2-type building blocks, fused La-centered Ni6Si6 hexagonal prisms, yielding larger oligomeric equilateral domains with the edge size equal to n. The domains extend along the c axis and show checkered ordering of the cationic and anionic parts, while all their atoms are located on mirror planes. Lan(n+1)+xNin(n+5)+ySi(n+1)(n+2)–z can be considered as a mirror series to the La-rich La(n+1)(n+2)Nin(n–1)+2Sin(n+1), where an exchange of the formal cationic and anionic sites, i.e., La and Si, occurs. The La–Ni–Si system is the first system where two such analogous series have been observed.
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| 31. |
- Guillou, F., et al.
(author)
-
Metamagnetic transition, magnetocaloric effect and electronic structure of the rare-earth anti-perovskite SnOEu3
- 2020
-
In: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 501
-
Journal article (peer-reviewed)abstract
- Rare-earth anti-perovskites with oxygen are an interesting magnetic materials family at the boundary between intermetallics and oxides, they however remain largely unexplored. Here, magnetic and heat capacity investigations, as well as density functional theory (DFT) calculations, were carried out on SnOEu3. At low magnetic field (B <= 0.5 T), a Neel temperature separates antiferromagnetic and paramagnetic phases at 31 K. When applying higher magnetic field below the Neel temperature, successive transformations toward a ferromagnetic state via a number of intermediate canted magnetic structures are observed and are associated with only modest latent heat and transition entropy. High-pressure magnetic measurements confirm the stable divalent state of Eu up to 1.05 GPa. A direct magnetocaloric effect progressively increases with applied magnetic field above the Neel temperature, reaching -16 J kg(-1) K-1 for Delta B = 7 T. On the other hand, the inverse magnetocaloric effect of the field-induced transition below T-N saturates at similar to+ 5 J kg(-1) K-1. DFT calculations support magnetic instabilities observed experimentally in SnOEu 3 and reveal an unusual exchange mechanism and band topology near the Fermi level.
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| 32. |
- Hammond, Oliver S., et al.
(author)
-
Ionic liquids and deep eutectics as a transformative platform for the synthesis of nanomaterials
- 2022
-
In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 58:24, s. 3865-3892
-
Research review (peer-reviewed)abstract
- Ionic liquids (ILs) are becoming a revolutionary synthesis medium for inorganic nanomaterials, permitting more efficient, safer and environmentally benign preparation of high quality products. A smart combination of ILs and unconventional synthesis methods allows added value to be drawn from the broad matrix of available property combinations. Mixed systems such as Deep Eutectic Solvents (DES) offer a similarly broad combinatorial playground, which is also beginning to translate into applications. Approached holistically, these liquids therefore enable new universal manufacturing techniques that provide solutions to the existing problems of nanomanufacturing, and beyond that will open completely new horizons and possibilities for controlling the growth and assembly of nanostructures. Examples that illustrate the power of ILs in the improved manufacturing of nanomaterials are explored, such as the synthesis of light phosphors with exceptional quantum yields, record-figure-of merit thermoelectrics, and efficient photocatalysts, alongside developments in DES nanostructure and deep eutectic-solvothermal and ionothermal techniques.
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| 33. |
- Hammond, Oliver S., et al.
(author)
-
Molecular Architecture Effects on Bulk Nanostructure in Bis(Orthoborate) Ionic Liquids
- 2023
-
In: Small. - : John Wiley and Sons Inc. - 1613-6810 .- 1613-6829. ; 29
-
Journal article (peer-reviewed)abstract
- A series of 19 ionic liquids (ILs) based on phosphonium and imidazolium cations of varying alkyl-chain lengths with the orthoborate anions bis(oxalato)borate [BOB]−, bis(mandelato)borate, [BMB]− and bis(salicylato)borate, [BScB]−, are synthesized and studied using small-angle neutron scattering (SANS). All measured systems display nanostructuring, with 1-methyl-3-n-alkyl imidazolium-orthoborates forming clearly bicontinuous L3 spongelike phases when the alkyl chains are longer than C6 (hexyl). L3 phases are fitted using the Teubner and Strey model, and diffusely-nanostructured systems are primarily fitted using the Ornstein-Zernicke correlation length model. Strongly-nanostructured systems have a strong dependence on the cation, with molecular architecture variation explored to determine the driving forces for self-assembly. The ability to form well-defined complex phases is effectively extinguished in several ways: methylation of the most acidic imidazolium ring proton, replacing the imidazolium 3-methyl group with a longer hydrocarbon chain, substitution of [BOB]− by [BMB]−, or exchanging the imidazolium for phosphonium systems, irrespective of phosphonium architecture. The results suggest there is only a small window of opportunity, in terms of molecular amphiphilicity and cation:anion volume matching, for the formation of stable extensive bicontinuous domains in pure bulk orthoborate-based ILs. Particularly important for self-assembly processes appear to be the ability to form H-bonding networks, which offer additional versatility in imidazolium systems. © 2023 The Authors.
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| 34. |
- Hammond, Oliver S., et al.
(author)
-
Small-Angle Neutron Scattering Insights into 2-Ethylhexyl Laurate : A Remarkable Bioester
- 2024
-
In: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 12:5, s. 1816-1821
-
Journal article (peer-reviewed)abstract
- Commercial (protiated) samples of the "green" and biodegradable bioester 2-ethylhexyl laurate (2-EHL) were mixed with D-2-EHL synthesized by hydrothermal deuteration, with the mixtures demonstrating bulk structuring in small-angle neutron scattering measurements. Analysis in a polymer scattering framework yielded a radius of gyration (R (g)) of 6.5 angstrom and a Kuhn length (alternatively described as the persistence length or average segment length) of 11.2 angstrom. Samples of 2-EHL dispersed in acetonitrile formed self-assembled structures exceeding the molecular dimensions of the 2-EHL, with a mean aggregation number (N-agg) of 3.5 +/- 0.2 molecules across the tested concentrations. We therefore present structural evidence that this ester can function as a nonionic (co)-surfactant. The available surfactant-like conformations appear to enable performance beyond the low calculated hydrophilic-lipophilic balance value of 2.9. Overall, our data offer an explanation for 2-EHL's interfacial adsorption properties via self-assembly, resulting in strong emolliency and lubricity for this sustainable ester-based bio-oil.
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| 35. |
- Hiti, Ethan A., et al.
(author)
-
Exploring the Role of Neutral 4-Amino-1,2,4-triazole in the Formation of Hexanuclear f-Element Hydrolysis Products
- 2024
-
In: Crystal Growth & Design. - 1528-7483 .- 1528-7505. ; 24:2, s. 834-842
-
Journal article (peer-reviewed)abstract
- Our recent observations of an unexpected Ce(III) hydrolysis product from the reaction of 4-amino-1,2,4-triazole (4-NH2-1,2,4-Triaz) with CeCl3·7H2O, [Ce6(μ3-O)4(μ3-OH)2(μ3-Cl)2(Cl)6(μ2-4-NH2-1,2,4-Triaz)12]·7H2O, the first high-nuclearity lanthanide complex where all Ln atoms are connected pairwise through 12 N-donor ligands or 12 neutral bridging ligands of any type, prompted us to explore the utility of this ligand in trapping additional f-element examples. Reactions of LnCl3·6H2O (Ln = Nd, Eu, Ho) with a large excess of 4-NH2-1,2,4-Triaz (20 equiv) and with the addition of small amounts of water to help solubilize the metal salts led to the isolation of the unique hydrolysis products [Nd6(μ3-OH)8Cl6(μ2-4-NH2-1,2,4-Triaz)12][Cl4]·2H2O, [Eu6(μ6-Cl)0.23(μ3-O0.77)4(μ3-O)2.6(μ3-Cl)0.4Cl6(μ2-4-NH2-1,2,4-Triaz)12], and [Ho6(μ6-Cl)0.21(μ3-O0.79)4(μ3-OH)2Cl6(μ2-4-NH2-1,2,4-Triaz)12][Cl]3.4. We also report a Ce(III) analogue prepared in glassware contaminated with Pb(OAc)2, namely, [Ce6(μ3-OH)8(BrPbBr5)(μ2-4-NH2-1,2,4-Triaz)11.5(OH2)6][Pb0.84Br4.2][Br]3.8·2(4-NH2-1,2,4-Triaz)·3.6H2O. The Nd(III) complex is the structurally most ordered with a clear [Nd6(μ3-OH)8] cluster core, while the Eu(III) and Ho(III) compounds contain partial occupancy of a μ6 position and thus result in an incomplete Ln6O9 cluster core formation. The crystallographic results suggest that the 4-NH2-1,2,4-Triaz ligand brings Ln(III) ions together, followed by the formation of an Ln6O8 or Ln6O9 core with whatever remaining anions or ligands can be incorporated. Given the complexity of the hydrolysis products of nuclear waste, we expect to continue to find a myriad of closely related complex structures of these types for the f-elements.
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| 36. |
- Hiti, Ethan A., et al.
(author)
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Isolation of anhydrous tetrabutylphosphonium lanthanide hexa- and penta-nitrates from ionic liquids
- 2023
-
In: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 232
-
Journal article (peer-reviewed)abstract
- Our attempts to use an ionic liquid strategy to force f-element coordination of soft donor adenine and 4,5-dicyanoimidazole using 1-pot reactions in water using hydrated lanthanide salts failed, instead resulting in the isolation of anhydrous lanthanide nitrate salts. Reactions of previously ground mixtures of 40 % aq. [P4444][OH] and adenine with Nd(NO3)3·6H2O or Sm(NO3)3·6H2O followed by hand grinding and heating to 90 °C for 10 h led to hot crystallization of anhydrous [P4444]2[Nd(NO3)5] and [P4444]2[Sm(NO3)5]. The same reaction with 4,5-dicyanoimidazole and Nd(NO3)3·6H2O but without heating (10 h, room temperature) to prevent ligand decomposition, led to crystallization of anhydrous [P4444]3[Nd(NO3)6]. [P4444]3[Nd(NO3)6] could also be isolated by conducting the first reaction without using adenine. The single crystal X-ray diffraction structures of the three new anhydrous salts were examined to provide clues to the observed behavior. The [P4444]+ cations allow charge balance while forming box-type encapsulations around the anionic counterpart which has been previously reported in similar structures. The fact that these anhydrous salts were prepared from water with hydrated starting materials and no precautions taken to keep the crystal growing process anhydrous, suggests synthetic strategies that can potentially be beneficial for more advanced separations procedures.
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| 37. |
- Kelley, Steven P., et al.
(author)
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Benchtop access to anhydrous actinide N-donor coordination complexes using ionic liquids
- 2020
-
In: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 56:30, s. 4232-4235
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Journal article (peer-reviewed)abstract
- By dehydrating actinide salts with an ionic liquid containing a common anion and subsequent reaction with N-heterocyclic ligands, we challenge the concept that actinides prefer O- over N-donors; rather the acidic hydrogen atoms of protic solvents hinder the formation of more elusive f-element N-donor coordination complexes.
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| 38. |
- Kelley, Steven P., et al.
(author)
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Dehydration of UO2Cl2 center dot 3H(2)O and Nd(NO3)(3)center dot 6H(2)O with a Soft Donor Ligand and Comparison of Their Interactions through X-ray Diffraction and Theoretical Investigation
- 2020
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:5, s. 2861-2869
-
Journal article (peer-reviewed)abstract
- We investigated whether the relatively Lewis basic imidazole-2-thiones could be used to substitute water ligands bound to f-element cations and generate f-element soft donor complexes. Reactions of 1,3-diethylimidazole-2-thione (C(2)C(2)ImT) with Nd(NO3)(3)center dot 6H(2)O and UO2Cl2 center dot 3H(2)O led to the isolation of the anhydrous thione complexes Nd(NO3)(3)(C(2)C(2)ImT)(3) and UO2Cl2(C(2)C(2)ImT)(2), characterized by single crystal X-ray diffraction. Differences in the strength of metal-thione interactions have been examined by means of the crystal structure analysis and density functional theory (DFT) calculations. The C(2)C(2)ImT ligands were found to be affected by both coordination and noncovalent interactions, making it impossible to deconvolute the effects of one from the other. Calculated partial atomic charges indicated greater ligand-to-metal charge transfer in the [UO2](2+) complex, indicative of a stronger interaction. The reactivity of C(2)C(2)ImT demonstrates its usefulness in the preparation of f-element soft donor complexes from readily available hydrates that could be useful intermediates for promoting the coordination and studying the effects of soft donor anions.
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| 39. |
- Kelley, Steven P., et al.
(author)
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Structural analysis of mono-substituted N-butyl-pyridinium salts : in search of ionic liquids
- 2021
-
In: Journal of coordination chemistry (Print). - : Informa UK Limited. - 0095-8972 .- 1029-0389. ; 74:1-3, s. 117-128
-
Journal article (peer-reviewed)abstract
- Four mono-substituted N-butylpyridinium salts, 1-butyl-4-dimethylaminopyridinium chloride [b4dmapy]Cl, 1-butyl-4-methylpyridinium bromide [b4mpy]Br, 1-butyl-4-methylpyridinium hexafluorophosphate [b4mpy][PF6], and 1-butyl-3-methylpyridinium hexafluorophosphate [b3mpy][PF6] were synthesized and characterized using single crystal X-ray diffraction. The crystal structures were examined with the intent of identifying ion interactions leading to higher melting points of the halide salts with respect to the [PF6]– salts. The changes in hydrogen bonding, C–H⋅⋅⋅π, and van der Waals interactions have been analyzed with respect to anion, functional groups, and the symmetry of the cation to establish interdependence with the compound’s physicochemical properties. It has been observed that the cation–anion interactions are represented by highly directional hydrogen bonds and show strong preference to positions of interaction depending on the anion. The cations of the halide salts show strong tendency towards higher dimensional formations, while those of the [PF6]– salts prefer low dimensional assemblies both being based mainly on the weaker van der Waals interactions. These interactions depend on the shape of the cation but may offer certain structure-ordering rigidity accommodating variable anions.
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| 40. |
- Kelley, Steven P., et al.
(author)
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Structural Consequences of Halogen Bonding in Dialkylimidazolium : A New Design Strategy for Ionic Liquids Illustrated with the I-2 Cocrystal and Acetonitrile Solvate of 1,3-Dimethylimidazolium Iodide
- 2020
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In: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 20:1, s. 498-505
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Journal article (peer-reviewed)abstract
- The reaction of 1,3-dimethylimidazolium-2-carboxylate with elemental iodine in acetonitrile rapidly affords crystalline iodide salts of the 1,3-dimethy1-2-iodoimidazolium cation ([C(1)mim-2-I](+)), [C(1)mim-2-I]I.0.5I(2), and [C(1)mim-2-1]I-0.5CH(3)CN, depending on the temperature. Analysis of the two structures shows the significant role of halogen bonding interactions between the cation and anion in the [C(1)mim-2-I]I salts, which reduces the ionicity of the compounds. This observation is backed by theoretical calculations revealing the importance of halogen bonding as a design strategy for ionic liquids (ILs), which, so far, has been underestimated. The halogen bonding is also analyzed in terms of this new design concept for ILs.
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| 41. |
- Kotur, Bogdan, et al.
(author)
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Crystal and electronic structures of a new hexagonal silicide Sc38Co144Si97
- 2022
-
In: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 316
-
Journal article (peer-reviewed)abstract
- Sc38Co144Si97 was prepared from the elements by arc melting under argon and subsequent annealing at 800 °C for 350 h. Single-crystal X-ray diffraction reveals Sc38Co144Si97 to crystallize in a new hexagonal structure type: Pearson's symbol hP279, space group P63/m, a = 33.624(7), c = 3.639(1) Å. The crystal structure of Sc38Co144Si97 can be considered as a 2D intergrowth of three kinds of fragments of simpler structure types: hexagons and quadrilaterals with the arrangements of the Sc6Co30Si19-type and triangles with the arrangement of the Gd4Co13(Si, P)9-type. Quantum chemical calculations have been performed to analyze the electronic structure and provide deeper insight into the structure-property relationships. The Extended Hückel (EH) calculation indicates that Co in Sc38Co144Si97 adopts close to a d10 configuration owing to the covalent interaction with Si. The Sc–Co and Sc–Si interactions are more ionic, and Co–Co and Co–Si bonds are more covalent interactions.
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| 42. |
- Kotur, B., et al.
(author)
-
Crystal and electronic structures of the new ternary silicide Sc12Co41.8Si30.2
- 2021
-
In: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 302
-
Journal article (peer-reviewed)abstract
- Sc12Co41.8Si30.2 was prepared from the elements by arc melting under argon and subsequent tempering at 800 °C for 350 h. Single-crystal X-ray diffraction reveals Sc12Co41.8Si30.2 to crystallize in a new hexagonal structure type: Pearson's symbol (PS) hP168, space group P6/mmm, a = 17.291(1), c = 8.0293(8) Å. The crystal structure is formed of three types of atomic layers along the [001] direction – two flat at z = 0 and z = 0.5 and one corrugated at z = 0.16–0.33 and z = 0.67–0.84, shows a substantial degree of positional and occupational disorder and close structural relationships to a series of hexagonal structures with PS hP164–hP171. Quantum chemical calculations have been performed to analyze the electronic structure and provide deeper insight into the structure-property relationships. The quantum chemical calculation indicates that the material features both two-center, two-electron localized bonding and multi-center multi-electron delocalized bonding.
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| 43. |
- Leu, Meike, et al.
(author)
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Synthesis of luminescent semiconductor nanoparticles in ionic liquids -the importance of the ionic liquid in the formation of quantum dots
- 2021
-
In: Green Chemistry Letters and Reviews. - : Informa UK Limited. - 1751-8253 .- 1751-7192. ; 14:1, s. 128-136
-
Journal article (peer-reviewed)abstract
- Zinc sulfide (ZnS) and cadmium sulfide (CdS) nanoparticles were synthesized in different ionic liquids (IL) with microwave irradiation. Particle characterization by means of powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and optical spectroscopy (UV-vis absorption and photoluminescence) showed a strong dependence of the particle size depending on the IL employed. Whilst all ILs yielded particles in the nanometer regime and showed in their optical properties quantum confinement, particularly small particles were obtained from choline-base ILs pointing to the strong influence of this IL cation in blocking the particle growth. Here, quantum dots of 1.5–3 nm size were yielded for both, ZnS and CdS.
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| 44. |
- Li, Min, et al.
(author)
-
Open-Framework Manganese(II) and Cobalt(II) Borophosphates with Helical Chains : Structures, Magnetic, and Luminescent Properties
- 2017
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 56:18, s. 11104-11112
-
Journal article (peer-reviewed)abstract
- Two borophosphates, (NH4)(1-2x)M1+x(H2O)(2)(BP2O8)center dot yH(2)O with M = Mn (I) and Co (II), synthesized hydrothermally crystallize in enantiomorphous space groups P6(5)22 and P6(1)22 with a = 9.6559(3) and 9.501(3) angstrom, c = 15.7939(6) and 15.582(4) angstrom, and V = 1275.3(1) and 1218.2(8) angstrom(3) for I and II, respectively. Both compounds feature helical chains composed of vertex-sharing tetrahedral PO4 and BO4 groups that are connected through O atoms to transition-metal cations, Mn2+ and Co2+, respectively. For the two crystallographically distinct-transition-metal cation sites present in the structure, this results in octahedral coordination with different degrees of distortion from the ideal symmetry. The crystal-field parameters, calculated from the corresponding absorption spectra, indicate that Mn2+ and Co2+ ions are located in a weak octahedral-like crystal field and suggest that the Co-ligand interactions are more covalent than the Mn-ligand ones. Luminescence measurements at room temperature reveal an orange emission that red-shifts upon lowering of the temperature to 77 K for I, while II is not luminescent. The luminescence lifetimes of I are 33.4 mu s at room temperature and 1.87 ms at 77 K. Both compounds are Curie-Weiss paramagnets with negative Weiss constants and effective magnetic moments expected for noninteracting Mn2+ and Co2+ cations but no clear long-range magnetic order above 2 K.
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| 45. |
- Li, Sichao, et al.
(author)
-
Anion architecture controls structure and electroresponsivity of anhalogenous ionic liquids in a sustainable fluid
- 2024
-
In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 128:17, s. 4231-4242
-
Journal article (peer-reviewed)abstract
- Three nonhalogenated ionic liquids (ILs) dissolved in 2-ethylhexyl laurate (2-EHL), a biodegradable oil, are investigated in terms of their bulk and electro-interfacial nanoscale structures using small-angle neutron scattering (SANS) and neutron reflectivity (NR). The ILs share the same trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+) cation paired with different anions, bis(mandelato)borate ([BMB]−), bis(oxalato)borate ([BOB]−), and bis(salicylato)borate ([BScB]−). SANS shows a high aspect ratio tubular self-assembly structure characterized by an IL core of alternating cations and anions with a 2-EHL-rich shell or corona in the bulk, the geometry of which depends upon the anion structure and concentration. NR also reveals a solvent-rich interfacial corona layer. Their electro-responsive behavior, pertaining to the structuring and composition of the interfacial layers, is also influenced by the anion identity. [P6,6,6,14][BOB] exhibits distinct electroresponsiveness to applied potentials, suggesting an ion exchange behavior from cation-dominated to anion-rich. Conversely, [P6,6,6,14][BMB] and [P6,6,6,14][BScB] demonstrate minimal electroresponses across all studied potentials, related to their different dissociative and diffusive behavior. A mixed system is dominated by the least soluble IL but exhibits an increase in disorder. This work reveals the subtlety of anion architecture in tuning bulk and electro-interfacial properties, offering valuable molecular insights for deploying nonhalogenated ILs as additives in biodegradable lubricants and supercapacitors.
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| 46. |
- Li, Sichao, et al.
(author)
-
Anion Architecture Controls Structure and Electroresponsivity of Anhalogenous Ionic Liquids in a Sustainable Fluid
- 2024
-
In: Journal of Physical Chemistry B. - : American Chemical Society. - 1520-6106 .- 1520-5207. ; 128:17, s. 4231-4242
-
Journal article (peer-reviewed)abstract
- Three nonhalogenated ionic liquids (ILs) dissolved in 2-ethylhexyl laurate (2-EHL), a biodegradable oil, are investigated in terms of their bulk and electro-interfacial nanoscale structures using small-angle neutron scattering (SANS) and neutron reflectivity (NR). The ILs share the same trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+) cation paired with different anions, bis(mandelato)borate ([BMB]−), bis(oxalato)borate ([BOB]−), and bis(salicylato)borate ([BScB]−). SANS shows a high aspect ratio tubular self-assembly structure characterized by an IL core of alternating cations and anions with a 2-EHL-rich shell or corona in the bulk, the geometry of which depends upon the anion structure and concentration. NR also reveals a solvent-rich interfacial corona layer. Their electro-responsive behavior, pertaining to the structuring and composition of the interfacial layers, is also influenced by the anion identity. [P6,6,6,14][BOB] exhibits distinct electroresponsiveness to applied potentials, suggesting an ion exchange behavior from cation-dominated to anion-rich. Conversely, [P6,6,6,14][BMB] and [P6,6,6,14][BScB] demonstrate minimal electroresponses across all studied potentials, related to their different dissociative and diffusive behavior. A mixed system is dominated by the least soluble IL but exhibits an increase in disorder. This work reveals the subtlety of anion architecture in tuning bulk and electro-interfacial properties, offering valuable molecular insights for deploying nonhalogenated ILs as additives in biodegradable lubricants and supercapacitors.
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| 47. |
- Li, Sichao, et al.
(author)
-
Anion Architecture Controls Structure and Electroresponsivity of Anhalogenous Ionic Liquids in a Sustainable Fluid
- 2024
-
In: Journal of Physical Chemistry B. - : American Chemical Society. - 1520-6106 .- 1520-5207. ; 128:17, s. 4231-4242
-
Journal article (peer-reviewed)abstract
- Three nonhalogenated ionic liquids (ILs) dissolved in 2-ethylhexyl laurate (2-EHL), a biodegradable oil, are investigated in terms of their bulk and electro-interfacial nanoscale structures using small-angle neutron scattering (SANS) and neutron reflectivity (NR). The ILs share the same trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+) cation paired with different anions, bis(mandelato)borate ([BMB]−), bis(oxalato)borate ([BOB]−), and bis(salicylato)borate ([BScB]−). SANS shows a high aspect ratio tubular self-assembly structure characterized by an IL core of alternating cations and anions with a 2-EHL-rich shell or corona in the bulk, the geometry of which depends upon the anion structure and concentration. NR also reveals a solvent-rich interfacial corona layer. Their electro-responsive behavior, pertaining to the structuring and composition of the interfacial layers, is also influenced by the anion identity. [P6,6,6,14][BOB] exhibits distinct electroresponsiveness to applied potentials, suggesting an ion exchange behavior from cation-dominated to anion-rich. Conversely, [P6,6,6,14][BMB] and [P6,6,6,14][BScB] demonstrate minimal electroresponses across all studied potentials, related to their different dissociative and diffusive behavior. A mixed system is dominated by the least soluble IL but exhibits an increase in disorder. This work reveals the subtlety of anion architecture in tuning bulk and electro-interfacial properties, offering valuable molecular insights for deploying nonhalogenated ILs as additives in biodegradable lubricants and supercapacitors.
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| 48. |
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| 49. |
- Liu, J., et al.
(author)
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Anomalous effects of Sc substitution and processing on magnetism and structure of (Gd1-xScx)(5)Ge-4
- 2019
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In: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 474, s. 482-492
-
Journal article (peer-reviewed)abstract
- The kinetic arrest observed in the parent Gd5Ge4 gradually vanishes when a small fraction (x = 0.025, 0.05 and 0.10) of Gd is replaced by Sc in (Gd1-xScx)(5)Ge-4, and the magnetic ground state changes from antiferromagnetic (AFM) to ferromagnetic (FM). A first order phase transition coupled with the FM-AFM transition occurs at T-C = 41 K for x = 0.05 and at T-C = 53 K for x = 0.10 during heating in applied magnetic field of 1 kOe, and the thermal hysteresis is near 10 K. The first-order magnetic transition is coupled with the structural Sm5Ge4-type to Gd5Si4-type transformation. The magnetization measured as a function of applied magnetic field shows sharp metamagnetic-like behavior. At the same time, the AFM to paramagnetic transition in (Gd1-xScx)(5)Ge-4 with x = 0.10, is uncharacteristically broad indicating development of strong short-range AFM correlations above the Ned temperature. Comparison of the magnetization data of bulk, powdered, and metal-varnish composite samples of (Gd0.95Sc0.05)(5)Ge-4 shows that mechanical grinding and fabrication of a composite have little effect on the temperature of the first-order transformation, but short-range ordering and AFM/FM ratio below T-C are surprisingly strongly affected.
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| 50. |
- Mishra, Manish Kumar, et al.
(author)
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CO2 capture from ambient air via crystallization with tetraalkylammonium hydroxides
- 2022
-
In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 51:46, s. 17724-17732
-
Journal article (peer-reviewed)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.
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