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A new phase of silver iodate, β-AgIO3, is obtained by heating α-AgIO3 at 2.7 GPa at <240 °C for 30 min. [ABSTRACT FROM AUTHOR]

Abstract: We present the synthesis of 2,6-diethyl-4,4-difluoro-8-(-4-iodophenyl)-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene labeled as iodophenyl-BODIPY (IP-BDPY) and the growth of microcrystals or spherulitic crystal plates in typical free solutions. Their crystal structures, the absorption and fluorescence spectroscopies were investigated. Relations between crystal structure and absorption, dichroism and fluorescence properties were established. The first results obtained for the preparation of IP-BDPY nanocrystals grown in sol–gel thin films were also introduced. Their absorption and fluorescence spectra were compared with the spectra of the corresponding bulk crystal and diaplectic amorphous solid obtained by a drastic crushing. Unexpected results were obtained: amorphization of molecular nanocrystals just after their growth by capillary forces generated during the drying of sol–gel thin films. [Copyright &y& Elsevier]

Abstract: Anhydrous yttrium iodate presents polymorphism; two crystalline phases are obtained under hydrothermal conditions. α-Y(IO3)3 crystallises in the monoclinic space-group P21/c with a three-dimensional structure, whereas β-Y(IO3)3 crystallises in the monoclinic space-group P21/n with a two-dimensional structure. The lattice parameters are a =7.038(1)Å, b =8.466(1)Å, c =13.317(1)Å, β =99.65(1)°, V =782.3(2)Å3, Z =4 for α-Y(IO3)3 and a =8.685(1)Å, b =5.964(1)Å, c =14.958(1)Å, β =96.99(2)°, V =769.0(2)Å3, Z =4 for β-Y(IO3)3. The α-form is isostructural with α-Dy(IO3)3 studied in this work and α-Ln(IO3)3 (Ln=Ce, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Lu) already studied. The β-form is isostructural with β-Ln(IO3)3 (Ln=Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho and Er) studied in this work. The structural evolutions as a function of the Ln3+ cationic radius are studied. α-Y(IO3)3 and β-Y(IO3)3 present good thermal stability since they decompose at 600°C. They are transparent up to 11.5μm and they have good optical damage thresholds on powder. [Copyright &y& Elsevier]

We present results obtained from high energy-resolution L3-edge XANES spectroscopy and first-principles calculations for the structure, bonding, and stability of mercury(II) complexes with thiolate and thioether ligands in crystalline compounds, aqueous solution, and macromolecular natural organic matter (NOM). Core-to-valence XANES features that vary in intensity differentiate with unprecedented sensitivity the number and identity of Hg ligands and the geometry of the ligand environment. Post-Hartree-Fock XANES calculations, coupled with natural population analysis, performed on MP2-optimized Hg[(SR)2···(RSR)n] complexes show that the shape, position, and number of electronic transitions observed at high energy-resolution are directly correlated to the Hg and S (l,m)-projected empty densities of states and occupations of the hybridized Hg 6s and 5d valence orbitals. Linear two-coordination, the most common coordination geometry in mercury chemistry, yields a sharp 2p to 6s + 5d electronic transition. This transition varies in intensity for Hg bonded to thiol groups in macromolecular NOM. The intensity variation is explained by contributions from next-nearest, low-charge, thioether-type RSR ligands at 3.0-3.3 Å from Hg. Thus, Hg in NOM has two strong bonds to thiol S and k additional weak Hg···S contacts, or 2 + k coordination. The calculated stabilization energy is -5 kcal/mol per RSR ligand. Detection of distant ligands beyond the first coordination shell requires precise measurement of, and comparison to, spectra of reference compounds as well as accurate calculation of spectra for representative molecular models. The combined experimental and theoretical approaches described here for Hg can be applied to other closed-shell atoms, such as AgI and AuI. To facilitate further calculation of XANES spectra, experimental data, a new crystallographic structure of a key mercury thioether complex, Cartesian coordinates of the computed models, and examples of input files are provided as Supporting Information. [ABSTRACT FROM AUTHOR]

The structural and thermal studies of six anhydrous lanthanum iodate polymorphs are presented. The variation of the [IO3-]:[La3+] molar ratio in the starting solution and the evaporation rate of the solution leads to either the centric La(IO3)3(HIO3) or the acentric La(IO3)3(HIO3)1.33 phases. The crystal structure of La(IO3)3(HIO3)1.33 was determined. The thermal treatments of these two phases up to 490 °C lead to β-La(IO3)3, observed at room temperature. To better understand the similar thermal behaviors of La(IO3)3(HIO3)1.33 and La(IO3)3(HIO3) compounds and their structural evolution, thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC) analyses and in situ temperature-dependent powder X-ray diffraction (XRD) experiments were carried out. These experiments allowed us to highlight the successive formation of δ-La(IO3)3 and γ-La(IO3)3. δ-La(IO3)3 is observed from the beginning of thermal decomposition of La(IO3)3(HIO3)1.33 (at 340 °C) or La(IO3)3(HIO3) (at 300 °C) up to 440 °C. A phase transition from δ-La(IO3)3 to γ-La(IO3)3 then occurs at 440 °C. Finally, the phase transition from γ-La(IO3)3 to β-La(IO3)3 occurs at 140 °C. A cycle of heating and cooling shows the reversible phase transition at 185 and 140 °C, respectively. β-, γ-, and δ-La(IO3)3 are three polymorph phases of the first α-La(IO3)3 already characterized. The structure of β-La(IO3)3 and γ-La(IO3)3 were determined on powder XRD analyses. The iodate compounds present a very broad domain of transparency from the visible range to the beginning of the far-infrared range. The intensities of SHG light generated by α-La(IO3)3, β-La(IO3)3, La(IO3)3(HIO3)1.33, and α-LiIO3 compounds with acentric structures were compared: β-La(IO3)3 < La(IO3)3(HIO3)1.33 < α-La(IO3)3 ≈ α-LiIO3. Finally, the luminescence spectroscopy of La(IO3)3(HIO3)1.33:Nd3+, α-La(IO3)3:Nd3+, and α-La(IO3)3:Yb3+ is studied. [ABSTRACT FROM AUTHOR]