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21.
Cover Picture: Coordination Chemistry of N‐Heterocyclic Nitrenium‐Based Ligands (Chem. Eur. J. 19/2015) 下载免费PDF全文
22.
Robert G. Surbella III Korey P. Carter Trevor D. Lohrey Dallas Reilly Mark Kalaj Bruce K. McNamara Jon Schwantes Rebecca J. Abergel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(61):13819-13825
A new uranyl containing metal–organic framework, RPL-1 : [(UO2)2(C28H18O8)] . H2O (RPL for Radiochemical Processing Laboratory), was prepared, structurally characterized, and the solid-state photoluminescence properties explored. Single crystal X-ray diffraction data reveals the structure of RPL - 1 consists of two crystallographically unique three dimensional, interpenetrating nets with a 4,3-connected tbo topology. Each net contains large pores with an average width of 22.8 Å and is formed from monomeric, hexagonal bipyramidal uranyl nodes that are linked via 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (TCPB) ligands. The thermal and photophysical properties of RPL-1 were investigated using thermogravimetric analysis and absorbance, fluorescence, and lifetime spectroscopies. The material displays excellent thermal stability and temperature dependent uranyl and TCPB luminescence. The framework is stable in aqueous media and due to the large void space (constituting 76 % of the unit cell by volume) can sequester organic dyes, the uptake of which induces a visible change to the color of the material. 相似文献
23.
Mark R. Bortolus Dr. Hélène P. A. Mercier Prof. Gary J. Schrobilgen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(41):8935-8950
The reactions of the fluoride-ion donor, XeF6, with the fluoride-ion acceptors, M′OF4 (M′=Cr, Mo, W), yield [XeF5]+ and [Xe2F11]+ salts of [M′OF5]− and [M2O2F9]− (M=Mo, W). Xenon hexafluoride and MOF4 react in anhydrous hydrogen fluoride (aHF) to give equilibrium mixtures of [Xe2F11]+, [XeF5]+, [(HF)nF]−, [MOF5]−, and [M2O2F9]− from which the title salts were crystallized. The [XeF5][CrOF5] and [Xe2F11][CrOF5] salts could not be formed from mixtures of CrOF4 and XeF6 in aHF at low temperature (LT) owing to the low fluoride-ion affinity of CrOF4, but yielded [XeF5][HF2]⋅CrOF4 instead. In contrast, MoOF4 and WOF4 are sufficiently Lewis acidic to abstract F− ion from [(HF)nF]− in aHF to give the [MOF5]− and [M2O2F9]− salts of [XeF5]+ and [Xe2F11]+. To circumvent [(HF)nF]− formation, [Xe2F11][CrOF5] was synthesized at LT in CF2ClCF2Cl solvent. The salts were characterized by LT Raman spectroscopy and LT single-crystal X-ray diffraction, which provided the first X-ray crystal structure of the [CrOF5]− anion and high-precision geometric parameters for [MOF5]− and [M2O2F9]−. Hydrolysis of [Xe2F11][WOF5] by water contaminant in HF solvent yielded [XeF5][WOF5]⋅XeOF4. Quantum-chemical calculations were carried out for M′OF4, [M′OF5]−, [M′2O2F9]−, {[Xe2F11][CrOF5]}2, [Xe2F11][MOF5], and {[XeF5][M2O2F9]}2 to obtain their gas-phase geometries and vibrational frequencies to aid in their vibrational mode assignments and to assess chemical bonding. 相似文献
24.
Neda Choodari Milani Yazdan Maghsoud Mahdieh Hosseini Abouzar Babaei Hamidreza Rahmani Stephen Mark Roe Khodayar Gholivand 《应用有机金属化学》2020,34(4):e5526
Seven novel complexes (C1–C7) were synthesized by the interaction between Cu(I) metal cation, L1, L2, L3, X and PPh3, where L1–L3 are derivatives of ((pyridine-2-ylmethylene)amino)phenol imine ligands and X = Cl−, Br−, I−, NCS−. All the complexes were characterized using infrared, 1H NMR and 31P NMR spectroscopies. The crystal structures of C1–C7 were also determined using single-crystal X-ray diffraction. The organization of the crystal structures and the intermolecular interactions are discussed. The supramolecular assemblies are driven by cooperative π…π interactions and hydrogen bonds, followed by CH…π linkages. The potential anticancer effect of C1–C7 was assessed for human glioblastoma cells using several anticancer experiments, which showed that these complexes have marked anticancer property against U87 cells. It was also found that the minimum and maximum anticancer effects are shown by C3- and C4-treated samples, respectively. Furthermore, theoretical approaches were used to investigate the nature of metal–ligand interactions which suggest a closed-shell and electrostatic character for Cu…N, Cu…P and Cu…X bonds. 相似文献
25.
Simon Knig Philipp Kreis Leonie Reinders Ronald Beyer Andreas Wego Christian Herbert Mark Steinmann Erik Frank Michael R. Buchmeiser 《先进技术聚合物》2020,31(8):1827-1835
The primary use of poly(acrylonitrile) (PAN) fibers, commonly referred to as acrylic fibers, is in textile applications like clothing, furniture, carpets, and awnings. All commercially available PAN fibers are processed by solution spinning; however, alternative, more cost‐effective processes like melt spinning are still highly desired. Here, the melt spinning of PAN‐co‐poly(methyl acrylate) (PMA) plasticized with propylene carbonate (PC) at 175°C is reported. The use of methyl acrylate (MA) as comonomer and PC as an external plasticizer renders the approach a combination of internal and external plasticization. Various mixtures of PAN and PC used in this work were examined by rheology, subjected to melt spinning, followed by discontinuous and continuous washing, respectively. The best fibers were derived from a PAN‐co‐PMA copolymer containing 8.1 mol‐% of MA having a number‐average molecular weight M n of 34 000 g/mol, spun in the presence of 22.5 wt.‐% of PC. The resulting fibers were analyzed by scanning electron microscopy and wide‐angle X‐ray scattering (WAXS), and were subjected to mechanical testing. 相似文献
26.
Mark P. Stockham Alice Griffiths Dr. Bo Dong Prof. Peter R. Slater 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(6):e202103442
Lithium garnets are promising solid-state electrolytes for next-generation lithium-ion batteries. These materials have high ionic conductivity, a wide electrochemical window and stability with Li metal. However, lithium garnets have a maximum limit of seven lithium atoms per formula unit (e.g., La3Zr2Li7O12), before the system transitions from a cubic to a tetragonal phase with poor ionic mobility. This arises from full occupation of the Li sites. Hence, the most conductive lithium garnets have Li between 6–6.55 Li per formula unit, which maintains the cubic symmetry and the disordered Li sub-lattice. The tetragonal phase, however, forms the highly conducting cubic phase at higher temperatures, thought to arise from increased cell volume and entropic stabilisation permitting Li disorder. However, little work has been undertaken in understanding the controlling factors of this phase transition, which could enable enhanced dopant strategies to maintain room temperature cubic garnet at higher Li contents. Here, a series of nine tetragonal garnets were synthesised and analysed by variable temperature XRD to understand the dependence of site substitution on the phase transition temperature. Interestingly the octahedral site cation radius was identified as the key parameter for the transition temperature with larger or smaller dopants altering the transition temperature noticeably. A site substitution was, however, found to make little difference irrespective of significant changes to cell volume. 相似文献
27.
The kinetics of the dissipation of chlortetracycline in the aquatic environment was studied over a period of 90 days using microcosm experiments and distilled water controls. The distilled water control experiments, carried out under dark conditions as well as exposed to natural sunlight, exhibited biphasic linear rates of dissipation. The microcosm experiments exhibited triphasic linear rates of degradation both in the water phase (2.7 × 10−2, 7 × 10−3, 1.3 × 10−3 μg g−1 day–1) and the sediment phase (3.4 × 10−2, 6 × 10−3, 1 × 10−3 μg g−1 day–1). The initial slow rate of dissipation in the dark control (3 × 10−3 μg g−1 day–1) was attributed to a combination of evaporation and hydrolysis, whereas the subsequent fast rate (1.8 × 10−3 μg g−1 day–1) was attributed to a combination of evaporation, hydrolysis, and microbial degradation. For the sunlight-exposed control, the initial slow rate of dissipation (1.5 × 10−3 μg g−1 day–1) was attributed to a combination of evaporation, hydrolysis, and photolysis, whereas the subsequent fast rate was attributed to a combination of evaporation, hydrolysis, photolysis, and microbial degradation (5.1 × 10−3 μg g−1 day–1). The initial fast rate of dissipation in the water phase of the microcosm experiment is attributed to a combination of evaporation, hydrolysis, photolysis, and microbial degradation, whereas all subsequent slow rates in the water phase and all rates of degradation in the sediment phase are attributed to microbial degradation of the colloidal and sediment particle adsorbed antibiotic. A multiphase zero-order kinetic model is presented that takes into account (a) dissipation of the antibiotic via evaporation, hydrolysis, photolysis, microbial degradation, and adsorption by colloidal and sediment particles and (b) the dependence of the dissipation rate on the concentration of the antibiotic, type and count of microorganisms, and type and concentration of colloidal particles and sediment particle adsorption sites within a given aquatic environment. 相似文献
28.
29.
Justin Mark Michael P. Hanrahan Dr. Katherine E. Woo Shannon Lee Prof. Dr. Aaron J. Rossini Prof. Dr. Kirill Kovnir 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(25):6392-6401
Lithiation of van der Waals tetrel-arsenides, GeAs and SiAs, has been investigated. Electrochemical lithiation demonstrated large initial capacities of over 950 mAh g−1 accompanied by rapid fading over successive cycling in the voltage range 0.01–2 V. Limiting the voltage range to 0.5–2 V achieved more stable cycling, which was attributed to the intercalation process with lower capacities. Ex situ powder X-ray diffraction confirmed complete amorphization of the samples after lithiation, as well as recrystallization of the binary tetrel-arsenide phases after full delithiation in the voltage range 0.5–2 V. Solid-state synthetic methods produce layered phases, in which Si-As or Ge-As layers are separated by Li cations. The first layered compounds in the corresponding ternary systems were discovered, Li0.9Ge2.9As3.1 and Li3Si7As8, which crystallize in the Pbam (No. 55) and P2/m (No. 10) space groups, respectively. Semiconducting layered GeAs and SiAs accommodate the extra charge from Li cations through structural rearrangement in the Si-As or Ge-As layers and eventually by replacement of the tetrel dumbbells with sets of Li atoms. Ge and Si monoarsenides demonstrated high structural flexibility and a mild ability for reversible lithiation. 相似文献
30.
Benjamin H. Strudwick Mark A. J. Koenis Hans J. Sanders Valentin P. Nicu Sander Woutersen Prof. Wybren Jan Buma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(54):12560-12566
Vibrational circular dichroism (VCD) studies are reported on a chiral compound in which a fullerene C60 moiety is used as an electron acceptor and local VCD amplifier for an alanine-based peptide chain. Four redox states are investigated in this study, of which three are reduced species that possess low-lying electronic states as confirmed by UV/Vis spectroelectrochemistry. VCD measurements in combination with (TD)DFT calculations are used to investigate (i) how the low-lying electronic states of the reduced species modulate the amplification of VCD signals, (ii) how this amplification depends on the distance between oscillator and amplifier, and (iii) how the spatial extent of the amplifier influences amplification. These results pave the way for further development of tailored molecular VCD amplifiers. 相似文献