- Transfer Gibbs energies for ClO3-, BrO3-, IO3-, ClO4- and IO4- anions for water-methanol and water-propan-2-ol mixtures: Some quantum-chemical aspects of ionic solvation
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The transfer Gibbs energies, ΔtrsG°, of KClO3, KBrO3, KIO3, KClO4, KIO4 and the corresponding caesium salts have been obtained through gravimetric measurements of the solubility in aqueous mixtures with methanol (MeOH) and propan-2-ol (PriOH) at 298.2 K. In addition, the solubility of Ph4P(pic) (pic = picrate anion) as well as K(pic) and KBPh4 and the corresponding caesium salts are reported in these mixtures at 298.2 K. Single-ion values of ΔtrsG° have been calculated using the tetraphenylphosphonium tetraphenylborate (TPTB) assumption. The semiempirical quantum-chemical AM1 method was used for calculations of interaction energy of BPh4- and Ph4P+ with a series of five solvent molecules and energy demands associated with a deformation of these ions. Trends observed for ΔtrsG° are discussed in terms of specific ion-solvent interactions and the structural effect of solvent mixtures.
- Benko, Jan,Vollarova, Ol'ga,Cernusak, Ivan,Pappova, Adriana
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- Functional Materials Design via Structural Regulation Originated from Ions Introduction: A Study Case in Cesium Iodate System
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Tailored structural regulation to achieve novel compounds with special properties is very attractive and important for functional material design. In this paper, CsIO3 was selected as a maternal structure and three new derivatives, namely, CsIO2F2, Cs3(IO2F2)3·H2O, and Cs(IO2F2)2·H5O2, were successfully prepared by introducing different units (F-, H2O, H5O2+, and IO2F2-) under hydrothermal condition for the first time. Then, the structural transformations were schematically analyzed and the corresponding properties originated from ions introduction were investigated. Therein, noncentrosymmetric CsIO3 and CsIO2F2 exhibit good nonlinear optical properties with large second-harmonic generation (SHG) effects (15 × and 3 × KH2PO4), wide band gaps (4.2 and 4.5 eV), wide transmittance ranges (a0.27-5.5 μm), and high laser damage thresholds (15 × and 20 × AgGaS2, respectively), which shows that they are potential nonlinear optical materials in near-ultraviolet to mid-infrared. To further analyze the structure-properties relationship, the first-principles calculations are applied to explore the origins of the optical properties, such as birefringences and SHG responses. Moreover, the protonated (H5O2)+ cations in Cs(IO2F2)2·H5O2 imply that it may feature enhanced conductivity, which was tentatively verified by the resistivity tests via the conventional dc four-probe method. The study case of structural regulation realized by ions introduction in this work may give a feasible guidance for functional materials design.
- Zhang, Min,Hu, Cong,Abudouwufu, Tushagu,Yang, Zhihua,Pan, Shilie
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- Structural modulation of molybdenyl iodate architectures by alkali metal cations in AMoO3(IO3) (A = K, RB, Cs): A facile route to new polar materials with large SHG responses
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Three new molybdenyl iodates, KMoO3(IO3) (1), RbMoO3(IO3) (2), and CsMoO3(IO3) (3), have been prepared through the hydrothermal reactions of MoO3 with AIO4 (A = K, Rb, or Cs) at 180°C. These compounds are isolated as nearly colorless, air-stable crystals. Single-crystal X-ray diffraction experiments reveal that 1 possesses a corrugated layered structure constructed from molybdenum oxide chains that are bridged by iodate anions. The puckering of the layers is caused by the alignment of bent molybdenyl (MoO22+) groups along one side of the molybdenum oxide chains. The K+ cations separate these layers from one another and serve to balance charge. In contrast, compounds 2 and 3, which are isostructural, form three-dimensional structures with small cavities filled with Rb+ or Cs+ cations. The differences between the structures of 1 and those of 2 and 3 are due to rotation of the molybdenyl units as translation occurs down the molybdenum oxide chains in order to accommodate the increased size of the Rb+ and Cs+ cations. This rotation allows for the iodate anions to bridge the molybdenum oxide chains in an additional dimension, creating a three-dimensional network structure. Furthermore, while 1 crystallizes in a centrosymmetric space group, 2 and 3 crystallize in polar space groups. Second-harmonic generation measurements on 2 and 3 show large responses of 400x α-quartz. Differential scanning calorimetry measurements demonstrate that 2 and 3 are thermally stable to 494 and 486°C, respectively. UV-vis diffuse reflectance spectra of these compounds show a high degree of transparency from 1 to 3 eV and a band gap of 3.1 eV.
- Sykora, Richard E.,Kang, Min Ok,Halasyamani, P. Shiv,Albrecht-Schmitt, Thomas E.
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p. 1951 - 1957
(2007/10/03)
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- On the knowledge of oxides A[MO4]: On LiMnO4, KMnO4, RbMnO4, CsMnO4 as well as RbIO4, CsIO4. (-What does the crystal structure of . . . mean? -)
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These investigations confirm again that, sufficient purity, symmetry and lack of disorder etc. of investigated single crystals provided: the structure of a solid is characterized only if a) lattice constants are determined precisely by powder data; b) a couple of single crystals is sufficiently investigated by film data; c) the quantitative comparison of crystal structures of a chemical series like A[MnO4] with another one like A2[SO4] alone enables one to estimate the quality of different structural investigations of the same material. d) The crystal structure of a solid is still non-existent.
- Hoppe,Fischer,Schneider
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p. 1135 - 1142
(2008/10/08)
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- Characterization of Molecular Alkali Metal Iodates by Mass Spectrometry and Matrix Isolation IR Spectroscopy
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Samples of the solids MIO3 (M = Li, Na, K, Rb, Cs) have been vaporized in vacuo and the ternary products characterized by mass spectrometry, and by infrared spectroscopy in low-temperature nitrogen, oxygen and argon matrices.The molecular species KiO3, RbIO3, and CsIO3 have been identified for the first time and their IR spectra shown to be consistent with overall C3v symmetry involving tridentate coordination.This conclusion is further confirmed, in the case of CsIO3 isolated in argon, by a detailed analysis of (18)O isotope patterns.In contrast, samples of LiIO3 and NaIO3 appeared to undergo decomposition to the iodide and oxygen.
- Biggs, Karen R.,Gomme, Robin A.,Graham, John T.,Ogden, J. Steven
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p. 9738 - 9741
(2007/10/02)
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