Showing papers in "Inorganic Chemistry in 2017"
TL;DR: Examination of the impact of organic cation and inorganic layer choice on the exciton absorption/emission properties, among the set of compounds considered, reveals that perovskite layer distortion has a more global effect on theexciton properties than octahedral distortion.
Abstract: A series of two-dimensional (2D) hybrid organic–inorganic perovskite (HOIP) crystals, based on acene alkylamine cations (i.e., phenylmethylammonium (PMA), 2-phenylethylammonium (PEA), 1-(2-naphthyl)methanammonium (NMA), and 2-(2-naphthyl)ethanammonium (NEA)) and lead(II) halide (i.e., PbX42–, X = Cl, Br, and I) frameworks, and their corresponding thin films were fabricated and examined for structure–property relationship. Several new or redetermined crystal structures are reported, including those for (NEA)2PbI4, (NEA)2PbBr4, (NMA)2PbBr4, (PMA)2PbBr4, and (PEA)2PbI4. Non-centrosymmetric structures from among these 2D HOIPs were confirmed by piezoresponse force microscopy—especially noteworthy is the structure of (PMA)2PbBr4, which was previously reported as centrosymmetric. Examination of the impact of organic cation and inorganic layer choice on the exciton absorption/emission properties, among the set of compounds considered, reveals that perovskite layer distortion (i.e., Pb–I–Pb bond angle between adj...
367 citations
TL;DR: The photoluminescent (PL) properties of CP1 and CP2 have been exploited as dual detection fluorosensors for hexavalent chromate anions and 2,4,6-trinitrophenol (TNP) because it was observed that the emission intensity of aqueous suspensions of CPs selectively quenches by chromateAnions or TNP among large pools of different anions or nitro compounds, respectively.
Abstract: Isostructural Zn(II)/Cd(II) mixed ligand coordination polymers (CPs) {[M(IPA)(L)]}n (CP1 and CP2) built from isophthalic acid (H2IPA) and 3-pyridylcarboxaldehyde nicotinoylhydrazone (L) were prepared using versatile synthetic routes: viz., diffusion of precursor solutions, conventional reflux methods, and green mechanochemical (grinding) reactions. Both robust CPs synthesized by different routes were characterized by various analytical methods, and their thermal and chemical stability as well as the phase purity was established. Crystallographic studies revealed that CP1 and CP2 are isostructural frameworks and feature a double-lined two-dimensional network composed of Zn2+/Cd2+ nodes connected through IPA and pillared by the Schiff base ligand L with a double-walled edge. The photoluminescent (PL) properties of CP1 and CP2 have been exploited as dual detection fluorosensors for hexavalent chromate anions (CrO42–/Cr2O72–) and 2,4,6-trinitrophenol (TNP) because it was observed that the emission intensity o...
292 citations
TL;DR: Steady/transient-state near-IR luminescence properties for MOFs 1, 4, and 5 were investigated under visible-light excitation, and it is indicated that it exhibits turn on/off switchable properties for small solvent molecules or heavy-metal ions.
Abstract: A series of five unique d–f heteronuclear luminescent metal–organic frameworks (MOFs) in an entangled polyrotaxane array and the light-harvesting block homonuclear zinc compound have been isolated successfully and characterized. The series of isostructural polymers feature 3,4-connected (4.82)(4.83.92)(6.8.9)2(6.92)(83) topology and high stability, exhibiting diverse void spaces. By taking advantage of the isostructural MOFs 2 and 3, the intensities of red and green emissions can be modulated by adjusting the ratios of EuIII and TbIII ions correspondingly, and white-light emission can be generated by a combination of different doped TbIII and EuIII concentrations. The Tb–Zn-based framework {[Tb3Zn6(bipy2)2(Hmimda)7 (H2O)3]·5H2O}n (3; H3mimda = 2-methyl-1-H-imidazole-4,5-dicarboxylic acid and bipy = 4,4′-bipyridine) can detect trace MgII ion with relatively high sensitivity and selectivity. Dehydrated MOF 3a shows a remarkable emission quenching effect through the introduction of I2 solids. Further investi...
277 citations
TL;DR: An overview of the field is provided with a focus on the group's contributions to identifying and addressing problems inherent to 3D lead-halide perovskites, and new materials developed for realizing the exceptional photophysical properties of lead- Halides in more environmentally benign materials are discussed.
Abstract: The impressive rise in efficiencies of solar cells employing the three-dimensional (3D) lead–iodide perovskite absorbers APbI3 (A = monovalent cation) has generated intense excitement. Although these perovskites have remarkable properties as solar-cell absorbers, their potential commercialization now requires a greater focus on the materials’ inherent shortcomings and environmental impact. This creates a challenge and an opportunity for synthetic chemists to address these issues through the design of new materials. Synthetic chemistry offers powerful tools for manipulating the magnificent flexibility of the perovskite lattice to expand the number of functional analogues to APbI3. To highlight improvements that should be targeted in new materials, here we discuss the intrinsic instability and toxicity of 3D lead–halide perovskites. We consider possible sources of these instabilities and propose methods to overcome them through synthetic design. We also discuss new materials developed for realizing the exce...
234 citations
TL;DR: A bifunctional robust and highly porous imidazolium-based ionic liquid decorated UiO-67 type MOF that can be used as a highly active heterogeneous catalyst for CO2 cycloaddition with epoxides under atmospheric pressure with or without cocatalyst TBAB (n-Bu4NBr).
Abstract: A bifunctional robust and highly porous imidazolium-based ionic liquid decorated UiO-67 type MOF (UiO-67-IL, 1) was successfully constructed via solvothermal assembly of the imidazolium-based ligand and Zr(IV) ions. It exhibits a highly selective adsorption for CO2 over CH4 and N2. Furthermore, 1 herein can be used as a highly active heterogeneous catalyst for CO2 cycloaddition with epoxides under atmospheric pressure with or without cocatalyst TBAB (n-Bu4NBr).
202 citations
TL;DR: The mechanism of Cr3+ luminescence quenched involves irreversible coordination to free pyridyl sites in the CP framework, while the Cr6+ quenching involves reversible overlap of the absorption bands of the analytes with those of the excitation and/or emission bands for 3.
Abstract: Three photoluminescent zinc coordination polymers (CPs), {[Zn2(tpeb)2(2,5-tdc)(2,5-Htdc)2]·2H2O}n (1), {[Zn2(tpeb)2(1,4-ndc)(1,4-Hndc)2]·2.6H2O}n (2), and {[Zn2(tpeb)2(2,3-ndc)2]·H2O}n (3) (tpeb = 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene, 2,5-tdc = 2,5-thiophenedicarboxylic acid, 1,4-ndc = 1,4-naphthalenedicarboxylic acid, and 2,3-ndc = 2,3-naphthalenedicarboxylic acid) were prepared from reactions of Zn(NO3)2·6H2O with tpeb and 2,5-H2tdc, 1,4-H2ndc, or 2,3-H2ndc under solvothermal conditions. Compound 1 has a two-dimensional (2D) grid-like network formed from bridging 1D [Zn(tpeb)]n chains via 2,5-tdc dianions. 2 and 3 possess similar one-dimensional (1D) double-chain structures derived from bridging the [Zn(tpeb)]n chains via pairs of 1,4-ndc or 2,3-ndc ligands. The solid-state, visible emission by 1–3 was quenched by Cr3+, CrO42–, and Cr2O72– ions in water with detection limits by the most responsive complex 3 of 0.88 ppb for Cr3+ and 2.623 ppb for Cr2O72– (pH = 3) or 1.734 ppb for CrO42– (pH = 12). Thes...
200 citations
TL;DR: The present study deals with the structural characterization and classification of the novel compounds 1-8 into perovskite subclasses and proceeds in extracting the structure-band gap relationships between them and defines a new family of hybrid halide perovSKites with a crystal structure that emerges from a blend of corner- and face-sharing octahedral connections in various proportions.
Abstract: The present study deals with the structural characterization and classification of the novel compounds 1–8 into perovskite subclasses and proceeds in extracting the structure–band gap relationships between them. The compounds were obtained from the employment of small, 3–5-atom-wide organic ammonium ions seeking to discover new perovskite-like compounds. The compounds reported here adopt unique or rare structure types akin to the prototype structure perovskite. When trimethylammonium (TMA) was employed, we obtained TMASnI3 (1), which is our reference compound for a “perovskitoid” structure of face-sharing octahedra. The compounds EASnI3 (2b), GASnI3 (3a), ACASnI3 (4), and IMSnI3 (5) obtained from the use of ethylammonium (EA), guanidinium (GA), acetamidinium (ACA), and imidazolium (IM) cations, respectively, represent the first entries of the so-called “hexagonal perovskite polytypes” in the hybrid halide perovskite library. The hexagonal perovskites define a new family of hybrid halide perovskites with a...
192 citations
TL;DR: A high-efficiency electrocatalyst for electrochemical water oxidation based on an Fe-doped Ni2P nanosheet array on a conductive carbon cloth with high electrochemical durability is reported.
Abstract: In this Communication, we report a high-efficiency electrocatalyst for electrochemical water oxidation based on an Fe-doped Ni2P nanosheet array on a conductive carbon cloth. This catalyst shows a low onset overpotential of 190 mV, and it demands overpotentials of only 215 and 235 mV to drive 50 and 100 mA cm–2, respectively, with high electrochemical durability. This work offers us an attractive earth-abundant 3D catalyst electrode in water-splitting devices toward the mass production of hydrogen fuels for applications.
185 citations
TL;DR: NU-1000 is a unique material combining both efficient sorption and exceptional fluorescent sensing of Cr2O72- in aqueous media and can also serve as an efficient photoluminescent probe for the selective detection of Cr(VI) in aQueous media.
Abstract: Highly efficient decontamination of heavily toxic Cr2O72– from water remains a serious task for public health and ecosystem protection. An easily regenerative and reused sorbent with suitable porosity may address this task. Herein, a series of water-stable and ecofriendly metal–organic frameworks (MOFs) with large surface areas were assessed for their ability to adsorb and separate Cr2O72– from aqueous solutions. Among these tested MOFs, NU-1000 shows an extraordinary capability to efficiently capture (within 3 min) Cr2O72– with a sorption capacity of up to 76.8 mg/g, which is the largest one for the neutral MOF-based Cr2O72– sorbents. NU-1000 also shows remarkable selectivity for Cr2O72– capture and can effectively reduce the Cr(VI) concentration from 24 ppm to 60 ppb, which is below the acceptable limit for the drinking water standard (100 ppb by the U.S. Environmental Protection Agency). Moreover, this adsorbent can be easily regenerated by Soxhlet extraction with an acidic methanol solution (2.5 M HCl...
164 citations
TL;DR: The (1 - x)ST-x(BNT-BAN) systems are candidate materials for pulsed capacitor applications and exhibit a high Wrec of 1.89 J/cm3 as well as a high η of 77%.
Abstract: Pulsed capacitors require high-recoverable energy-storage density (Wrec) and high energy-storage efficiency (η), which can be realized through the selection and adjustment of the composition. In this work, (1 – x)SrTiO3–x(0.95Bi0.5Na0.5TiO3–0.05BaAl0.5Nb0.5O3) [(1 – x)ST–x(BNT–BAN)] ceramics were successfully prepared via the pressureless solid-state reaction method. The dielectric constant increases gradually with the introduction of BNT–BAN and obtains a maximum value of 3430 with the composition of 0.4ST–0.6(BNT–BAN) at 100 Hz, which is 10.39 times higher than that of the pure ST sample (∼330). Dispersive relaxor behaviors and ferroelectric performances can be enhanced with the introduction of BNT–BAN. The composition of 0.5ST–0.5(BNT–BAN) exhibits a high Wrec of 1.89 J/cm3 as well as a high η of 77%. Therefore, the (1 – x)ST–x(BNT–BAN) systems are candidate materials for pulsed capacitor applications.
160 citations
TL;DR: The luminescent investigations confirm that the emission behavior of the Eu complex possesses excellent water stability and pH stability, and it is the first example of a MOC-based fluorescent probe with high selectivity, high sensitivity, and low detection limit, targeting Cr(III) and Cr(VI) (CrO42-/Cr2O72-) ions in aqueous solution.
Abstract: A unique metal–organic complex (MOC) with formula [Eu2(tpbpc)4·CO3·4H2O]·DMF·solvent (Htpbpc = 4′-[4,2′;6′,4″]-terpyridin-4′-yl-biphenyl-4-carboxylic acid) has been successfully constructed under solvothermal conditions. The Eu complex, as proved by structural analysis, exhibits a fascinating 1D linear-type chain structure which is further extended to a 3D H-bonded supramolecular framework. The luminescent investigations confirm that the emission behavior of the Eu complex possesses excellent water stability and pH stability, and it is the first example of a MOC-based fluorescent probe with high selectivity, high sensitivity, and low detection limit, targeting Cr(III) and Cr(VI) (CrO42–/Cr2O72–) ions in aqueous solution. Importantly, the luminescence can be fast and simple, regenerated in detecting CrO42– and Cr2O72– ions. Furthermore, the simple fluorescent-based test paper was successfully prepared and provided a reliable and visual detection of Cr3+, CrO42–, and Cr2O72– ions in daily applications.
TL;DR: The recent uses of B(C6F5)3 in borylation reactions are shown while also focusing on current advances in novel borane and borocation usage that eclipses that of the stalwart B( C6F 5)3.
Abstract: As main-group chemistry, in particular boron chemistry, has expanded and developed over the past 20 years, one reagent has risen to prominence as well. Tris(pentafluorophenyl)borane, B(C6F5)3 (commonly known as BCF), has demonstrated extensive applications in a wide variety of reactions, including borylation, hydrogenation, hydrosilylation, frustrated Lewis pair (FLP) chemistry, Lewis acid catalysis, and more. The high Lewis acidity of B(C6F5)3 is derived from the electronic effects of its three C6F5 rings, rendering it a versatile reagent for a great number of reactions. In addition, the steric bulk of these rings also allows it to function as the Lewis acid in a FLP, granting this reagent yet another synthetically useful application. However, as main-group chemistry continues to evolve as a field, new reagents are required that go beyond BCF, increasing not only the range of reactions available but also the breadth of compounds attainable. Great strides have already been made in order to accomplish this...
TL;DR: This Viewpoint focuses on 3D SCCs, specifically metallacages and helicates, first briefly presenting the fundamentals in terms of the synthesis and characterization of their host-guest properties, followed by an overview of the possible biological applications with representative examples.
Abstract: In the supramolecular chemistry field, coordination-driven self-assembly has provided the basis for tremendous growth across many subdisciplines, spanning from fundamental investigations regarding the design and synthesis of new architectures to defining different practical applications. Within this framework, supramolecular coordination complexes (SCCs), defined as large chemical entities formed from smaller precursor building blocks of ionic metal nodes and organic multidentate ligands, resulting in intricate and well-defined supramolecular structures, hold great promise. Notably, interest in the construction of discrete 3D molecular architectures, such as those offered by SCCs, has experienced extraordinary progress because of their potential application as sensors, catalysts, probes, and containers and in basic host–guest chemistry. Despite numerous synthetic efforts and a number of inherent favorable properties, the field of 3D SCCs for biomedical applications is still in its infancy. This Viewpoint ...
TL;DR: Luminescent property studies reveal that the CPs 1-3 are promising luminescent sensors that can highly select and sensitively detect ferric and chromate/dichromate ions, in which the CP 1 with a 1D structure showed the best performance, free from the interference of other ions present in an aqueous medium.
Abstract: Three new water-stable luminescent Cd(II) coordination polymers (CPs), {[Cd2(bptc)(2,2′-bipy)2(H2O)2]}n (1), {[Cd2(bptc)(phen)2]·4H2O}n (2), and {[Cd2(bptc)(4,4′-bipy)(H2O)2]·4H2O}n (3), were solvothermally synthesized with mixed ligands of 3,3′,5,5′-biphenyltetracarboxylic acid (H4bptc) and N-donor ligands (2,2′-bipy = 2,2′-bipyridine; phen = 1,10-phenanthroline; 4,4′-bipy = 4,4′-bipyridine). The CPs 1–3 show structural diversity from a 1D ladder chain to a 2D layer to a 3D porous framework, tuned by different ancillary ligands. Topological analyses reveal that the CP 2 is a 4-connected uninodal 2D net with the Schlafli point symbol {44·62}, while the CP 3 displays a 4,6-connected 2-nodal 3D net with the point symbol {3·42·52·6}{32·42·52·64·74·8}. Luminescent property studies reveal that the CPs 1–3 are promising luminescent sensors that can highly select and sensitively detect ferric and chromate/dichromate ions, in which the CP 1 with a 1D structure showed the best performance, free from the interferen...
TL;DR: It is inferred that it is crucial to choose an appropriate doping element to decrease the Li/Ni disorder of LiMO2 materials and enhance their electrochemical performances, and the findings will help in the research of other layered oxide materials.
Abstract: Decreasing Li/Ni disorder has been a challenging problem for layered oxide materials, where disorder seriously restricts their electrochemical performances for lithium-ion batteries (LIBs). Element...
TL;DR: The Zn-MOF represents the first example of MOF-based luminescent sensors which can detect and differentiate Fe(III) and Cr(VI) ions selectively, and the possible sensing mechanism was discussed in detail.
Abstract: A new luminescent Zn(II)-based metal–organic framework (MOF), [Zn2(TPOM)(NDC)2]·3.5H2O (Zn-MOF; TPOM = tetrakis(4-pyridyloxymethylene)methane and H2ndc = 2,6-naphthalenedicarboxylic acid), was successfully synthesized by a hydrothermal reaction. The MOF exhibits excellent luminescence emission, and it can detect Fe(III) and Cr(VI) ions with high selectivity, well antiinterference performance, and short response time. In addition, Zn-MOF was selected as a parent coordination compound to encapsulate Eu3+ cations to obtain a Eu3+-incorporated sample (Eu3+@Zn-MOF). Subsequently, we explored the potential application of Eu3+@Zn-MOF as a probe for the selective sensing of Fe(III) and Cr(VI) ions, and it revealed that we could differentiate Fe(III) and Cr(VI) ions by the combination Zn-MOF and Eu3+@Zn-MOF. More importantly, it represents the first example of MOF-based luminescent sensors which can detect and differentiate Fe(III) and Cr(VI) ions selectively. And the possible sensing mechanism was discussed in de...
TL;DR: The results manifest that the Ba0.88Eu0.08ZrGe3O9 phosphor can be an eligible red-emitting phosphor candidate for WLEDs and field-emission displays and has better degradation resistance than the commercial Y2O3:Eu phosphor.
Abstract: A variety of Eu3+-activated BaZrGe3O9 phosphors was synthesized via solid-state reaction. The phase formation of BaZrGe3O9:Eu3+ samples was verified by powder X-ray diffraction analysis, while Rietveld refinement method was used to confirm the crystal structure. The electronic structure and characteristic photoluminescence as well as cathodoluminescence properties were researched in detail. The samples show strong absorption at 394 nm, which matches well with the commercial near-ultraviolet chips. Under 394 nm excitation, the phosphors exhibit the characteristic emissions of Eu3+ ions consistent with the 5D0–7FJ transitions. Then we investigated the thermal stability detailedly. The temperature-dependent photoluminescence emission spectra suggest that the obtained phosphors have favorable thermal stability. A white light-emitting diode (WLED) lamp with low correlated color temperature and good color render index was fabricated with blue-emitting BaMgAl10O17:Eu2+, green-emitting Sr2SiO4:Eu2+ (commercial), ...
TL;DR: The as-prepared Ag@Ln-MOFs composite shows highly efficient catalytic performance for the reduction of 4-nitrophenol and can be readily reduced to afford Ag nanoparticles.
Abstract: New porous anionic Ln-MOFs, namely, [Me2NH2][Ln(CPA)2(H2O)2] (Ln = Eu, Gd), have been prepared through the self-assembly of 5-(4-carboxy phenyl)picolinic acid (H2CPA) and lanthanide ions. They feature open anionic frameworks with 1-D hydrophilic channels and exchangeable dimethylamine ions. The Eu phase could detect Fe3+ ions with high selectivity and sensitivity in either aqueous solution or biological condition. The ratios of lanthanide ions on this structure platform could be rationally tuned to not only achieve dichromatic emission colors with linear correlation but also attain three primary colors (RGB) and even white light with favorable correlated color temperature. Furthermore, the Ag(I)-exchanged phases can be readily reduced to afford Ag nanoparticles. The as-prepared Ag@Ln-MOFs composite shows highly efficient catalytic performance for the reduction of 4-nitrophenol.
TL;DR: The present investigation clearly demonstrates selective detection of CrO42-/Cr2O72- and Fe3+/Pd2+ in aqueous media, and the probable mechanism for the quenching phenomena based on structural aspects has also been discussed.
Abstract: Zn(II)/Cd(II)-based dual ligand Luminescent Metal–Organic Frameworks (LMOFs) {[M(ATA)(L)]}n·xH2O (1) and (2) were synthesized by versatile synthetic routes, viz., diffusion of precursor solutions, conventional reflux, and green mechanochemical (grinding) reactions from bipyridyl-based Schiff base, (E)-N′-(pyridin-4-ylmethylene)isonicotinohydrazide (L) and amino functionalized 2-aminoterephthalic acid (H2ATA) as linkers. Chemical and thermal stability, phase purity, and characterization of both LMOFs were established by various analytical methods. SXRD analysis revealed the 3D framework is composed of two-dimensional [M(ATA)]n nets doubly pillared by L through the terminal nitrogen atom. Selective and sensitive detection of chromate anions (CrO42–/Cr2O72–) and Fe3+/Pd2+ cations in the aqueous phase by fluorescent quenching of the LMOFs 1 and 2 has been established. Competitive experiments in the presence of interfering anions/cations with 1 and 2 revealed no major change in the quenching efficiency. The ob...
TL;DR: This article discusses how one can design, perform, observe, understand, and engineer the formation of compounds from inorganic melts using complementary techniques of in situ X-ray diffraction and probe the mobile species present in melts.
Abstract: The discovery of new materials and their efficient syntheses is a fundamental goal of chemistry. A related objective is to identify foundational and rational approaches to enhance the art of synthesis by combining the exquisite predictability of organic synthesis with the high yields of solid-state chemistry. In contrast to so-called solid-state methods, inorganic syntheses in liquid fluxes permit bond formation, framework assembly, and crystallization at lower temperatures because of facile diffusion and chemical reactions with and within the flux itself. The fluxes are bona fide solvents similar to conventional organic or aqueous solvents. Such reactions can produce a wide range of materials, often metastable, from oxides to intermetallics, but typically the formation mechanisms are poorly understood. This article discusses how one can design, perform, observe, understand, and engineer the formation of compounds from inorganic melts. The focus is also design concepts such as "dimensional reduction", "phase homologies", and "panoramic synthesis", and their broad applicability. When well-defined building blocks are present and stable in the reaction, prospects for increased structural diversity and product control increase substantially. Common structural motifs within these materials systems may be related to structural precursors in the melt that may be controlled by tuning reaction conditions and composition. Stabilization of a particular building block is often accomplished with tuning of the flux composition, which controls the Lewis basicity and redox potential. In such tunable and dynamic fluxes, the synthesis can be directed toward new materials. Using complementary techniques of in situ X-ray diffraction, we can create time-dependent maps of reaction space and probe the mobile species present in melts. Certain thoughts toward the ultimate goal of targeted materials synthesis by controlling inorganic melt chemistry are discussed.
TL;DR: The chemical and physical requirements for new inorganic nonlinear-optical materials necessary for solid-state lasers to generate coherent radiation in the ultraviolet (UV) and deep-UV regions are described and the "birefringence challenge" is described.
Abstract: New inorganic nonlinear-optical (NLO) materials are necessary for solid-state lasers to generate coherent radiation in the ultraviolet (UV) and deep-UV regions The purpose of this Viewpoint is to describe the chemical and physical requirements for such materials, as well as the current state of the field In addition, the “birefringence challenge” is described and a flowchart is presented for characterizing new second-harmonic-generation materials Finally, several new materials are suggested that may have UV and/or deep-UV NLO applications
TL;DR: Various annealing treatments of the VEG precursor, under controlled atmosphere and temperature, led to the successful synthesis of the three pure oxides, with sub-micrometer crystallite size, from a single polyol route through the precipitation of an intermediate precursor.
Abstract: In this study, vanadium sesquioxide (V2O3), dioxide (VO2), and pentoxide (V2O5) were all synthesized from a single polyol route through the precipitation of an intermediate precursor: vanadium ethylene glycolate (VEG). Various annealing treatments of the VEG precursor, under controlled atmosphere and temperature, led to the successful synthesis of the three pure oxides, with sub-micrometer crystallite size. To the best of our knowledge, the synthesis of the three oxides V2O5, VO2, and V2O3 from a single polyol batch has never been reported in the literature. In a second part of the study, the potentialities brought about by the successful preparation of sub-micrometer V2O5, VO2, and V2O3 are illustrated by the characterization of the electrochromic properties of V2O5 films, a discussion about the metal to insulator transition of VO2 on the basis of in situ measurements versus temperature of its electrical and optical properties, and the characterization of the magnetic transition of V2O3 powder from SQUID measurements. For the latter compound, the influence of the crystallite size on the magnetic properties is discussed.
TL;DR: The as-prepared anionic hexanuclear Ln(III) cluster-based MOFs can serve as a multifunctional material for an optical and environmental area.
Abstract: Two hexanuclear Ln(III) cluster-based metal–organic frameworks (MOFs) (Ln = Tb or Eu) and a series of isomorphic bimetallic Ln(III)-MOFs have been synthesized by changing the ratio of Tb(III) and Eu(III) under solvothermal conditions. The excellent linear color tunability (from green to red) makes them suitable for barcode application. In addition, the anionic Ln(III)-MOFs exhibit superior uptake capacity toward methylene blue (MB+) by an ion-exchange process, and its reversible adsorption performance makes 1 suitable for removal of organic dye MB+. The as-prepared anionic hexanuclear Ln(III) cluster-based MOFs can serve as a multifunctional material for an optical and environmental area.
TL;DR: A water-stable 3D luminescent metal-organic framework constructed from heterometallic clusters and electron-rich π-conjugated 1,4-naphthalenedicarboxylic acid ligands exhibits highly sensitive, selective, and reversible detection of ronidazole.
Abstract: A water-stable 3D luminescent metal–organic framework (MOF), [Eu6Zn(μ3-OH)8(NDC)6(H2O)6]n (1), constructed from heterometallic [EuIII6ZnII] clusters and electron-rich π-conjugated 1,4-naphthalenedicarboxylic acid (H2NDC) ligands exhibits highly sensitive, selective, and reversible detection of ronidazole, which represents the first example of luminescent MOFs based on Ln-TM heterometallic clusters for the detection of antibiotics in aqueous solution.
TL;DR: The synthesis, thermal and optical properties, and calculations of the electronic band structures for one- and two-layer compounds comprising both cesium and guanidinium cations for Cs+ and C(NH2)3+ are demonstrated.
Abstract: Interest in hybrid organic–inorganic lead halide compounds with perovskite-like two-dimensional crystal structures is growing due to the unique electronic and optoelectronic properties of these compounds. Herein, we demonstrate the synthesis, thermal and optical properties, and calculations of the electronic band structures for one- and two-layer compounds comprising both cesium and guanidinium cations: Cs[C(NH2)3]PbI4 (I), Cs[C(NH2)3]PbBr4 (II), and Cs2[C(NH2)3]Pb2Br7 (III). Compounds I and II exhibit intense photoluminescence at low temperatures, whereas compound III is emissive at room temperature. All of the obtained substances are stable in air and do not thermally decompose until 300 °C. Since Cs+ and C(NH2)3+ are increasingly utilized in precursor solutions for depositing polycrystalline lead halide perovskite thin films for photovoltaics, exploring possible compounds within this compositional space is of high practical relevance to understanding the photophysics and atomistic chemical nature of su...
TL;DR: It is worth noting that the material exhibits selective adsorption and recyclable detection of heavy-metal Cr3+ ion in aqueous solutions, which may be the synergy from the metal charge, bond ability of metal ions to carboxylate oxygen atom, and soft-hard acid-base properties.
Abstract: Heavy-metal ions and nitroaromatic substances are highly toxic and harmful to human health and the ecological environment. It is an urgent issue to selectively detect and capture these toxic substances. By introducing the triazole ligand to the π-conjugated aromatic carboxylate system and borrowing the organic template open framework idea, a stable fluorescent framework [Me2NH2]4[Zn6(qptc)3(trz)4]·6H2O (1) (H4qptc = terphenyl-2,5,2′5′-tetracarboxylic acid, trz = 1,2,4-triazole) has been successfully synthesized, which features Zn4(trz)2 chain-based 3D anionic structure with channels filled by [Me2NH2]+ cations. It is worth noting that the material exhibits selective adsorption and recyclable detection of heavy-metal Cr3+ ion in aqueous solutions, which may be the synergy from the metal charge, bond ability of metal ions to carboxylate oxygen atom, and soft–hard acid–base properties. Furthermore, it can selectively sense of 2,4,6-trinitrophenol with a large quenching coefficient Ksv of 2.08 × 106 M–1.
TL;DR: The layered polymorph of vacancy-ordered triple perovskite Cs3Bi2Br9 shows the top of the valence band and bottom of the conduction band minima are, unusually, dominated by Bi s and p states, respectively, which produces a sharp exciton peak in the absorption spectra.
Abstract: We report a study on the optical properties of the layered polymorph of vacancy-ordered triple perovskite Cs3Bi2Br9. The electronic structure, determined from density functional theory calculations, shows the top of the valence band and bottom of the conduction band minima are, unusually, dominated by Bi s and p states, respectively. This produces a sharp exciton peak in the absorption spectra with a binding energy that was approximated to be 940 meV, which is substantially stronger than values found in other halide perovskites and, instead, more closely reflects values seen in alkali halide crystals. This large binding energy is indicative of a strongly localized character and results in a highly structured emission at room temperature as the exciton couples to vibrations in the lattice.
TL;DR: The mechanisms of these biomimetic oxidase reactions are proposed for the first time involving any heterometallic catalyst on the basis of mass spectral analysis, EPR spectroscopy, and cyclic voltammetry.
Abstract: A new Cu(II) complex of an asymmetrically dicondensed Schiff base (H2L = N-(2-hydroxyacetophenylidene)-N′-salicylidene-1,3-propanediamine) derived from 1,3-propanediamine, salicylaldehyde, and o-hydroxyacetophenone has been synthesized. Using this complex, [CuL] (1), as a metalloligand, two new trinuclear Cu-Mn complexes, [(CuL)2Mn(N3)(H2O)](ClO4)·H2O (2) and [(CuL)2Mn(NCS)2] (3), have been prepared. Single-crystal structural analyses reveal that complexes 2 and 3 both have the same bent trinuclear {(CuL)2Mn}2+ structural unit in which two terminal bidentate square-planar (CuL) units are chelated to the central octahedral Mn(II) ion. This structural similarity is also evident from the variable-temperature magnetic susceptibility measurements, which suggest that compounds 2 and 3 are both antiferromagnetically coupled with comparable exchange coupling constants (−21.8 and −22.3 cm–1, respectively). The only difference between 2 and 3 lies in the coordination around the central Mn(II) ion; in 3, two SCN– gr...
TL;DR: The systematic studies on electrochemical properties demonstrate that (p)-CoS2@CNT possesses hierarchical morphology, moderate specific surface area, proper pore diameter distribution, and high graphitization, which lead to remarkable specific capacitances.
Abstract: Herein three novel cobalt metal–organic frameworks (Co-MOFs) with similar ingredients, [Co(bib)(o-bdc)]∞ (1), [Co2(bib)2(m-bdc)2]∞ (2), and {[Co(bib)(p-bdc)(H2O)](H2O)05}∞ (3), have been synthesized from the reaction of cobalt nitrate with 1,4-bis(imidazol-1-yl)benzene (bib) and structure-related aromatic acids (1,2-benzenedicarboxylic acid = o-bdc, 1,3-benzenedicarboxylic acid = m-bdc, and 1,4-benzenedicarboxylic acid = p-bdc) by the solvothermal method It is aimed to perform systematic research on the relationship among the conformation of benzoate acid, lattice dimension of Co-MOF, and pore diameter of MOF-derived carbon composite Through the precursor strategy, Co-MOFs 1–3 have been utilized to synthesize porous cobalt@carbon nanotube composites (Co@CNTs) After the in situ gas-sulfurization, secondary composites CoS2@CNTs were successfully obtained, which kept similar morphologies of corresponding Co@CNTs without destroying previous highly dispersed structures Co-MOFs and two series of composites
TL;DR: If perovskite solar cells can be made stable, they will be an exciting, highly complementary addition to existing photovoltaic technologies.
Abstract: Perovskite solar cells have experienced a remarkably rapid rise in power conversion efficiencies, with state-of-the-art devices now competing with multicrystalline silicon and thin-film cadmium telluride in terms of efficiency. Unfortunately, the lead halide perovskite absorbers suffer from a lack of chemical stability and decompose in response to a variety of environmental stimuli. In this Forum Article, we provide a brief overview of the decomposition mechanisms in lead halide perovskite thin films, as well as the processes contributing to cell failure in finished devices. We finish by briefly surveying recent efforts to extend the device lifetime. Ultimately, if perovskite solar cells can be made stable, they will be an exciting, highly complementary addition to existing photovoltaic technologies.