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Solid-state X-ray scintillators are widely applied in medical imaging and space exploration. However, it is still a great challenge to probe into the intrinsic nature of scintillating behaviour due to the ambiguous structure–function relationship. Herein, four structure-defined X-ray scintillating Pb(ii)-based metal–organic frameworks (SMOFs) were successfully obtained under solvothermal conditions, [Pb(1,4-ndc)(DMF)]n (SMOF-1), [Pb(1,4-ndc)(DMA)]n (SMOF-2), [Pb2(2,6-ndc)2(H2O)]n·nDMF (SMOF-3) and [Pb4(2,6-ndc)3Cl2]n (SMOF-4), where 1,4-H2ndc = 1,4-naphthalene dicarboxylate, 2,6-H2ndc = 2,6-naphthalene dicarboxylate, DMF = N,N-dimethylformamide, and DMA = N,N-dimethylacetamide. SMOFs 1–4 show scintillating signals under X-rays triggered by a highly purified tungsten target. Compared with SMOFs 1–3, SMOF-4 exhibits excellent scintillating performance owing to its solvent-free and denser structure, which favours more efficient conversion ability of X-rays to visible light. X-ray stimulated luminescence (XSL) spectra present multiple emission peaks, which is further confirmed by wavelength-dependent luminescence spectra under UV-Vis light, and density of state and DFT calculations. The synergistic effects of heavy metal Pb(ii) centres as effective X-ray absorbers and organic ligands as luminescent motifs endow these Pb(ii)-based MOFs with application prospects in X-ray detection. [ABSTRACT FROM AUTHOR]

Viologen (N,N′-disubstituted bipyridinium) compounds are well known for their electron-transfer photochromic properties and many potential applications. However, viologen-based organic molecules, especially those with aliphatic hydrocarbon substituents, are inclined to be hygroscopic, and most of the known viologen compounds need dozens of seconds or even several minutes to exhibit photoinduced color change. The viologen–carboxylate zwitterion ligand, N,N′-dipropionate-4,4′-bipyridinium (L), is highly hygroscopic and its shortest coloration time is 5 s upon irradiation of a Xe lamp (ca. 110 mW cm−2). After coordination with ZnCl2, the obtained new compound [Zn2LCl4]n (ZnLCl) is highly stable in a wet environment (e.g. 60% relative humidity), and its shortest coloration time is 1 s upon irradiation of the same Xe lamp. X-ray diffraction analysis coupling with multiple experimental spectra (UV-vis, ESR, XPS, and IR) and density of states (DOS) calculations revealed that the photoinduced coloration of L and ZnLCl is contributed mainly by O → pyridinium and Cl → pyridinium electron transfer, respectively. The lower electronegativity of Cl over O and the shorter donor–acceptor separation may explain why ZnLCl has a shorter coloration time. Moreover, enhancement of molecular rigidity by the coordination structure may account for the improvement of moisture stability. [ABSTRACT FROM AUTHOR]

Abstract: We evaluated the individual atom contributions to the second harmonic generation (SHG) coefficients of LiCs2PO4 (LCPO) by introducing the partial response functionals on the basis of first principles calculations. The SHG response of LCPO is dominated by the metal‐cation‐centered groups CsO6 and LiO4, not by the nonmetal‐cation‐centered groups PO4 expected from the existing models and theories. The SHG coefficients of LCPO are determined mainly by the occupied orbitals O 2p and Cs 5p as well as by the unoccupied orbitals Cs 5d and Li 2p. For the SHG response of a material, the polarizable atomic orbitals of the occupied and the unoccupied states are both important. [ABSTRACT FROM AUTHOR]

Crystalline nanotube array would create great opportunity for novel electrical application. Herein we report the first example of a metal halide based crystalline nanotube array which is constructed from an unprecedented giant [PbII18I54(I2)9] wheel cluster, as determined by synchrotron Xray diffraction. The electrical properties of the single crystal were studied and the present compound shows typical semiconductivity and highly anisotropic conductivity. [ABSTRACT FROM AUTHOR]

Two new lead(ii) coordination polymers, [Pb(NO3)(tzib)]n (1) and [Pb(tzib)2]n (2), were successfully synthesized from the reaction of a rigid ligand 1-tetrazole-4-imidazole-benzene (Htzib) and lead(ii) nitrate in different solvents. The obtained polymers have been characterized by single-crystal X-ray diffraction analyses, which show that both polymers feature 2D layer structures. The inorganic anion nitrate in 1 shows a μ2–κO3:κO3 bridging mode to connect adjacent lead ions into a zigzag chain, and then the organic ligands tzib− join the neighboring chains into a 2D layer by a μ3–κN1:κN2:κN6 connection mode. In 2, there are two different bridging modes of the tzib− ligand: μ3–κN1:κN2:κN6 and μ3–κN1:κN6 to coordinate the lead ions into a 2D layer structure. Interestingly, both polymers displayed broadband emissions covering the entire visible spectra, which could be tunable to near white-light emission by varying excitation wavelengths. [ABSTRACT FROM AUTHOR]

In a state of disorder: An inorganic supramolecular complex, (Hg6P4)(CuCl3)2, was prepared that undergoes a ferroelectric transition at about 37   K, and its spontaneous polarization was determined to be about 114   μC m−2 in the polycrystalline form using the high ‐ precision pyroelectric current method. Weak electrostatic supramolecular interactions in 1 lead to the dynamic disorder of ions and ferroelectric transition. [ABSTRACT FROM AUTHOR]

A series of one-dimensional (1-D) N-succinopyridine-based complexes: [Cu(L−)(H2O)2]Cl·2H2O (1), [Pr(L−)(H2O)4]Cl2 (2), [Ln(L−)(H2O)5]Cl2·3H2O (Ln = Eu (3), Gd (4)), and [Er(L−)(H2O)4]Cl2·H2O (5) (HL = N-succinopyridine (−OOC–CH(N+C5H5)–CH2–COOH)) have been prepared and characterized by single-crystal X-ray diffraction. The frameworks of complexes 1, 2 and 5 constructed from dinuclear metal building blocks exhibit 1-D double-strand loop-like chains; these chains are further connected to each other by hydrogen bonds forming a 3-D supramolecular architecture. Whereas complexes 3 and 4 feature hydrogen bonding 2-D supramolecular networks assembled from 1-D chains that are constructed from mononuclear metal building blocks. The effects of different metal ions, steric hindrance and coordination diversities of HL on the polymeric architectures have been discussed. In addition, thermogravimetric and magnetic properties of these complexes were also investigated in this paper. [ABSTRACT FROM AUTHOR]

Four Zn(ii) tetrazolate coordination compounds have been hydrothermally synthesized and structurally determined by single-crystal X-ray diffraction. They are formulated as [Zn(3-tzbd)2]n·nH2O (1), [Zn2(3-tzbd)2(OH)2(4,4′-bipy)]n·nH2O (2), [Zn2(3-tzbd)3(N3)(4,4′-bipy)2]n·nH2O (3) and Zn2(3-tzbd)4(phen)2 (4), where 3-Htzbd = 3-(5H-tetrazol)benzaldehyde. The 3-tzbd− ligand, which was in situ generated through a [2 + 3] cycloaddition reaction of nitrile and azide, displays diverse coordination modes. Compound 1 exhibits a (4,4)-connected two-dimensional (2D) layer generated by the linkage of dinuclear units of [Zn2(μ2-3-tzbd)2] and μ2-3-tzbd− ligands. In 2, Zn(ii) atoms are connected by μ2-3-tzbd− ligands and μ3-OH− anions to form unusual double-stranded stair-like chains, which are further linked by 4,4′-bipy to create a 2D sheet. Compound 3 features an unprecedented one-dimensional (1D) four-legged, triple-ladder chain composed of tetranuclear units [Zn4(μ2-3-tzbd)4(μ2-N3)2]. Two Zn(ii) atoms in 4 are bridged by μ2-3-tzbd− ligands to result in an isolated dinuclear structure. In addition, the luminescent properties of 1–4 were investigated in the solid state at room temperature. The relevant density of states (DOS) calculation results show that their photoluminescence mainly originates from ligand-centered emission and is dependent on the organic ligand incorporated into the compounds. [ABSTRACT FROM AUTHOR]

Two new 3D pillared metal–organic frameworks (MOFs) [Cd 2 (adc) 2 (bpp) 3 ·4H 2 O] n (1) and [Cd 2 (adc) 2 (bpp) 3 ] n (1b) with a 2D breathing mode of reversible dehydration–rehydration have been designed and synthesized. These 3D pillared MOFs contracted and expanded in two dimensions accompanied by dehydration–rehydration. The 1b exhibited faster water vapor response compared to commercial silica gel desiccant at room temperature and humidity. This kind of flexible 3D pillared metal–organic framework of 1 and 1b would be a reliable sensor for monitoring water vapor. [Display omitted] • A 3D metal–organic framework 1 shows dehydration–rehydration with 2D breathing mode. • In situ single-crystal XRD analysis and IR spectrum were used to study the water vapor sensor. • Water absorption rate of 1 is higher than silica gel. Two 3D pillared metal–organic frameworks (MOFs) [Cd 2 (adc) 2 (bpp) 3 ·4H 2 O] n (1) and [Cd 2 (adc) 2 (bpp) 3 ] n (1b) with a 2D breathing mode of reversible dehydration–rehydration have been designed and synthesized. The dynamic behavior between 1 and 1b was detected by in situ single-crystal XRD analysis, which demonstrated that this 3D pillared MOF contracted and expanded in two dimensions accompanied by dehydration–rehydration. Additionally, 1b exhibited faster water vapor response compared to commercial silica gel desiccant at room temperature (21 °C) and humidity (RH% 50), which was detected by in situ IR spectrum. Therefore, the results suggests that this kind of flexible 3D pillared metal–organic frameworks of 1 and 1b would be a reliable sensor for monitoring water vapor. (H 2 adc = 4,4′-azodibenzoic acid, bpp = 1,3-Di(4-pyridyl)propane). [ABSTRACT FROM AUTHOR]

Abstract The appearance of the nitrogen-rich energetic MOFs provides another opportunity for the new-generation of high energetic explosives. In this work, an insensitive energetic nitrogen-rich ligand, 3-amino-1, 2, 4-triazole (Hatz) was imported into the system of transition-metal azides via the coordination polymerization strategy in the hope to prepare mixed-ligand nitrogen-rich high energetic MOF materials with low sensitivity and finally a solvent-free 3D energetic compacted metal-organic framework (MOF), Cd 3 (atz) 4 (N 3 ) 2 ( 1 ) was successfully isolated under hydrothermal conditions. Compound 1 was characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis (EA), different scanning calorimetry (DSC), and thermogravimetry analysis (TGA). Topological analysis shows that the 3D framework of 1 can be abstracted into a ten-connected topological network. The volatile azido ion can be viewed as a counter anion to be stabilized in a 3D framework as the connection of Cd(II) ions with two independent atz− ligands still remains a 3D framework. Compound 1 has a high calculated density ( ρ ) of 2.517 g cm−3. The standard molar enthalpy of formation ( Δ f H o ) of 1 was calculated to be 1330.10 kJ mol−1, which is higher than those of most of the previously 3D energetic MOFs. Sensitivity tests demonstrate that 1 is insensitive to external mechanical stimuli. TGA demonstrates that 1 has an excellent thermostability which can be stable up to 372 °C. Compound 1 can be served as a high-energy-density material with a favorable level of safety due to its excellent energetic performances, low sensitivities and excellent thermostability. Graphical abstract Importing an insensitive energetic nitrogen-rich ligand, 3-amino-1, 2, 4-triazole (Hatz) into the system of transition-metal azides via the coordination polymerization strategy, a N-rich high energetic MOF material with low sensitivity, Cd 3 (atz) 4 (N 3 ) 2 was isolated. This compound has a high calculated density ( ρ ) of 2.517 g cm−3. The standard molar enthalpy of formation ( Δ f H o ) of this compound was calculated to be 1330.10 kJ mol−1, which is higher than those of most of the previously 3D energetic MOFs. fx1 Highlights • A nitrogen-rich high energetic 3D MOF, Cd 3 (atz) 4 (N 3 ) 2 , was successfully synthesized. • This MOF has a high calculated density of 2.517 g·cm−3 and can be stable up to 372 °C. • The volatile azido contained 3D MOF has a very high calculated molar enthalpy of formation of 1330.10 kJ·mol−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • The plasma significantly promotes dry reforming of methane reaction. • The well stable plasma-involved dry reforming of methane reaction. • The atomic-level adjacent NiFe bimetallic catalyst exhibits high activity. • Rich surface oxygen and strong CO 2 adsorption contribute to stability. The plasma technology can effectively reduce the high temperature (≥700 °C) reaction condition of dry reforming of methane (DRM) reaction. But the inevitable carbon deposition problem seriously hinders the progress of plasma-involved DRM reaction. In order to promote the carbon elimination reaction between the adsorbed CO 2 and carbon deposition produced by CH 4 cracking, we have developed an effective atomic-level adjacent NiFe bimetallic catalyst. Compared to the Ni-based monometallic catalyst, the atomic-level adjacent NiFe bimetallic catalyst shows high activity and excellent stability in the plasma-involved DRM reaction. The conversions of CO 2 and CH 4 are 80.5% and 73.8%, respectively. Meanwhile, the catalytic performance remains well stable during the 100 h time-on-stream evaluation. The atomic-level adjacent NiFe bimetals were characterized by XRD, TEM and EXAFS et al., which are responsible for the improved activities. Most importantly, the addition of Fe can increase the surface oxygen and enhance CO 2 adsorption confirmed by XPS and CO 2 -TPD, which beneficial to improve the ability to convert carbon deposition and improve the stability of catalyst. This work provides a feasible synthetic strategy for designing the high activity and well stability catalyst for the plasma-involved DRM reaction. [ABSTRACT FROM AUTHOR]

In a state of disorder: An inorganic supramolecular complex, (Hg6P4)(CuCl3)2, was prepared that undergoes a ferroelectric transition at about 37   K, and its spontaneous polarization was determined to be about 114   μC m−2 in the polycrystalline form using the high ‐ precision pyroelectric current method. Weak electrostatic supramolecular interactions in 1 lead to the dynamic disorder of ions and ferroelectric transition. [ABSTRACT FROM AUTHOR]

A novel open-framework cadmium selenite bromide, [Cd10(SeO3)8Br4]·HBr·H2O (1), has been obtained by a solid-state reaction at 450°C, and the structure has been determined by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in Pbcm of the orthorhombic system: a=10.882(3), b=16.275(5), c=18.728(6)Å, V=3317(2)Å3, R1/wR2=0.0411/0.0659. Compound 1 is characteristic of a novel 3-D open-framework structure, composing ∞ 2[CdSeO3] layers and the pillars of edge-shared CdO3Br2 square pyramids. The lattice water molecules and the HBr molecules locate in the voids of the framework. Optical absorption spectrum of 1 reveals the presence of an optical gap of 1.65eV. Solid-state photoluminescent study indicates that compound 1 exhibits strong violet emission. TG–DSC measurement shows that compound 1 is thermally stable up to 200°C. [ABSTRACT FROM AUTHOR]

Abstract: Sr2/3Zn1/3TiO3 (1) and Ba5/6Zn1/6TiO3 (2) with perovskite structure have been prepared by a facile sol–gel method, among which the A sites (Sr and Ba for 1 and 2, respectively) were partially replaced by zinc ions. The photocatalysts were characterized by powder X-ray diffraction, UV–vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The results of photocatalysis experiment showed that both 1 and 2 exhibited good activity for water reduction to form H2 without cocatalysts loading under ultraviolet light irradiation. Compared with pure SrTiO3 and BaTiO3, 1 and 2 showed remarkable improvement in H2 production efficiency, respectively. And the photocatalytic mechanisms of them were investigated by the theoretical method. This study demonstrated that the substitutional doping of appropriate ions could change the crystal and band structures and significantly promote electron transport in catalysts, which result in their good photocatalytic activities. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of Cd(NO3)2, Co(NO3)2, Na(3-cba) and NaN3 yielded a 3D heterometallic coordination polymer, [Cd(μ5-3-tzba)(μ2-3-cba)(μ3-OH)Co(H2O)] n ·2nH2O 1 (3-H2tzba=3-(5H-tetrazol)benzoic acid and 3-Hcba=3-cyanobenzoic acid), which was characterized by single-crystal X-ray diffraction. The in situ [2+3] cycloaddition reaction of nitrile and azide in presence of Cd(II) salt afforded tetrazolate-based 3-tzba2− ligand. In 1, metal-oxo chains [Cd(μ3-OH)Co] n are linked by 3-tzba2− in an unprecedented μ5-κN1:κN2:κN3:κN4:κO1,O2 coordination mode to form 2D layers, which are further pillared by 3-cba− to generate a 3D open framework encapsulating 1D chiral channels. Variable-temperature magnetic studies show that 1 exhibits antiferromagnetic interactions between Co(II) ions bridged by μ3-OH group. [Copyright &y& Elsevier]

Abstract: The reaction of Zn(II) ions and chelidamic acid (2,6-dicarboxy-4-hydroxypyridine) gave a novel 1D coordination polymer, [Zn3(C7H2NO5)2·8(H2O)] n (1), which are characterized by X-ray single crystal diffraction. The crystal structure of 1 reveals that Zn(II) centers are linked via chelidamic acid to form one-dimensional chains, further linked by hydrogen bonds to form a 3-D network. The optical properties were investigated in terms of diffuse reflectance and fluorescent spectra, which exhibit strong green luminescence. The electronic band structure along with the density of states (DOS) calculated by the DFT method indicate that compound 1 is a semiconductor and that the origin of the emission band may be mainly ascribed to ligand-to-ligand charge transfer (LLCT) where the electrons are transferred from the O-2p to C-2p states. [Copyright &y& Elsevier]

Abstract: Three new metal complexes, Cu(4-Hcba)2(4-cba)2(Py)2 (4-Hcba=4-cyanobenzoic acid) 1 and M[H(4-cba)2]2(Py)2 (M=Ni 2, Co 3), have been prepared by the treatment of 4-Hcba with the respective metal nitrate M(NO3)2 (M=Cu, Ni, Co) in the presence of pyridine (Py). Single-crystal X-ray diffraction analyses (3 is isostructural to 2) show that the obtained complexes are of isolated mononuclear and the metal atoms have distorted octahedral coordination environment. Two different types of intramolecular hydrogen bonds exist: asymmetrical O–H⋯O for 1 and symmetrical O⋯H⋯O for 2 and 3. The crystal packing between the molecular complexes is controlled mainly by T-shaped C–H⋯π interactions between pyridine and phenyl rings. Preliminary discussions on IR, UV–VIS and fluorescent spectra have also been carried out. [Copyright &y& Elsevier]

Self-assembly of Cd(II) and Htzib (1-tetrazole-4-imidazole-benzene) under solvothermal condition generated a 3D polymer [Cd 2 Cl 2 (tzib) 2 n ·nH 2 O, which could display relative high thermal stability and interesting tunable ultraviolet-to-visible luminescent property. • Polymer 1 owns novel 3D structure. • Polymer 1 displays interesting tunable ultraviolet-to-visible emissions by simply varying excitation wavelength. • Polymer 1 possesses relative high thermal stability. Solvothermal reaction of CdCl 2 ·2.5H 2 O and 1-tetrazole-4-imidazole-benzene (Htzib) yielded a new cadmium(II) coordination polymer [Cd 2 Cl 2 (tzib) 2 n ·nH 2 O (1), which has been characterized by single-crystal X-ray diffraction analysis. In 1 , metal center Cd(II) ions are linked by μ 2 -Cl and tzib– with μ 3 - κ 3 N1:N2:N6 and μ 4 - κ 4 N1:N3:N4:N6 coordination modes into a novel 3D structure. Due to the lattice water molecules filled in the closed cages of 1, they cannot easily escape from the 3D framework. Because of this structural feature, polymer 1 displays relative high thermal stability up to ~400 °C. Moreover, luminescent properties and theoretical calculations of 1 are also discussed. Interestingly, tunable ultraviolet-to-visible emissions for 1 are observed. [ABSTRACT FROM AUTHOR]