Chain-like Structure Research Articles

Developments of cyclodextrin-coated Fe3O4@Fe0 nanoparticles to both efficiently activate persulfates and rapidly access hydrophobic PAHs in water

We report new activated persulfate systems with cyclodextrin (CD)-coated Fe3O4@Fe0 nanoparticles (Fe3O4@Fe0-CD) that are characterized by both highly activating persulfates and rapidly accessing hydrophobic PAHs. Fe3O4@Fe0-β-CD displays chain-like structure of core–shell Fe3O4@Fe0 nanoparticles coated with a CD layer (about 5.9 nm). CD coating stabilizes the polycrystalline structure of Fe3O4@Fe0 nanoparticles and accelerates mass transfer of PAHs in water, thereby making Fe3O4@Fe0-β-CD intrinsically stable and reactive. Fe3O4@Fe0-β-CD/PS, featured by high yields of highly reactive Fe(IV), had about 30-fold rate constants of naphthalene (Nap) in water as much as Fe3O4@Fe0/PS. Fe3O4@Fe0-β-CD/PS completely removed Nap in water during 13 of total 18 supplementations of Nap and/or PS, whereas Fe3O4@Fe0/PS completely removed Nap only at the first supplementation of Nap. Likewise, Fe3O4@Fe0-β-CD/PS completely removed Nap in simulated groundwater, and degraded four PAHs in soils by >63%. This study may provide a technical basis for the developments of new PS activators to remove recalcitrant hydrophobic contaminants in water and soils.

Flame-Made Ir–IrO2/TiO2 Particles as Anode Catalyst Support for Improved Durability in Polymer Electrolyte Fuel Cells

The development of metal oxide support with high electrical conductivity has attracted attention to improving the durability and performance of polymer electrolyte fuel cells. Iridium oxide–titanium oxide particles are outstanding candidates, owing to their excellent properties. In this study, catalyst support comprising titanium oxide particles with low-loading iridium–iridium oxide species (Ir–IrO2/TiO2) with a chain-like structure was synthesized by a flame aerosol process. The flame aerosol process is a versatile and one-step method allowing the production of metal-loaded metal oxide particles with a low amount of precious metal. The effect of the Ir loading contents on the morphology and electrical conductivity of the synthesized particles was investigated. The volume resistivity of Ir–IrO2/TiO2 particles containing 10 wt % IrO2 (Ir–IrO2/TiO2-10) (0.95 Ω cm) was much lower than that of TiO2 particles (108 Ω cm), which demonstrates the improvement of the conductivity of TiO2 particles resulting from the Ir loading. The electrochemical surface area of 20 wt % Pt-loaded Ir–IrO2/TiO2-10 particles was 42 m2 g–1-Pt, and Pt nanoparticles were distributed homogeneously on the Ir–IrO2/TiO2 particle surface. The performance of a membrane electrode assembly (MEA) based on the developed Ir–IrO2/TiO2 catalyst support as an anode shows no significant differences compared to that of MEA based on a carbon-supported Pt catalyst. MEA prepared from the Ir–IrO2/TiO2-10 particles exhibited remarkable stability after 20 min testing at a voltage of 1.7 V, whereas the cell potential of a carbon-supported Pt catalyst decreased dramatically under the same conditions.

Development and characteristics of a low rare-earth containing magnesium alloy with high strength-ductility synergy

In this study, we successfully developed a low RE containing Mg-3Y-2Gd-1Nd-0.5Zr (wt%) alloy with high strength-ductility synergy by combined processes of hot extrusion, hot rolling and ageing. This alloy exhibits an excellent strength-ductility balance (UTS of 345 ± 2.0 MPa, TYS of 301 ± 5.0 MPa and EL of 9.2 ± 1.9%), which is better than that of many Mg-RE wrought alloys with higher RE concentration and even comparable to that of 6061 Al wrought alloy. A long-range chain-like structure consisting of β′ phase, β H phase, β M phase and zig-zag atomic columns is observed for the first time in the studied alloy. The combined process of hot extrusion and hot rolling boosts the formation of deformed grains and low angle grain boundaries, and makes the deformed grains dominate in the alloy strengthening. Under this circumstance, the following ageing generates a novel heterogeneous structure comprising the long-range chain-like structure with broad interparticle spacing and the spacious precipitate-free zones in the deformed grains, which plays a key role in the concurrent strengthening and toughening of the alloy. The present study demonstrates that the deformed grains with long-range chain-like structures and precipitate-free zones is desirable microstructure for the low RE containing Mg alloys to achieve high strength-ductility synergy.

2D and 3D TEM Characterisation of Benzene and Ethylene Soot

Flame-generated soot particles from two different fuels, benzene (B) and ethylene (E), at different ageing conditions, were analysed to assess their morphological and structural features. Samples were collected at 6, 10 and 14 mm from the nozzle location. Traditional 2D transmission electron microscopy (TEM) and a novel 3D TEM were used to investigate morphology variations. High-resolution TEM (HRTEM) was used to capture structural characteristics. Samples were then placed on lacey carbon microgrids. A field emission gun TEM was used to capture images of the agglomerates. Tilt series of ±60 degrees were acquired at 1-degree steps to perform the 3D reconstruction. IMOD software and backwards projection were used to reconstruct the tomogram from the tilt series. The 2D analysis revealed that soot particles’ agglomerations for both fuels change from a bundle to a chain-like structure as they “age”, i.e., extracted at a higher “flame height”. In B, the primary particle diameter increases as they get “older,” whereas in E, the opposite happens, and overall, E particles are bigger than B ones. The nanostructure presents ordered regions with parallel-stacked layers of carbon lamellae. This is more evident in the aged soot samples, with the difference that in E a thick amorphous layer is present at the edge of the particles, which is not observable for B. A nanostructure analysis suggests a trend of increasing fringes length as the soot ages, going from 1.04 nm of B6 to 1.22 nm of B10 to 1.05 nm of B14 and from 1.139 nm of E6 to 1.20 nm of E14 (±0.02 nm). The tortuosity does not vary greatly across all the samples, ranging between 1.132 and 1.149 (±0.004). Separation is also quite similar everywhere, with 0.404 nm of B6, 0.392 nm of B10, 0.399 nm of B14, 0.397 nm of E6 and 0.396 nm of E14 (±0.002 nm). Ring structures and particle overlaps, two examples of geometrical characteristics concealed in 2D, can be seen in the 3D reconstructions. Furthermore, the comparison between 3D and 2D volume and surface area raises questions about the reliability of those parameters as derived from 2D measurements. This study advances knowledge of how soot structure can be affected by the fuel type and emphasises the significance of how soot is investigated.

Host-Guest Symmetry Matching in Two Crystalline Magnesium Sulfate Oxalates Obtained Via a Solvent-Free Route.

The combination of π-conjugated oxalate anion with sulfate group has been explored in the solvent-free synthesis of two new magnesium sulfate oxalates. One of them has a layered structure crystallized in the noncentrosymmetric space group Ia, while the other has a chainlike structure crystallized in the centrosymmetric space group P21/c. The noncentrosymmetric solid has a wide optical bandgap and exhibits a moderate second-harmonic-generation response. Density functional theory calculations were carried out to disclose the origin of its second-order nonlinear-optical response.

Facile fabrication of Zr-based metal–organic framework/Ketjen black-carbon nanotubes composite sensor for highly sensitive detection of methyl parathion

A novel methyl parathion (MP) electrochemical sensor was fabricated from the multifunctional composite of Zr-based metal–organic framework (UiO-66) and Ketjen black-carbon nanotubes (KB-CNTs), which achieved the sensitive detection of MP in food samples. For the UiO-66/KB-CNTs composite, Zr-based UiO-66 with Zr-OH groups possessed good affinity for phosphate groups on methyl parathion molecules, which enhanced the selective recognition and enrichment capability towards MP, and KB-CNTs possessed three-dimensional interconnected carbon conductive network with synergistic point-line carbon conductive contact, which showed excellent electrical conductivity. Moreover, KB with pearl chain-like structure and more conductive contact points realized the full contact between KB-CNTs and UiO-66 with Zr-OH groups. The fabricated UiO-66/KB-CNTs/GCE sensor showed good MP detection performance with low limit of detection of 1.53 nM in linear MP concentration range of 0.005–12 µM. Moreover, the fabricated sensor showed good repeatability, reproducibility, and selectivity. A good practical feasibility can be achieved at the UiO-66/KB-CNTs/GCE sensor for the detection of MP in grape juice and apple juice samples (Recovery rate: 96.14–102.93, relative standard deviation: 2.17%-4.95%).

One-Dimensional Chiral Copper Iodide Chain-Like Structure Cu4 I4 (R/S-3-quinuclidinol)3 with Near-Unity Photoluminescence Quantum Yield and Efficient Circularly Polarized Luminescence.

Chiral organic-inorganic hybrid metal halide materials have shown great potential for circularly polarized luminescence (CPL) related applications for their tunable structures and efficient emissions. Here, this work combines the highly emissive Cu4 I4 cubane cluster with chiral organic ligand R/S-3-quinuclidinol, to construct a new type of 1D Cu-I chains, namely Cu4 I4 (R/S-3-quinuclidinol)3 , crystallizing in noncentrosymmetric monoclinic P21 space group. These enantiomorphic hybrids exhibit long-term stability and show bright yellow emission with a photoluminescence quantum yield (PLQY) close to 100%. Due to the successful chirality transfer from the chiral ligands to the inorganic backbone, the enantiomers show intriguing chiroptical properties, such as circular dichroism (CD) and CPL. The CPL dissymmetry factor (glum ) is measured to be ≈4×10-3 . Time-resolved photoluminescence (PL) measurements show long averaged decay lifetime up to 10 µs. The structural details within the Cu4 I4 reveal the chiral nature of these basic building units, which are significantly different than in the achiral case. This discovery provides new structural insights for the design of high performance CPL materials and their applications in light emitting devices.

Using PCL oligomers to study the differences in melting behavior between polymers and small molecules crystals

Polymer crystals usually show a completely different melting behavior than small molecules. Instead of starting from the crystal growth front, the lamellar crystals within polymer spherulites always experience a successive thickening process upon heating before they simultaneously melt. However, a systematic comparative study of the different melting behavior of crystals formed by small and large polymer chains is still scarce. In this work, two PCL oligomers with similar molecular weight are selected to study their crystallization and melting behavior. The defect-free oligomer (PCL2.4) exhibits a similar melting behavior as polymeric crystals (where spherulites melt simultaneously). In contrast, the other oligomer (PCL2.0) with a mid-chain defect shows prominent surface melting starting at the spherulite growth front. SAXS, SSA thermal fractionation, and flash DSC results confirm that an extended chain-like crystal structure could form at relatively high crystallization temperatures. According to the Gibbs-Thomson equation, the melting temperature of PCL2.0 crystals at the spherulite growth front is relatively lower than in the inner part due to different surface free energies. On the other hand, the thermal stability of PCL2.4 is enhanced due to melting and recrystallization during heating, and the spherulites show identical melting points and lamellar thicknesses at their growth front centers.

Distributed Eco-Driving Control of a Platoon of Electric Vehicles Through Riccati Recursion

This paper presents a distributed optimization procedure for the cooperative eco-driving control problem of a platoon of electric vehicles subject to safety and travel time constraints. Individual optimal trajectories are generated for each platoon member to account for heterogeneous vehicles and for the road slope. By rearranging the problem variables, the Riccati recursion can be applied along the chain-like structure of the platoon and be used to solve the problem by repeatedly transmitting information up and down the platoon. Since each vehicle is only responsible for its own part of the computations, the proposed control strategy is privacy-preserving and could therefore be deployed by any group of vehicles to form a platoon spontaneously while driving. The energy efficiency of this control strategy is evaluated in numerical experiments for platoons of electric trucks with different masses and rated motor powers.

Rheological and mechanical properties of 3D printable alkali-activated slag mixtures with addition of nano clay

Alkali-activated slag mixture (AAS) is seen as a prospective option to replace Portland cement for three-dimensional (3D) printing to reduce carbon emission. This paper investigates the use of nano clay and adjusting SiO2/Na2O (Ms value) of an alkaline solution to meet the demands for the additive manufacturing process, such as pumpability and buildability. Results showed that the use of nano clay can considerably improve the structural build-up of AAS mixtures. The dynamic and static yield stress of AAS mixtures declined as Ms value of the activator increased. In terms of mechanical properties, the compressive strength increased with an increase of Ms value, while the flexural strength decreased slightly as Ms value increased. A higher Ms value can result in a lower porosity, but more micro-cracks. The mixture with Ms value of 0.8 and 1% nano clay addition was found to be the most suitable for 3D printing as it had greater buildability during printing with less bottom deformation, and had higher strength and lower porosity in the later stages. The main reaction product for the AAS mixture is found to be the C-A-S-H gel with a chain-like structure.

A Comparative Thermal and Economic Investigation of Similar Shell & Tube and Plate Heat Exchangers with Low Concentration Ag-H2O Nanofluid

Plate Heat Exchanger (PHE) and Shell and Tube Heat Exchanger (STHE) with identical heat transfer areas and material characteristics are proposed and a comparative thermal and economic comparative analysis is carried out on both exchangers. Ag-water nanofluid is used at low concentrations (0, 2.5, 5, 10 mg/L), flow rates (2, 5, and 8 L/min), and inlet temperatures (36, 46, and 56 °C) as hot flow and the heat transfer coefficient (U), electrical power consumption of the pump, and costs per unit of average U value are considered as the calculated parameters for each heat exchanger in co-current and counter-current flows. The results revealed that PHE generates a higher U value compared to the STHE under different Ag-water nanofluid concentrations. This is due to the existence of grooves on the plates of PHE which generates turbulent flow. The impact of nanofluid concentration on U is negligible for lower concentrations in both PHE and STHE. It is also found that the nanofluid flow rate has the highest impact on the U value, just like conventional fluid. Besides, even though counter-current flow increases the U values for both PHE and STHE, the flow pattern has a higher impact on the U value of PHE than that of STHE. For both PHE and STHE, increasing the nanofluid flow rate enhances the amount of U. However, the effect of flow rate on the U value of PHE is greater than that of the STHE. It is also shown that throughout the entire experimental temperature domain, PHE has had higher performance than STHE, and as the fluid temperature increased from 36 to 56 °C, there was a slight increase in the overall heat transfer of both PHE and STHE. Furthermore, for the same flow rate, both PHE and STHE had almost the same pump power consumption, and increasing the nanofluid flow rate from 2 L/min to 8 L/min promoted the electrical power consumption of the pump. Finally, we found that the costs per unit of heat transfer coefficient for PHE are significantly lower than STHE. The presented results also indicated that using a vortex generator at the inlet of STHE tubes, to form turbulent flow, increases the U values of STHE for both co-current and counter-current flows but these U values are lower than the corresponding U values of PHE. Small plates gap in PHE structure cause higher fluid flow velocities and create a chain-like structure of nanoparticles (NPs) between PHE’s plates (especially at higher nanofluids concentrations).

Network structure of response to freeze-thaw cycles in egg white protein gels filled with emulsion: Digestive kinetics regulated by the state of water and embedded oil

In this paper, we focused on the effects of freeze-thaw treatment on the network structure of egg white protein (EWP) emulsion-filled gel (EFG). The freeze-thaw stability of EFG based on egg white protein was analyzed in terms of microstructure, digestive dynamics and processing properties in this work. The results showed that the initial spatial distribution of oil droplets and fine network of gel were damaged during freeze-thaw cycles observed by confocal laser scanning microscopy (CLSM). These phenomena led to the rising of swelling ratio (from 9.882% ± 0.535%–34.985% ± 1.843%) and the change of acid uptake process, which affected the pH value and pepsin activity inside gel. The effect of freeze-thaw cycles on amino acids release during digestion was evaluated by the model of digestive kinetics. Meanwhile, the characteristics of emulsion and gel matrix were detected, illustrating the effect of the ions and percentage of oil on gel subjected to freezing. With the repeats of freeze-thaw treatment, the initial gel network was reorganized for the thicker chain-like structure with higher cohesiveness (from 0.44 ± 0.014 to 0.75 ± 0.041), while ions could be used as stabilizer in frozen. Furthermore, the lower relaxation time proved the improved stability caused by ions, which resulted from the enhanced limitation of network structure to fillings. These findings provided valuable information on the relationship between the freeze-thaw stability of emulsion-filled gel and in vitro digestion, with a view to broader application in the direction of future fat replacement. • The well-distributed emulsion in gel would flocculate after freeze-thaw cycles. • Oil phase in gel promoted the structural changes of EFG during freeze-thaw cycles. • Freeze-thaw treatment slowed release of amino acid during the digestion of EFG. • LF-NMR proved the damage of bond between water and gel matrix due to freezing. • The properties of EFG after freezing were maintained by ions-induced firm structure.

Methylamine Magnesium Borohydrides as Electrolytes for All-Solid-State Magnesium Batteries

Solid-state magnesium electrolytes may pave the way for novel types of rechargeable, sustainable, and cheap batteries with high volumetric and gravimetric capacities. There are, however, currently no solid-state magnesium electrolytes that fulfill the requirements for solid-state battery applications. Here, we present the synthesis, structure, and properties of six new methylamine magnesium borohydride compounds, α- and β-Mg(BH4)2·6CH3NH2, Mg(BH4)2·3CH3NH2, and α-, α′- and β-Mg(BH4)2·CH3NH2. The β-Mg(BH4)2·CH3NH2 polymorph displays a record high Mg2+ ionic conductivity of σ(Mg2+) = 1.50 × 10–4 S cm–1 at room temperature. The high Mg2+ conductivity of β-Mg(BH4)·CH3NH2 is facilitated by a one-dimensional chain-like structure interconnected by weak dihydrogen bonds and dispersion interactions, forming a migration pathway across the chains. The oxidative stability of Mg(BH4)2·CH3NH2 is ∼1.2 V vs Mg/Mg2+, and the reversible plating and stripping were confirmed by cyclic voltammetry and symmetric cell cycling, revealing high stability toward magnesium electrodes for at least 50 cycles at 60 °C.

Experimental investigation of wall-to-bed heat transfer of carbon nanotubes in a fluidized bed

Wall-to-bed heat transfer characteristics of multi-walled carbon nanotubes (MWCNTs) were determined in a fluidized bed (0.15 m i.d. by 2.0 m height). Two types of CNTs with different nanotube shapes were used: entangled CNTs (ENCNTs) and vertically aligned CNTs (VACNTs). The flow regimes of MWCNTs were identified as fixed bed, partial fluidization, and complete fluidization from the pressure drop across the bed (ΔP) with gas velocity. In the partial fluidization regime, different gas channeling phenomena occurred depending on the nanotubes shape on the CNT particles, affecting the bed hydrodynamics. The instantaneous surface temperature (Tsi) of the heat transfer probe decreased and its fluctuation increased with the gas velocity proportional to the bed particle movement near the wall. Fluctuations in ΔP and Tsi at the wall had a strong correlation for all MWCNTs, and the wall-to-bed heat transfer was greatly influenced by the movement of particles induced by a preferential flow path of gas in the bed such as gas channeling and bubbles. Fluctuations in ΔP and Tsi of VACNTs were considerably lower than those of ENCNTs because of the formation of a chain-like network structure of the bed. The wall-to-bed heat transfer coefficient (hw) in the CNT fixed bed was considerably higher than that of comparable particles owing to their high conductivity. The average hw of the CNTs increased with gas velocity, and the rate of increase depended on the shape of the nanotubes. The hw of the VACNTs which form easily tangled agglomerates by many long nanotubes, was lower than that of the ENCNTs. Correlations for hw prediction were firstly developed for the partial and complete fluidization regimes. The predicted values well accorded with the experimental results, and the hw changes of the MWCNTs with gas velocity could be predicted well based on the proposed correlation and two-phase model of the bubbling fluidized bed.

Numerical Study on the Magnetization Characteristics of Chainlike Magnetic Nanoparticles

This work investigated chainlike magnetic nanoparticles (CMNPs), which are a type of magnetic nanoparticle (MNP) with a dipole–dipole interaction in which individual nanoparticles are connected to form a chainlike structure. We numerically analyzed the ac magnetization characteristics of the CMNP and the single-core MNP (SMNP) using the Landau–Lifshitz–Gilbert equation. Owing to the magnetic dipole–dipole interaction, the magnetization of the CMNP is approximately 10 times that of the SMNP under a certain excitation field. MNPs with a chainlike structure are thus expected to have enhanced magnetization characteristics and better performance in medical applications. Additionally, it was found that stronger magnetization can be expected from a CMNP connecting 10 or more magnetic cores with a size of approximately 10–12 nm.

Novel nitrogen-rich lanthanum nitrides induced by the ligand effect under pressure.

N-rich La-N compounds have been studied by first-principles calculations in this work. We identified nine unknown polynitrides, which reveals that the miraculous ligand effect of La plays an important role in the electronic properties and hybridization of nitrogen atoms. Unique tri-coordination atoms with alternate sp2 and sp3 hybridizations are formed in the N18 ring of LaN8. The ligand effect of La induces a novel 1-D chain-like N10 cage polymeric structure in LaN10 and stabilizes it under mild pressure (25 GPa). Moreover, the ligand effect of the introduced La atom on the N10 cage has been clarified by the analysis of the structural evolution behavior from I4̄3m-N10 to Imm2-LaN10. In addition, Imm2-LaN10 with excellent energy (4.56 kJ g-1) and explosive performance (Vd = 16.88 km s-1, Vp = 1887.53 kbar) is a good energetic material candidate.

Difficult-to-measure integration measurement method for designing processes in a chain-like structure of conflicted cells in a supply chain

The paper presents an approach for integrating conflicted cells in a chain-like structure based on a measurement of the level of integration of this structure. The authors’ prior experience suggests an assumption that conflicts always arise when cells are connected by a flow of materials, information, and money, although at different intensity levels. Usually, the intensity levels of said conflicts depend on the cooperation culture within a supply chain. This is a highly multidi-mensional problem, reflected by the literature referred to in this paper and related to this subject matter. The proposed approach treats technological processes between conflicted cells as an area of potential integration of these cells. Then, the integration becomes a problem of selecting the appropriate variant of realizing a technological process conducted in an area common for potentially conflicted cells of a company. The same approach may be used for cells belonging to separate production and distribution companies operating within a mutual supply chain. The paper proposes a method for measuring the integration level of neighboring cells, as a difficult-to-measure feature, by deter-mining an integration loss index. Also, the paper presents a multi-criteria method based on the fuzzy set theory for selecting a preferred variant of a technological process. A presented example uses this method in a supply chain to maximize the integration level between Shipping and Recipient cells/links. It has been assumed that the preferred realization variant of the flow process will be based on the following criteria: 1) shipping cost; 2) shipping quality; 3) shipping time. Also, an algorithm is shown for applying the presented methodology, which is helpful for managers interested in increasing the integration level of a supply chain. The methodology allows for increasing the integrity of conflicted cells both in newly designed supply chains as well as in existing ones when remodeled or reorganized. Moreover, the paper indicates some problems associated with the efficient implementation of the proposed method.

Micelle-like Nanoassemblies of Short Peptides Create Antimicrobial Selectivity in a Conventional Antifungal Drug

The discovery of novel antibacterial drugs against infectious diseases has decreased over the past few decades because of their poor cost performance. In this study, we report that the nanoassembly of a short-peptide hydrogelator (P1) endowed novel antifungal selectivity to a conventional antifungal drug, amphotericin B (AmB), which expands its application spectrum. Clinical use of AmB is limited because of poor water solubility and poor selectivity in its toxicity, which often causes harmful effects on tissues. P1 was the low-molecular-weight hydrogelator (LMWHg) that showed low cytotoxicity and was enzymatically degraded. In general, an LMWHg entraps foreign hydrophobic molecules inside the hydrophobic space in the self-assembled body. P1 successfully solubilized AmB in water as a form of a nanocomplex (NC) that had a chain-like structure. The NCs showed remarkably low toxicity toward Saccharomyces cerevisiae as a model fungus when compared with free AmB, meaning that P1 suppressed the antifungal activity of AmB via coassembly. The suppressed antifungal activity of AmB recovered when P1 in the NCs was degraded by a protease to liberate AmB from the coassembly with P1. P1 at a high concentration formed a hydrogel incorporating AmB (AmB-P1 gel), in which the antifungal activity of AmB was suppressed as well as that in the NC. The coassembly with AmB affected the morphology of the P1 self-assembly. While S. cerevisiae that did not secrete proteases formed a colony on the AmB-P1 gel, Aspergillus oryzae that secreted proteases did not grow on the AmB-P1 gel at all, resulting in the selective killing of the fungus. Because some of malignant, infectious fungi secrete proteases, the coassembly strategy of conventional antifungal drugs with self-assembling molecules should lead to “drug repositioning” of approved drugs in the health and medical fields.

Two Novel Pyrene Tetra-Sulfonate Europium Coordination Polymers: Structure Formation Mechanism Analysis and Sequential Modulation Strategy

For the purpose of broadening the understanding of the sulfonic acid coordination mechanism, a coordination system consisting of Eu(III) ion and 1,3,6,8-pyrene tetra-sulfonate (1,3,6,8-PTS) ligand was chosen as the typical research object. By step regulating the volume ratio of mixed solvents and the molar ratio of metal salts to ligands, two pyrene tetra-sulfonate europium coordination polymers, Eu6(μ6-O)(μ3-OH)8(NO3)6(1,3,6,8-H2PTS)(H2O)10 (1) and Eu(NO3)(1,3,6,8-PTS)0.5(H2O)3·0.5bipy (2), were obtained in sequence. Compound 1 shows a 1D chain-like structure interconnected with 1,3,6,8-PTS bridging ligands and rare [Eu6(μ6-O)(μ3-OH)8(NO3)6]2+ cluster nodes, while compound 2 shows a 2D layered structure. Further structural comparison with compound Eu(1,3,6,8-PTS)(H2O)7·4H2O·Hbipy (EuPTSbp-1) was discussed in detail and the structure formation mechanism was analyzed. On this basis, a sequential modulation strategy for pyrene tetra-sulfonate europium coordination polymers was proposed.

Two Sm/Hg and Gd/Hg bimetallic complexes: Reasonable synthesis, structure and properties

Two new lanthanide mercury isonicotinic acid complexes [Sm(IA)3(H2O)2]2n2n(HgCl4)·3nCl·7nH3O·2nH2O (1; IA = isonicotinic acid anion) and {[Gd(IA)3(H3O)2]2(Hg3Br8)}n(nHgBr2)·2nNO3 (2; IA = isonicotinic acid anion) were synthesized. The crystal structures are characterized by single-crystal X-ray diffraction. Complex 1 is characteristic of a one-dimensional (1-D) chain-like structure, while complex 2 features a two-dimensional (2-D) layer-like structure. The photophysical properties of in solid state have been investigated by photoluminescence and solid-state UV/Vis diffuse reflectance spectra. The photoluminescence reveals that they display red or ultraviolet photoluminescence and, the photoluminescence are resulted from the characteristic emissions of the 4f electron intrashell transitions of the 4G5/2 → 6HJ (J = 7/2, 9/2 and 11/2 of the Sm3+ ions in 1) and the 6P7/2 → 8S7/2 of the Gd3+ ions in 2. The CIE (Commission Internationale de I'Éclairage) chromaticity coordinates for 1 are (0.6597, 0.34) and its CCT (Correlated Color Temperature) is 12853 K. The solid-state UV/Vis diffuse reflectance spectra reveal that the semiconductor bandgaps are 5.01 eV and 2.77 eV.