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A sensitive detection method combined with an effective on-line concentration may improve the analytical performance of a paper-based analytical device (PAD), and its merits of low cost and portability in POCT are fully demonstrated. Here, a sensitive PAD system with chemiluminescence (CL) detection and electrokinetic preconcentration was introduced, and the performance was demonstrated by the detection of hemin. A commercially available low cost and miniaturized optical detection module was used for the CL detection. Firstly, hemin was stacked on a simple paper fluidic channel based on field amplified stacking (FAS), and then a CL reagent (luminol–H2O2) was loaded on the stacked band to initiate the CL reaction. The photons were directly detected using the detection module. With optimization of the background electrolyte (BGE), voltage and CL reagent, a limit of detection (LOD) of 0.58 nM for hemin was obtained with a linear range of 1–1000 nM (R2 = 0.995). With FAS, the signal intensity was about 13-fold enhanced. This PAD also exhibited satisfactory selectivity over possible interfering components at a 104 times higher concentration. The applicability of the PAD was demonstrated by the detection of hemin from iron supplements and human serum samples. With total manual operation, recovery rates of 84.8–115.6% were obtained with an RSD of less than 14.3%. With the introduction of the optical detection model, and together with FAS, both the LOD and dynamic range of this PAD were effectively improved. [ABSTRACT FROM AUTHOR]

The paper reports on the synthesis, crystal structure, thermal and magnetic properties of spin crossover (SCO) salts containing the [Fe(bpp)2]2+ cation (bpp = 2,6-bis(pyrazol-3-yl)pyridine) and different rigid polycarboxylate anions, such as anthracene-9,10-dicarboxylate (ADC), benzene-1,3,5-tricarboxylate (BTC) and biphenyl-4,4′-dicarboxylate (BPDC). Compound [Fe(bpp)2](ADC)·9H2O (1) shows a porous hydrogen-bonded structure with water molecules sitting in the channels. It contains low-spin (LS) Fe2+ cations that undergo crossover to the high-spin (HS) state upon dehydration. Anhydrous 1 remains HS on cooling at low temperatures. A similar magnetic behaviour is obtained for the partially protonated BTC salt [Fe(bpp)2](HBTC)·5H2O (2), showing a spin change concomitant with dehydration to a HS phase that undergoes gradual and partial SCO on cooling, affecting 25% of the Fe2+ cations. Instead, the BPDC salt [Fe(bpp)2](BPDC)·5H2O (3) has a ground HS state in its fully hydrated form. [ABSTRACT FROM AUTHOR]

Radical-cation salts of formula β?-(BEDT-TTF)4[(H3O)Fe(C2O4)3]·guest have produced a large number of superconductors and provided a route to introduce magnetism and chirality into the same multifunctional material. A relationship has been found in these salts between the length of the b axis and the superconducting Tc. Increasing the b axis length by introducing larger guest molecules, such as benzonitrile and nitrobenzene, gives the highest superconducting Tcs in this family of salts. Smaller guests such as pyridine show no superconducting transition, whilst asymmetrical guests which are larger than nitrobenzene have given a different bilayered structure. Other potential guest molecules have been limited by their ability to be used as the solvent in which the crystals are grown via electrocrystallisation. This paper reports a method which introduces guest molecules into the crystal which are a solid or liquid additive within the crystal-growing solvent 1,2,4-trichlorobenzene:ethanol. We present the crystal structures of five new BEDT-TTF radical-cation salts with tris(oxalato)ferrate anions using guest molecules toluene, phenol, benzaldehyde, 4-bromobenzaldehyde, and kojic acid. [ABSTRACT FROM AUTHOR]

We previously reported that Zr substitution improves the chemical stability of Ba3Y4O9 and nominally 20 mol% Zr-substituted Ba3Y4O9 is an oxide-ion conductor at intermediate temperatures (500–700 °C). However, the influence of Zr substitution on the structural properties of Ba3Y4O9 was poorly understood. This paper aims to comprehensively understand the crystal structure of Ba3Y4O9 with Zr substitution by powder X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) measurements, and first-principles calculations. From the results, firstly we found that the hexagonal unit cell of Ba3Y4O9 reported in the database should be revised as doubled along the c-axis in terms of the periodicity of oxide-ion positions. The revised unit cell of Ba3Y4O9 consists of 18 layers of BaO3 and 24 layers of Y which periodically stack along the c-axis. In this work, we focused on the cationic lattice and noticed that the periodical stacking of Ba and Y layers comprises a similar sequence to that in the body-centered cubic (BCC) structure. There are two regions in the Ba3Y4O9 structure: one is a hetero-stacking region of Ba and Y layers (Ba–Y–Ba–Y–Ba) and the other is a homo-stacking region (Ba–Y–Y–Ba). It is noteworthy that the former region is similar to a cubic perovskite. In Zr-substituted Ba3Y4O9, Zr ions preferentially substitute for Y ions in the hetero-stacking region, and therefore the local environment of Zr ions in Ba3Y4O9 is quite similar to that in BaZrO3. Besides, the Zr substitution for Y in Ba3Y4O9 increases the fraction of the cubic-perovskite-like region in the stacking sequences. The structural change in the long-range order strongly affects the other material properties such as chemical stability and the ionic-conduction mechanism. Our adopted description of perovskite-related compounds based on the stacking sequence of the BCC structure should help in understanding the complex structure and developing new perovskite-related materials. [ABSTRACT FROM AUTHOR]

Viologen is capable of generating radicals in response to an applied stimulus, giving it an abundance of stimuli responsive properties. However, the radical state of viologen is often unstable, which hinders further studies on the radical properties of viologen. In this paper, the salicylhydrazide group was chosen as a donor group to bond with mono-substituted bipyridyl groups to obtain three novel D–A type viologen compounds. The compounds were harvested and characterized by X-ray single crystal diffraction, optical spectroscopy, EPR and DFT calculation, etc. The results show that compounds 1–3 adopt certain free radical states at room temperature under ambient light, which may be attributed to the electron-donating properties of the salicylhydrazide group and the degree of system conjugation. In addition, compound 1 has a hydrochromic property and compounds 2 and 3 have photocurrent effects under UV radiation. [ABSTRACT FROM AUTHOR]

In this paper, a new high-pressure (HP) polymorph of the otherwise known oxyfluoride K2MoO2F4 is presented. The crystal structure was determined by use of single-crystal X-ray diffractometry and its features are described in detail herein. HP-K2MoO2F4 crystallizes in the monoclinic space group C2/m (no. 12) with the cell parameters a = 13.8579(5), b = 5.8109(2), c = 6.9442(3) Å, β = 90.36(1)°, V = 559.18(4) Å3, and Z = 4 at T = 301(2) K. Bond valence (BV) and charge distribution (CHARDI) calculations were carried out to support the assignment of oxygen and fluorine to the various anion positions and Madelung part of lattice energy (MAPLE) calculations were used to validate the structure model. Infrared spectroscopy provided further information on the structure and water content of the inseparable side phase. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis and characterization of a Cl-bearing member of the phosphate family of compounds with a tetragonal crystal structure and similar topology in the basic projection. The title compound was obtained under hydrothermal conditions and its crystal structure was determined by single crystal low temperature X-ray diffraction. The structure of NaCo7.38(PO4)4Cl4 is formed with CoO4Cl2 octahedra sharing faces and assembled into eight-component ring clusters with a very short Co–Co distance of 3.014 Å. These clusters are linked in a three-periodic network via vertex-bridge contacts of adjacent octahedra and PO4 tetrahedra. Na atoms occupy the open channels of the framework. The structure is discussed as a derivative of cubic sulphohalite, Na6(SO4)2ClF, with the symmetry lowering from the widespread Fm3¯m space group of sulphohalite to the tetragonal acentric space group I4¯2m in our case; these space groups are symmetrically related by subordination "group → subgroup". Theoretical calculations of possible pathways of Na migration through the framework showed that although the structure contains a sufficient number of voids for sodium ions, their migration is limited by the size of the channels. However, the obtained results indicated that the migration of Li+ ions is very likely through a two-periodic network parallel to the ab plane, which means that Li-containing structural varieties of NaCo7.38(PO4)4Cl4 with possible formulae Li5Co2+Co3+3(PO4)4Cl4 or Li4Co3+4(PO4)4Cl4 can possess ionic conductivity. The angle of intracluster Co–O–Co bonds of 105.4° allows us to assume that there is an antiferromagnetic exchange interaction between the Co atoms, and we assume that the intercluster exchange interactions between Co2+/3+ ions through the intermediate PO4 groups are also probable. [ABSTRACT FROM AUTHOR]

This paper reports three new crystallographically characterized europium complexes with composition as follows: [Eu(fod)3(L1)] (1), [Eu(fod)3(L2)] (2) and [Eu(fod)3(L3)] (3) {L1 = benzimidazole (bzi), L2 = 4,7-diphenyl-1,10-phenanthroline (bath), L3 = 2-(2-pyridyl) benzimidazole (py-im) and fod = anion of 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione (Hfod)}. The single crystal (SC) XRD analysis shows that complex 1 is seven-coordinated while complexes 2 and 3 are eight-coordinated with the geometrical structures of a mono-capped octahedron and a trigonal dodecahedron, respectively. The NMR spectra of the complexes validate the SC-XRD results in solution. The complexes are stable in solution as no dissociation of any ligand was observed in the NMR spectra of the complexes. The photophysical properties of the complexes in solution, solid state, and PMMA thin films were studied. The hypersensitive transition 5D0 → 7F2 dominates the emission spectra in all phases, showing the highly asymmetric environment around the Eu(III) ion. The bath ligand is found to be the best sensitizer of the Eu ion and hence complex 2 shows the strongest luminescence properties with the highest absolute quantum yield among the three complexes. The CIE coordinate analysis shows that pure red-luminescence is emitted by the Eu complexes in the solid state since the coordinates found in this phase are closer to the standard NTSC 1987 values. The optical band gaps were determined for the complexes and the observed values suggest that the complexes can have possible applications in the field of semiconductor materials. [ABSTRACT FROM AUTHOR]

Exploring the functionalities of materials requires a profound understanding of the crystal structure. In this paper, room temperature crystal structures of a new solid solution (1 − x)Ba(Cu1/3Nb2/3)O3-(x)PbTiO3 have been investigated in the entire compositional span and different crystallographic phases and phase coexistence regions have been discovered. The confirmation of the symmetry of these crystal structures has been done with the help of Rietveld analysis of the high-resolution XRD data. Despite both the end components, Ba(Cu1/3Nb2/3)O3 and PbTiO3, having tetragonal (P4mm) symmetry, new cubic and monoclinic phases have been discovered for the intermediate compositions with multiple phase boundaries. The composition region 0.05 ≤ x ≤ 0.55 exhibits a cubic crystal structure and increasing PbTiO3 concentration to 0.62 results in a unique coexistence of two tetragonal phases with different tetragonalities. This transformation is mediated by coexisting cubic and tetragonal phases, for 0.59 and 0.60. The crystal structure of the solid solution later transforms into coexisting monoclinic and tetragonal phases for a wider compositional span i.e., 0.65 ≤ x ≤ 0.85. This composition region is very fascinating, as two phenomenologically different monoclinic structures have been observed in it. Finally, a tetragonal phase at x = 1 is achieved through the mediation of two coexisting tetragonal phases, for the region 0.85 < x ≤ 0.975. The evolution of different crystallographic structures and the coexisting phases are critically comprehended using the variations in the lattice parameters and unit cell volume. The presence of multiple phase boundaries spread across a wide range of compositions makes this solid solution very intriguing and a viable choice for exploring different properties with compositional tuning. [ABSTRACT FROM AUTHOR]

The Cr3+-doped near-infrared (NIR) phosphors have been extensively investigated owing to their promising applications in biomedicine, food safety detection, and night vision surveillance. However, achieving broadband (FWHM > 160 nm) NIR emission is still challenging. In this paper, novel Y2Mg2Ga2−xSi2O12:xCr3+ (YMGS:xCr3+, x = 0.005–0.08) phosphors were prepared by a high-temperature solid-state reaction. The crystal structure, photoluminescence properties of the phosphor, and the device performance of a pc-LED were researched in detail. When excited at 440 nm, the YMGS:0.04Cr3+ phosphor exhibited broadband emission in the range of 650–1000 nm, peaking at 790 nm with a full width at half-maximum (FWHM) of up to 180 nm. The wide FWHM of YMGS:Cr3+ is conducive to its extensive application in NIR spectroscopic technology. In addition, the YMGS:0.04Cr3+ phosphor could maintain 70% of the initial emission intensity at 373 K. By combining the commercial blue chip with the YMGS:0.04Cr3+ phosphor, the resulting NIR pc-LED demonstrated a near-infrared output power of 14 mW with a photoelectric conversion efficiency of 5% at a drive current of 100 mA. This work provides a broadband emission NIR phosphor option for NIR pc-LED devices. [ABSTRACT FROM AUTHOR]

Transition metal-based two-dimensional nanomaterials with competing magnetic states are at the cutting edge of spintronic and low-power memory devices. In this paper, we present a Fe-rich NbFe1+xTe3 layered telluride (x ≈ 0.5), which shows an interplay of spin-glass and antiferromagnetic states below the Néel temperature of 179 K. The compound has a layered crystal structure, where the NbFeTe3 layers are terminated by the Te atoms and van der Waals gaps. Bulk single crystals grown by chemical vapor transport reactions possess the (1¯01) cleavage plane suitable for the exfoliation of two-dimensional nanomaterials. Combination of high-resolution transmission electron microscopy and powder X-ray diffraction reveals the zigzag ladders of Fe atoms inside the structural layers, as well as complementary zigzag chains of the partially occupied Fe positions in the interstitial region. Fe atoms carry large effective magnetic moment of 4.85(3)μB per atom in the paramagnetic state yielding intriguing magnetic properties of NbFe1+xTe3. They include frozen spin-glass state at low temperatures and spin-flop transition in high magnetic fields indicating promising flexibility of the magnetic system and its potential control by magnetic field or gate tuning in the spintronic devices and heterostructures. [ABSTRACT FROM AUTHOR]

Copper sulfides have gained significant attention as alternative electrodes for rechargeable batteries. A simple and easily scalable synthetic pathway to access these materials is highly desirable. This paper describes the facile synthesis of metal-rich digenite Cu1.8S nanocrystals from a structurally characterized new single-source molecular precursor in various high boiling solvents of varied polarity. The as-prepared nanostructures were thoroughly characterized by PXRD, Raman spectroscopy, EDS, XPS, electron microscopy techniques and diffuse reflectance spectroscopy to understand the crystal structure, phase purity, elemental composition, morphology and band gap. It was found that the reaction solvent has a profound role on their crystallite size, morphology and band gap, however the crystal structure and phase purity remained unaffected. Pristine Cu1.8S nanostructures have been employed as an anode material in lithium-ion batteries (LIBs). The cell delivers a high initial charge capacity of ∼462 mA h g−1 and retains a capacity of 240 mA h g−1 even after 300 cycles at 0.1 A g−1. DFT calculations revealed that multi-size polyhedron layers in the direction perpendicular to the two Li movement channels aid in the sustainable uptake of Li atoms with controlled volume expansion. The structure-mediated flexibility of the metal-rich Cu1.8S lattice during lithiation permits high cyclability with reasonable retention of capacity. [ABSTRACT FROM AUTHOR]

Co-precipitation of Ni0.8Co0.1Mn0.1(OH)2 (NCM811) and Mg-doped (0.25 wt% and 0.5 wt%) NCM811 precursors is carried out from concentrated metal sulphate solutions. In this paper, the aim is to study the role of magnesium dopant in the co-precipitation step of NCM811, the cathode active material and further the Li-ion battery cell performance. Based on the results, magnesium was fully co-precipitated in the NCM811 precursors, as expected from thermodynamic calculations. The presence of magnesium in these precursors was also confirmed by several characterization methods and magnesium was evenly distributed in the sample. It was observed that tapped density decreased and surface area increased with an expected increase in Mg content. Surprisingly, Mg doping did not improve the cyclability of coin cells, due to the stable crystal structure of NCM811. However, a slight improvement in cyclability was seen in pouch cells after 1000 cycles. A washing effect was clearly seen in lattice parameters and washing also decreased the capacity retention after 62 cycles for all samples. [ABSTRACT FROM AUTHOR]

The 6p orbit coupling of bismuth ions and the magnetism of iron ions endow bismuth–iron compounds with magnetic, optical and electrical properties. In this paper, non-rare-earth bismuth–iron crystals, KBa8Fe12(Bi6−xFex)O38 (x = 0.2, 1.1, 2.0, 2.9, and 3.8), with a large magnetocaloric effect were prepared by a hydrothermal method. The structure–function relationship is discussed. With the increase of the Fe content, the lattice parameters and unit cell volume decrease, while the magnetization intensity shows an increase on the whole and a fluctuation at the same time. The increase of the Fe content can improve the magnetocaloric effect. Importantly, the maximum magnetic entropy change (ΔSM) of KBa8Fe12(Bi4.9Fe1.1)O38 is as high as 1.54 J kg−1 K−1 at the low temperature of 2 K. [ABSTRACT FROM AUTHOR]

In recent years, the research and development of new white LEDs have attracted extensive attention. Whether the new LEDs have a higher color rendering index and can simulate natural sunlight without damaging human health is the issue of concern. Therefore, we introduce in detail the ultraviolet (UV) excited luminescence characteristics of Eu ions, Ce ions, and other ions in different host lattice (aluminate, silicate, phosphate, and borate) matrices. This paper summarizes the introduction and application of rare-earth ions as activation center phosphors and expounds on the application potential of cyan and blue phosphors in many fields such as display technology from the aspects of excitation and emission characteristics, lifetime, color purity, and thermal stability. Finally, we put forward our views on improving the thermal stability of phosphors and selecting crystals with suitable structures as the host for the preparation of phosphors. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) have emerged as a new class of colloidal semiconductor nanomaterials due to their fascinating optoelectronic properties and potential applications. However, the intrinsic lattice defects and phase instability are still dilemmas that limit their further applications. This paper provides an updated review of the synthesis strategy of MHPs based on surface engineering, including encapsulation, passivation, and repair. This surface engineering approach could protect MHPs from degradation in the external environment, stabilize the crystal structure and reduce surface defects of perovskites. With these treatments, the MHPs present improved optical and photoactive phase stability. However, traditional colloidal perovskite nanocrystals (NCs) are synthesized through a single reaction phase, leading to tedious purification and ionization processes. We intend to comprehensively study how surface engineering affects the optical properties of NCs. Furthermore, we provide new insights into the interface engineering of perovskite nanocrystals which could inspire potential future directions for preparing MHP NCs in multiphase colloidal solutions of this domain. [ABSTRACT FROM AUTHOR]

Saponification, resulting from pigment–binder interactions, is one of the most endangering phenomena affecting the appearance and stability of painted works of art. The crystallization of metal carboxylates (soaps) in paint layers is recently assumed as the most critical point for the development of undesirable changes induced by saponification, however, the factors triggering it are not fully understood. The red pigment cinnabar (HgS) has been suspected of contributing to saponification, however, the paucity of reliable reference structural data limited the experimental research of its effect at the molecular level. Within this study we synthesized mercury(II) carboxylates of the formula Hg(C16)x(C18)2−x (x = 0.0; 0.2; 0.5; 0.8; 1.0; 1.2; 1.5; 1.8; 2.0) where C16 and C18 are hexadecanoate (palmitate) and octadecanoate (stearate), respectively, and characterize them by combination of X-ray powder diffraction (XRPD) and 13C and 199Hg solid state NMR (ssNMR). For a more detailed interpretation of their structural and thermal behavior, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used. The crystal structure of the studied mercury carboxylates was described on the basis of complementary ssNMR and XRPD measurements, Rietveld refinement and DFT calculations. All the subjected compounds crystallize in a monoclinic lattice of the C2/c symmetry. Mercury atoms are arranged in a slightly distorted square antiprismatic geometry and are monodentatically bonded to carboxylate anions. The structural disorder at the aliphatic end of the stearic acid chains was detected in the mixed carboxylates. Within the paper, the structural (dis)similarity with the corresponding lead carboxylates is discussed. The synthesized and characterized mercury carboxylates were applied to describe neo-formed mercury soaps in a model experiment simulating an egg-based paint system. [ABSTRACT FROM AUTHOR]

Explaining the intensification of upconversion luminescence (UCL) from a single phase NIR-upconverting (UC) crystal due to non-lanthanide dopant insertion appears challenging in the absence of proper mechanistic investigation. In this paper, through extensive synchrotron based X-ray probing, we made an attempt to understand the variations in the structural attributes of UC crystals generated through non-lanthanide ion doping. The structures of the NaYF4/Yb3+/M3+ (M3+ = Er3+/Tm3+) UC crystals doped with different Li+ concentrations were primarily investigated using Rietveld refinement analysis from synchrotron X-ray diffraction (SXRD) and supported with absorption data (XAFS), where necessary. The structural investigation was also supported by TEM, HRTEM, XANES, FT-IR and Raman spectroscopy. Rietveld analysis revealed that all the generated Li+ doped NaYF4 crystals belong to the P6 space group. Most of the Li+ ions were found to be localized in octahedral voids and lattice positions, simultaneously, in the P6 crystal structures. The overall study showed that the change in the UCL intensity behavior with Li+ incorporation could not be predicted from the lattice parameters, morphology or the particle size variation. A detailed XAFS study rather suggested the possible existence of local lattice disorder, which was found to be reflected in terms of lattice strain obtained from Williamson--Hall analysis, irrespective of the activator ions. The remarkable coherence between the variation trends of UCL intensity and lattice strain indicated that the perturbation of the local symmetry field is in some way connected with the local disorder that may not always manifest through average structural attributes like lattice parameters. [ABSTRACT FROM AUTHOR]

Disordered crystals have garnered increasing attention as new laser materials because of their broad emission bandwidths. This paper reports a novel Yb-doped strontium yttrium phosphate (Yb:YSr3(PO4)3) crystal with a disordered structure, as well as its crystal growth, structure, spectral properties, and laser performance. The crystal structure (cubic, 4¯3m point group) was refined using the Rietveld method. The absorption cross-section and fluorescence lifetime were determined to be 1.31 × 10−20 cm2 at 976 nm and 1267 μs, respectively. The stimulated emission cross-section was 1.04 × 10−20 cm2 at 1013 nm, with an emission bandwidth of 55 nm. In addition, continuous-wave laser operation was realized using the Yb:YSr3(PO4)3 crystal with different output coupler transmissions, where the obtained maximum output power and slope efficiency were 1.3 W and 61%, respectively. A dual-wavelength regime with wavelengths centered at 1039 nm and 1047 nm (Δν = 2.2 THz) was achieved under certain conditions; thus, this crystal is expected to be employed for developing terahertz sources. In addition, the laser can operate at multiple wavelengths, ranging from 1023 to 1050 nm. The results indicate that the Yb:YSr3(PO4)3 crystal with a disordered structure may be a promising multi-wavelength laser crystal. [ABSTRACT FROM AUTHOR]

A systematic investigation of the system manganese(II) salt–H2SBA–auxiliary ligand–solvent successfully led to the isolation of six new multidimensional coordination polymers: [Mn5(2-pic)2(DMA)4(SBA)4]·4DMA (1), [Mn3(pyzc)2(DMF)(H2O)(SBA)2]·DMF·H2O (2), [Mn5(pyzc)2(DMA)4(SBA)4]·4DMA (3), [Mn5(mpyzc)2(DMA)4(SBA)4]·4DMA (4), [Mn2(phen)2(H2O)(SBA)2]·2DMA (5) and [Mn3(phen)2(SBA)3]·5DMF (6), where SBA = 4,4′-sulfonyldibenzoate 2-pic = 2-picolinate, pyzc = 2-pyrazinecarboxylate acid, mpyzc = 5-methyl-2-pyrazinecarboxylate and phen = 1,10-phenanthroline. The selected use of N-containing ligands to block the coordination sites of manganese enabled us to understand their influence in controlling the nuclearity and the dimensionality of the extended manganese carboxylate coordination networks. Single crystal X-ray crystallography established that the structures of all the solids were built of homometallic clusters varying from monomeric to pentameric manganese(II) carboxylate units. While the solids 1, 3 and 4 are isostructural, possessing a 2D coordination network containing pentanuclear SBUs of the composition {Mn5N2O3}, the 2D solids 2 and 5 are respectively built from binuclear {Mn2N4O7} and trinuclear {Mn3N2O14} SBUs. The solid 6 is the lone example of a 3D coordination network in this system. Dielectric measurements showed comparable dielectric behavior for the isostructural solids 1, 3 and 4 with ε′ ∼ 17 at room temperature. Relatively lower values observed for 2 and 5 (ε′ ∼ 14) were due to a combined effect of strong manganese carboxylate interaction and the presence of ordered polar guest molecules. Significantly higher values for 6 (∼21) could be attributed to disordered guest molecules. All the six solids exhibited antiferromagnetic behavior at lower temperatures. This paper also discusses the growth of the solids in terms of supramolecular aggregation of manganese carboxylate complex species with or without an auxiliary ligand, proposing a mechanistic pathway to trace the chemical events from molecules to the final solid. [ABSTRACT FROM AUTHOR]

Co-crystallization of the antibacterial agent proflavine (PF) with the inorganic salt ZnCl2 by mechanochemical and solution methods results in the formation of novel compounds ZnCl3(HPF) (1) and [HPF]2[ZnCl4]·H2O (2), both containing the proflavinium cation (HPF)+. Both compounds show a 50–125% enhanced antimicrobial activity with respect to a reference standard of AgNO3, and a 25–50% enhancement to the behaviour of the separate components against pathogen indicator strains of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. In terms of crystal structure, both compounds ZnCl3(HPF) and [HPF]2[ZnCl4]·H2O are characterized by extensive π-stacking interactions between the proflavine moieties. The same interaction is predominant in the previously unknown crystal structures of neutral proflavine (PF), as well as in that of its dihydrated monochloride salt, [HPF]Cl·2H2O, which are also described in this paper. [ABSTRACT FROM AUTHOR]

The majority of the fabrication procedures of lanthanide-doped materials involve thermal treatment that often results in crystallite regrowth, stabilizing the specific crystal structure and resulting in luminescence enhancement. The efficiency and intensity of up-conversion luminescence are closely related to the structure and synthesis process of the materials. Herein, well-crystallized and pure tetragonal NaY(MoO4)2 microcrystals with a uniform octahedral shape have been successfully synthesized via an environmentally friendly hydrothermal method, followed by annealing treatment. The phases, structures, morphologies, and compositions of the synthesized products annealed at 500–1000 °C remain unchanged, indicating high thermal stability. Furthermore, the NaY(MoO4)2:Yb3+/Er3+ microcrystals exhibit strong green emission when irradiated using infrared (980 nm) or ultraviolet (378 nm) wavelengths. Upon 980 nm excitation, up to 37-fold luminescence enhancement is achieved when the samples are annealed at about 700 °C. Interestingly, the high colour purity of the strong green emission is not only independent of the dopant concentration and heat treatment temperature, but it is also independent of the excitation conditions, including power and wavelength, and this makes it particularly suitable as a green safety signal light and luminescent security ink in paintings. As-prepared safety inks with NaY(MoO4)2:Yb3+/Er3+ microcrystals were used for visual fingerprint recognition printed on A4 paper with three-level fingerprint security features, significantly increasing the difficulty of illegal imitation and enhancing the levels of anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Cadmium sulphide (CdS) is a promising material for photocatalytic hydrogen production. Compared with hexagonal CdS (h-CdS), the research on cubic CdS (c-CdS) is much less. Especially, detailed studies on the preparation condition optimization and photostability of c-CdS are still insufficient. In this paper, c-CdS was prepared by a simple precipitation method and characterized by XRD, SEM, TEM and XPS techniques. Firstly, the Cd to S molar ratio and aging time were optimized to find out their influences on the crystal structure, morphology, chemical state and hydrogen production performance of CdS. The c-CdS obtained at a Cd : S ratio of 5 : 8 and an aging time of 6 h (denoted as CdS-8-6) possesses the highest performance of 37.7 μmol h−1. Secondly and more importantly, cyclic hydrogen production tests were conducted on CdS-8-6 and a series of determinations were carried out on the recovered samples to investigate its photostability during reaction. [ABSTRACT FROM AUTHOR]

A careful selection of organic and inorganic components enables the production of unusual structure types with promising practical properties by facile syntheses. In this paper, we describe novel supramolecular architectures comprising organic adamantane-like divalent building blocks and iodide or polyiodide anions. Highly acidic conditions facilitated the formation of a doubly protonated organic ligand out of 5,7-dimethyl-1,3-diazaadamantane that generates three different crystal structures with inorganic counterions. In these structures, cationic substructures are constructed by transforming neutral organic ligands into [(C10N2H20)I]+ or [(C10N2H20)(H2O)]2+ cations, which crystallize with charge-compensating iodine-based anions of different complexities. All three crystal structures are characterized by various noncovalent forces, ranging from strong (N)H⋯I, (O)H⋯I, and (N)H⋯O hydrogen bonds to secondary and weak I⋯I interactions. Raman and diffuse reflectance spectroscopy as well as DFT calculations were employed to describe the electronic structures and optical properties of new supramolecular architectures, with particular attention to the role of non-covalent interactions. [ABSTRACT FROM AUTHOR]

A bibliographic and literature-based analysis of the impact of the Cambridge Structural Database (CSD) and the papers associated with crystal structures in the CSD has been undertaken. The analysis shows the broad impact of the CSD in the chemical sciences and also highlights how areas where the CSD has impact have changed over time. In addition, we note the changing nature of crystallography as a science, observing how crystal structures are now impactful. A brief illustration of some more unusual contributions to the CSD and publications using the CSD is also presented. [ABSTRACT FROM AUTHOR]

The synthesis, crystallisation and detailed description of the crystal structure of the THF solvates of four halogen (F, Cl, Br and I) derivatives of dianthranilide (5H,11H-dibenzo[b,f][1,5]diazocine-6,12-dione) have been reported. The influence of the halogen size on the conformation of the halogen derivative, the overall supramolecular architecture including the existing scheme of intermolecular interactions and the selected energy issues have been discussed in detail. The solvates which are described in this paper exhibit an interesting arrangement of molecules in their crystals resembling a "honeycomb". The variety of interactions between the respective molecules, including hydrogen bonds, halogen-mediated noncovalent interactions and π–π contacts, makes them an attractive target for crystallographic studies. The results of our analysis may lead to a better understanding of the role of a halogen functional group in the rational design of specific multicomponent crystalline networks based on compounds consisting of two substituted phenyl rings separated by a fused heterocyclic moiety. [ABSTRACT FROM AUTHOR]

This paper reports on the oxidative dissolution ability in dichloromethane and water of the methimazole–iodine system towards gold and palladium in powder. This research has a potential application in the recovery process of these metals from electrical and electronic waste equipment (WEEE). The iodine-adduct of methimazole (1-methyl-3H-imidazole-2-thione; MeImHS) oxidises gold and palladium powders in dichloromethane to form the complexes [AuI(MeImHS)2]I3 and [PdII(MeImHS)4](I4)0.73·2(I)0.27. The X-ray crystal structure of the palladium complex shows a square-planar Pd(II) ion S-coordinated to four MeImHS units with the charge essentially balanced by an unusual tetraiodide I42− with minor amounts of iodide. The oxidative dissolution of palladium in water medium produces the cation [PdII(MeImHS)4]2+. Considering the reaction conditions under which the process was performed ([I2] = 1.14 × 10−3 M, T = 20 °C, pH = 5, reaction time 24 h), the obtained value of 64% of oxidation yields from Pd(0) to Pd(II) is to be considered satisfactory. No appreciable oxidation was observed for the gold powder in water. The feasibility of recovering palladium from the triiodide salt of the complex cation [PdII(MeImHS)4]2+ was verified by carrying out a two-step reduction process using magnesium powder. [ABSTRACT FROM AUTHOR]

Exploring efficient and stable oxygen evolution reaction (OER) catalysts with earth-abundant elements has been an urgent task in water splitting. Metal–organic frameworks (MOFs), possessing abundant active metal sites and tunable porous crystalline structures, are promising as OER catalysts. In this paper, a MOF based on benzotriazole-5-carboxylate (Co3-btca) that contains unsaturated coordinated metal centers and a 1D channel was selected to act as an OER catalyst. To optimize the OER performance, isostructural bimetallic and trimetallic frameworks were obtained by doping with Fe and/or Ni ions. The optimized Co2.36Fe0.19Ni0.45-btca possesses the lowest overpotential of 292 mV at 10 mA cm−2 and a small Tafel slope of 72.6 mV dec−1. The enhanced catalytic performance could be attributed to the synergistic effect between the unsaturated coordinated Co, Fe and Ni sites, which are beneficial for the nucleophilic attack of OH− forming adsorption intermediates. [ABSTRACT FROM AUTHOR]

A specific number of structures described in this paper with adamantane and memantine fragments have been synthesised and characterised. Their single crystals have been grown and their crystal structures have been determined. XPac analysis has shown that there are four sets of isostructural crystals based on adamantane/memantine-specific hydrogen bond patterns and packing of bulky substituents. The use of packing density analysis, QTAIMC and Hirshfeld surface analyses has allowed the elucidation of the influence of the nature and position of functional groups and molecular arrangement on the strength of non-covalent interactions in crystals and overall packing efficiency. The nature and size of a fragment in the para-position of the phenyl ring have been found to have the highest influence on the packing architecture. [ABSTRACT FROM AUTHOR]

In this paper, we reported, for the first time, the preparation of La2MnTiO6 double perovskite nanostructures using a simple sol–gel method in the presence of citric acid as the size controlling agent. The crystalline structure, morphology, and elemental composition of the prepared samples were characterized by XRD, TEM, FE-SEM, and EDX mapping analysis. Owing to superior electronic properties of the double perovskite, we used the prepared samples in the photocatalytic degradation of acid blue 113 (AB 113) under visible light irradiation. The photocatalytic degradation of AB 113 was nearly 72% after 120 min irradiation. Also, the effects of the photocatalyst amount and pH value of the dye solution were studied. Investigation on the photocatalytic degradation mechanism using various radical scavenging agents revealed that the photo-generated holes are the dominant oxidants for the degradation of AB 113. The reusability experiment showed that the prepared sample has good recyclability even for 6 reaction cycles. [ABSTRACT FROM AUTHOR]

In this paper, a series of mononuclear/binuclear Cu(i) complexes, [CuI(dpq)(PPh3)2](CF3SO3)·CH3OH (1a), [CuI(dppz)(PPh3)2](CF3SO3)·CH3OH (1b), [CuI2(dpq)2(dppm)2](CF3SO3)2 (2a), [CuI2(dppz)2(dppm)2](CF3SO3)2 (2b), [CuI(dpq)(dppp)](CF3SO3)·CH3OH (3a), [CuI(dppz)(dppp)](CF3SO3)·CH3OH (3b), [CuI(dpq)(POP)](CF3SO3)·CH3OH (4a), [CuI(dppz)(POP)](CF3SO3)·CH3OH (4b), [CuI(dpq)(xantphos)](CF3SO3) (5a), and [CuI(dppz)(xantphos)](CF3SO3) (5b) {dppm = 1,1-bis(diphenylphosphino)methane; dppp = 1,3-bis(diphenylphosphino)propane; POP = bis[2-(diphenylphosphino)phenyl]ether; xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; dpq = pyrazino[2,3-f][1,10]-phenanthroline; dppz = dipyrido[3,2-a: 2′,3′-c]phenazine} have been synthesized and characterized by using IR, NMR, elemental analysis, terahertz (THz) time-domain absorption spectroscopy, UV-vis and fluorescence spectroscopy methods as well as single crystal X-ray diffraction analysis. The single crystal X-ray diffraction results indicated that the immediate geometry around each central Cu(i) in the above complexes is a distorted tetrahedron with the central metal atom being coordinated by the two phosphorus atoms of the phosphine ligands and two nitrogen atoms of the bidentate N-containing heterocyclic ligand moieties. It is found that complexes 1a–5a and 5b show photoluminescence in the solid state at room temperature with the highest quantum yield up to 0.5519, and the increased conjugation in the diimine ligands leads to emission reduction along with a red-shift in the emission maxima. Detailed photo-physical studies and density functional theory calculations (DFT) of these complexes have revealed that their lowest energy absorptions and emissions are ascribed to metal-to-ligand charge transfer (MLCT) excited states. The above results indicate that conjugation effects of N-heteroaromatic ligands play a significant role in the emission properties of mononuclear/binuclear Cu(i) complexes. For the first time, terahertz time-domain spectroscopy is applied for qualitatively understanding the photophysical properties of complexes, revealing that terahertz time-domain spectra are sensitive to the weak interaction between the ligands, especially the diimine ligands, and terahertz spectra are strongly correlated with photoluminescence quantum yields of the complexes. [ABSTRACT FROM AUTHOR]

Sulfamethoxazole (SMZ) is a synthetic broad-spectrum antibiotic of biopharmaceutical classification system (BCS) class IV, with both low solubility and permeability, requiring probably higher drug doses in orally-administered formulations to promote an expected systemic absorption. To overcome such limitations and especially to increase its solubility, this study has a main purpose of the development of novel optimized crystalline forms of SMZ. Herein, two crystalline salts of SMZ (SMZBr and SMZNO3) have been synthesized from solution crystallization and characterized using X-ray (single and powder), spectroscopic (infrared, FT-IR) and thermal (DSC and TGA) techniques. Furthermore, a solubility study was performed in pure water and compared with the SMZCl salt and SMZ form I. It was observed that the SMZBr salt exhibits phase stability in water media and shows enhanced solubility compared to the SMZCl salt and SMZ form I. Additionally, a qualitative litmus paper test was employed to verify the volatiles released during the thermal drug degradation. [ABSTRACT FROM AUTHOR]

This paper reports a possible mechanism of acetic acid formation from CO2, CH3I and H2 in aqueous media and the central role played by a water-soluble Rh-based electron storage catalyst. In addition to water-solubility, we also report the crystal structures of two presumed intermediates. These findings together reveal (1) the advantage of water, not only as a green solvent, but also as a reactive Lewis base to extract H+ from H2, (2) the role of the metal (Rh) centre as a point for storing electrons from H2 and (3) the importance of an electron-withdrawing ligand (quaterpyridine, qpy) that supports electron storage. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis, crystal structures and magnetic properties of three complexes with formulae [Cu3Ln2(L)2(teaH)2(N3)2Cl2]·xCH3CN (H2L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, teaH3 = triethanolamine; Ln = Ho, x = 3 for 1, Ln = Dy, x = 2 for 2 and Ln = Gd, x = 3 for 3), and the structural topologies of 1–3 are unprecedented. The structural analyses revealed that the metal ions in 1–3 formed a kite-like topology with Ln1, Ln2 and Cu1 located on the body, while Cu2 and Cu3 located on both wings. The dc data of 3 were fitted, which showed that the magnetic couplings are antiferromagnetic between CuII and between GdIII ions, while they are ferromagnetic between CuII and GdIII ions. AC magnetic susceptibility studies for 1 and 2 indicated that both complexes exhibit frequency dependent χ′′ signals at low temperature, but no χ′′ peaks were observed, which may be due to the deviation from ideal geometry for HoIII in 1 and DyIII in 2 and the presence of weak magnetic couplings between paramagnetic ions within the two complexes. For 3, the ac magnetic susceptibilities with zero dc fields show no frequency dependent χ′′ signals because of the isotropy of GdIII. The orientation of the easy magnetization axes of two DyIII in 2 was estimated using the Magellan program, indicating that the magnetic anisotropy axes for Dy1 and Dy2 are almost perpendicular with the angle of 86.630°. [ABSTRACT FROM AUTHOR]

Searching for new IR nonlinear optical (NLO) crystals with a high laser damage threshold (LDT) is still a challenge. In this paper, two new halides, β-RbCdI3·H2O and CsCdI3·H2O, have been synthesized by a conventional solution reaction. Both of them crystallize in the monoclinic space group Pc (no. 7). In their crystal structures, all the corner-sharing [CdI4] tetrahedra connect with each other to form 1D chains, which further connect with [Rb(H2O)]+/[Cs(H2O)]+ complexes to form three-dimensional (3D) frameworks. All the polar [CdI4]2− groups align in such a way that results in a favorable net polarization. Powder second-harmonic generation (SHG) measurements indicate that β-RbCdI3·H2O and CsCdI3·H2O show phase-matchable SHG responses of 2.7 and 2.6 times that of KH2PO4 (KDP). The infrared transmission range can reach 21 μm. The UV-vis diffuse reflectance spectra indicate that the band gaps of β-RbCdI3·H2O and CsCdI3·H2O are about 3.26 and 3.54 eV, respectively. A preliminary measurement indicates that the LDT of their powders is about 90 and 100 MW cm−2, respectively, suggesting that β-RbCdI3·H2O and CsCdI3·H2O are two new promising IR NLO materials. Their band structure and optical property calculations based on DFT methods are carried out. [ABSTRACT FROM AUTHOR]

This paper reports the syntheses, crystal structure and photophysical properties of eight-coordinate complexes [Sm(dbm)3(impy)] and [Tb(dbm)3(impy)] (dbm is the anion of 1,3-diphenyl-1,3-propanedione and impy is 2-(1H-imidazol-2-yl)pyridine). The complexes are thoroughly characterized by elemental analysis, FTIR, ESI-MS+ and thermal analysis (TGA/DTA). The distorted square antiprismatic structure of the complexes is revealed by single crystal X-ray diffraction analysis. The central metal is coordinatively saturated by six coordinated oxygen atoms of three dbm units and pyridyl and imidazolyl nitrogen atoms of impy. The steady-state and time resolved photoluminescence of the solid complexes and their PMMA hybrid films are investigated and discussed. The decay time of Sm(iii) samples is fitted by a mono-exponential function while that of Tb(iii) is fitted by a bi-exponential function. The CIE chromaticity of the solid [Sm(dbm)3(impy)] and its hybrid films does not show any significant change in colour and a light red colour is emitted by both. The CIE chromaticity of [Tb(dbm)3(impy)] indicates that the overall emission of the solid and the hybrid films is comprised of a blue contribution. The contribution of the blue colour in the luminescence emerging from the 3% hybrid film (w/w) appears to be minimal due to negligible ligand fluorescence and light green luminescence results. The luminescence from the 1.5% hybrid film is purely blue since ligand fluorescence dominates. The solid and its 6% hybrid film emit a turquoise colour. This colour is slightly more intense in the case of the hybrid film. [ABSTRACT FROM AUTHOR]

A comprehensive theoretical study of 18 metal azides is reported. Herein, the first theoretical model of impact sensitivity is developed which can safely distinguish sensitive and insensitive (alkali) metal azides. The model includes four solid-state criteria and three features of isolated atoms and molecules. Using ten azides with experimentally known crystal structures, we obtained the values of sensitivity function Ω which correlates well (R2 = 0.91) with experimental impact energies. When three azides with a predicted crystal structure are added, the correlation becomes slightly poorer (R2 = 0.84), but it still predicts alkali metal azides to be insensitive. Thus, the impact energies for sensitive azides lie in the range of 1–16 N cm−2, while the predicted values for alkali metal azides lie in the range of 40–87 N cm−2. Theoretical background for the proposed model of impact sensitivity is discussed in the paper. [ABSTRACT FROM AUTHOR]

First principles calculations of the α-quartz phase of Si1−xSnxO2 predict great benefits of the substitution of Si by Sn with the d11 piezoelectric constant (5.72 pC N−1) for Si0.8Sn0.2O2, which is predicted to be twice that of quartz (2.85 pC N−1). Furthermore, the value of the d11 piezoelectric constant increases four times in the case of substitution with tin in comparison with that for germanium. The first Sn-substituted α-quartz single crystals have been grown under hydrothermal conditions, but the degree of substitution is still very low (xmax = 0.001). The analyses of additional compounds recovered after growth runs indicate that Sn crystallizes in a six-fold coordination with silicon by forming a mixed Si/Sn oxide in the autoclave, which may explain the low degree of substitution in the α-quartz single crystals. A new compound with the formula Na2Si4SnO9(OH)4 is identified, and the structure is determined. This paper predicts high performance of the Sn-substituted single quartz crystals. Crystal growth experiments show that Sn substitution is possible in the structure of quartz-type by using a crystal growth process favoring the formation of four-fold coordinated Sn species [SnO4] in the solution for obtaining a high Sn ratio in the quartz-crystals. [ABSTRACT FROM AUTHOR]

This article compares the reactivity patterns of β-ketoiminate (AcNac) and β-thioacetyliminate (SacNac), with special reference to the unsymmetrical β-diketiminate (NacNac), on the selective {Ru(acac)2} metal platform that encompasses the electronically rich acac (= acetylacetonate) moiety. In this regard, structural and spectroelectrochemical aspects have been reported for the newly designed complexes [RuIII(acac)2(AcNacR)] (1a–1c), [RuIII(acac)2(SacNacH)] (2) and [RuIII(acac)2(NacNacR)] (3a–3c) [R = para-substituents (H, Cl, OMe) of the N-bearing aryl group]. The subsequent exploration of the impact of metal chelation on the reactivity profile of the β-ketoiminate analogues revealed the following: (a) the facile oxygenation of the methine centre (Cβ–H) of the unsymmetrical NacNac in 3 led to ketodiimine (L1) in [RuII(acac)2(L1)] (4), while analogues AcNac and SacNac in 1 and 2, respectively, remained resistant to oxidative functionalisation due to their relatively lower charge densities at the methine (Cβ) centres. (b) Hydrolysis of the relatively weak C–S bond of SacNac resulted in a μ3-S bridged [{Ru(acac)2}3(μ3-S)] complex (2′). (c) Unlike 2 and 3, AcNac in 1 underwent an interesting transformation selectively in a non-polar solvent (toluene) to the 3-acetyl AcNac (L2−) moiety in 5 ([RuIII(acac)2(L2)]) via the generation of a new C–C bond at its backbone, indicating the ambiphilic feature of AcNac. The paper also addresses the aforesaid transformation processes and fractional redox non-innocence of AcNac, SacNac and NacNac in 1n, 2n and 3n (n = +1, 0, −1), respectively. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the effect on the structural, magnetic and magnetocaloric properties of La and Sr-deficiencies in the La0.67Sr0.33MnO3 compound. Rietveld refinement of the X-ray powder diffraction patterns confirms that all of the compounds have crystallized into a rhombohedral crystal symmetry with an R3̅c space group. X-ray photoelectron spectroscopy measurements revealed that the parent compound has a mixed valance of Mn3+/Mn4+, whereas Mn2+/Mn3+/Mn4+ mixed valency is found in the case of both La and Sr-deficient compounds. The La0.67Sr0.33MnO3 compound shows a magnetic transition temperature of 365 K, while the La and Sr-deficient compounds exhibit transition temperatures of 367 K and 355 K, respectively. Among the studied compounds, the Sr-deficient compound shows the highest magnetic entropy change (ΔSM) of 5.08 J kg−1 K−1 at 352 K for a 50 kOe field with a relative cooling power (RCP) of 142 J kg−1 and an adiabatic temperature change of 3.48 K, while the parent and La-deficient compounds exhibit a −ΔSM of 4.78 J kg−1 K−1 at 364 K and of 4.12 J kg−1 K−1 at 364 K, respectively. The temperature dependence of the electrical resistivity with and without applied magnetic fields reveals that the La-deficient compound has one order and the Sr-deficient compound has two orders of suppression in the electrical resistivity. Thus, the Sr-deficient compound shows promising behaviour for reduction of the magnetic transition temperature towards room temperature, along with an increase in the ΔSM values, and enhancement in the electrical conductivity. Therefore, it could be possible to tune the transition temperature towards room temperature without compromising the magnetic entropy change in order to develop materials for magnetic refrigeration applications. [ABSTRACT FROM AUTHOR]

The present paper reports the structures and the third order nonlinear optical properties of four coordination polymers prepared by hydrothermal methods using nickel acetate or cobalt acetate, bisimidazolyl ligands and different aromatic carboxylic acids, namely [Co(H2O)2(1,2-BIB)2](Co(DBS)(1,2-BIB)]2·7H2O (1), [Ni(H2O)2(1,2-BIB)](CBA)·H2O (2), [Ni(1,2-BIB)(SDA)]·4H2O (3) and [Ni(H2O)(1,2-BIB)(HBTA)]·2H2O (4) (1,2-BIB = 1,2-bis((1H-imidazol-1-yl)methyl)benzene, H2DBS = sodium 3,5-dicarboxybenzenesulfonate, H2CBA = 2-(carboxymethyl)benzoic acid, H2SDA = 4,4′-sulfonyldibenzoic acid and H3BTA = benzene-1,3,5-tricarboxylic acid). Compound 1 has a one-dimensional structure, containing a polymeric cationic chain and a polymeric anionic chain. In compound 2, the Ni(II) ions are alternately linked by 1,2-BIB ligands and CBA ligands to form a joint-like chain structure. In compound 3, the metal ions are connected by 1,2-BIB to form a ladder-like structure, and SDA ligands are located on both sides of the chain. In compound 4, the Ni(II) ions are alternately connected by 1,2-BIB and BTA ligands to form a two-dimensional structure. We investigated the third-order nonlinearity of the compounds by a single-beam Z-scan technique. Interestingly, the compounds exhibit different third-order nonlinearities. Compound 1 has a saturable absorption (SA) and a self-defocusing effect with the nonlinear absorption coefficient β being -12.4 × 10-7 m W-1 and the nonlinear refractive index γ being -8.51 × 10-14 m² W-1. Compound 2 presents only a selfdefocusing effect with the nonlinear refractive index γ being -128.87 × 10-14 m² W-1, while compounds 3 and 4 show a reverse-saturation absorption (RSA) effect with the nonlinear absorption coefficient β being 4.42 × 10-7 and 2.97 × 10-7 m W-1, respectively. We calculated the band structure and the total (TDOS) and partial density of states (PDOS) of the four compounds. The calculated results are satisfactory for explaining the experimental results. This shows that intramolecular MLCTs or LMCTs have a significant impact on the third-order nonlinearity of the compounds. [ABSTRACT FROM AUTHOR]

In this paper we report the synthesis of the new layered perovskite oxide carbonate, Ba3Yb2O5CO3. This phase is formed when 3BaCO3 : 1Yb2O3 mixtures are heated in air at temperatures ≤1000 °C, while above this temperature the carbonate is lost and the simple oxide phase Ba3Yb4O9 is observed. The structure of Ba3Yb2O5CO3 was determined from neutron diffraction studies and consists of a tripled perovskite with double Yb–O layers separated by carbonate layers, the first example of a material with such a structure. Further studies showed that analogous Ba3Ln2O5CO3 phases could be formed for other rare earths (Ln = Y, Dy, Ho, Er, Tm and Lu). The results highlight the ability of the perovskite structure to accommodate carbonate groups, and emphasise the need to consider their potential presence particularly for perovskite systems prepared in lower temperature synthesis routes. [ABSTRACT FROM AUTHOR]

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as huperphlegmine A from Huperzia phlegmaria. [ABSTRACT FROM AUTHOR]

Different concentration variants of Y2/3Cu3−xZnxTi4O12 (x = 0.00, 0.10, 0.20 and 0.30) ceramics were fabricated by the semi-wet route at a lower sintering temperature of 950 °C. The effect of zinc substitution at the Cu-site in yttrium copper titanate in the context of the microstructure, dielectric and magnetic properties has been discussed and reported in this paper. XRD demonstrated a single phase formation of YCZTO ceramic only up to the concentration x = 0.20. Rietveld refinement of the XRD profile gave the space group Im3̅, which crystallizes in a pseudo-cubic phase with no change during its refinement. SEM studies revealed the presence of small grains in two different ranges, 1–2 μm and 2–3 μm, with no distinct grain boundaries in any composition. SAED patterns obtained by TEM also suggested the formation of a thermodynamically stable polycrystalline phase of YCZTO ceramics. A thin film of Y2/3Cu3−xZnxTi4O12 (x = 0.00 and 0.10) ceramic, when subjected to AFM studies, revealed that both undoped and zinc-doped YCTO ceramics exhibited a Leptokurtic type of distribution of round shaped grains with an average size of 59 nm and 90.8 nm. With an increase in the temperature, both dielectric constant and dielectric loss increase. A magnetic study confirmed that the ceramic remains in the paramagnetic phase at 300 K, although it undergoes an antiferromagnetic to paramagnetic transition around its Neel temperature. [ABSTRACT FROM AUTHOR]

In this paper we describe the synthesis, characterization, and X-ray crystal structures of two ligands, diethyl-N,N′-bis(p-tolyl)malonimidate and 1,3-bis(dimethylamino)-N,N’-bis(p-tolyl)propanediimidate. Their corresponding rhodium(i) dicarbonyl, dimethylaluminium, and bis-ligated zinc complexes have also been prepared and characterized. The donor properties of the ligands have been studied and have been compared to those of the traditional anionic N,N’-chelating ligand nacnac. [ABSTRACT FROM AUTHOR]

Non-metallic η²-H2 complexes are extremely rare; moreover in the case of boranes (with the exception of the BH5 molecule) the existence of such structures was only indicated by computational studies. In a recent paper we have demonstrated that external electron donor groups can stabilize the η²-H2 complexes, similar to the backdonation in the case of transition metals. In this paper we present evidence of a new stabilizing effect: electron donation from the B-R bonds to the H2 σ* orbital. The stability and electronic structure of several mono-, di-, and trisubstituted borane-H2 complexes were investigated by ab initio calculations. SiR3 groups were found to facilitate the σ(B-R)σ*(H-H) interaction, increasing the stability of the η² complexes. Furthermore in the case of tris(trimethyl)silylborane, the exceptional stability of a novel neutral pentavalent borane structure is shown. [ABSTRACT FROM AUTHOR]

Well-dispersed uniform spheres (∼0.7–1.5 μm in diameter) of YPO4 and (Y,Ln)PO4 (Ln = Eu, Tb, Dy, Ho, Tm, Ce, and Eu/Tb) tetragonal phosphate hydrates have been directly synthesized via microwave-assisted processing. The polycrystalline spheres, which are made of confined 10–17 nm nanocrystals, are direct solid solutions rather than a mechanical mixture of individual particles. Their growth follows an aggregation process, maintaining the composition of the material. The phosphate hydrates converted into anhydrous tetragonal materials via calcination, and the spherical shape and excellent dispersion of the original particles were well retained up to 1000 °C. Upon UV excitation, the YPO4:Ln3+ samples exhibit characteristic emissions of Ln3+ (Ln = Eu, Tb, Dy, Ho, Tm, and Ce) and yield red, green, near white, green, blue, and blue-green emissions, respectively. The color-tunable emissions (from green to red) can be varied by increasing the Eu content, and the Tb3+→ Eu3+ energy transfer process was observed for the tetragonal phosphate in the Y/Tb/Eu system. The efficiency of the Tb3+→ Eu3+ energy transfer was discovered to be ∼28% for (Y0.88Tb0.02Eu0.10)PO4. The thermal stability of (Y0.88Tb0.02Eu0.10)PO4 is lower than that of (Y0.98Tb0.02)PO4 and (Y0.95Eu0.95)PO4. Thus, the 5D4→7F5 transition of Tb3+ at 546 nm splits into UGRAPHIC DISPLAY="INLINE" ID="UGT1" SRC="UGT1"/→7F5 (at ∼538–546 nm) and UGRAPHIC DISPLAY="INLINE" ID="UGT2" SRC="UGT2"/→7F5 (at ∼557 nm) transitions during the heating process. This phenomenon has been ascribed to the variation of the Tb3+ crystal environment. The UGRAPHIC DISPLAY="INLINE" ID="UGT3" SRC="UGT3"/ energy level gradually shifts to a higher one at an elevated temperature, inducing more and more excited electrons transferring from the higher UGRAPHIC DISPLAY="INLINE" ID="UGT4" SRC="UGT4"/ energy level to the lower UGRAPHIC DISPLAY="INLINE" ID="UGT5" SRC="UGT5"/ one via nonradiative relaxation. Therefore, an enhanced emission intensity at ∼557 nm (UGRAPHIC DISPLAY="INLINE" ID="UGT6" SRC="UGT6"/→7F5 transition) and a weakened one at ∼538–546 nm (UGRAPHIC DISPLAY="INLINE" ID="UGT7" SRC="UGT7"/→7F5 transition) were observed. (Y0.95Eu0.05)PO4/PVA transparent films were successfully fabricated by solution casting, and they exhibit both outstanding flexibility and high transmittances of ≥83% in the 400–850 nm region. The hybrid films can be coated on paper money for anti-fake labeling applications. [ABSTRACT FROM AUTHOR]

Silver bismuth diselenide (AgBiSe2) has attracted much attention as an efficient thermoelectric material, owing to its intrinsically low lattice thermal conductivity. While samples synthesized using a solid-state reaction showed n-type conductivity and their dimensionless figure of merit (ZT) reached ∼1 by electron doping, theoretical calculations predicted that a remarkably high thermoelectric performance can be achieved in p-type AgBiSe2. In this paper, we present the effect of Te substitution on the crystal structure and thermoelectric properties of AgBiSe2, expecting p-type conductivity due to the shallowing of the energy potential of the valence band. We found that all AgBiSe2−xTex (x = 0–0.8) prepared using a solid-state reaction exhibits n-type conductivity from 300 to 750 K. The room-temperature lattice thermal conductivity decreased to as low as 0.3 W m−1 K−1 by Te substitution, which was qualitatively described using the point defect scattering model for the solid solution. We show that ZT reaches ∼0.6 for x = 0.8 at a broad range of temperatures, from 550 to 750 K, due to the increased power factor, although the carrier concentration has not been optimized yet. [ABSTRACT FROM AUTHOR]

Two cyclometalated complexes [Ir(dfppy)2(aip)](PF6) (1) and [Ir(ppy)2(aip)](PF6) (2) have been synthesized based on a photoactive anthracene-based ligand aip and cyclometalating ligands dfppyH and ppyH [dfppyH = (2-(2,4-difluorophenyl)-pyridine), ppyH = 2-phenyl-pyridine]. Their crystal structures indicate that an aip ligand uses its phenanthroline moiety to chelate an {Ir(dfppy)2}+ unit in 1, while an {Ir(ppy)2}+ unit in 2. In CH2Cl2, the anthracene units in aip, 1 and 2 underwent photo-oxidation upon irradiation with 365 nm light, forming species aip-O, 1-O and 2-O, respectively. This photo-oxidation resulted in luminescence switching, from a luminescent state (emission at 493 nm) to a non-luminescent state for aip, while from a non-luminescent state to a luminescent state with an emission at 519 nm for 1 and 578 nm for 2. Additionally, the luminescence of aip, 1-O and 2-O in CH2Cl2 can be modulated by using TFA to protonate the imidazole units and/or non-coordinated phenanthroline moiety in these compounds. Upon adding TFA, aip showed luminescence quenching, while species 1-O and 2-O revealed both luminescence-intensity decrease and emission-wavelength increase (Δλ = 9 nm for 1-O, and Δλ = 4 nm for 2-O). In this paper, we discuss the luminescence switching/modulation of aip, 1 and 2 by light-irradiation-induced photo-oxidation of their anthracene units and by TFA treatment. [ABSTRACT FROM AUTHOR]

Two novel Ba(ii) complexes [Ba(TCPA)2(H2O)4] 1 and [Ba(H2O)8]·2(o-FcCOC6H4COO)·6H2O 2 [HTCPA = 2,4,6-trichlorophenoxyacetic acid and o-HOOCC6H4-COFc = o-ferrocenylcarbonyl benzoic acid] have been synthesized by a facile microwave method. The solid-state structures were well established by means of X-ray crystallography as well as routine analysis of the infrared spectrum (FTIR), elemental analysis, field emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TG). Different polyhedra of tricapped triangular prisms for 1 and dodecahedra for 2 were present. It is worth noting that the central Ba(ii) ion in 1 is nine-coordinated by two carboxylate oxygen atoms from TCPA ligands and seven oxygen atoms from coordinated water molecules. By contrast, the eight-coordinated Ba(ii) in 2 forms barium-water clusters assembled by O–H…O hydrogen-bonds contributed by coordinated water molecules. The uncoordinated o-OOCC6H4-COFc ligands in 2 play a key role in the process of charge balance. FESEM images exhibited different surface appearances between the ligand and barium complexes, that is: flower-like HTCPA, branch-like o-HOOCC6H4-COFc, block-like complex 1 and corner-truncated cubes for complex 2. The allelopathic activity of the complexes and their corresponding ligands was evaluated against two herbaceous plants of barnyard grass and turnip (Raphanus sativus). All the tested compounds showed certain activity with good RI values. An antifungal bioassay was also carried out in vitro on three strains of Botrytis cinerea Pers., Glomerella cingulata Schr and Cytospora sp. Complex 1 and HTCPA can work against all three tested fungi, whereas o-HOOCC6H4-COFc and 2 only worked for Botrytis cinerea Pers. The complex presented in this paper has potential applications in weed control, and this work provides an experimental basis for future studies on Ba-based pesticides. [ABSTRACT FROM AUTHOR]