The 50 most-cited articles in Inorganic Chemistry, 2018

Recently simulation groups have reported the lanthanide series elements as the dopants that have the strongest effect on the stabilization of the ferroelectric non-centrosymmetric orthorhombic phase in hafnium oxide. This finding confirms experimental results for lanthanum and gadolinium showing the highest remanent polarization values of all hafnia-based ferroelectric films until now. However, no comprehensive overview that links structural properties to the electrical performance of the films in detail is available for lanthanide-doped hafnia. La:HfO 2 appears to be a material with a broad window of process parameters, and accordingly, by optimization of the La content in the layer, it is possible to improve the performance of the material significantly. Variations of the La concentration leads to changes in the crystallographic structure in the bulk of the films and at the interfaces to the electrode materials, which impacts the spontaneous polarization, internal bias fields, and with this the field cycling behavior of the capacitor structure. Characterization results are…

Natural enzyme mimetics with high catalytic activity at nearly neutral pH values are highly desired for their applications in biological systems. Herein for the first time a stable MOF, namely MOF-808, has been shown to possess high intrinsic peroxidase-like catalytic activity under acidic, neutral, and alkaline conditions. As a novel peroxidase mimetic, MOF-808 can effectively catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine when H 2 O 2 serves as oxidant, accompanied by a significant color variation in the solution. The catalytic activity and the color variation were greatly dependent on H 2 O 2 concentration, and thus MOF-808 can be applied to the colorimetric sensing of H 2 O 2 . The H 2 O 2 detection limit is 4.5 μM, and the linear range is 10 μM to 15 mM. In view of the significant inhibition effect produced by ascorbic acid, a facile and sensitive approach for colorimetric sensing of ascorbic acid was successfully established. The AA detection limit is 15 μM, and the linear range is 30–1030 μM. Further investigation found that the catalytic activity of MOF-808 could…

Abstract High-entropy compounds with compositional complexity can be designed as new thermoelectric materials. Here a data-driven model was developed, which chose suitable elements to reduce the enthalpy of formation and hence to increase the chance of single phase formation. Using this model, two high-entropy sulfides were designed, metallic Cu5SnMgGeZnS9 and semiconducting Cu3SnMgInZnS7. They were then successfully fabricated as single-phase dense ceramics with homogeneously distributed cations, and their phase stability and atomic local structures were investigated using density functional theory calculations. Finally, a zT value of 0.58 at 773 K was obtained for Cu5Sn1.2MgGeZnS9, where additional Sn was used to tune the carrier concentration. This work provides a simple approach to find new high-entropy functional materials in the largely unexplored multielement chemical space.

A Zn(II)-based fluorescent metal-organic framework (MOF) was synthesized and applied as a highly sensitive and quickly responsive chemical sensor for antibiotic detection in simulated wastewater. The fluorescent chemical sensor, denoted FCS-1, exhibited enhanced fluorescence derived from its highly ordered, 3D MOF structure as well as excellent water stability in the practical pH range of simulated antibiotic wastewater (pH = 3.0-9.0). Remarkably, FCS-1 was able to effectively detect a series of sulfonamide antibiotics via photoinduced electron transfer that caused detectable fluorescence quenching, with fairly low detection limits. Two influences impacting measurements related to wastewater treatment and water quality monitoring, the presence of heavy-metal ions and the pH of solutions, were studied in terms of fluorescence quenching, which was nearly unaffected in sulfonamide-antibiotic detection. Additionally, the effective detection of sulfonamide antibiotics was rationalized by the theoretical computation of the energy bands of sulfonamide antibiotics, which revealed a good…

The stability issue of organometallic halide perovskites remains a great challenge for future research as to their applicability in different functional material fields. Herein, a novel and facile two-step synthesis procedure is reported for encapsulation of CH 3 NH 3 PbBr 3 perovskite quantum dots (QDs) in MOF-5 microcrystals, where PbBr 2 and CH 3 NH 3 Br precursors are added stepwise to fabricate stable CH 3 NH 3 PbBr 3 @MOF-5 composites. In comparison to CH 3 NH 3 PbBr 3 QDs, CH 3 NH 3 PbBr 3 @MOF-5 composites exhibited highly improved water resistance and thermal stability, as well as better pH adaptability over a wide range. Luminescent investigations demonstrate that CH 3 NH 3 PbBr 3 @MOF-5 composites not only featured excellent sensing properties with respect to temperature changes from 30 to 230 °C but also exhibited significant selective luminescent response to several different metal ions in aqueous solution. These outstanding characteristics indicate that the stable CH 3 NH 3 PbBr 3 @MOF-5 composites are potentially interesting for application in fluorescence sensors or…

Mn 4+ -doped Y 2 MgTiO 6 phosphors are synthesized by the traditional solid-state method. Powder X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectrometer are employed to characterize the samples. The Mn 4+ -doped Y 2 MgTiO 6 phosphors show the far-red emission at ∼715 nm, which is assigned to the 2 E g → 4 A 2 spin-forbidden transition of Mn 4+ . The temperature-dependent luminescent dynamics of Mn 4+ is described by a complete model associated with electron–lattice interaction and spin–orbit coupling. The noncontact optical thermometry of Y 2 MgTiO 6:Mn 4+ is discussed based on the fluorescence intensity ratio of thermally coupled anti-Stokes and Stokes sidebands of the efficient ∼715 nm far-red emission in the temperature range of 10–513 K. The maximum sensor sensitivity of Y 2 MgTiO 6:Mn 4+ is determined to be as high as 0.001 42 K –1 at 153 K, which demonstrates potential applications for the optical thermometry at low-temperature environments.

Photocatalytic generation of H 2 and O 2 by water splitting remains a great challenge for clean and sustainable energy. Taking into the consideration promising heterojunction photocatalysts, analogous energy issues have been mitigated to a meaningful extent. Herein, we have architectured a highly efficient bifunctional heterojunction material, i.e., p-type Co(OH) 2 platelets with an n-type ZnCr layered double hydroxide (LDH) by an ultrasonication method. Primarily, the Mott–Schottky measurements confirmed the n- and p-type semiconductive properties of LDH and CH material, respectively, with the construction of a p–n heterojunction. The high resolution transmission electron microscopy results suggest that surface modification of ZnCr LDH by Co(OH) 2 hexagonal platelets could form a fabulous p–n interfacial region that significantly decreases the energy barrier for O 2 and H 2 production by effectively separating and transporting photoinduced charge carriers, leading to enhanced photoreactivity. A deep investigation into the mechanism shows that a 30 wt % Co(OH) 2 -modified ZnCr LDH…

A high-entropy alloy (HEA) of HfNbTiVZr was synthesized using an arc furnace followed by ball milling. The hydrogen absorption mechanism was studied by in situ X-ray diffraction at different temperatures and by in situ and ex situ neutron diffraction experiments. The body centered cubic (BCC) metal phase undergoes a phase transformation to a body centered tetragonal (BCT) hydride phase with hydrogen occupying both tetrahedral and octahedral interstitial sites in the structure. Hydrogen cycling of the alloy at 500 °C is stable. The large lattice strain in the HEA seems favorable for absorption in both octahedral and tetrahedral sites. HEAs therefore have potential as hydrogen storage materials because of favorable absorption in all interstitial sites within the structure.

In the present study, Tl 4 CdI 6 nanostructures were synthesized via a facile sonochemical method. The effect of molar ratio of TlI to CdI 2, reaction time, power of sonication, and the capping agents was investigated on morphology, size, and purity of the products. The as-prepared nanomaterials were characterized by X-ray diffraction, X-ray energy dispersive spectroscopy, field emission scanning, transmission electron microscopy, and Raman spectroscopy. The optical property of Tl 4 CdI 6 nanoparticles was investigated by ultraviolet–visible spectroscopy (UV–vis), and the band gap was estimated about 2.82 eV. The photocatalytic behaviors of the nanoparticles were investigated by removal and degradation of different organic dyes under the UV irradiation. The results indicated a highest degradation for acid black 1 of 85.7% in 110 min. This sample was selected as an optimum sample for photocatalytic application.

Zirconium-based metal-organic frameworks were recently investigated as catalysts for degradation of organophosphate toxic compounds, such as pesticides or chemical warfare agents. The most utilized UiO-66 is considered as a stable material for these applications in an aqueous environment. However, the presented results indicate that the properties of UiO-66 are changing considerably in aqueous media under common conditions used for organophosphate degradations, and therefore its catalytic activity is not related to the number of structural defects created during the material synthesis. We delineate the stability of UiO-66 in water of various pHs, the in situ formation of new catalytic sites, and the correlation of these two parameters with the degradation rate of a model organophosphate pollutant, dimethyl-4-nitrophenyl phosphate (methyl-paraoxon). The stability was quantified using high-performance liquid chromatography (HPLC) by measuring the amounts of leached terephthalic acid, the linker of UiO-66, and monocarboxylic acids, the modulators bound at UiO-66 defects. We demonstrate…

In this work, a bio-metal-organic framework (Bio-MOF) coated with a monodispersed layer of chitosan (CS; CS/Bio-MOF) was synthesized and applied as a pH-responsive and target-selective system for delivery of doxorubicin (DOX) in the treatment of breast cancer. The efficiency of the nanocarrier in loading and releasing DOX was assessed at different pH levels. To monitor the in vitro drug release behavior of the drug-loaded carrier, the carrier was immersed in a phosphate buffered saline solution (PBS, pH 7.4) at 37 °C. According to the observations, the nanocarrier presents a slow and continuous release profile as well as a noticeable drug loading capacity. In addition, the carrier demonstrates a pH-responsive and target-selective behavior by releasing a high amount of DOX at pH 6.8, which is indicative of tumor cells and inflamed tissues and releasing a substantially lower amount of DOX at higher pH values. In addition, the results indicated that pH is effective on DOX uptake by CS/Bio-MOF. A 3.6 mg amount of DOX was loaded into 10 mg of CS/Bio-MOF, resulting in a 21.7% removal at…

Upconversion (UC) based luminescent materials have promising applications in noncontact temperature sensors. How to improve the sensitivity is one main object at present. This work presented several strategies for optical temperature sensing based on UC spectra of the Y 2 WO 6:Yb 3+ -Er 3+ /Ho 3+ /Tm 3+ phosphors. The improvement for the relative ( S R ) and absolute ( S A ) sensitivities were discussed by using a fluorescence intensity ratio technique. It includes thermally coupled levels (TCLs) and non-TCLs. It was proposed that a piecewise expression could be employed to achieve high S A value for TCLs. However, improving the S R value is limited for TCLs. With regard to the non-TCLs, S R and S A are not restricted, but not easy to be improved synchronously. On the other hand, the morphology and UC spectra of the samples were also studied. The above investigation could be instructive to develop new luminescent materials with high sensitivity.

A series of 12-connected lanthanide cluster based metal–organic frameworks (MOFs) have been constructed by [Ln 6 (μ 3 -OH) 8 (COO−) 12 ] secondary building units (SBUs) and 2-aminobenzenedicarboxylate (BDC-NH 2 ) ligands. These obtained materials exhibit high chemical stability and generic thermal stability, especially in acidic and basic conditions. They also present commendable CO 2 adsorption capacity, and Yb-BDC-NH 2 was further confirmed by a breakthrough experiment under both dry and wet conditions. Moreover, these materials possess both Lewis acid and Brønsted base sites that can catalyze one-pot tandem deacetalization–Knoevenagel condensation reactions.

Photocatalytic hydrogen (H 2 ) generation through water splitting has attracted substantial attention as a clean and renewable energy generation process that has enormous potential in converting solar-to-chemical energy using suitable photocatalysts. The major bottleneck in the development of semiconductor-based photocatalysts lies in poor light absorption and fast recombination of photogenerated electron–hole pairs. Herein we report the synthesis of CuS/TiO 2 heterostructured nanocomposites with varied TiO 2 contents via simple hydrothermal and solution-based process. The morphology, crystal structure, composition, and optical properties of the as-synthesized CuS/TiO 2 hybrids are evaluated in detail. Controlling the CuS/TiO 2 ratio to an optimum value leads to the highest photocatalytic H 2 production rate of 1262 μmol h –1 g –1, which is 9.7 and 9.3 times higher than that of pristine TiO 2 nanospindles and CuS nanoflakes under irradiation, respectively. The enhancement in the H 2 evolution rate is attributed to increased light absorption and efficient charge separation with an…

Noncentrosymmetric (NCS) fluorooxoborates are one of the most attractive systems for discovering the new deep-ultraviolet (DUV) nonlinear optical (NLO) materials. Here, we report the formation, crystal structure, and optical properties of a new NCS alkaline earth fluorooxoborate: CaB 5 O 7 F 3 . It exhibits excellent NLO performances including large band gap (8.75 eV), large second harmonic generation intensity (2 × KH 2 PO 4 and 0.4 × β-BaB 2 O 4, under 1064 and 532 nm radiation, respectively), and moderate birefringence (0.07 @ 1064 nm) that enables frequency doubling down to 183 nm. It demonstrates that CaB 5 O 7 F 3 is a promising DUV NLO material.

In this article we synthesized a series of phosphors K 2 MgGeO 4:Bi 3+ with high brightness for white light-emitting diodes (WLEDs) conversion and investigated their crystal structures and luminescence properties using powder X-ray diffraction, diffuse reflectance spectra, X-ray photoelectron spectroscopy, photoluminescence spectra, and absolute quantum efficiency. K 2 MgGeO 4:Bi 3+ phosphor exhibits intense absorption in near-UV area and presents a broad asymmetric emission band with the main peak located at 614 nm, which was ascribed to the 3 P 1 → 1 S 0 transition of Bi 3+ . The absolute quantum efficiency of the K 2 MgGeO 4:0.01Bi 3+ phosphor was measured to be 66.6%. Also, this orange emission with color chromaticity coordinates of (0.4989, 0.4400) has an excellent resistance to thermal quenching: its integrated intensity at 393 K still maintained ∼85% of the one at room temperature. The WLEDs devices with R a = 93.8 were fabricated by employing K 2 MgGeO 4:0.01Bi 3+ as an orange phosphor, which contains abundant red light component in its emission spectrum. The excellent…

Abstract In2Se3 has been known for over 100 years and recently attracted interest as a promising candidate for a variety of applications, such as solar cells, photodiodes, and phase-change memories. Despite the broad concern for possible uses, its polymorphism and structure are poorly characterized. By combining X-ray diffraction, transmission electron microscopy, and quantum-chemical calculations, we present here the crystal structures of two layered room-temperature polytypes: 3R and 2H In2Se3. Both polymorphs are stacking variants of the same Se–In–Se–In–Se layers comprising two coordination environments for the In atoms, one tetrahedral and one octahedral. By using chemical-bonding analysis, we look at the different In positions in α-In2Se3 and compare them to those in the metastable β-phase.

A systematic study of the performance of several density functional methodologies to study spin-crossover (SCO) on first row transition metal complexes is reported. All functionals have been tested against several mononuclear systems containing first row transition metal complexes and exhibiting spin-crossover. Among the tested functionals, the hybrid meta-GGA functional TPSSh with a triple-ζ basis set including polarization functions on all atoms provides the best results across different metals and oxidation states, and its performance in both predicting the correct ground state and the right energy window for SCO to occur is quite satisfactory. The effect of some additional contributions, such as zero-point energies, relativistic effects, and intramolecular dispersion interactions, has been analyzed. The reported strategy thus expands the use of the TPSSh functional to other metals and oxidation states other than Fe II, making it the method of choice to study SCO in first row transition metal complexes. Additionally, the presented results validate the potential use of the TPSSh…

The design and synthesis of metal–organic frameworks (MOFs) enclosed with multiple catalytic active sites is favorable for cooperative catalysis, but is is still challenging. Herein, we developed a sequential postsynthetic ionization and metalation strategy to prepare bifunctional multivariate Zr-MOFs incorporating zinc porphyrin and imidazolium functionalities. Using this facile strategy, tetratopic [5,10,15,20-tetrakis(4-carboxyphenyl)porphyrinato]zinc(II) (ZnTCPP) ligands were successfully installed into the cationic Zr-MOF to obtain ZnTCPP⊂(Br – )Etim-UiO-66. These MTV-MOFs, including TCPP⊂Im-UiO-66, TCPP⊂(Br – )Etim-UiO-66, and ZnTCPP⊂(Br – )Etim-UiO-66, were well characterized and used in CO 2 capture and conversion into cyclic carbonate from allyl glycidyl ether and CO 2 under cocatalyst-free and 1 bar CO 2 pressure conditions. It was found that the structural features and CO 2 affinity properties of these MTV-MOFs can be tuned by introducing imidazolium groups or doping zinc sites. Additionally, ZnTCPP⊂(Br – )Etim-UiO-66 exhibited enhanced catalytic activities compared to…

Iron(III) ions play a vital role in living biological systems, while organic pollutants including pesticides and antibiotics pose a great threat to the ecological environment. Effective detection for these species is crucial for human health and environmental protection. In this work, we designed and synthesized a new amino-decorated bridging ligand H 2 APDA and employed it to react with the environmentally friendly Mg(II) ions to construct a novel magnesium luminescent metal–organic framework (Mg-LMOF), namely [Mg 2 (APDA) 2 (H 2 O) 3 ]·5DMA·5H 2 O (Mg-APDA). The as-synthesized Mg-LMOF is a three-dimensional framework with one-dimensional hexagonal channels. These microporous channels are decorated with Lewis-base amino sites and uncoordinated O atoms, which facilitate the Mg-APDA to anchor and recognize various analytes. Mg-APDA can be used as a multiresponsive luminescent sensor to detect Fe(III) ions, pesticides, and antibiotics effectively. To the best of our knowledge, this work represents the first amino-decorated Mg-LMOF as an efficient fluorescent sensor for detecting metal…

A metal–organic framework (MOF)-based highly selective and sensitive probe ( [email protected] ) for the detection of Hg(II) ion has been developed. To the best our knowledge, this is the foremost example of a chemodosimeter-based approach to sense Hg(II) ion using a MOF-based probe. The chemical stability of [email protected] renders the sensitive detection of Hg 2+ ion in an aqueous phase. [email protected] has been found to be selective for Hg(II) ions even in the presence of other metal ions.

Two stable 3D polyoxometalate-based metal–organic frameworks (PMOFs), [Cu I 12 (trz) 8 (H 2 O) 2 ][α-SiW 12 O 40 ]·2H 2 O ( 1 ) and [Cu I 12 (trz) 8 Cl][α-PW 12 O 40 ] ( 2 ) (Htrz = 1- H -1,2,4-triazole) based on Keggin-type POMs were successfully obtained and fully characterized. The basic building units of the two PMOFs are [Cu I 12 (trz) 8 ], but polyoxoanion (POA) template effect leads to different structures and properties: 1 represents an interesting example that [α-SiW 12 O 40 ] 4– locate in the nine-membered Cu-trz rings through Cu···O weak interactions to form a 3D framework, whereas 2 shows a 3D structure constructed from 2D bilayer cationic network [Cu I 12 (trz) 8 Cl] 3+ and [α-PW 12 O 40 ] 3– lying in the adjacent layers via Cu···O weak interactions. PMOF 1 as unusual visible-light photocatalyst exhibit significantly enhanced photocatalytic activity under visible-light and excellent stability during the photocatalysis process for recovering and recycling, as well as photocatalytic hydrogen evolution activity.

High-quality white light-emitting diodes (w-LEDs) are mainly determined by conversion phosphors and the enhancement of cyan component that dominates the high color rendering index. New phosphors (Lu 2 M)(Al 4 Si)O 12:Ce 3+ (M = Mg, Ca, Sr and Ba), showing a cyan-green emission, have been achieved via the co-substitution of Lu 3+ -Al 3+ by M 2+ -Si 4+ pair in Lu 3 Al 5 O 12:Ce 3+ to compensate for the lack of cyan region and avoid using multiple phosphors. The excitation bands of (Lu 2 M)(Al 4 Si)O 12:Ce 3+ (M = Mg, Ca, Sr and Ba) show a red-shift from 434 to 445 nm which is attributed to the larger centroid shift and crystal field splitting. The enhanced structural rigidity associated with the accommodation of larger M 2+ leads to a decreasing Stokes shift and the corresponding blue-shift (533 → 511 nm) in emission spectra, along with an improvement in thermal stability (keeping ∼93% at 150 °C). The cyan-green phosphor Lu 2 BaAl 4 SiO 12:Ce 3+ enables to fabricate a superhigh color rendering w-LED ( R a = 96.6), verifying its superiority and application prospect in high-quality…

The sodium superionic conductor Na 3 PS 4 is known to crystallize in one of two different structural polymorphs at room temperature (i.e., cubic or tetragonal, depending on the synthetic conditions). Experimentally, the cubic structure is known to exhibit a higher ionic conductivity than the tetragonal structure, despite theoretical investigations suggesting that there should be no difference at all. Employing a combination of Rietveld and pair distribution function (PDF) analyses, as well as electrochemical impedance spectroscopy, we investigate the open question of how the crystal structure influences the ionic transport in Na 3 PS 4 . Despite the average structures of Na 3 PS 4 prepared via ball-milling and high-temperature routes being cubic and tetragonal, respectively, the structural analysis by PDF indicates that both compounds are best described by the structural motifs of the tetragonal polymorph on the local scale. Ultimately, the high ionic conductivity of Na 3 PS 4 prepared by the ball-milling approach is confirmed to be independent of the crystal structure. This work…

Fifteen water-soluble rhenium compounds of the general formula [Re(CO) 3 (NN)(PR 3 )] +, where NN is a diimine ligand and PR 3 is 1,3,5-triaza-7-phosphaadamantane (PTA), tris(hydroxymethyl)phosphine (THP), or 1,4-diacetyl-1,3,7-triaza-5-phosphabicylco[3.3.1]nonane (DAPTA), were synthesized and characterized by multinuclear NMR spectroscopy, IR spectroscopy, and X-ray crystallography. The complexes bearing the THP and DAPTA ligands exhibit triplet-based luminescence in air-equilibrated aqueous solutions with quantum yields ranging from 3.4 to 11.5%. Furthermore, the THP and DAPTA complexes undergo photosubstitution of a CO ligand upon irradiation with 365 nm light with quantum yields ranging from 1.1 to 5.5% and sensitize the formation of 1 O 2 with quantum yields as high as 70%. In contrast, all of the complexes bearing the PTA ligand are nonemissive and do not undergo photosubstitution upon irradiation with 365 nm light. These compounds were evaluated as photoactivated anticancer agents in human cervical (HeLa), ovarian (A2780), and cisplatin-resistant ovarian (A2780CP70) cancer…

Classical amino-functionalized Fe-terephthalate metal–organic framework NH 2 -MIL-53(Fe) and its parent framework MIL-53(Fe) were prepared via simple hydrothermal methods. The catalytic performaces of these two Fe-MOFs were explored for the selective oxidation of H 2 S. The physicochemical properties of the fresh and used Fe-MOFs catalysts were investigated by XRD, BET, SEM, FT-IR, CO 2 -TPD, and XPS techniques. It was found that the introduction of amino groups reduces the activation energies for H 2 S oxidation and endows this catalyst surface with moderate basic sites. As a result, the NH 2 -MIL-53(Fe) catalyst displays high H 2 S conversion and near 100% S selectivity in the temperature range of 130–160 °C, outperforming commercial Fe 2 O 3 and activated carbon. Moreover, a plausible reaction route for H 2 S selective oxidation over NH 2 -MIL-53(Fe) is proposed. This work opens up the possibility of utilizing MOFs as efficient catalyst for desulfuration reactions.

One of the major challenges in photodegradation of organic dyes is designing a visible light active and highly efficient photocatalyst that can degrade both cationic and anionic dyes. To design such an ideal catalyst, this work synthesized graphitic–C 3 N 4 @NiAl layered double hydroxide nanocomposites (g-C 3 N 4 @NiAl–LDH NCPs) with various g-C 3 N 4 contents through a convenient and high-yield method. The photocatalytic process was optimized by evaluating the impacts of type of dye (cationic and anionic), photocatalyst dosage, pH, and contact time. According to the results, the photocatalytic performance of g-C 3 N 4 @NiAl–LDH NCPs in degradation of cationic and anionic dyes is more noticeable than the photocatalytic activities of its discrete components. The observed improvement in the photocatalytic performance of the g-C 3 N 4 @NiAl–LDH NCPs can be attributed to the intimacy of their contact interfaces and a synergistic effect between pristine g-C 3 N 4 and NiAl–LDH, which results in effective mass transfer and separation of photogenerated charge carriers. The impact of some…

Supercapacitors are regarded to be highly probable candidates for next-generation energy storage devices. Herein, a bimetallic Co/Ni MOF is used as a sacrificial template through an alkaline hydrolysis and selective oxidation process to prepare an accordion-like ternary NiCo 2 O 4 /β-Ni x Co 1– x (OH) 2 /α-Ni x Co 1– x (OH) 2 composite, which is composed of Co/Ni(OH) 2 nanosheets with large specific surface as the frame and NiCo 2 O 4 nanoparticles with high conductivity as the insertion, for supercapacitor application. This material exhibits both high specific capacitance (1315 F·g –1 at 5 A·g –1 ) and excellent cycle performance (retained 90.7% after 10 000 cycles). This hydrolysis–oxidation process, alkali hydrolysis followed by oxidation with H 2 O 2, offers a novel approach to fabricate the Ni/Co-based electrode materials with enhanced supercapacitor performance.

Due to the enormous demand for effective conversion of solar energy and large-scale hydrogen production, cost-effective and long-lasting photocatalysts are believed to be necessary for global production of sustainable and clean hydrogen fuel. Robust and highly efficient p–n heterojunction photocatalysts have a striking ability to enhance light-harvesting capacity and retard the recombination of photoexcitons. A series of p-MoS 2 /n-CaIn 2 S 4 heterojunction composites with different MoS 2 contents have been synthesized via a facile two-step hydrothermal technique in which rose-like p-MoS 2 nanoflowers are decorated upon n-type cubic CIS microflowers. In the synthesis protocol highly dispersed MoS 2 nanoflowers provided more active edge sites for the growth of c-CIS nuclei, leading to a hierarchical architecture with intimate interfacial contact. The formation of a hierarchical flower-like morphology of the photocatalyst has been established by an HRTEM and FESEM study. Electrochemical characterization, especially the slope of the curve from Mott–Schottky analysis and nature of the…

Non-rare-earth Mn 4+ -doped double-perovskite (Ba 1– x Sr x ) 2 YSbO 6:Mn 4+ red-emitting phosphors with adjustable photoluminescence are fabricated via traditional high-temperature sintering reaction. The structural evolution, variation of Mn 4+ local environment, luminescent properties, and thermal quenching are studied systematically. With elevation of Sr 2+ substituting content, the major diffraction peak moves up to a higher angle gradually. Impressively, with increasing the substitution of Ba 2+ with Sr 2+ cation from 0 to 100%, the emission band shifts to short-wavelength in a systematic way resulting from the higher transition energy from excited states to ground states. Besides, this blue-shift appearance can be illuminated adequately using the crystal field strength. The thermal quenching of the obtained solid solution is dramatically affected by the composition, with the PL intensity increasing 16% at 423 K going from x = 0 to 1.0. The w-LEDs component constructed by coupling the UV-LED chip with red/green/blue phosphors demonstrate an excellent correlated color…

A new three-dimensional europium-based metal–organic framework has been synthesized with the newly designed ligand L (6-[1-(4-carboxyphenyl)-1 H -1,2,3-triazol-4-yl]nicotinic acid). This compound acts as a dual sensor for the phosphate anion and Fe 3+ ion in aqueous media. The mechanistic aspect of this selectivity and sensitivity was explored through several spectroscopic methods and then correlated with the corresponding structure.

Structure and microwave properties of x Zn 0.5 Ti 0.5 NbO 4 -(1 – x )Zn 0.15 Nb 0.3 Ti 0.55 O 2 ceramics in the range of x = 0.0–1.0 were investigated. Rietveld refinement analysis and Raman spectra show that rutile- and orthorhombic-type solid solutions formed at 0–0.2 and 0.65–1, a composite at 0.2–0.64. In the solid solution regions, chemical bonds are enlarged. In this case, the Zn/Ti/Nb–O1 bond covalency and bond susceptibility are reduced, and lattice energy and thermal expansion coefficient increase along with x increases, which is mainly responsible for the development of microwave dielectric properties. Furthermore, far-infrared spectra and a classical oscillator model were used to discuss the intrinsic dielectric properties in detail. Temperature stable ceramic was obtained for x = 0.516: ε r ∼ 46.11, Q × f ∼ 27 031 GHz, and τ f ∼ −1.51 ppm/°C, which is promising for microwave applications.

The scholastic significance of supramolecular chemistry continues to grow with the recent development of catalytic transformations in confined space of supramolecular architectures. It has come a long way from a natural cavity containing molecules to modern smart materials capable of manipulating reaction pathways. The rise of self-assembled coordination complexes provided a diverse array of host structures. Starting from purely organic compounds to metalloligand surrogates, supramolecular host cavities were tuned according to the requirement of the reactions. The understanding of their participation in a reaction led to better usage of those assemblies for specific reaction sequences. Commencing from cyclodextrin, a wide range of organic molecules was used for cage-catalyzed organic transformations. However, difficulties in synthesis and a tedious purification procedure led chemists to choose a different pathway of metal-ligand coordination-driven self-assembly. The latter stood out as a potential replacement of the organic cages, overcoming the previous drawbacks. In the glut of…

Depending on intrinsic (e.g., radius ratio rule r Ln / r Zr ) and extrinsic factors (e.g., processing conditions), pyrochlore-type Ln 2 Zr 2 O 7 oxides achieve variable degrees of structural disorder. We report on a systematic study of the structural and microstructural characteristics of the Gd 2– x Ln x Zr 2 O 7 system, exploring the effect of replacing Gd with a wide range of homovalent lanthanide ions (Ln = Nd, Sm, Dy, Ho, Y, and Er; x = 0.20 and 0.80). All compositions were prepared via a mechanochemical reaction between the corresponding oxides and characterized by X-ray diffraction (standard and synchrotron sources) using the Rietveld method, as well as by Raman spectroscopy. Irrespective of chemical composition, this study reveals that all compositions exhibit a fluorite-like structure. Furthermore, by firing each sample at 800 and 1400 °C, we are able to analyze the transition to pyrochlore-like structures, featuring different degrees of disorder, in all but Gd 1.20 Y 0.80 Zr 2 O 7, which retains the fluorite structure even after heating. The structural data are used to…

A novel two-dimensional cationic framework [Zn 2 (TCA)(BIB) 2.5 ]·(NO 3 ) ( 1 ) (H 3 TCA = tricarboxytriphenyl amine, BIB = 1,3-bis(imidazol-1-ylmethyl)benzene) was successfully achieved. Compound 1 not only presents a moderate affinity toward CO 2 molecules, but it also displays good catalytic performance and substrate selectivity toward both CO 2 conversion with epoxides and Knoevenagel condensation under solvent-free environments, taking advantage of the Lewis acidity endowed by lower four-coordinated Zn(II) centers and Lewis basicity originated from the amines within TCA 3– . More importantly, the bifunctional heterogeneous catalyst compound 1 shows easy recovery and reuse without an obvious decrease of activity. Strikingly, compound 1 exhibits good catalytic efficiency for CO 2 coupled with propylene oxide forming propylene carbonate even at ambient temperature under 1 atm pressure. To the best of our knowledge, compound 1 is presented to be the first cationic MOF holding great promise as a heterogeneous solvent-free catalyst toward both CO 2 epoxidation and Knoevenagel…

The hierarchical CuCo 2 O 4 @carbon quantum dots (CQDs) hollow microspheres constructed by 1D porous nanowires have been successfully prepared through a simple CQDs-induced hydrothermal self-assembly technique. XPS analysis shows the CuCo 2 O 4 @CQDs possesses the Co(II)-rich surface associated with the oxygen vacancies, which can effectively boost the Faradaic reactions and oxygen evolution reaction (OER) activity. For example, the as-synthesized 3D porous CuCo 2 O 4 @CQDs electrode exhibits high activity toward overall electrochemical water splitting, for example, an overpotential of 290 mV for OER and 331 mV for hydrogen evolution reaction (HER) in alkaline media have been achieved at 10 mA cm –2, respectively. Furthermore, an asymmetric supercapacitor (ASC) (CuCo 2 O 4 @CQDs//CNTs) delivers a high energy density of 45.9 Wh kg –1 at 763.4 W kg –1, as well as good cycling ability. The synergy of Co(II)-rich surface, oxygen vacancies, and well-defined 3D hollow structures facilitates the subsequent surface electrochemical reactions. This work presents a facile method to fabricate…

Clean fuels with extremely low sulfur content are highly desirable due to environmental concerns. Herein, three water-stable and eco-friendly metal–organic frameworks with tunable window diameters, denoted as MOF-808X, have been employed as PTA solid supports. An array of PTA@MOF-808X composites were facilely synthesized via the encapsulation strategy. With tunable window sizes and adjustable PTA loading amounts, the obtained PTA@MOF-808X composites were screened for catalytic oxidative desulfurization (ODS) with H 2 O 2 serving as oxidant. The experiments found that 42%PTA@MOF-808A had the highest catalytic ODS activity and could completely remove dibenzothiophene (DBT) in a model fuel with an initial sulfur content of 1000 ppm within 30 min, which falls far below the acceptable limits for fuel standards (10 ppm). Further investigations revealed that this high catalytic activity could be attributed to the cooperative catalysis of metal clusters in the host framework and the guest PTA molecules. Moreover, 42%PTA@MOF-808A could be facilely recovered and reused for at least five runs…

A series of half-sandwich Ir III pentamethylcyclopentadienyl and Ru II arene complexes containing P^P-chelating ligands of the type [(Cp x /arene)M(P^P)Cl]PF 6, where M = Ir, Cp x is pentamethylcyclopentadienyl (Cp*), or 1-biphenyl-2,3,4,5-tetramethyl cyclopentadienyl (Cp xbiPh ); M = Ru, arene is 3-phenylpropan-1-ol (bz-PA), 4-phenylbutan-1-ol (bz-BA), or p -cymene ( p -cym), and P^P is 2,20-bis(diphenylphosphino)-1,10-binaphthyl (BINAP), have been synthesized and fully characterized, three of them by X-ray crystallography, and their potential as anticancer agents explored. All five complexes showed potent anticancer activity toward HeLa and A549 cancer cells. The introduction of a biphenyl substituent on the Cp* ring for the iridium complexes has no effect on the antiproliferative potency. Ruthenium complex [(η 6 - p -cym)Ru(P^P)Cl]PF 6 ( 5 ) displayed the highest potency, about 15 and 7.5 times more active than the clinically used cisplatin against A549 and HeLa cells, respectively. No binding to 9-MeA and 9-EtG nucleobases was observed. Although these types of complexes interact…

The hybrid structure of nanoparticles (NPs) with nanosheets has the advantage of both anisotropic properties of NPs and large specific surface areas of nanosheets, which is desirable for many technological applications. In this study, MgCr 2 O 4 spinel NPs decorated on highly porous MgO nanosheets forming MgO/MgCr 2 O 4 ( x ) nanocomposites were synthesized by a one pot coprecipitation method followed by a heat treatment process of the solvated wet gel of MgCr-LDH with polar solvent N, N -dimethylformamide (DMF) at 400 °C. This novel synthetic methodology generates materials consisting of porous metal oxides nanosheets adhered with spinel phase NPs due to the slow generation of gases such as H 2 O, CO 2, and NH 3 under moderate temperature during the heat treatment process. The synergistic effect of much wider band gap MgO nanosheets and narrow band gap MgCr 2 O 4 NPs added increased stability due to the stronger bonding coordination of MgCr 2 O 4 NPs with MgO nanosheets. The obtained MgO/MgCr 2 O 4 ( x ) nanocomposites possess large specific surface areas, highly porous structure,…

Tb 3+ -doped zinc-based coordination polymer nanospindle bundles (Zn-PDC/Tb 3+, or [Zn(2,5-PDC)(H 2 O) 2 ]·H 2 O/Tb 3+ ) were synthesized by a simple solution precipitation route at room temperature, employing Zn(NO 3 ) 2, Tb(NO 3 ) 3, and 2,5-Na 2 PDC as the initial reactants, and a mixture of water and ethanol with the volume ratio of 10:10 as the solvent. The as-obtained nanostructures presented strong fluorescent emission under the excitation of 298 nm light, which was attributed to the characteristic emission of the Tb 3+ ion. It was found that the above-mentioned strong fluorescence of the nanostructures could be selectively quenched by cefixime (CFX) in aqueous solution. The other common antibiotics hardly interfered. Thus, as-obtained Zn-PDC/Tb 3+ nanostructures could be prepared as a highly sensitive fluorescence probe for selective detection of CFX in an aqueous system. The corresponding detection limit reached 72 ppb. The theoretic calculation and UV–vis absorption experiments confirmed that the fluorescence quenching of Zn-PDC/Tb 3+ nanostructures toward CFX should be…

Absolute temperature sensitivity ( S a ) reflects the precision of sensors that belong to the same mechanism, whereas relative temperature sensitivity ( S r ) is used to compare sensors from different mechanisms. For the fluorescence intensity ratio (FIR) thermometry based on two thermally coupled energy levels of one rare earth (RE) ion, we define a new ratio as the temperature-sensing parameter that can vary greatly with temperature in some circumstances, which can obtain higher S a without changing S r . Further discussion is made on the conditions under which these two forms of temperature-sensing parameters can be used to achieve higher S a for biomedical temperature sensing. Based on the new ratio as the temperature-sensing parameter, the S a and S r of the BaTiO 3: 0.01%Pr 3+, 8%Yb 3+ nanoparticles at 313 K reach as high as 0.1380 K –1 and 1.23% K –1, respectively. Similarly, the S a and S r of the BaTiO 3: 1%Er 3+, 3%Yb 3+ nanoparticles at 313 K are as high as 0.0413 K –1 and 1.05% K –1, respectively. By flexibly choosing the two ratios as the temperature-sensing parameter,…

Persistent luminescence (PersL) imaging without real-time external excitation has been regarded as the next generation of autofluorescence-free optical imaging technology. However, to achieve improved imaging resolution and deep tissue penetration, developing new near-infrared (NIR) persistent phosphors with intense and long duration PersL over 1000 nm is still a challenging but urgent task in this field. Herein, making use of the persistent energy transfer process from Cr 3+ to Er 3+, we report a novel garnet persistent phosphor of Y 3 Al 2 Ga 3 O 12 codoped with Er 3+ and Cr 3+ (YAG G:Er–Cr), which shows intense Cr 3+ PersL (∼690 nm) in the deep red region matching well with the first biological window (NIR-I, 650–950 nm) and Er 3+ PersL (∼1532 nm) in the NIR region matching well with the third biological window (NIR-III, 1500–1800 nm). The optical imaging through raw-pork tissues (thickness of 1 cm) suggests that the emission band of Er 3+ can achieve higher spatial resolution and more accurate signal location than that of Cr 3+ due to the reduced light scattering at longer…

The electronic and structural properties of ten heteroleptic [Cu(NN)(PP)] + complexes have been investigated. NN indicates 1,10-phenanthroline (phen) or 4,7-diphenyl-1,10-phenanthroline (Bphen); each of these ligands is combined with five PP bis-phosphine chelators, i.e., bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)benzene (dppb), and bis[(2-diphenylphosphino)phenyl] ether (POP). All complexes are mononuclear, apart from those based on dppm, which are dinuclear. Experimental data—also taken from the literature and including electrochemical properties, X-ray crystal structures, UV–vis absorption spectra in CH 2 Cl 2, luminescence spectra and lifetimes in solution, in PMMA, and as powders—have been rationalized with the support of density functional theory calculations. Temperature dependent studies (78–358 K) have been performed for selected complexes to assess thermally activated delayed fluorescence. The main findings are (i) dependence of the ground-state geometry on the…

Three iridium(III)-based metal–organic frameworks (MOFs), namely [Cd 3 {Ir(ppy-COO) 3 } 2 (DMF) 2 (H 2 O) 4 ]·6H 2 O·2DMF ( 1 ), [Cd 3 {Ir(ppy-COO) 3 } 2 (DMA) 2 (H 2 O) 2 ]·0.5H 2 O·2DMA ( 2 ), and [Cd 3 {Ir(ppy-COO) 3 } 2 (DEF) 2 (H 2 O) 2 ]·8H 2 O·2DEF ( 3 ) (ppy-COOH = methyl-3-(pyridin-2-yl)benzoic acid, DMF = N, N -dimethylformamide, DMA = N, N -dimethylacetamide, DEF = N, N -diethylformamide), have been synthesized and characterized. Single-crystal structural determinations reveal that compounds 1 – 3 are isostructural, showing a three-dimensional framework structure with (3,6) connected rtl topologyin whose trimers of {Cd 3 (COO) 6 } are cross-linked by Ir(ppy-COO) 3 3– . The structures are completely different from those of other Ir(III)-based MOFs. Compound 1 was selected for a detailed study on sensing properties. The excellent luminescence as well as good water stability of 1 makes it a highly selective and sensitive multiresponsive luminescent sensor for Fe 3+ and Cr 2 O 7 2– . The detection limits are 67.8 and 145.1 ppb, respectively. Compound 1 can also be used as an…

Ba 1+ x MoO 4 (−0.03 ≤ x ≤ 0.03) ceramics were fabricated by a conventional two-step sintering technique. X-ray diffraction patterns show that there appeared new diffraction peaks when x > 0, which were identified as Ba 2 MoO 5 . The Rietveld refinement results indicate that the unit cell volume is the largest at x = −0.02, because it has the lowest packing fraction and covalency. The far-infrared reflectivity (IR) spectra were fitted and analyzed for calculating the intrinsic properties, which comply well with the data obtained from microscopic polarizabilities and damping coefficient angle. The proportion of each mode in the dielectric response demonstrates that the Ba–O 8 polyhedra have a decisive role on the dielectric properties. And based on the Raman modes, the internal relations of the structural-properties were revealed with the changes of Ba 2+ content.

The self-assembly of a zinc salt with the novel ligand 4,4′,4″-[(1,3,5-triazine-2,4,6-triyl)tris(sulfanediyl)]tribenzoic acid generated 3D microporous metal–organic frameworks (MOFs), namely, {[Zn 4 (L 3– ) 2 (O 2– )(H 2 O) 2 ]·4EtOH} n . The frameworks with multiple Lewis basic sites exhibit easily sensitized properties. After encapsulation of the Tb 3+ cation in this Zn-MOF, the as-obtained fluorescent-functionalized Tb@Zn-MOFs not only maintain distinguished chemical stabilities but also exhibit strong characteristic emissions of trivalent terbium ions. Interestingly, Tb@Zn-MOF has been chosen to be a potential highly selective and sensitive luminescent platform for the reversible detection of PO 4 3– ions in aqueous and living cell buffer solutions with a fast response time of 10 s and a low detection limit (0.1 ppm). Strikingly, this work presents the first example of a fluorescent sensor that can quantitate PO 4 3– in simulated biological fluids and monitor these ions in the water system in a wide range of concentrations from 10 –6 to 10 –3 M.

Using the open N,N′-chelating sites of MOF-253 (Al(OH)(dcbpy), dcbpy = 2,2′-bipyridine-5,5′-dicarboxylic acid) to coordinate with Re(I), a linker anchored Re complex MOF-253-Re(CO) 3 Cl active for photocatalytic CO 2 reduction was obtained. Unlike the homogeneous bipyridine containing Re complexes which produce CO during photocatalytic CO 2 reduction, formate was obtained as the main CO 2 reduction product over the as-obtained MOF-253-Re(CO) 3 Cl. The linker anchored MOF-253-Re(CO) 3 Cl showed superior photocatalytic performance compared to its homogeneous counterpart since the usual formation of the bimolecular Re intermediate leading to the deactivation of the homogeneous Re complex was significantly inhibited in the MOF supported Re complex. To enhance its light absorption, a linker anchored Ru sensitizer was simultaneously constructed in MOF-253-Re(CO) 3 Cl (Ru-MOF-253-Re). The total TON (TON is defin ed as mole of the evolved H 2, CO, and HCOO − over per amount of Rhenium) for CO 2 reduction (28.8 in 4 h) over the as-obtained Ru-MOF-253-Re system is comparable or even superior…

P2-type layered oxides based on the elements Fe and Mn have attracted great interest as sodium ion battery (SIB) cathode materials owing to their inexpensive metal constituents and high specific capacity. However, they suffer from rapid capacity fading and complicated phase transformations. In this study, we modulate the crystal structure and optimize the electrochemical performances of Na 0.67 Mn 0.5 Fe 0.5 O 2 by Al doping for Mn or Fe, respectively, and the roles of Al in the enhancement of the rate capability and cycling performance are unraveled. (1) The substitution of Al for Mn or Fe decreases the lattice parameters a and c but enlarges d spacing and lengthens Na–O bonds, which enhances Na + diffusion and rate capability especially for Na 0.67 Mn 0.5 Fe 0.47 Al 0.03 O 2 . (2) Al doping reduces the thickness of TMO 2 and strengthens TM–O/O–O bonding. This enhances the layered structure stability and the capacity retention. (3) Al doping mitigates Mn 3+ and Jahn–Teller distortion, mitigating the irreversible phase transition. (4) Al doping also alleviates the lattice volume…

Transition metal-organic frameworks (MOFs), on account of their unique inherent properties of large pore volume, high specific surface area, tunable pores, and good catalytic activity, have been highly regarded as superior catalysts recently for water electrolysis, supercapacitors, batteries, sensors, and so on. Herein, we report on a cobalt MOF phase with 3D well-aligned nanosheets array architecture on carbon cloth (Co-MOF NS/CC), fabricated by a facile ambient liquid-phase deposition, could serve as a self-standing Janus catalytic electrode toward both glucose and water oxidation. It shows good glucose-sensing performance with low determination limit and large detection range. Also, it exhibits high water-oxidation efficiency with low overpotential and good durability. This work demonstrates the potential of utilizing transition-metal based well-aligned MOF nanoarrays for electrocatalytic oxidation.

Luminescent materials based on copper complexes are currently receiving increasing attention because of their rich photophysical properties, opening a wide field of applications. The copper iodide clusters formulated [Cu 4 I 4 L 4 ] (L = ligand), are particularly relevant for the development of multifunctional materials based on their luminescence stimuli-responsive properties. In this context, controlling and modulating their photophysical properties is crucial and this can only be achieved by thorough understanding of the origin of the optical properties. We thus report here, the comparative study of a series of cubane copper iodide clusters coordinated by different phosphine ligands, with the goal of analyzing the effect of the ligands nature on the photoluminescence properties. The synthesis, structural, and photophysical characterizations along with theoretical investigations of copper iodide clusters with ligands presenting different electronic properties, are described. A method to simplify the analysis of the 31 P solid-state NMR spectra is also reported. While clusters with…