A series of compounds based on the macrocyclic ligand cyclohexanocucurbit6uril (Cy6Q6) with formulas {Ln(H2O)6Cy6Q6}·2(CdCl4)·H3O·xH2O isomorphous with Ln=La (1), Ce (2), Pr (3) and Nd (4), x=11 (1), ...11 (2), 10 (3) and 11 (4), {Sm(H2O)5Cy6Q6}·2(CdCl4)·H3O·10H2O (5) and {Ln(H2O)5(NO3)@Cy6Q6}·2(CdCl4)·2H3O·xH2O isomorphous with Ln=Gd (6), Tb (7) and Dy (8), x=8 (6), 6 (7) and 6 (8), have been successfully synthesized by the self-assembly of Cy6Q6 with the corresponding lanthanide nitrate under hydrochloric acid aqueous solution in the presence of CdCl2. Single-crystal X-ray diffraction analyses revealed that compounds 1–8 all crystallize in monoclinic space group P21/c, and display 1D coordination polymer structures. The lanthanide contraction effect on the structures of 1–8 has also been investigated and discussed in detail. In contrast, the reaction of Cy6Q6 with the Ho(NO)3, Tm(NO)3, Yb(NO)3 under the same conditions resulted in the compounds 9–11 with formulas Cy6Q6·2(CdCl4)·2H3O·xH2O isomorphous with x=10 (9), 10 (10), and 9 (11), in which no lanthanide cations are observed. The structural difference of these compounds indicates that the Cy6Q6 may be used in the separation of lanthanide cations.
The reaction of cyclohexanocucurbit6uril with lanthanide ions (La3+, Ce3+, Pr3+, Nd3+, Sm3+, Gd3+, Tb3+, Dy3+, Ho3+, Tm3+ and Yb3+) under hydrochloric acid in the presence of CdCl2 resulted in eleven compounds, which demonstrate interesting lanthanide contraction effect and provide a means of separating lanthanide ions. Display omitted
•Eleven compounds of the Ln3+ with the Cy6Q6 were synthesized and described.•Compounds 1-8 demonstrate interesting lanthanide contraction effect.•In solid-state structures of compounds 9-11, no lanthanide ions were observed.•This study provides a means of separating lanthanides cations.
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Fluorescence probes serves as unique detection methods for its simplicity and low detection limit (LOD) and especially bioimaging ability. Research on the probes has already sprouted during the last ...decade with the help of its molecular recognition properties. This review spotlights recent progress in sensing and bioimaging biologically, environmentally and industrially important metal ions e.g. Zn
2+
, Cu
2+
, Hg
2+
, Ag
+
etc. using suitable fluorescent chemosensors including carbon quantum dots (CQD).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In time-of-flight secondary ion mass spectrometry (TOF-SIMS), ionized molecules and molecular fragments (secondary ions) are generated in collisions of high-energy ions (primary ions) with a solid ...sample surface. Mass spectra of the emitted secondary ions are typically used to identify molecular species and to determine their spatial distribution on the sample surface. Here, we extend this application in a TOF-SIMS study of a series of polycyclic aromatic hydrocarbons (PAHs) where we focus on the fragmentation of these molecules, with the purpose of better understanding the fragmentation patterns of heavy aromatic molecules in petroleum. For all PAHs, the collision process generated (i) a series of smaller cation fragments and (ii) cations close in size to the original PAH (molecular cations). Stark differences are measured for various PAHs regarding the abundance of smaller fragments versus molecular cations. Observation of hydrogen-deficient (H-deficient) cation fragments indicates the formation of polyynes and allenes. For PAHs producing higher fractions of small cation fragments, these ions are surprisingly hydrogen rich (H-rich). The H/C ratio of fragments does not scale with the fraction of Clar sextet carbon, nor with energies of low-lying electronic transitions. Free radical cation fragments tend to be suppressed. For sufficiently large fragments, aromatic cations appear to be formed and include some free radical aromatics. There is ample production of molecular ions with loss of a single carbon atom or a methine group, which corresponds to the reduction of a 6-membered aromatic ring to a 5-membered ring. There is some enhancement of free radical molecular cations due to the corresponding formation of neutral polyynes. Fragment anions are also produced with a strong preference for very H-deficient carbon clusters, in some cases being the same as carbon cluster anions observed in space. Comparisons of PAH TOF-SIMS spectra with those of asphaltenes are discussed in detail.
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Composite solid electrolytes have attracted significant interest because they overcome the defects of single‐component solid electrolytes. However, the discontinuous ion transport and weak mechanical ...support caused by randomly distributed powders lead to inferior ionic conductivity and poor mechanical strength. Herein, a hierarchically self‐assembled metal‐organic framework (MOF) network is designed to provide continuous ion transport and mechanical support for composite polymer electrolytes. This unique structure is achieved by constructing well‐ordered MOF nanocrystals along 1D polyimide fibers to provide continuous linear pathways for lithium ions at the micrometer scale, and the 1D MOF fibers are interconnected to form a monolithic 3D network for continuous Li+ transport in the bulk of composite electrolytes. Meanwhile, sub‐nano pores and Lewis acid sites in MOF nanocrystals can selectively confine the movement of larger anions as ion sieves to promote Li+ transport. In addition, the strong banding between MOF and polyimide, coupled with the robustness of the polyimide skeleton, endows the MOF network with high mechanical strength and flexibility. Accordingly, the resultant composite electrolyte delivers a high ionic conductivity and desired mechanical strength. This work shows that rational spatial arrangement of incorporated powders from disorder to order by a self‐assembly strategy can yield novel properties for composite solid electrolytes and solid‐state lithium batteries.
A hierarchically self‐assembled metal‐organic framework (MOF) network is constructed by a self‐assembled strategy, consisting of continuous and well‐ordered MOF nanocrystals and mechanically robust polyimide skeleton, in which the self‐assembled MOF provides fast and continuous ion transport, and the polyimide skeleton enables high mechanical strength and great flexibility of the MOF network.
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To achieve high ionic conductivity for solid electrolyte, an artificial Li‐rich interface layer of about 60 nm thick has been constructed in polymer‐based poly(ethylene oxide)‐lithium ...bis(trifluoromethanesulfonyl)imide composite solid electrolyte (briefly noted as PEOm) by adding Li‐based alloys. As revealed by high‐resolution transmission electron microscopy and electron energy loss spectroscopy, an artificial interface layer of amorphous feature is created around the Li‐based alloy particles with the gradient distribution of Li across it. Electrochemical analysis and theoretical modeling demonstrate that the interface layer provides fast ion transport path and plays a key role in achieving high and stable ionic conductivity for PEOm‐Li21Si5 composite solid electrolyte. The PEOm‐5%Li21Si5 composite electrolyte exhibits an ionic conductivity of 3.9 × 10–5 S cm−1 at 30 °C and 5.6 × 10−4 S cm−1 at 45 °C. The LiFePO4 | PEOm‐5%Li21Si5 | Li all‐solid‐state batteries could maintain a stable capacity of 129.2 mA h g−1 at 0.2 C and 30 °C after 100 cycles, and 111.3 mA h g−1 after 200 cycles at 0.5 C and 45 °C, demonstrating excellent cycling stability and high‐rate capability.
A Li‐rich artificial solid electrolyte interface (SEI) layer about 60 nm thick is successfully designed and constructed in a Li alloy filled poly(ethylene oxide) polymer electrolyte to achieve high ionic conductivity for lithium metal batteries. The LiFePO4|Li all‐solid‐state batteries exhibit high cycling performance of 111.3 mA h g–1 after 200 cycles at 0.5 C in 45 °C.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Groundwater samples were collected from 36 wells during summer and monsoon seasons in a coastal region in Tamil Nadu, India in 2011. The chemical analysis of groundwater samples indicated that ...groundwater in the region was fresh to saline with cationic concentrations in the order Na
+
> Ca
2+
> Mg
2+
> K
+
and anionic concentrations in the order Cl
−
> HCO
3
−
> SO
4
2−
> NO
3
−
. Most of the groundwater samples had a chemical composition dominated by sodium and chloride ions. Scatter plots suggested that the principal processes influencing groundwater quality in the area are likely to be: ion exchange; reverse ion exchange; silicate weathering and evaporation. A Gibbs plot indicated that evaporation was the dominant process influencing groundwater salinity in the summer season, whereas both water–rock interactions and evaporation influenced the chemical composition and salinity of groundwater in the monsoon season. A principal component analysis of the data shows four principal components for the monsoon and three components for the summer seasons, which account for 85% and 87% of the total variance, respectively. The assessment has indicated that there is widespread seawater intrusion in coastal aquifers, which has led to changes in hydrochemical processes in the study area.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present a statistical study of nose‐like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named ...after the characteristic shapes of energy bands or gaps in the energy‐time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequently in heavy ions than in H+ and are most often observed during quiet times. The heavy‐ion noses penetrate to lower L shells than H+ noses, and there is an energy‐magnetic local time (MLT) dependence in the nose locations and energies that is similar for all species. The observations are interpreted by using a steady state model of ion drift in the inner magnetosphere. The model is able to explain the energy and MLT dependence of the different types of nose structures. Different ion charge‐exchange lifetimes are the main cause for the deeper penetration of heavy‐ion noses. The species dependence and preferred geomagnetic conditions of multiple‐nose events indicate that they must be on long drift paths, leading to strong charge‐exchange effects. The results provide important insight into the spatial distribution, species dependence, and geomagnetic conditions under which nose structures occur.
Key Points
A statistical study of H+, He+, and O+ nose structures observed by the ECT‐HOPE mass spectrometer on board the Van Allen Probes is performed
Multiple‐nose structures are preferentially observed in heavy ions and during low activity levels
The dependence of nose structures on energy, L, and MLT is generally consistent with a simple model of ion drift and charge‐exchange losses
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•Efficient green-emitting Ce3+/Tb3+ ions co-activated Ca2GdHf2Al3O12 phosphors were prepared.•They can effectively excited by near-UV light around 408 nm.•Intense green emissions around 543 nm were ...realized via energy transfer from Ce3+ to Tb3+ ions.•High photoluminescence efficiency (IQE = 82.7% and EQE = 60.6%) was obtained.•A warm-white LED with high-color-rendering (Ra = 94.4, R12 = 89.0, R9 = 80.6) was achieved.
High light-quality and low color temperature are two crucial factors for a comfortable healthy illumination. Phosphor-converted white light-emitting diodes (LEDs) could be readily realized by combining near-UV (380–420 nm) LED chips with tri-color phosphors, and thus near-UV-excitable inorganic phosphors with efficient visible luminescence are highly demanded for fabricating high-performance near-UV-pumped white LEDs. Herein, we demonstrated a novel highly efficient green-emitting phosphor based on Ce3+/Tb3+ ions co-activated Ca2GdHf2Al3O12 (abbreviated as: CGHAO) garnet compound, which enabled the realization of ultra-high color rendering warm-white LEDs. Notably, the CGHAO:Ce3+,Tb3+ phosphors could be efficiently excited by near-UV light around 408 nm and exhibited intense green emissions around 543 nm with high internal quantum efficiency of 82.7% and external quantum efficiency of 60.6%. The energy transfer from Ce3+ to Tb3+ ions was studied in detail, and the composition of CGHAO:Ce3+,Tb3+ phosphors was optimized. Utilizing the optimal CGHAO:0.04Ce3+,0.4Tb3+ green phosphor as color converter, a prototype near-UV-pumped white LED device was fabricated, and upon 120 mA driving current it demonstrated bright warm-white light with excellent CIE chromaticity coordinates of (0.391, 0.360), low correlated color temperature of 3575 K, ultra-high color rendering index (Ra = 94.4, R12 = 89.0, and R9 = 80.6) and good luminous efficacy of 27.40 lm·W−1. This work offers a new strategy for designing efficient LED phosphors for high-color-quality solid-state lighting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Originating from the ionic concentration polarization, ionic current rectification (ICR) is closely related to ion selectivity. Since it is the region with the greatest selectivity, the tip of the ...conical nanopore became the focus of research. However, even if the characteristic of the tip is fixed, the changes of pore length and cone angle still affect the magnitude of ICR─rectification factor (RF). This shows that only focusing on the selectivity of the tip is not comprehensive. Through the simulations based on the one-dimensional Poisson-Nernst-Planck model, it is found that the pore length and cone angle can influence the RF by changing the Dukhin number of pore base (
). Here,
is a parameter describing the ratio of excess ion concentration and bulk ion concentration. In addition, it is proved that the RF is determined by
(
of the pore tip) and
together. On the basis of the results, we suggest that a uniformly charged conical nanopore can be equivalent to the series connection of many ultrashort nanochannels with different
. The differences in
between adjacent channels lead to unbalanced ion transport, ultimately leading to enrichment or depletion of ion concentration under different polarities. Besides, ICR in bipolar diodes also exhibits
dependence. We anticipate that this work will provide help to understand the mechanism behind ICR.
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