Luminescent coordination polymers based on Ca²⁺ and octahedral cluster anions [{M₆Clⁱ₈}Clᵃ₆}²⁻ (M = Mo, W) : synthesis and thermal stability studies

Luminescent coordination polymers (CPs) based of inexpensive stable precursors are attractive materials for applications. Here we report the synthesis and evaluation of the stability and photophysical characteristics of the first examples of phosphorescent CPs based on octahedral molybdenum and tungsten cluster anions. Specifically 1D CP trans-[{Ca(OPPh₃)₄}{{M₆Clⁱ₈}Clᵃ₆}]∞ (M = Mo, W) can be obtained either directly at increased temperature or via intermediate phases [cis-Ca(OPPh₃)₄(H₂O)₂][{M₆Clⁱ₈}Clᵃ₆]∙2CH₃CN that are stable at room-temperature, but convert to the titled CP at temperatures above 100 °C

Phase transitions in a metal–organic coordination polymer: [Zn₂(C₈H₄O₄)₂(C₆H₁₂N₂)] with guest molecules. Thermal effects and molecular mobility

<p>Thermal effects of a series of [Zn₂(C₈H₄O₄)₂(C₆H₁₂N₂)] porous compound with the guest molecules located in the pores were studied using differential scanning calorimetry combined with solid-state ¹H nuclear magnetic resonance spectroscopy. The intercalation of the molecules was shown to produce various thermal anomalies and phase transitions, which were characterized and analyzed.</p

Photocrystallographic, Spectroscopic, and Calorimetric Analysis of Light-Induced Linkage NO Isomers in [RuNO(NO2)(2)(pyridine)(2)OH]

International audienceThrough photocrystallography at T = 80 K, light- induced linkage isonitrosyl NO isomers (.O- bound) are detected and refined in the complex fac-[ RuNO( NO2) 2Py2OH] center dot H2O ( Py = pyridine) after irradiation with light in the blue spectral range. The infrared and Raman spectra reveal the downshift of the.( NO),.( Ru- NO), and delta( Ru- N- O) vibrations by 120150 cm- 1 upon photoexcitation. Furthermore, the infrared spectrum show a significant downshift of the (vas)( NO2) and (vs)( NO2) bands by ca. 10 cm- 1 but without any isomerization of the NO2 ligands. Furthermore, the downshifts of the.( RuO- H) and delta( Ru- O- H) vibrational modes show the trans influence of the NO isomer on the OH ligand. The populations of the isonitrosyl isomer determined ( 66- 75% at. = 443445 nm) by all three techniques ( X- ray crystallography, IR and Raman spectroscopy) agree well. Such a high population of the isonitrosyl structure is visible in the photodifference map. The activation parameters Ea = 63.9 +/- 1 kJ/ mol and k0 = ( 1.8 +/- 0.1) x 1013 s- 1 of the reverse transition were determined by differential scanning calorimetry ( DSC). The second metastable state ( side- on (KNO)-N-2 mode) was generated by a two-step irradiation with blue light followed by irradiation with light in the near-infrared spectral range ( 980 nm) and identified through its characteristic NO stretching vibration at. V = 1592 and 1600 cm- 1

Synthesis, Structural, Thermal, and Electronic Properties of Palmierite-Related Double Molybdate α‑Cs2Pb(MoO4)2

Krystaly Cs2Pb (MoO4) 2 byly připraveny krystalizací ze své vlastní taveniny a struktura krystalů byla podrobně studována. Při 296 K molybdenát krystalizuje v a-formě s nízkou teplotou a má monoklinickou nadstavbu příbuznou palmititu (prostorová skupina C2 / m, a = 2,13755 (13) nm, b = 1,23123 (8) nm, c = 1,68024 ) Nm, P = 115,037 (2) °, Z = 16)Cs2Pb (MoO4)2 crystals were prepared by crystallization from their own melt, and the crystal structure has been studied in detail. At 296 K, the molybdate crystallizes in the low temperature α-form and has a monoclinic palmierite-related superstructure (space group C2/m, a = 2.13755(13) nm, b = 1.23123(8) nm, c = 1.68024(10) nm, β = 115.037(2)°, Z = 16

Synthesis, Structural, Thermal, and Electronic Properties of Palmierite-Related Double Molybdate α‑Cs₂Pb(MoO₄)₂

Cs₂Pb­(MoO₄)₂ crystals were prepared by crystallization from their own melt, and the crystal structure has been studied in detail. At 296 K, the molybdate crystallizes in the low-temperature α-form and has a monoclinic palmierite-related superstructure (space group <i>C</i>2/<i>m</i>, <i>a</i> = 2.13755(13) nm, <i>b</i> = 1.23123(8) nm, <i>c</i> = 1.68024(10) nm, β = 115.037(2)°, <i>Z</i> = 16) possessing the largest unit cell volume, 4.0066(4) nm³, among lead-containing palmierites. The compound undergoes a distortive phase transition at 635 K and incongruently melts at 943 K. The electronic structure of α-Cs₂Pb­(MoO₄)₂ was explored by using X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy methods. For α-Cs₂Pb­(MoO₄)₂, the photoelectron core-level and valence-band spectra and the XES band representing the energy distribution of Mo 4d and O 2p states were recorded. Our results allow one to conclude that the Mo 4d and O 2p states contribute mainly to the central part and at the top of the valence band, respectively, with also significant contributions throughout the whole valence-band region of the molybdate under consideration