Showing papers on "Isostructural published in 2016"
TL;DR: It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development.
Abstract: Controlled photoluminescence tuning is important for the optimization and modification of phosphor materials. Herein we report an isostructural solid solution of (CaMg)x(NaSc)1–xSi2O6 (0 < x < 1) in which cation nanosegregation leads to the presence of two dilute Eu2+ centers. The distinct nanodomains of isostructural (CaMg)Si2O6 and (NaSc)Si2O6 contain a proportional number of Eu2+ ions with unique, independent spectroscopic signatures. Density functional theory calculations provided a theoretical understanding of the nanosegregation and indicated that the homogeneous solid solution is energetically unstable. It is shown that nanosegregation allows predictive control of color rendering and therefore provides a new method of phosphor development.
166 citations
TL;DR: In this paper, the existence of a kinetically stable two-dimensional (2D) penta-CN2 sheet, which is isostructural to the recently discovered penta graphene, was predicted.
Abstract: Using first-principles calculations combined with ab initio molecular dynamics and tight binding model, we predict the existence of a kinetically stable two-dimensional (2D) penta-CN2 sheet, which is isostructural to the recently discovered penta-graphene. The concentration of N in this new carbon nitride sheet exceeds the maximum N content, namely 21.66%, that has been achieved experimentally in honeycomb geometry. It even exceeds the N content found recently in hole-doped carbon nitride C0.5N0.5 as well as in porous graphitic C3N4. The penta-CN2 sheet contains N–N single bonds with an energy density of 4.41 kJ/g, higher than that predicted recently in nitrogen-rich B–N compound. Remarkably, penta-CN2 has an in-plane axial Young’s modulus of 319 N/m, even stiffer than the h-BN monolayer. The electronic band structure of penta-CN2 exhibits an interesting double degeneracy at the first Brillouin zone edges which is protected by the nonsymmorphic symmetry and can be found in other isostructural chemical ana...
159 citations
TL;DR: In this article, a series of fluorene-based lanthanide metal-organic frameworks (Ln2(FDC)3DMA(H2O)3]·DMA·4.
Abstract: Fast and selective detection of heavy metal ions in the aqueous phase plays a key role in meeting human health and environmental concerns. Herein we report a series of fluorene-based lanthanide metal–organic frameworks ([Ln2(FDC)3DMA(H2O)3]·DMA·4.5H2O, Ln = Sm (1), Eu (2), Gd (3) and Tb (4), H2FDC = 9,9-dimethyl-2,7-fluorenedicarboxylic acid, DMA = dimethylacetamide). Single crystal X-ray diffraction reveals that 1–4 are isostructural and display a 3D neutral framework. 2 exhibits intense characteristic red emission of Eu3+ ions in the solid state and high selectivity for Pb2+ and Fe3+ ions through fluorescence enhancement and the quenching effect in aqueous solutions, respectively. Interestingly, the fluorescence intensity of 2 shows a good linear relationship with Pb2+ concentration in the range of 0.02–0.1 mM. Furthermore, the dynamic and static quenching constants are calculated to be 320 M−1 and 10 680 M−1 by the fluorescence lifetime and titration experiments in low concentration of Fe3+. In addition, 4 exhibits different fluorescence response behaviors in the presence of Sm3+ or Eu3+ in aqueous solution.
147 citations
TL;DR: In this article, a new family of noncentrosymmetric isostructural compounds, Na2Hg3M2S8 (M = Si, Ge, and Sn), was successfully synthesized.
Abstract: A new family of noncentrosymmetric isostructural compounds, Na2Hg3M2S8 (M = Si, Ge, and Sn), was successfully synthesized. They crystallize in the tetragonal space group P4c2 with Z = 2. Their major structures are composed of infinite cross-connected ∞(HgS3)n chains and isolated [MS4] ligands and show the interesting tunnel features. Interestingly, compared with the structures of A2Hg3M2S8 (A = alkali metal, Na–Cs), it can be found that the structural symmetries show a gradually rising tendency from Cs to Na analogues as a result of cation size effect, which rarely exists in quaternary alkali metal chalcogenides. Property measurements show that title compounds exhibit strong second harmonic generation (SHG) effects with a phase-matching behavior at 2.09 μm, wide transparency range in the infrared (IR) region, and large laser-damage thresholds (LDTs). Remarkably, Na2Hg3Si2S8 and Na2Hg3Ge2S8 achieve the suitable balance between large SHG effects (1.3 and 2.2 × benchmark AgGaS2) and high LDTs (4.5 and 3 × A...
139 citations
TL;DR: 2 unusual isostructural nanocage-based three-dimensional Ln-MOFs, 1-Ln (Ln=Tb, Eu), are constructed, using a new diisophthalate ligand with active Lewis basic triazole sites to exhibit highly efficient luminescent sensing for Fe3+ cations and Cr2 O7 2- anions, as well as selective CO2 capture over CH4.
Abstract: Two unusual isostructural nanocage-based 3D Ln-MOFs, 1-Ln (Ln = Tb and Eu), were constructed using a new diisophthalate ligand with active Lewis basic triazole sites. 1-Eu exhibits highly efficient luminescent sensing for Fe3+ cations and Cr2O72- anions, and selective CO2 capture over CH4.
135 citations
TL;DR: The luminescence explorations demonstrated that 1-Eu exhibits high quenching efficiency and low detection limit for sensing nitrobenzene and Cr2O72-.
Abstract: Two new three-dimensional isostructural lanthanide metal–organic frameworks (Ln(III)-MOFs), [LnL(H2O)3]·3H2O·0.75DMF (1-Ln; Ln = Dy(III) and Eu(III) ions, H3L = biphenyl-3′-nitro-3,4′,5-tricarboxylic acid, DMF = N,N′-dimethylformamide), were synthesized and characterized. The appearance of temperature-dependent out-of-phase (χ″M) signal reveals that complex 1-Dy displays slow magnetic relaxation behavior with the energy barrier (ΔUeff) of 57 K and a pre-exponential factor (τ0) of 3.89 × 10–8 s at 1200 Oe direct current field. The luminescence explorations demonstrated that 1-Eu exhibits high quenching efficiency and low detection limit for sensing nitrobenzene and Cr2O72–. Meanwhile, the fluorescence intensity of the quenched 1-Eu samples will be resumed after washing with DMF or water, indicating that 1-Eu may be used as a highly selective and recyclable luminescence sensing material for sensing nitrobenzene and Cr2O72– anion.
132 citations
TL;DR: It is shown that a tunable breaking and forming of a diatomic bond can be achieved through physical means, i.e., by a moderate biaxial strain, in the newly discovered MoN2 two-dimensional (2D) material, and it is predicted that as the lattice parameter is increased under strain, there exists an isostructural phase transition.
Abstract: The change of bonding status, typically occurring only in chemical processes, could dramatically alter the material properties. Here, we show that a tunable breaking and forming of a diatomic bond can be achieved through physical means, i.e., by a moderate biaxial strain, in the newly discovered MoN2 two-dimensional (2D) material. On the basis of first-principles calculations, we predict that as the lattice parameter is increased under strain, there exists an isostructural phase transition at which the N–N distance has a sudden drop, corresponding to the transition from a N–N nonbonding state to a N–N single bond state. Remarkably, the bonding change also induces a magnetic phase transition, during which the magnetic moments transfer from the N(2p) sublattice to the Mo(4d) sublattice; meanwhile, the type of magnetic coupling is changed from ferromagnetic to antiferromagnetic. We provide a physical picture for understanding these striking effects. The discovery is not only of great scientific interest in e...
117 citations
TL;DR: The structure and properties of two new UiO-67-type metal-organic frameworks, along with their linker synthesis and powder and single crystal synthesis, are presented, and it is seen that these linkers are partly shielding the Zr cluster.
Abstract: The structure and properties of two new UiO-67-type metal–organic frameworks, along with their linker synthesis and powder and single crystal synthesis, are presented. The new MOFs, UiO-67-Me and UiO-67-BN, are based on 3,3′-dimethylbiphenyl and 1,1′-binaphthyl linker scaffolds, and show a much higher stability to water than the thoroughly investigated UiO-67, which is based on the biphenyl scaffold. On the basis of structure models obtained from single crystal X-ray diffraction, it is seen that these linkers are partly shielding the Zr cluster. The new materials have higher density than UiO-67, but show a higher volumetric adsorption capacity for methane. UiO-67-BN exhibits excellent reversible water sorption properties, and enhanced stability to aqueous solutions over a wide pH range; it is to the best of our knowledge the most stable Zr-MOF that is isostructural to UiO-67 in aqueous solutions.
113 citations
TL;DR: In this article, five novel three-dimensional lanthanide metal-organic frameworks (Ln-MOFs) constructed by 4-(3′,5′-dicarboxylphenoxy) phthalic acid (H4dcppa) have been fully characterized.
Abstract: Five novel three-dimensional lanthanide metal–organic frameworks (Ln–MOFs) constructed by 4-(3′,5′-dicarboxylphenoxy) phthalic acid (H4dcppa), namely, {[Eu(Hdcppa)(H2O)2]·H2O}n (Eu-1), [Eu1.5(dcppa) (HCOO)0.5(H2O)2]n (Eu-2), {[Ln2K2(dcppa)2(H2O)6]·mH2O}n (Ln = Eu-3, Tb-4, Gd-5, m = 5 for Eu-3 and Tb-4; m = 4 for Gd-5) (HCOOH = formic acid) have been prepared by hydro(solvo)thermal method and fully characterized. Structural analyses indicated that H4dcppa ligand took four different coordination fashions in 1–5 and, thus, resulted in diversity of the targeted Ln–MOFs: Eu-1 displays the rare 3D (5,5)-connected vbk net, containing one-dimensional left- and right-handed helical chains; Eu-2 possesses a 3D (3,8)-connected tfz-d topology constructed by trinuclear paddlewheel [Eu3(CO2)6] SBUs; 3–5 are isostructural and show 3D (Ln-dcppa4–) + 2D (K-dcppa4–) → 3D (LnK-dcppa4–) structure. Eu-3, with regular 1D channels and open Lewis basic oxygen atoms on the pore surface was utilized for specific sensing and bindin...
96 citations
TL;DR: Electronic structure calculations suggest that the O2 adducts in Co-BTTri are best described as cobalt(II)–dioxygen species with partial electron transfer, while the stronger binding sites in co-BDTriP form cobalt (III)–superoxo moieties.
Abstract: The air-free reaction of CoCl2 with 1,3,5-tri(1H-1,2,3-triazol-5-yl)benzene (H3BTTri) in N,N-dimethylformamide (DMF) and methanol leads to the formation of Co-BTTri (Co3[(Co4Cl)3(BTTri)8]2·DMF), a sodalite-type metal-organic framework. Desolvation of this material generates coordinatively unsaturated low-spin cobalt(II) centers that exhibit a strong preference for binding O2 over N2, with isosteric heats of adsorption (Qst) of -34(1) and -12(1) kJ/mol, respectively. The low-spin (S = 1/2) electronic configuration of the metal centers in the desolvated framework is supported by structural, magnetic susceptibility, and computational studies. A single-crystal X-ray structure determination reveals that O2 binds end-on to each framework cobalt center in a 1:1 ratio with a Co-O2 bond distance of 1.973(6) A. Replacement of one of the triazolate linkers with a more electron-donating pyrazolate group leads to the isostructural framework Co-BDTriP (Co3[(Co4Cl)3(BDTriP)8]2·DMF; H3BDTriP = 5,5'-(5-(1H-pyrazol-4-yl)-1,3-phenylene)bis(1H-1,2,3-triazole)), which demonstrates markedly higher yet still fully reversible O2 affinities (Qst = -47(1) kJ/mol at low loadings). Electronic structure calculations suggest that the O2 adducts in Co-BTTri are best described as cobalt(II)-dioxygen species with partial electron transfer, while the stronger binding sites in Co-BDTriP form cobalt(III)-superoxo moieties. The stability, selectivity, and high O2 adsorption capacity of these materials render them promising new adsorbents for air separation processes.
94 citations
TL;DR: From a luminescent point of view, the heterodinuclear strategy has been successfully applied and allows significant brightness enhancement (+35%) and color tuning from green to yellow to orange to red.
Abstract: Reactions in water between the sodium salt of benzene-1,2,4,5-tetracarboxylic acid (H4btec) and lanthanide ions (Sm-Dy) led to a series of isostructural lanthanide-based coordination polymers with the general chemical formula [Ln4(btec)3(H2O)12·20H2O]∞ with Ln = Sm-Dy. The family has been structurally characterized. From a luminescent point of view, the heterodinuclear strategy has been successfully applied and allows significant brightness enhancement (+35%) and color tuning from green to yellow to orange to red.
TL;DR: Because of the comparable emission intensities of Eu(3+) and Tb(3%) ions, bimetallic CP 8 can be used as a ratiometric luminescent sensor for organic solvent molecules and the luminescence color of the 8 sensor in pyridine and in other guest solvents undergoes obvious changes that can be clearly distinguished by the naked eye.
Abstract: Eleven water-stable isostructural mono/bimetallic lanthanide coordination polymers (Ln-CPs) {[EuxTb1-x (HL)(H2O)3]·H2O}n (x = 1.0 (1), 0.9 (3), 0.8 (4), 0.7 (5), 0.6 (6), 0.4 (7), 0.3 (8), 0.2 (9), 0.1 (10), 0.05 (11), 0 (2), H4L = 5,5'-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid) with uncoordinated Lewis basic triazole sites within the pores were prepared. The Ln-CPs represented by 1 showed a rapid and drastic emission quenching induced by external Fe(3+) and Cr(3+) cations and CrO4(2-) and CO3(2-) anions in aqueous solution. In addition, because of the comparable emission intensities of Eu(3+) and Tb(3+) ions, bimetallic CP 8 can be used as a ratiometric luminescent sensor for organic solvent molecules. Moreover, the luminescent color of the 8 sensor in pyridine and in other guest solvents undergoes obvious changes that can be clearly distinguished by the naked eye.
TL;DR: In this paper, a series of five lanthanide(III) metal-organic frameworks with a general formula of [Ln3(bcpb)4(μ-HCOO)(μ-H2O)2(DEF)]n (1−5) was generated by solvothermal reactions from Ln(NO3)3·6H 2O {Ln = Eu (1), Tb (2), Gd (3), Dy (4), and Sm (5)} and 3,5-bis(3-carboxyp
Abstract: A new series of five lanthanide(III) metal–organic frameworks with a general formula of [Ln3(bcpb)4(μ-HCOO)(μ-H2O)(H2O)2(DEF)]n (1–5) was generated by solvothermal reactions from Ln(NO3)3·6H2O {Ln = Eu (1), Tb (2), Gd (3), Dy (4), and Sm (5)} and 3,5-bis(3-carboxyphenyl)pyridine (H2bcpb) in an aqueous N,N-diethylformamide (DEF) medium. The obtained products were characterized by elemental analysis, FT-IR spectroscopy, thermogravimetric analysis (TGA), and powder and single crystal X-ray diffraction. The latter reveals that all compounds (1–5) are isostructural and feature very intricate 2D metal–organic frameworks. These were topologically analyzed, revealing a very complex hexanodal underlying net that can be simplified further to a binodal 3,5-connected layer with the 3,5L52 topology. Solid-state photoluminescence properties of 1–5 were studied in detail. Compound 1 exhibits a strong red luminescence upon excitation at 338 nm and its lifetime is 532 μs. Compound 2 shows an intense green luminescence upon excitation at 336 and its lifetime is 981 μs. The triplet state (3ππ*) of bcpb2− studied by using the Gd(III) derivative 3 demonstrated that the ligand effectively populates Tb(III) emission (Φ = 70.96%), whereas the corresponding Eu(III) derivative 1 shows a weak luminescence efficiency (Φ = 15.81%) as the triplet state of bcpb2− has a poor match with the 5D0 energy level of Eu(III). A notable feature of 1 is its remarkable sensing ability for Cu2+ ions and 2,4,6-trinitrophenol (TNP). Besides, a series of heterobimetallic Tb-based MOFs, [Tb3(1−x)Eu3x(bcpb)4(μ-HCOO)(μ-H2O)(H2O)2(DEF)]n {x = 0.001, 0.002, 0.003, 0.01, 0.02, 0.03, 0.04, 0.10, 0.15, 0.20} (compounds 2a–2j, respectively), was prepared. The luminescence studies reveal that the simultaneous presence of the characteristic sharp emission bands of Eu3+ and Tb3+ allows the tuning of the photoluminescence colors of such materials by adjusting the doping concentration of the Eu3+ ions.
TL;DR: The series of MOFs FJU-14 are demonstrated as the first examples of the isostructural MOFs whose robustness, thermal stability, and CO2 capacity can be greatly improved via rational modulation of counteranions in the tetrahedral cages.
Abstract: Microporous metal organic frameworks (MOFs) show promising application in several fields, but they often suffer from the weak robustness and stability after the removal of guest molecules. Here, three isostructural cationic metal–organic frameworks {[(Cu4Cl)(cpt)4(H2O)4]·3X·4DMAc·CH3OH·5H2O} (FJU-14, X = NO3, ClO4, BF4; DMAc = N,N′-dimethylacetamide) containing two types of polyhedral nanocages, one octahedron, and another tetrahedron have been synthesized from bifunctional organic ligands 4-(4H-1,2,4-triazol-4-yl) benzoic acid (Hcpt) and various copper salts. The series of MOFs FJU-14 are demonstrated as the first examples of the isostructural MOFs whose robustness, thermal stability, and CO2 capacity can be greatly improved via rational modulation of counteranions in the tetrahedral cages. The activated FJU-14-BF4-a containing BF4– anion can take CO2 of 95.8 cm3 cm–3 at ambient conditions with an adsorption enthalpy only of 18.8 kJ mol–1. The trapped CO2 density of 0.955 g cm–3 is the highest value amon...
TL;DR: The high catalytic efficiency and size-dependent selectivity for smaller epoxides show the potential utility of 1 as a promising heterogeneous catalyst for the cycloaddition of CO2.
Abstract: A series of three new isostructural metal–organic frameworks (MOFs) of nickel(II), [{Ni(muco)(bpa)(2H2O)}·2H2O] (1), [{Ni(muco)(bpe)(2H2O)}·2.5H2O] (2), and [{Ni(muco)(azopy)(2H2O)}·2H2O] (3) [where muco = trans,trans-muconate dianion, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethylene, and azopy = 4,4′-bis(azobipyridine)], have been synthesized and characterized by single-crystal X-ray diffraction analysis and other physicochemical methods. Compounds 1–3 exhibit an interesting 3-fold-interpenetrated three-dimensional pillar-layered framework structure constituted of 4-coordinating (4-c) NiII nodes with {66}-neb net topology. Remarkably, in spite of 3-fold interpenetration, the structures possess one-dimensional channels with dimensions of ∼8.05 × 5.25 A2. Gas (N2, Ar, H2, and CO2) adsorption studies of compounds 2 and 3 revealed selective adsorption properties for CO2 over other gases. In all three structures, the 4-c NiII node has two coordinated H2O molecules that can be reversibly remove...
TL;DR: In this article, a one-pot synthesis of CoII and MnII organic frameworks with anionic frameworks and counterions (Me2NH2) was presented. But the results were limited to a single-dimensional structure.
Abstract: Isostructural CoII and MnII organic frameworks with anionic frameworks and counterions (Me2NH2)+, namely {[M2Cl2(BTC)4/3]·(Me2NH2)+2·4/3H2O}n (M = Co (1) and Mn (2)), have been constructed by one-pot synthesis. Complexes 1 and 2 take paddle-wheel-like dinuclear metal cluster-based three-dimensional structures. Thermogravimetric analysis and variable-temperature powder X-ray diffraction spectra suggested that 1 displays better thermal stability than 2. Both exhibit relatively high proton conductivities at 65% relative humidity (RH) and room temperature (σ > 2.5 × 10–4 S cm–1); however, complex 1 possesses the better cycling capability and stability with Ea = 0.21 eV under 65% RH.
TL;DR: Static and dynamic magnetic characterization of two mononuclear tetrahedral CoII complexes suggest that, despite their similar anisotropic features, CoS4 and CoSe4 relax magnetically via different processes, providing experimental evidence that solid-state effects may affect the magnetic behavior of SIMs.
Abstract: This study reports the static and dynamic magnetic characterization of two mononuclear tetrahedral CoII complexes, [Co{iPr2P(E)NP(E)iPr2}2], where E = S (CoS4) and Se (CoSe4), which behave as single-ion magnets (SIMs). Low-temperature (15 K) single-crystal X-ray diffraction studies point out that the two complexes exhibit similar structural features in their first coordination sphere, but a disordered peripheral iPr group is observed only in CoS4. Although the latter complex crystallizes in an axial space group, the observed structural disorder leads to larger transverse magnetic anisotropy for the majority of the molecules compared to CoSe4, as confirmed by electron paramagnetic resonance spectroscopy. Static magnetic characterization indicates that both CoS4 and CoSe4 show easy-axis anisotropy, with comparable D values (∼−30 cm–1). Moreover, alternating-current susceptibility measurements on these CoII complexes, magnetically diluted in their isostructural ZnII analogues, highlight the role of dipolar m...
TL;DR: Thorough removal of chlorinated impurities allows for modest catalytic turnover in the conversion of 4- phenylbutyl azide into N-protected 2-phenylpyrrolidine, which is the first example of a palladium-catalyzed radical-type transformation facilitated by a redox-active ligand as well as the first C-H amination mediated by ligand-to-substrate single-electron transfer.
Abstract: The synthesis, spectroelectrochemical characterization (ultraviolet–visible and nuclear magnetic resonance), solid state structures, and computational metric parameters of three isostructural PdCl(NNO) complexes 1 [PdCl(NNOISQ)], 2 {[PdCl(NNOAP)]−}, and 5 {[PdCl(NNOIBQ)]+} (NNO = o-aminophenol-derived redox-active ligand with a pendant pyridine) with different NNO oxidation states are described. The reduced diamagnetic complex 2 readily reacts with halogenated solvents, including lattice solvent from crystalline pure material, as supported by spectroscopic data and density functional theory calculations. Thorough removal of chlorinated impurities allows for modest catalytic turnover in the conversion of 4-phenylbutyl azide into N-protected 2-phenylpyrrolidine, which is the first example of a palladium-catalyzed radical-type transformation facilitated by a redox-active ligand as well as the first C–H amination mediated by ligand-to-substrate single-electron transfer.
TL;DR: The analysis of the whole magnetic data allows the conclusion that the magnetization relaxation in these polymorphs mainly takes place through a virtual excited state (Raman process); despite the notable difference between the supramolecular networks of 1 and 2, they exhibit almost identical magnetization dynamics.
Abstract: A mononuclear cobalt(II) complex [Co(3,5-dnb)2(py)2(H2O)2] {3,5-Hdnb = 3,5-dinitrobenzoic acid; py = pyridine} was isolated in two polymorphs, in space groups C2/c (1) and P21/c (2). Single-crystal X-ray diffraction analyses reveal that 1 and 2 are not isostructural in spite of having equal formulas and ligand connectivity. In both structures, the Co(II) centers adopt octahedral {CoN2O4} geometries filled by pairs of mutually trans terminal 3,5-dnb, py, and water ligands. However, the structures of 1 and 2 disclose distinct packing patterns driven by strong intermolecular O–H···O hydrogen bonds, leading to their 0D→2D (1) or 0D→1D (2) extension. The resulting two-dimensional layers and one-dimensional chains were topologically classified as the sql and 2C1 underlying nets, respectively. By means of DFT theoretical calculations, the energy variations between the polymorphs were estimated, and the binding energies associated with the noncovalent interactions observed in the crystal structures were also eval...
TL;DR: Constrained DFT calculations (CDFT) support the ferromagnetic interactions within the layers and investigate the single-ion magnetic anisotropy of the metal ions indicating significant differences between 2-Ni and 2-Co.
Abstract: Reaction of cobalt(II) and nickel(II) thiocyanate with ethylisonicotinate leads to the formation of [M(NCS)2(ethylisonicotinate)2]n with M = Co (2-Co) and M = Ni (2-Ni), which can also be obtained by thermal decomposition of M(NCS)2(ethylisonicotinate)4 (M = Co (1-Co), Ni (1-Ni)). The crystal structure of 2-Ni was determined by single crystal X-ray diffraction. The Ni(II) cations are octahedrally coordinated by two N and two S bonding thiocyanate anions and two ethylisonicotinate ligands and are linked by pairs of anionic ligands into dimers, that are connected into layers by single thiocyanate bridges. The crystal structure of 2-Co was refined by Rietveld analysis and is isostructural to 2-Ni. For both compounds ferromagnetic ordering is observed at 8.7 K (2-Ni) and at 1.72 K (2-Co), which was also confirmed by specific heat measurements. Similar measurements on [Co(NCS)2(4-acetylpyridine)2]n that exhibits the same layer topology also prove magnetic ordering at 1.33 K. Constrained DFT calculations (CDFT) support the ferromagnetic interactions within the layers. The calculated exchange constants in 2-Ni were used to simulate the susceptibility by quantum Monte Carlo method. The single-ion magnetic anisotropy of the metal ions has been investigated by CASSCF/CASPT2 calculations indicating significant differences between 2-Ni and 2-Co.
TL;DR: Three isostructural imidazole-cation-templated metal phosphates (FJU-25) are the first examples to demonstrate that the tuning of metal cation nodes can be an efficient strategy to significantly improve the proton conductivity without changing the structure of the propton-conducting pathway.
Abstract: Three isostructural imidazole-cation-templated metal phosphates (FJU-25) are the first examples to demonstrate that the tuning of metal cation nodes can be an efficient strategy to significantly improve the proton conductivity without changing the structure of the proton-conducting pathway.
TL;DR: Fe-doping can be used to monitor the effects of the heteroatom center within a parent Ga(III) framework without the requirement of synthesizing the isostructural Fe( III) analogue [Fe2(OH)2(L)], MFM-300(Fe2), which has thus far been unable to prepare.
Abstract: Metal-organic frameworks (MOFs) are usually synthesized using a single type of metal ion, and MOFs containing mixtures of different metal ions are of great interest and represent a methodology to enhance and tune materials properties. We report the synthesis of [Ga2(OH)2(L)] (H4L = biphenyl-3,3',5,5'-tetracarboxylic acid), designated as MFM-300(Ga2), (MFM = Manchester Framework Material replacing NOTT designation), by solvothermal reaction of Ga(NO3)3 and H4L in a mixture of DMF, THF, and water containing HCl for 3 days. MFM-300(Ga2) crystallizes in the tetragonal space group I4122, a = b = 15.0174(7) A and c = 11.9111(11) A and is isostructural with the Al(III) analogue MFM-300(Al2) with pores decorated with -OH groups bridging Ga(III) centers. The isostructural Fe-doped material [Ga(1.87)Fe(0.13)(OH)2(L)], MFM-300(Ga(1.87)Fe(0.13)), can be prepared under similar conditions to MFM-300(Ga2) via reaction of a homogeneous mixture of Fe(NO3)3 and Ga(NO3)3 with biphenyl-3,3',5,5'-tetracarboxylic acid. An Fe(III)-based material [Fe3O(1.5)(OH)(HL)(L)(0.5)(H2O)(3.5)], MFM-310(Fe), was synthesized with Fe(NO3)3 and the same ligand via hydrothermal methods. [MFM-310(Fe)] crystallizes in the orthorhombic space group Pmn21 with a = 10.560(4) A, b = 19.451(8) A, and c = 11.773(5) A and incorporates μ3-oxo-centered trinuclear iron cluster nodes connected by ligands to give a 3D nonporous framework that has a different structure to the MFM-300 series. Thus, Fe-doping can be used to monitor the effects of the heteroatom center within a parent Ga(III) framework without the requirement of synthesizing the isostructural Fe(III) analogue [Fe2(OH)2(L)], MFM-300(Fe2), which we have thus far been unable to prepare. Fe-doping of MFM-300(Ga2) affords positive effects on gas adsorption capacities, particularly for CO2 adsorption, whereby MFM-300(Ga(1.87)Fe(0.13)) shows a 49% enhancement of CO2 adsorption capacity in comparison to the homometallic parent material. We thus report herein the highest CO2 uptake (2.86 mmol g(-1) at 273 K at 1 bar) for a Ga-based MOF. The single-crystal X-ray structures of MFM-300(Ga2)-solv, MFM-300(Ga2), MFM-300(Ga2)·2.35CO2, MFM-300(Ga(1.87)Fe(0.13))-solv, MFM-300(Ga(1.87)Fe(0.13)), and MFM-300(Ga(1.87)Fe(0.13))·2.0CO2 have been determined. Most notably, in situ single-crystal diffraction studies of gas-loaded materials have revealed that Fe-doping has a significant impact on the molecular details for CO2 binding in the pore, with the bridging M-OH hydroxyl groups being preferred binding sites for CO2 within these framework materials. In situ synchrotron IR spectroscopic measurements on CO2 binding with respect to the -OH groups in the pore are consistent with the above structural analyses. In addition, we found that, compared to MFM-300(Ga2), Fe-doped MFM-300(Ga(1.87)Fe(0.13)) shows improved catalytic properties for the ring-opening reaction of styrene oxide, but similar activity for the room-temperature acetylation of benzaldehyde by methanol. The role of Fe-doping in these systems is discussed as a mechanism for enhancing porosity and the structural integrity of the parent material.
TL;DR: Red-emitting nitride phosphors excited with blue light have great potential for the fabrication of warm white light-emitted diodes (WLEDs) and four types of coordinated structure models are proposed, corresponding to different coordination environments of Eu(2+), which induces different structural rigidity and stability.
Abstract: Red-emitting nitride phosphors excited with blue light have great potential for the fabrication of warm white light-emitting diodes (WLEDs). Chemical composition and structural modification are generally adopted to optimize the photoluminescence behaviors of the targeted phosphors. Herein, on the basis of the famous CaAlSiN3 phosphors, Eu2+-doped (Ca1–xLix)(Al1–xSi1+x)N3 solid solutions via the cations’ cosubstitution of (CaAl)5+ pair by (LiSi)5+ pair are successfully synthesized by a solid state reaction, and the lattice parameters show a linear decrease with chemical compositions suggesting the formation of the isostructural phase relationship. Four types of coordinated structure models, corresponding to different coordination environments of Eu2+, are proposed over the course of structural evolution, which induces different structural rigidity and stability, and then they are responsible for three-stage changes of emission spectra of Eu2+ in (Ca1–xLix)(Al1–xSi1+x)N3 solid solution.
TL;DR: In this article, a new family of 2-fold interpenetrated primitive cubic (pcu) networks of formula [M(L)2(Cr2O7)]n (M = Co2+, Ni2+, Cu2+ and Zn2+; L = 4,4′-azopyridine), DICRO-3-M-i, has been synthesized and their structures, permanent porosity and gas sorption properties were comprehensively characterised.
Abstract: A new family of 2-fold interpenetrated primitive cubic (pcu) networks of formula [M(L)2(Cr2O7)]n (M = Co2+, Ni2+, Cu2+ and Zn2+; L = 4,4′-azopyridine), DICRO-3-M-i, has been synthesised and their structures, permanent porosity and gas sorption properties were comprehensively characterised. Molecular simulations indicate that CO2 molecules occupy both of the two distinct ultramicropores that run through this isostructural series. The orientation of the Cr2O72− pillars is thought to contribute to high isosteric enthalpy of adsorption (Qst) towards CO2 and temperature programmed desorption experiments reveal that DICRO-3-Ni-i selectively adsorbs CO2 from gas mixtures that simulate flue gas. Performance in this context is among the highest for physisorbents measured to date and these materials are readily regenerated at 50 °C.
TL;DR: The synthesis, structural characterization, luminescence properties, and proton conduction performance of a new family of isostructural cationic 2D layered compounds are reported, and the observed transitions are attributed solely to f-f transitions of the lanthanide ions present.
Abstract: The synthesis, structural characterization, luminescence properties, and proton conduction performance of a new family of isostructural cationic 2D layered compounds are reported. These have the general formula [Ln(H4NMP)(H2O)2]Cl·2H2O [Ln = La3+, Pr3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, H6NMP = nitrilotris(methylphosphonic acid)], and contain Cl– as the counterion. In the case of Ce3+, a 1D derivative, [Ce2(H3NMP)2(H2O)4]·4.5H2O, isostructural with the known lanthanum compound has been isolated by simply crystallization at room temperature. The octa-coordinated environment of Ln3+ in 2D compounds is composed by six oxygen atoms from three different ligands and two oxygens from each bound water. Two of the three phosphonate groups act as both chelating and bridging linkers, while the third phosphonate group acts solely as a bridging moiety. The materials are stable at low relative humidity at less at 170 °C. However, at high relative humidity transform to other chloride-free phases, including the 1D stru...
TL;DR: This work demonstrates that the rational arrangement of open nitrogen sites will favorably improve the C2H2 uptake and thus provides useful information for future design of porous MOFs with high acetylene storage capacities.
Abstract: Replacing the benzene spacer in the organic linker 5,5′-(benzene-1,4-diyl)diisophthalate with the nitrogen containing heterocyclic rings, namely, pyrazine, pyridazine, and pyrimidine results in three organic linkers, which were reacted with copper ions under solvothermal conditions to form three isostructural metal–organic frameworks (ZJNU-46, ZJNU-47 and ZJNU-48) exhibiting exceptionally high sorption capacities with regard to acetylene due to the simultaneous immobilization of open metal sites and Lewis basic nitrogen sites in the frameworks. At 1 atm and 295 K, the gravimetric C2H2 adsorption uptakes reach 187, 213 and 193 cm3 (STP) g−1 for these three compounds. The gravimetric C2H2 adsorption amount of ZJNU-47a is the second highest reported for MOF materials. Notably, despite their same porosities, and densities of open metal sites and uncoordinated nitrogen sites, distinctly different C2H2 adsorption capacities were observed for these three compounds, which we think are mainly associated with the difference in the relative position of nitrogen atoms leading to different binding affinities of the frameworks towards C2H2 guest molecules, and thus different C2H2 adsorptions. This work demonstrates that the rational arrangement of open nitrogen sites will favorably improve the C2H2 uptake and thus provides useful information for future design of porous MOFs with high acetylene storage capacities.
TL;DR: The rare-earth bis(alkyl) compound Sm{C(SiHMe2)3}2THF2 (1b) is prepared by the reaction of samarium(II) iodide and 2 equiv of KC(SiMe2), and compounds 1a,b are isostructural.
TL;DR: Photoluminescence studies reveal that complexes 1Eu, 5Er and 6Yb exhibit characteristic lanthanide luminescence with sharp and well-separated emission bands.
Abstract: Salen-type mononuclear lanthanide complexes with formula (Et3NH)[Ln(3-NO2-salen)2]·solvent (Ln = Eu (1Eu), Tb (2Tb), Dy (3Dy), Ho (4Ho), Er (5Er), Yb (6Yb); 3-NO2-salen2− = N,N′-bis(3-nitro-salicylaldehyde)ethylenediamine dianion) are reported. These compounds are isostructural in which two crystallographically distinct 3-NO2-salen2− act as tetradentate ligands encapsulating the lanthanide ions in a meridional mode forming the [LnN4O4] cores. Slow magnetization relaxation processes associated with single ion magnet (SIM) behaviors are observed in complexes 3Dy, 5Er and 6Yb with the Kramer ions but not in 2Tb and 4Ho with non-Kramer ions. Photoluminescence studies reveal that complexes 1Eu, 5Er and 6Yb exhibit characteristic lanthanide luminescence with sharp and well-separated emission bands. Complex 1Eu is of particular interest in which the organic ligand functioning as a powerful absorbing sensitizer apparently broadens the excitation range into 300–500 nm with the maximum of 460 nm.
TL;DR: In this article, two isostructural energetic cocrystals containing 1,3,5-trinitrobenzene (TNB) were obtained with the energetic materials 1, 3, 5-triiodo-2, 4, 6-trinzene and TBTNB in ratios of 2:1 TNB/ TITNB and 2: 1:1 TBT NB/TBTNB, respectively.
Abstract: Two isostructural energetic cocrystals containing 1,3,5-trinitrobenzene (TNB) were obtained with the energetic materials 1,3,5-triiodo-2,4,6-trinitrobenzene (TITNB) and 1,3,5-tribromo-2,4,6-trinitrobenzene (TBTNB) in ratios of 2:1 TNB/TITNB (1) and 2:1 TNB/TBTNB (2). These materials contain the shortest nitro–iodo and second shortest nitro–bromo interactions seen in the Cambridge Structural Database for organohalides. Computational studies indicate that the cocrystals are more stable than their respective component crystals by 11.5 kJ/mol for 1 and 8.2 kJ/mol for 2. While the formation of an isostructural 2:1 cocrystal with 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) was calculated to be favorable by 8.5 kJ/mol, only a physical mixture of the two coformers was obtained experimentally. Both 1 and 2 possess high crystallographic densities (2.203 and 1.980 g/cm3, respectively) and were found to be insensitive in small-scale impact drop tests, possessing sensitivity between that of TNB and TXTNB (X = I or B...
TL;DR: In this paper, a series of new isostructural lanthanide(III) complexes are reported which are constructed from Schiff base and β-diketonate ligands, namely, [Ln2(DBM)6(L)] (Ln = Sm (1), Eu (2), Gd (3), Dy (4), Yb (5); L = N,N′-bis(pyridin-2-ylmethylene)ethane-1,2-diamine, DBM = dibenzoyl
Abstract: A series of new isostructural lanthanide(III) complexes are reported which are constructed from Schiff base and β-diketonate ligands, namely, [Ln2(DBM)6(L)] (Ln = Sm (1), Eu (2), Gd (3), Dy (4), Yb (5); L = N,N′-bis(pyridin-2-ylmethylene)ethane-1,2-diamine, DBM = dibenzoylmethanide). The structures of the isomorphous complexes 1–5 were determined by single-crystal X-ray crystallography. The two Ln(III) ions in the molecules of 1–5 are bridged by a Schiff base ligand that displays a curved configuration. Complexes 1, 2 and 5 exhibit lanthanide ion-based luminescence not only in the solid state but also in methanol solution. The lifetimes and quantum yields of luminescence were also determined. The magnetic analysis reveals that complexes 4 and 5 exhibit field-induced single-molecule magnet behavior with energy barriers (Ueff/kB) of 46.8 and 23.0 K at direct current fields of 2000 Oe, respectively.