Search

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]

Four novel indole thiosemicarbazone derivatives, 1-(indole-2-methylene)-4-substituted-thiosemicarbazides, were synthesized via a one-step reaction by introducing substituents with different conjugacy (methyl, ethyl, cyclohexyl, phenyl). Different from the traditional Schiff-base photochromic compounds, these compounds in this work present dual response signals to UV light, and they exhibit not only reversible solid-state photochromic behavior but also aggregation-induced emission (AIE) characteristics. Furthermore, the structure–activity relationships were revealed by experimental studies, and their photochromism and fluorescence emission were enhanced efficiently with the increase of the conjugation. Furthermore, based on the single crystal structure, FT-IR spectra and theoretical calculations, the proposed photochromic mechanism originates from the intermolecular proton transfer between the thio–keto and thio–enol configurations, and the AIE property is closely related to the restriction of intramolecular rotation. Furthermore, the picture of anti-counterfeiting suggests that the dual responses of these compounds are extremely suitable for multiple encryptions. This work enriches the AIE system and provides a reference for constructing excellent multi-photoresponsive materials. [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]

In this study, the structural, electronic, and vibrational properties of the thinnest crystal structure that can be obtained by thinning bulk Cd down to a monolayer are investigated by performing first-principles calculations. Total energy optimization and dynamic stability calculations reveal that the single layer crystal structure has a hexagonal unitcell with a two-atomic basis where alternating layers are formed by trigonal arrangements of Cd atoms. Softening occurs with decreasing zone center optical phonon frequencies as a result of structural relaxation when going from a bulk to a single layer (SL) structure. It is also shown that the thinnest structure obtained from bulk Cd crystals maintains its metallic features despite the dimensional crossover. In addition, it is predicted through calculations that the SL Cd crystal strongly interacts with oxygen and that the oxidized regions even undergo chemical transformation to form a CdO crystal. In the double-layer CdO crystal resulting from the oxidation of individual Cd layers, the layers are connected to each other with partially covalent bonds, and this structure is a semiconductor with a band gap of 2.10 eV. On the one hand, the robust metallic structure of the thinnest possible Cd crystal provides flexibility for its use in nanoscale applications, on the other hand, the fact that its electronic properties can be changed by oxidation is important for optoelectronic device applications. [ABSTRACT FROM AUTHOR]

Designing and discovering negative thermal expansion (NTE) materials is important in precisely controlled thermal expansion devices. In this work, the NTE of a cubic metal fluoride, ReO3-type VF3, was predicted by density functional theory within the quasi-harmonic approximation. These results reveal that cubic VF3 displays a negative thermal expansion behavior below 200 K, and the predicted minimum negative thermal expansion coefficient is approximately −6.4 × 10−6 K−1 at 80 K. The negative thermal expansion was mainly dominated by the prominently negative Grüneisen parameter situated at M(0.5,0.5,0) and R(0.5,0.5,0.5). The underlying mechanism was attributed to the anisotropic F atom vibration, where the amplitude of transverse vibration perpendicular to the V–F–V connection was much larger than that of the vibration along the parallel V–F–V direction. This research provides a good understanding of the relationship between NTE and crystal structure. [ABSTRACT FROM AUTHOR]

Metal hydroborates and their derivatives have been receiving attention as potential solid-state ion conductors for battery applications owing to their impressive electrochemical and mechanical characteristics. However, to date only a fraction of these compounds has been investigated as solid-state electrolytes. Here, MB12H11NH3 (M = Li and Na) hydroborates are synthesized and investigated as electrolyte materials for all-solid-state batteries. The room temperature #945;-NaB12H11NH3 was structurally solved in P212121 (a = 7.1972(3) Å, b = 9.9225(4) Å, and c = 14.5556(5) Å). It shows a polymorphic structural transition near 140 °C to cubic Fm3m. LiB12H11NH3 and NaB12H11NH3 exhibit cationic conductivities of σ(Li+) = 3.0 × 10-4 S cm-1 and σ(Na+) = 1.2 × 10-4 S cm-1 at 200 °C. Hydration is found to improve ionic conductivity of the hydroborates. It is presumed that modest ionic conductivities could be due to a lack of significant reorientational dynamics in the crystal structure resulting from the presence of the bulky -NH3 group in the anion. [ABSTRACT FROM AUTHOR]

Crystallization of the verdazyl-based valence tautomeric ion [Co(dipyvd)2]2+ (where dipyvd is the radical ligand 1-isopropyl-3,5-di(2'-pyridyl)-6-oxoverdazyl) with a variety of different counterions results in materials that show varying degrees of valence tautomeric (VT) transition in the solid state. The X-ray structure of the SbF6 salt at 150 K reveals a localized structure for the S = 1/2 tautomer, with a Co3+ cation and distinct anionic and radical ligands. Comparison with the structure of the same material at 300 K reveals large structural changes in the ligand as a result of the valence tautomeric equilibrium. Data for the S = 3/2 form is less conclusive; X-ray spectroscopy on the PF6 salt suggests a degree of low spin Co2+ character for the S = 3/2 tautomer at very low temperature though this is inconsistent with EPR data at similar temperatures and structural information at 150 K. Magnetic measurements on the [BArF4]- and triflate salts in organic solvents show that the VT equilibrium is dependent on solvent and ion pairing effects. [ABSTRACT FROM AUTHOR]

Retrosynthetic design and synthesis with structural isolation of two unprecedented core modified N-confused N-fused porphodimethene-like porphyrinoids possessing a [5.5.5.5] tetracyclic ring with tunable photophysical properties is reported. The solid-state X-ray crystal structure reveals the expected cis geometry for the meso-sp³ carbons. Controlled chemical oxidation of the porphodimethene analogue 11 bearing the N-confused pyrrole moiety to the corresponding porphotrimethene 12 has been achieved in quantitative yield, while 10 bearing the N-methyl N-confused pyrrole moiety remained unsusceptible to chemical oxidation. All three S2N3 hybrid N-confused N-fused porphodi(tri)methene-like porphyrinoids 10-12 could recognize the fluoride anion with high selectivity; however, porphodimethene 10 and porphotrimethene 12 do so via deprotonation rather than an anion recognition based mechanism as has been anticipated in the case of porphodimethene 11. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) emissive probes are becoming increasingly popular in biological sensing and imaging due to the advantages of non-invasiveness and deep tissue-penetrating ability. Herein, a series of complexes of trivalent lanthanide ions (Ln = Yb, Er, and Gd) with the commercially available azo dye chromophore 2R (Na2H2C2R) as ligand and featuring respectively H2O and dimethylsulfoxide (DMSO) as ancillary ligands have been prepared. Formulated as [Ln2(HC2R)2(H2O)10]·8H2O (1-3, Ln = Yb, Er, Gd) and [Ln2(HC2R)2(DMSO)10]·2DMSO (4-6, Ln = Yb, Er, Gd), their structures have been determined by singlecrystal X-ray diffraction studies. Photophysical property studies revealed NIR emissions of the DMSO complexes characteristic of Yb(III) and Er(III), effectively sensitized by the dye ligand arising mainly from the π-π* transition of the chromophore. The long-wavelength excitation of the complexes, covering the whole visible-light range and extending into the NIR region, portends the potential applications of such complexes for flexible bioimaging and sensing. [ABSTRACT FROM AUTHOR]

New noncentrosymmetric cerium(IV) iodate fluoride Rb2Ce(IO3)5F was prepared employing a hydrothermal technique. The compound crystallizes in the Cmc21 space group (#36) with cell parameters a = 11.1518(6) Å, b = 8.1187(4) Å and c = 17.1581(10) Å. The crystal structure of Rb2Ce(IO3)5F consists of layers composed of 8-vertex CeO7F and 7-vertex Rb(1)O7 and Rb(2)O6F polyhedra interconnected by I(2)O3 groups. These layers are stitched by trigonal pyramidal I(1)O3 and I(3)O3 groups into a 3D framework. Synthesized iodate fluoride is thermally stable in air up to 430 °C. According to DFT calculations, Rb2Ce (IO3)5F is a direct-gap semiconductor with a band gap of ca. 2.33 eV. This value is in good agreement with an estimated optical gap value of 2.35 eV. The important feature of Rb2Ce(IO3)5F is the ability to generate a second optical harmonic signal comparable to that of KH2PO4. [ABSTRACT FROM AUTHOR]

We synthesized a perovskite-type RbNbO3 at 1173 K and 4 GPa from non-perovskite RbNbO3 and investigated its crystal structure and properties towards ferroelectric material design. Single-crystal X-ray diffraction analysis revealed an orthorhombic cell in the perovskite-type structure (space group Amm2, no. 38) with a = 3.9937(2) Å, b = 5.8217(3) Å, and c = 5.8647(2) Å. This non-centrosymmetric space group is the same as the ferroelectric BaTiO3 and KNbO3 but with enhanced distortion. Structural transition from orthorhombic to two successive tetragonal phases (Tetra1 at 493 K, Tetra2 at 573 K) was observed, maintaining the perovskite framework before reverting to the triclinic ambient phase at 693 K, with no structural changes between 4 and 300 K. The first transition is similar to that of KNbO3, whereas the second to Tetra2, marked by c-axis elongation and a significant cp/ap ratio jump (from 1.07 to 1.43), is unique. This distortion suggests a transition similar to that of PbVO3, where an octahedron's oxygen separates along the c-axis, forming a pyramid. Ab initio calculations simulating negative pressure like thermal expansion predicted this phase transition (cp/ap = 1.47 at −1.2 GPa), aligning with experimental findings. Thermal analysis revealed two endothermic peaks, with the second transition entailing a greater enthalpy change and volume alteration. Strong second harmonic generation signals were observed across Ortho, Tetra1, and Tetra2 phases, similar to BaTiO3 and KNbO3. Permittivity increased during the first transition, although the second transition's effects were limited by thermal expansion-induced bulk sample collapse. Perovskite-type RbNbO3 emerges as a promising ferroelectric material. [ABSTRACT FROM AUTHOR]

YGa3(BO3)4 single crystals were grown from a K2Mo3O10-based flux, and also RGa3(BO3)4 (R = Y, Pr–Yb) spontaneous crystals (RGB) were obtained by a high-temperature flux growth technique from a complex R2O3–Bi2O3–B2O3–Ga2O3 solvent. A number of gallium orthoborates, including new ones (PrGa3(BO3)4, TmGa3(BO3)4), were obtained under identical conditions, their stability was determined, and their morphological features were shown. The crystal structure was confirmed by powder X-ray diffraction and their unit cell parameters were calculated. The micromorphology of the crystals was examined by the SEM method. Differential thermal analysis measurements show that RGa3(BO3)4 (R = Y, Pr–Yb) is an incongruently melting compound with temperatures varying with the rare earth cation type. [ABSTRACT FROM AUTHOR]

An original approach for the determination of unit cell parameter temperature dependence using a conventional single-crystal X-ray diffractometer is proposed. The approach is based on the calibration of the goniometer equatorial circle segment using the position of several Kα1/Kα2 doublets from reference single crystals. It allows for the refinement of lattice parameters of single crystals with a relative error of less than 10−4. Its capabilities are demonstrated using an example of tetragonal single crystals. The space group, crystal structure, and composition of t-Ag0.8Li0.2InSe2 were determined using single-crystal X-ray diffraction analysis of three small (linear sizes ∼0.1 mm) fragments from a larger (linear sizes up to 10 mm) single-crystal grown using the Bridgman method. The dynamics of the crystal structure changes in the temperature range of 90–500 K were studied. The obvious anisotropy of t-Ag0.8Li0.2InSe2 thermal behavior was shown with an overall increase in the volume of the tetragonal unit cell by 0.51%—parameter a increased by 0.34, while parameter c decreased by 0.17%. The nonlinear dependence of the thermal expansion tensor elements on temperature was determined: α 11 × 106 = −4.28 + 0.08T − 1.95 × 10−4T2 and α 33 × 106 = −5.59 + 0.01T − 1.97 × 10−5T2. [ABSTRACT FROM AUTHOR]

For isotactic polybutene-1 (iPB-1), II-I transition is of great industrial importance; however, the traditional nucleation-controlled solid-solid II-I transition mechanism eventually encountered challenges and the roles of iPB-1 amorphous phase gained the interest of many researchers. With three nucleating agents, namely WBQ-88, TMB-5 and WBG-II, incorporated into iPB-1, the amorphous phase was tuned with a form II crystalline structure remaining fixed. Based on the observed Tm,II decrease and Tm,I increase during the II-I transition as well as the resulting final Tm,I synergistically tuned by nucleating agent incorporation and crystallization conditions, it is proposed that the entire II-I transition of iPB-1 involves a form II consumption process and a form I formation process. The same as-crystallized form II structures of iPB-1 containing various nucleating agents are involved in a fixed form II consumption process. The amount of iPB-1 chain segments in the amorphous phase, which have the ability to crystallize, as well as their actual ability to crystallize synergistically determine the initiation of form I crystallization. Consequently, the started form I crystallization triggers II-I transition by overcoming the energy barrier for form II crystal cells to be destroyed. Both the initiation and the subsequent form I crystallization process can be enhanced by nucleating agent incorporation or isothermal crystallization at different Tc values, comprehensively resulting in a fast II-I transition process with final form I crystalline structures determined. The results provide an understanding of the II-I transition mechanism and shed light on the development of techniques to accelerate the II-I transition for iPB-1 industrial applications. [ABSTRACT FROM AUTHOR]

A series of versatile phthalocyanine precursors, consisting of gem-dibromovinyl phthalonitrile derivatives, were synthesized and characterized by various spectroscopic techniques. The assigned structures were further supported by X-ray crystallographic techniques. The crystal structures showed primarily C-H...N, C-H...Br, C-Br...N and π...π interactions. The overall intermolecular interactions in the structures were quantified and fully described by Hirshfeld surface analysis. In addition, energy-frame calculations were used to analyse the three-dimensional topology of the crystal packing. The dispersion energy framework of all compounds was shown to be dominant over the electrostatic framework. [ABSTRACT FROM AUTHOR]

The development of new compounds in the domain of metal dinitridocarbonates is most efficiently performed via solid-state metathesis or simply by addition reactions. Our discovery of Pb7I6(CN2)4 is the result of a solid-state reaction of PbCN2 with PbI2 at 420 ℃. Its crystal structure was solved and refined from X-ray diffraction data based on a single crystal with the space group P63/mmc. The crystal structure is based on a network of lead tetrahedra, lead trigonal bipyramids and lead octahedra interconnected by [NCN]2- and iodide. Properties of the material were investigated by diffuse reflection measurement, photoluminescence measurements, and electronic band structure calculations demonstrating that this material is a semiconductor. [ABSTRACT FROM AUTHOR]

LiCa8[CrIVN3]2N2F (Pnnm (#58), a = 17.5230(13) Å, b = 7.3379(5) Å, c = 4.9433(4) Å) is an example of a multinary nitridochromate fluoride, that provides additional information on almost elusive tetravalent nitridochromates. Shorter Cr–N bond lengths compared to those in the previously reported nitridochromates(III), as well as diamagnetic behavior and vibrational spectroscopy data suggest Cr(IV), which is in good agreement with the charge balance and crystal structure refinement. According to band structure calculations, LiCa8[CrIVN3]2N2F is a semiconductor with a band gap of 1.1 eV. The compound features trigonal planar [CrN3]5− units of Cs symmetry, and lithium, calcium, nitrogen and fluorine atoms arranged in a fragment of the rock salt type structure. [ABSTRACT FROM AUTHOR]

The assembly of a metal–organic framework (MOF) containing bent phenanthroline linkers and iron trinuclear clusters remains rare. Herein, we report the synthesis and single crystal structure of a two-dimensional (2D) MOF, Fe-cage-MOF, assembled from 2,9-substituted phenanthroline based carboxylate linkers and pre-synthesized iron trinuclear clusters. The distinctive octahedral cages and ordered 1D channels endow the MOF with permanent porosity and potential for selective capture of the greenhouse gas sulfur hexafluoride. [ABSTRACT FROM AUTHOR]

A series of ten N^N chelating ligands based on a 2,2′-bipyridine (bpy) metal-binding domain and featuring sterically hindering substituents in the 6- and 6,6′-positions has been synthesized and characterized. The ligands have been incorporated into a family of 15 heteroleptic complexes of type [Cu(P^P)(N^N)][PF6] where P^P is the wide bite-angle bisphosphane ligand bis(2(diphenylphosphanyl)phenyl)ether (POP) or (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane) (xantphos). Substituents in several of the N^N ligands ligands possess phenyl rings remotely tethered to enable intra- and intermolecular π–π-interactions in the [Cu(P^P)(N^N)]+ cations. Single crystal X-ray structures of 12 complexes are reported. The effects of the functional groups in the bpy ligand on the photophysical properties of the complexes have been studied; solid-state emission maxima range from 518 to 567 nm. Values of the solid-state photoluminescence quantum yields (PLQYs) of the [Cu(P^P)(N^N)][PF6] compounds respond to the nature of the N^N ligand. In general, we observed that the [Cu(P^P)(N^N)]+ complexes containing 6,6′-disubstituted complexes with phenyl moieties connected via a CH2CH2 or CH2CH2CH2 spacer to the bpy domain have the highest values of PLQY. The most significant compounds are [Cu(POP)((2-PhEt)2bpy)][PF6] (PLQY = 67%) and [Cu(POP)((3-PhPr)2bpy)][PF6] (PLQY = 72%) where (2-PhEt)2bpy = 6,6′-bis(2-phenylethyl)-2,2′-bipyridine and (3-PhPr)2bpy = 6,6′-bis(3-phenylpropyl)-2,2′-bipyridine. These PLQY values are among the best performing previously reported families of [Cu(P^P)(N^N)][PF6] compounds. [ABSTRACT FROM AUTHOR]

A new sodium tellurate has been hydrothermally synthesized and comprehensively analysed using spectroscopic and thermogravimetric techniques, resulting in the determination of its composition as NaTeO3(OH). The analysis of synchrotron X-ray and neutron diffraction data indicates that NaTeO3(OH) has a crystal structure similar to that of the previously reported tellurate, KTeO3(OH), with the space group P21/a (No. 14). NaTeO3(OH) consists of zigzag one-dimensional chains built by edge-sharing TeO6 octahedra, running parallel to the c-axis and connected to sodium and hydrogen atoms. The hydrogen atoms covalently bond to the terminal oxygen atoms on the one-dimensional chain and also form hydrogen bonds with other terminal oxygen atoms on nearby chains. The structure has been confirmed by optimization using the pseudopotential method and performing Bond Valence Sum (BVS) analysis. Although Li+ ions in LiTeO3(OH) can be exchanged reversibly with H+ ions, no ion exchange behaviour is observed in NaTeO3(OH). The difference is attributed to the size of the alkali ions and their crystal structure. [ABSTRACT FROM AUTHOR]

Multi-band emission characteristics open up more possibilities for the application of phosphors in LEDs. In this work, a novel Bi3+-activated Sr3NaSbO6 phosphor is developed. The Bi3+ occupation, luminescence properties and application in LEDs of the phosphor are investigated and discussed. There are Sr and Na sites in the crystal structure for Bi3+ substitution, corresponding to two different luminescence centers, which can be excited by commercial UV chips. By changing the excitation wavelength, Bi3+ in the two lattice sites can be excited separately, and a switchable multi-band emission can be obtained accordingly. The blue emission peaks at 450 nm, and the other emission has an ultra-wide full-width at half-maximum of 206 nm, which can cover a wider visible spectrum. All the results show that the phosphor has application prospects in LEDs. [ABSTRACT FROM AUTHOR]

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) are considered as next-generation of NIR light sources for spectroscopy. However, it is still a challenge to develop an inexpensive broadband NIR phosphor with relatively long-wavelength (λem > 800 nm) emission. In this work, an octahedral Al3+-containing pyrophosphate Al0.5Ta0.5P2O7 with a cubic structure was chosen as a host for Cr3+. Synthesizing this material indicates that this phosphor exhibits a broadband NIR emission peaking at 850 nm with a full width at half maximum (FWHM) of 155 nm under 465 nm excitation. The crystal structure, morphology, local structure, and photoluminescence properties of this material were investigated in detail. The results revealed a full understanding of this new material. A NIR pc-LED device fabricated by using this material combined with a 450 nm LED chip generates a NIR output power of 10.7 mW and a NIR photoelectric conversion efficiency of 3.4% under a 100 mA driving current, which shows the possibility of this material to be utilized in NIR pc-LED applications. Moreover, this material exhibits a linear relationship between emission intensity, decay time and temperature in a wide temperature range, implying that excellent multi-model temperature sensing applications can be expected. [ABSTRACT FROM AUTHOR]

In this work, we report the structural and magnetic characterization of two new B-site rock-salt ordered double perovskites ALaCoTeO6 (A = K+ and Na+) with mixed A-site cations. KLaCoTeO6 crystallizes in the space group P4/nmm with a long-range ordering degree of 84.8% for the A-site K+/La3+ cations, whereas NaLaCoTeO6 adopts an unexpected triclinically distorted I1¯-structure with Na/La3+ disordering, validated by combined Rietveld refinements against high-resolution neutron diffraction data and Cu Kα1 X-ray powder diffraction data. Magnetic susceptibility at low temperatures shows clear antiferromagnetic (AFM) transitions for both compounds. KLaCoTeO6 exhibits the highest AFM transition temperature of 20 K amongst all the Co/Te-ordered 3C-type A2CoTeO6 (A = Pb2+, Sr2+, and Ca2+) and ALaCoTeO6 double perovskites due to its larger Co2+–O–Te6+ bond angle and A-site cationic ordering-induced larger distortion of the Co2+-based face-centered cubic sublattice. Moreover, we found that the average radius of the A-site cations plays a decisive role in the AFM transition temperatures of all these ordered double perovskites, that is, a larger A-site cation always results in a higher AFM transition temperature. This provides a strategy to subtly manipulate the magnetic properties of ordered double perovskites. [ABSTRACT FROM AUTHOR]

This article describes the synthesis and crystal structure of ten new Tc(V) complexes with pyrazine containing homologous alkoxy ligands. We carried out an analysis of the Hirshfeld surfaces for the described compounds and found out that with increasing length of the hydrocarbon substituent from CH3 to C10H21 the percentage of H⋯H interactions in crystals increases from 28% to 59%. The purpose of this article was to show the pattern of increase in interplanar distances in crystals depending on the length of the hydrocarbon substituent, and also to study the thermochemical properties of Tc(V) complexes. The mechanism of thermolysis does not depend on the length of the hydrocarbon substituent and differs only in the temperature range of the reactions. The absorption bands of the obtained complexes in IR and UV-vis spectra do not depend on the length of the hydrocarbon substituent. Using a complex with a propyl substituent as an example, the UV-vis spectral data of the mother solution are presented. Based on DFT calculations of spectra and molecular models, an indirect identification of the reaction intermediate is provided. Using a complex with a methyl substituent as an example, data on MALDI spectrometry are presented. [ABSTRACT FROM AUTHOR]

The influence of the metal ratio on the geometric characteristics and crystal structures of heterometallic clusters with {Re6−xMoxQ8} cores was studied. For this purpose, nine new molecular cluster complexes of the type [Re6−xMoxS8L6] (x = 2, 3 or non-integer value between 2 and 3; L = pyridine, 4-ethylpyridine or 4-tert-butylpyridine) were synthesized. The compounds were obtained by one-step replacement of the cyanide apical ligands of [Re6−xMoxS8(CN)6]5−/4− cluster complexes with the corresponding organic compounds under solvothermal conditions. The crystal structures of all the obtained compounds were investigated by single-crystal X-ray diffraction analysis. Analysis of the crystal structures showed that clusters with the same apical ligands and different x values have similar geometries and form isostructural packings, demonstrating the formation of solid solutions. [ABSTRACT FROM AUTHOR]

The discovery of phosphors with highly efficient broadband near-infrared emission is urgent for constructing NIR sources for various applications. Herein, we synthesized a series of near-infrared emitting garnet-type (A3B2C3O12) Lu2−xCaAl3.99Cr0.01SiO12:xGd/La and Lu2CaAl3.99−yCr0.01SiO12:ySc/Ga phosphors and systematically investigated the effect of A/B-site substitution on the crystal structure and luminescence properties. Structural and optical analyses revealed that the A/B-site substitution weakened the crystal field strength, further enhancing the broadband emission of the allowed 4T2 → 4A2transition and diminishing the narrow-peak emission of the forbidden 2E → 4A2 transition. As expected, NIR phosphors, exemplified by Lu1.7CaAl3.99Cr0.01SiO12:0.3Gd and Lu2CaAl3.49Cr0.01SiO12:0.5Sc, showed outstanding thermal stabilities at 423 K (150 °C) registering values of 103.02% and 94.91%, with high quantum efficiencies of 80.48% and 85.01%, respectively. In addition, pc-LEDs with broadband NIR output and good optoelectronic properties have been realized, demonstrating the great potential of broadband NIR pc-LEDs for applications. This work not only provides a series of high-efficiency phosphors for NIR pc-LED applications, but also provides a systematic idea and an efficient method to improve the luminescence performance of garnet-type phosphors. [ABSTRACT FROM AUTHOR]

The goal of this study was to investigate how the electron-donating capability around the lower valent metal ion and the electron-accepting capability of the higher valent metal ion influence metal to metal charge transfer (MMCT) properties in mixed-valence complexes. A series of trinuclear ruthenium complexes represented as [Ru2(ap-4-Me)3(CH3COO)N≡CRuCpMex(dppe)][PF6] (CpMex = polymethylcyclopentadienyl, x = 0, 1, and 5; and dppe = 1, 2-bis(diphenylphosphino)ethane, ap-4-Me = 2-anilino-4-methylpyridine) and their one-electron oxidized products were synthesized and fully characterized. The UV–vis-NIR spectra confirmed that as the electron donor character of the CpMex(dppe)RuCN fragment enhanced or the electron-accepting capability of the higher valent diruthenium cluster increased, the RuII → Ru V2 or Ru VI2 Ru2 MMCT bands shifted to lower energies, which was supported by TDDFT calculations. [ABSTRACT FROM AUTHOR]

For a series of chiral para-alkylphenyl glycerol ethers—para-Alk–C6H4–OCH2CH(OH)CH2(OH) [Alk = Me (1), Et (2), n-Pr (3), n-Bu (4), iso-Pr (5), tert-Bu (6)]—we used information on their solubility in cyclohexane and thermochemical melting parameters to calculate the standard free energies of dissolution, , and melting, ΔG 0f. Our observations showed consistent patterns in these parameters within the homologous series. This analysis allowed us to compare the energy characteristics of the crystal structures, thus enabling the quantification of enantiophobic and enantiophilic effects. Furthermore, it facilitated the examination of trends in chiral discrimination as the molecular constitution changed sequentially. We identified distinct trends for enantiopure substances and corresponding racemic compounds within the series studied. In particular, the difference in crystal packing energies among the series members following these trends favours racemic molecular compounds by approximately 2.5 kJ mol−1. However, for (R)-3 and (R)-4, the realised crystal structures are more energetically favoured than expected, thus deviating from the established correlations. This anomaly allows homochiral crystal structure 3 to bridge the energy gap and crystallise from the racemic mixture as a thermodynamically more favourable conglomerate of enantiomeric crystals. In contrast, for racemic compound rac-5, the energy of its molecular packing is lower than expected from the correlations but insufficient to make conglomerate 5 thermodynamically more favourable. At the same time, the formation of racemic compound rac-6 was abnormally preferable in terms of energy. In addition, we presented the X-ray diffraction data for the homo- and heterochiral crystals of 5, thereby complementing the structural information available for the "chiral pool" class of glycerol derivatives. [ABSTRACT FROM AUTHOR]

Monodispersed and faceted Bi2Fe4O9 micro-cuboid crystals with a mullite-type structure have been successfully synthesized by a facile hydrothermal method. The single crystalline Bi2Fe4O9 micro-cuboids exhibited a length of 10–20 μm and a square cross-section with a side length of 1–2 μm. The preferential growth of the Bi2Fe4O9 micro-cuboid crystals has been determined to be along 〈001〉 with the dominant (110) and (−110) facets enclosed. These micro-cuboid crystals were probably formed by a dissolution–recrystallization mechanism, where a phase transition from irregular-shaped sillenite Bi25FeO40 agglomerates to perovskite BiFeO3 microspheres occurred and finally resulted in the micro-cuboid crystals. More interestingly, these micro-cuboids demonstrated a remarkable photo-Fenton catalytic degradation activity towards RhB under visible light irradiation (λ > 400 nm). 90.2% RhB decomposition at 120 min can be achieved and the corresponding apparent rate constant is 0.0175 min−1, 11.67 times and 3.65 times larger than that of Fenton-like oxidation and pure photocatalysis, respectively. The as-prepared Bi2Fe4O9 micro-cuboid crystals also showed intriguing morphology-dependent ferromagnetism at room temperature, possibly allowing the magnetic recollection and reuse of Bi2Fe4O9 samples as well as their magnetic-field-mediated photocatalytic performances. [ABSTRACT FROM AUTHOR]

Identifying and evaluating novel and extremely stable materials for catalysis is one of the major challenges that mankind faces today to rapidly reduce the dependence on fossil fuels. To contribute to achieving this goal, we have evaluated within the density-functional framework the properties of a new two-dimensional MXene structure, the asymmetric MXene YZrCOF monolayer. Phonon dispersion calculations at 0 K and 300 K indicate that the studied material is dynamically stable. The calculations also indicate that the material has a rigid crystal structure with a wide band gap, a strong potential difference, and a band-gap alignment that favors the production of both H2 and O2 molecules from water splitting. We also report the outcome of the strain effect on the electrical and photocatalytic characteristics of the studied material. We will demonstrate that even under a large strain, the YZrCOF monolayer is stable and useful for photocatalytic applications. [ABSTRACT FROM AUTHOR]

Five new alkylaluminum complexes with different pyridinyl-substituted imines or cyclohexyl-substituted imines were synthesized and characterized successfully. The aluminum complex [FlCHNCH(CH3)Py]AlMe2(Py = 2-pyridyl) (1) was obtained by reacting 9-[2-pyridyl-CH(CH3)-N＝CH]Fl (Fl = fluorenyl) (L1) and equimolar AlMe3. The reactions of 9-(2-pyridyl-N＝CH)Fl (L2) and 9-[2-N(CH3)2-cyclohexyl-N＝CH]Fl (L3) with equimolar AlMe3 or AlEt3 afforded other alkylaluminum complexes [FlCHNPy]AlMe2(Py = 2-pyridyl) (2), [FlCHNPy]AlEt2 (Py = 2-pyridyl) (3), [FlCHNCyN(CH3)2]AlMe2 (Cy = 2-cyclohexyl) (4) and [FlCHNCyN(CH3)2]AlEt2 (Cy = 2-cyclohexyl) (5). All these complexes (1–5) were characterized using NMR spectroscopy, elemental analysis, and X-ray crystal structure analysis. The catalytic properties of these new alkylaluminum complexes for the hydrophosphonylation of aldimines were examined. Complex 5 showed the best catalytic performance under mild reaction conditions with a low catalyst loading (1 mol%), and 20 different substituents of aldimines were isolated with more than 90% yields. [ABSTRACT FROM AUTHOR]

Marbofloxacin (MB) is a newly developed fluoroquinolone antibiotic used especially as a veterinary drug. It may be regarded as the improved version of enrofloxacin owing to its antibacterial activity, enhanced bioavailability, and pharmacokinetic–pharmacodynamic (PK–PD) properties. In this study, nine heavy rare-earth ions (Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) were selected in light of their potential antibacterial activity and satisfactory biosafety to afford the corresponding rare-earth metal complexes of MB: the MB–Ln series. Their chemical structures and coordination patterns were characterized using IR spectroscopy, HRMS, TGA, and X-ray single-crystal diffraction analysis. Our results confirmed that all the MB–Ln complexes yielded the coincident coordination modes with four MB ligands coordinating to the Ln(III) center. In vitro antibacterial screening on five typical bacteria strains revealed that the MB–Ln complexes exhibited antibacterial activities comparable with MB, as indicated by the MIC/MBC values, in which Escherichia coli and Salmonella typhi were the most sensitive ones to MB–Ln. Furthermore, the MB–Ln complexes were found to be much less toxic in vivo than MB, as suggested by the evaluated LD50 (50% lethal dose) values. All the MB–Ln series complexes fell in the LD50 range of 5000–15 000 mg kg−1, while the LD50 value of MB was only 1294 mg kg−1. Furthermore, MB–Lu, as the selected representative of MB–Ln, could effectively inhibit the activity of DNA gyrase, the same as MB, suggesting the primary antibacterial mechanism of the MB–Ln series. The results demonstrated the good prospects and potential of metal-based veterinary drugs with better drug performance. [ABSTRACT FROM AUTHOR]

Ideonella sakaiensis PETase (IsPETase) is a unique polyethylene terephthalate (PET) hydrolase that displays great potential for mitigating PET waste at moderate temperatures. Although IsPETase exhibits greater specific activity towards PET, rapid activity loss limits its commercial application. Herein, semi-saturation mutation was carried out to stabilize the most flexible region in IsPETase and a thermostable S92P/D157A variant with a Tm value of 70.8 °C (ΔTm = 24.1 °C) was constructed, which enabled a 109.3-fold increase in products released from amorphous PET depolymerization at 40 °C. The further depolymerization of untreated post-consumer PET obtained 17.34 mM products (95.0% TPA). The crystal structure indicated that the "wobbling" W156 residue in IsPETaseWT was fixed in the substrate-binding conformation in the S92P/D157A variant, which contributed to an increase in thermostability and could provide steady interaction with the substrate. Previous studies emphasized that the W156 residue exhibiting a "wobbling effect" is critical to substrate binding, while the different structure–function relationship of the S92P/D157A variant indicated that the wobbling of W156 may not be a pre-requisite for efficient PET biodegradation. Instead, engineering PET hydrolases for fixing the conserved W156 residue in the substrate-binding conformation was proposed. The S92P/D157A variant exhibited a preference for PET in the gauche conformation, which is consistent with its efficiency towards the degradation of low crystallinity PET, further cementing the importance of conformation selection and providing complementary evidence for the function of the fixed W156 residue in PET binding and catalytic processes. Collectively, our results could contribute to the understanding and engineering of more effective PET hydrolases, promoting the industrial application of the enzymatic PET recycling process. [ABSTRACT FROM AUTHOR]

Four Ni4O4 cubanes with formula [Ni4(Cl2-L)4(μ3-OMe)4(MeOH)4] (1), [Ni4(Br2-L)4(μ3-OMe)4(MeOH)4] (2), [Ni4(I2-L)4(μ3-OMe)4(MeOH)4] (3) and [Ni4(BrCl-L)4(μ3-OMe)4(MeOH)4] (4) (Cl2-LH = 3,5-dichlorosalicylaldehyde, Br2-LH = 3,5-dibromosalicylaldehyde, I2-LH = 3,5-diiodosalicylaldehyde, BrCl-LH = 3-bromo-5-chlorosalicylaldehyde) were obtained by self-assembly from commercially available 3,5-halogen-substituted salicylaldehydes and NiCl2·6H2O in high yields at room temperature. The X-ray crystal structure analysis of 4 showed a cubane-type structural topology as each Ni(II) ion is six-coordinated in a distorted octahedral geometry defined by four oxygen atoms from the MeOH molecule (three as bridging methoxy-oxygens and one as terminal group) and two oxygen atoms from the 3-bromo-5-chlorosalicylaldehyde ligands. The cubane core is stabilized via an intramolecular O–H⋯O hydrogen bond, while in the crystal, complex molecules are linked into the zigzag chain to the a-axis via strong Br⋯Br interaction. Both SQUID and μSQUID measurements indicate the coexistence of ferromagnetic and antiferromagnetic interactions in two complexes. The fitting of the magnetic data yields different magnetic parameters for each complex, clearly highlighting the differences in the magnetic properties among these systems. DFT calculations have also been performed on compounds 1–4 to explain the exchange interaction mechanisms between the Ni(II) ions, supporting both the magnitude and sign of the coupling constants. [ABSTRACT FROM AUTHOR]

Despite extensive research on the photoluminescence properties of Bi3+ ions, the origins of their emission and excitation bands remain elusive. Herein, we present a comprehensive analysis of the photoluminescence properties of Bi3+-activated LuXnGaO4 (Xn = Mg, Zn), elucidating the underlying factors governing the intra-ionic and extra-ionic electronic transitions. By integrating crystal structure data and spectroscopic data analyses with semi-empirical formula calculations, the origins of excitation and emission states were elucidated. Moreover, the impact of alterations in chemical surroundings on the luminescence of Bi3+ was investigated. Both LuXnGaO4:Bi3+ phosphors exhibit three excitation peaks in the near ultraviolet region and display a broadband yellow emission. However, the luminous behavior of LuMgGaO4:Bi3+ and LuZnGaO4:Bi3+ differs due to variations in the band gap, bond length and neighboring atoms. It is anticipated that the investigation of Bi3+-activated gallates presents a promising avenue for advancing wide-band and long-wavelength emitting phosphors. [ABSTRACT FROM AUTHOR]

This research utilized a recently developed co-melting crystallization method to synthesize four distinct energetic coordination compounds (ECCs). The method involves the direct heating of organic ligands with inorganic salts, leading to the formation of the desired ECCs upon cooling and subsequent crystallization. This approach effectively bypasses various challenges associated with the conventional solvent-based ECC preparation process. In this study, the organic ligands employed were pyrazole and 4-chloropyrazole, while the inorganic salts included copper nitrate and copper perchlorate. A rigorous pre-experiment was meticulously designed to validate the feasibility of this method, followed by control experiments to underscore its advantages. Subsequently, comprehensive characterizations were conducted on the four ECCs, with a primary emphasis on their crystal structures and energetic properties. Notably, ECCs-3 and ECCs-4, among the synthesized ECCs, exhibit significant potential for applications in pyrotechnic materials and ignition agents. This work extends the practical applicability of the co-melting crystallization method we have developed, providing further substantiation of its advantages and potential. [ABSTRACT FROM AUTHOR]

The self-assembly of cluster-based halide framework materials has been a matter of great interest but with great challenges. Herein, by exploiting hexamethylenetetramine (Hmta) with Td symmetry as a structural modifier, we successfully constructed and systematically characterized an unusual three-dimensional (3D) hybrid bromoargentate, namely K[NH4][Ag4Br6(Hmta)] (1), bearing a diamond-type [Ag4Br6(Hmta)]n2n− anionic skeleton built up from adamantane-like units of inorganic [Ag4Br6] clusters and organic Hmta ligands. UV–Vis diffuse reflectance analysis showed that the optical bandgap of the title compound was 2.68 eV, indicating a visible-light-responsive semiconductive behavior. More importantly, upon alternate light illumination, the so-designed compound exhibited remarkable photoelectric switching properties, with photocurrent densities (0.38 and 1.10 μA cm−2 for visible and full-spectrum light, respectively) that compete well with and even exceed those of some high-performance metal halide counterparts. Further theoretical calculations, including band structure, density of states, and wave functions, revealed that compound 1 has a unique valence band and conduction band distribution, rendering it with small effective masses (especially the electrons), which may be responsible for its good photoelectricity. Furthermore, in this work, Hirshfeld surface analysis, thermogravimetric analysis, and X-ray photoelectron spectroscopy (XPS) studies were performed. [ABSTRACT FROM AUTHOR]

L -Alanyl- L -glutamine (Ala–Gln) is a dipeptide which is widely used in medical and nutritional fields. Two new crystalline forms (form III and form IV) and a DMSO solvate form (SDMSO) of Ala–Gln were discovered in this study, which were distinguished from the known forms by Raman spectroscopy and powder X-ray diffraction (PXRD). Single crystal structures of the three new solid forms were obtained. Moreover, the crystal structure data of known forms: form II, dihydrate form (2H) and ethanol solvate form (SEtOH), which have not been reported to the best of our knowledge, were solved. The results showed that there were four kinds of molecular arrangements and frameworks in the Ala–Gln solid forms. The comparison of the molecular arrangements and cell parameters indicated that the forms III, 2H and SEtOH were isomorphic. The hydrogen bonding network of the DMSO solvate was different from those of forms II, III and IV. By comparing the bulk density, lattice energy and thermal analysis results of the three polymorphs of Ala–Gln, the order of bulk density and lattice energy was consistent with the decomposition enthalpy. Besides that, it was found that the crystal shape of the solvates can be retained after solvent removal. [ABSTRACT FROM AUTHOR]

New polar K2NbO2F3 crystals were obtained under mild hydrothermal conditions, which differ from the higher temperature synthesis of previously known Nb-containing oxyfluorides. X-ray diffraction analysis of the single crystal, performed in the polar space group Pna21, is consistent with the existence of the second harmonic generation (SHG) effect in powders. A monotonous increase in SHG power in samples with increasing powder grain size indicates phase matching of neodymium laser radiation and its second harmonic. However, SHG is relatively small and does not exceed a third of the intensity of standard KH2PO4 powders. The weakness of the second-order optical nonlinearity in K2NbO2F is related to the strong pseudo-symmetry of the crystal structure, corresponding to the space group Pnam-D2h16, and thus the structure is very close to centrosymmetric. Structural evidence for the polarity of the K2NbO2F3 crystal is the subtle differences in the Nb–O bonds along the c axis in the (NbO3F3) octahedra, together with the presence of similar differences in the K1–O bonds. Extremely weak, close to the detection limit, very small deviations from the centrosymmetry of the entire structure also correlate with the existence of an almost second-order irreversible transformation of K2NbO2F3 into a centrosymmetric phase at temperatures 50–60 °C below the decomposition temperature of the substance at 560 °C. [ABSTRACT FROM AUTHOR]

Novel half-sandwich ruthenium complexes termed [(p-cymene)RuClL] were synthesized by chelating arylhydrazone ligands with [(p-cymene)RuCl2]2 and were then fully characterized using different spectroscopic and analytical techniques. The crystal structure of complex 4 indicated that the hydrazone ligands bonded to the ruthenium ion in a bidentate manner through the imine nitrogen and imidazolate oxygen, exhibiting a pseudo-octahedral geometry centered by the ruthenium atom. The as-fabricated air and moisture stable half-sandwich ruthenium complexes demonstrated excellent catalytic activity towards the N-alkylation of hydrazides under mild conditions. Under the catalysis of ruthenium complexes, acyl hydrazides were reacted with different types of alcohols in a one-pot reaction, resulting in N-alkylation hydrazides with different substituents. This catalyst exhibited characteristics such as high catalytic efficiency, broad substrate scope, and mild reaction conditions, indicating that it has great potential for industrial applications. [ABSTRACT FROM AUTHOR]

The SrCoO3−δ system has broad application potential due to its diverse crystal structures, oxidation stoichiometric ratio, and significant electrical and magnetic properties. However, it faces the challenges of a complex crystal structure and oxygen defect control in this material system. Herein, we introduce oxygen defects into SrCoO3−δvia Er doping to regulate the structural, electrical and magnetic transport properties. Sr1−xErxCoO3−δ (x = 0–0.25) undergoes an evolution of structure and oxygen content (measured using the iodometric method) from hexagonal SrCoO2.626 (H + Co3O4) to cubic perovskite Sr0.9Er0.1CoO2.689 (CP) and finally to ordered tetragonal Sr0.8Er0.2CoO2.635 (OT). Among the three phases, Sr0.9Er0.1CoO2.689 (CP) exhibits the lowest resistivity, only 4.06 mΩ cm at room temperature, which is attributed to its high three-dimensional symmetry, overlap of O 2p and Co 3d orbitals at high oxygen ion concentration. Further introduction of Er ions and oxygen defects promotes the transformation from low spin Co4+ (LS, t 52g e 0g , S = 1/2) to high spin Co3+ (HS, t 42g e 2g , S = 2), and from the CoO6 octahedron (low magnetic moment transformation) to the CoO4.25 tetrahedron (high magnetic moment). The oxygen-deficient CoO4.25 layer appears, which can enhance the ordering of A sites and oxygen vacancies, and the CP phase transforms into room-temperature ferromagnetic Sr0.8Er0.2CoO2.635 (OT, TC∼330 K). Er ions provide unpaired electrons in the 2f orbital, which results in a strong magnetization of Sr0.8Er0.2CoO2.635 (OT, 4.66 μB/Co) at low temperatures. [ABSTRACT FROM AUTHOR]

Single crystals of sodium zincophosphate chloride were obtained under medium-temperature hydrothermal conditions and its crystal structure was determined using low temperature X-ray diffraction. The Na9Zn2(PO4)4Cl structure is formed from centrosymmetric pairs of strongly distorted trigonal bipyramids ZnO4Cl sharing Cl vertices, which are linked via PO4 tetrahedra in the anionic layers neutralized by means of Na+ cations. We show that the title compound represents the Zn alternative to Na9Zr(PO4)4Cl. Both triclinic phosphates are characterized by close unit cell parameters and volumes. However, the formal replacement of one Zr4+ for two Zn2+ cations in their formulae is accompanied by significant structural transformations leading to the creation of various mixed-type anionic constructions: chains versus layers. Theoretical calculations of possible pathways of alkali ion migration through the structure and activation energies revealed that the Li substituted counterpart Li9Zn2(PO4)4Cl can be considered as a potential solid electrolyte. [ABSTRACT FROM AUTHOR]

Perfluorohalogenated naphthalenes (PFXNaPs) are unique small molecules with great potential to exhibit a new type of σ-hole and π-hole bonding, owing to the incorporation of multiple F atoms onto the naphthalene ring. In this study, we develop a synthetic protocol for PFXNaPs, conduct crystal engineering investigations, and explore the intermolecular interactions of PFXNaPs through π-hole and σ-hole bondings. We successfully synthesise PFXNaPs using Mg amide-mediated halogenation reactions of electron-deficient F7 and F6 naphthalenes, achieving good to excellent yields. Crystal structure analyses of 3,6-I2F6 naphthalene unveil intermolecular π-hole stacking between two C atoms in the naphthalene ring, involving cooperation with the σ-hole bonding of two I atoms. This intermolecular interaction mode has not been classified in previous reports. Computational studies show that the π-hole bonding in PFXNaPs is substantially enhanced compared to corresponding benzene molecules without diminishing the σ-hole bonding. The unique stacked interaction in PFXNaPs is primarily governed by electrostatic interaction and dispersion correction energies, with the contribution of C⋯C contacts being 10 times greater than that in benzene analogs. The results enable further applications of PFXNaPs in the fields of perfluorohalogenated arenes and organic crystalline materials. [ABSTRACT FROM AUTHOR]

The supramolecular organization of organic salts has been widely researched, revealing recurring patterns in crystalline lattices that describe their supramolecular properties. In recent years, our research group has underscored the importance of considering the crystalline structures as a whole, incorporating all the necessary energetic and topological information for a comprehensive understanding of the crystalline system. Given this context, we investigated a series of ammonium mono- and dicarboxylate salts (1–12) to determine whether subtle structural modifications in the anionic organic component lead to relevant energy and topology changes in the crystalline lattice. To achieve this, we selected structures whose carboxylate anion only possesses an alkyl chain and is devoid of other functional groups. The ammonium cation (NH4+) was fixed to determine the effect of variations in the alkyl chains of the selected mono- and dicarboxylates, such as length and degree of unsaturation. Additionally, probable crystallization mechanisms were proposed to elucidate some of the topological and energetic aspects involved in the crystallization of these compounds. Destabilizing interactions were observed in 10 crystalline structures, and the MEP data showed that the most destabilizing interactions occur by the proximity of portions with the same type of charge. Some dimers have unexpectedly low intermolecular interaction energies despite having large contact areas. Based on these data we demonstrate the additivity of intermolecular interactions, that is, the low intermolecular interaction energy in these dimers is the result of the sum of destabilizing energies and stabilizing energies. The cluster energy efficiency data revealed that most crystal lattices display typical characteristics of uncharged organic compounds. The proposed crystallization mechanisms showed a gradual increase in nucleus complexity in the initial stages and the total number of nucleation stages, resulting in five main patterns: monomer → 1D → 3D (1–2), monomer → dimer → 2D → 3D (3), monomer → 1D → 2D → 3D (4–5), monomer → dimer → 3D (6), and monomer → 2D → 3D (7–12). [ABSTRACT FROM AUTHOR]