Space Group P2 Research Articles

Near Ultraviolet‐Excitable Cyan‐Emissive Hybrid Copper(I) Halides Nonlinear Optical Crystals with Near‐Unity Photoluminescence Quantum Yield and High‐Efficiency X‐ray Scintillation

AbstractDesigning and synthesizing multifunctional hybrid copper halides with near ultraviolet (NUV) light‐excited high‐energy emission (<500 nm) remains challenging. Here, a pair of broadband‐excited high‐energy emitting isomers, namely, α‐/β‐(MePh3P)2CuI3 (MePh3P=methyltriphenylphosphonium), were synthesized. α‐(MePh3P)2CuI3 with blue emission peaking at 475 nm is firstly discovered wherein its structure contains regular [CuI3]2− triangles and crystallizes in centrosymmetric space group P21/c. While β‐(MePh3P)2CuI3 featuring distorted [CuI3]2− planar triangles shows inversion symmetry breaking and crystallizes in the noncentrosymmetric space group P21, which exhibits cyan emission peaking at 495 nm with prominent near‐unity photoluminescence quantum yield and the excitation band ranging from 200 to 450 nm. Intriguingly, β‐(MePh3P)2CuI3 exhibits phase‐matchable second‐harmonic generation response of 0.54×KDP and a suitable birefringence of 0.06@1064 nm. Furthermore, β‐(MePh3P)2CuI3 also can be excited by X‐ray radioluminescence with a high scintillation light yield of 16193 photon/MeV and an ultra‐low detection limit of 47.97 nGy/s, which is only 0.87 % of the standard medical diagnosis (5.5 μGy/s). This work not only promotes the development of solid‐state lighting, laser frequency conversion and X‐ray imaging, but also provides a reference for constructing multifunctional hybrid metal halides.

Facile synthesis of mesoporous zinc oxide nanoparticle as a drug delivery system evaluated by IVIVE in PBPK modeling

This study focuses on the development of mesoporous zinc oxide nanoparticles (mZNPs) via the sol–gel technique, utilizing polyethylene glycol-6000 (PEG-6000) as a capping agent. The research aims to investigate the suitability of these nanoparticles for drug delivery purposes. The analysis of the synthesized material validates the existence of a hexagonal system of zinc oxide with space group P6 3cm and HRTM confirmed the crystallinity and morphology of the nanoparticles ranging from 15–20 nm, revealing the formation of pores attributed to the presence of PEG-6000. The mZNPs exhibit a BET surface area of 28.3 m2. g−1, with Langmuir surface area measurements indicating 46 m2. g−1. Analysis employing the BJH method outlines pore diameters ranging from approximately 2–5 nm at a relative pressure of around 0.99. Furthermore, these mZNPs demonstrated drug delivery attributes, with 43.3% loading efficiency and 80.33% entrapment efficiency for aspirin. Notably, the release kinetics of aspirin from the mZNPs were investigated in simulated fluids of varying pH, with the highest release (98.1%) observed in simulated intestinal fluid (pH 6.8). The formulation exhibits typical time-dependent release kinetics under mild pH conditions (7.4 and 6.8), while transitioning to erosion-controlled diffusion mechanisms in acidic pH conditions (1.2). Furthermore, mathematical models, including Higuchi’s, Korsmeyer’s, and Weibull’s, were employed to assess release kinetics, offering parameters for in-vitro to in-vivo pharmacokinetic predictions. In the framework of PBPK modeling, renal clearance was computationally simulated at a rate of 45 min−1, whereas biliary clearance was modeled to occur at 0.05 min−1. Utilizing these model-derived parameters, the projected half-life of aspirin administered via mZNPs was determined to be 3.1 h. The potential applications of these findings extend to the development of effective drug delivery systems, warranting consideration for future animal model studies involving aspirin and mZNPs.

Structure and properties analysis of yttrium doped high-voltage LiNi0.5Mn1.5O4 cathode materials for Li-ion batteries

High voltage cathode spinel material of LiNi0.5Mn1.5O4 was doped by yttrium (Y) element in the form of LiNi0.5Mn1.5−x Y x O4 (x = 0, 0.05, 0.1) for Li-ion batteries. Structure and properties analysis was conducted to study the effect of Y addition on the crystal structure and the electrochemical performances of LiNi0.5Mn1.5−x Y x O4. The results show that undoped LiNi0.5-Mn1.5O4 (x = 0) fit to cubic spinel structure with space group Fd-3m with some LixNi1-xO detected as impurities. The addition of Y with x = 0.05 and 0.1 resulted in the change of LiNi0.5Mn1.5−x Y x O4 structure to space group P4 332. The Y addition was confirmed to enter 4b site co-existed with Mn and this result is closely related to the increase in lattice parameters a from 8.1384(1) Å to 8.1496(5) Å and 8.1627(1) for x = 0, 0.05 and 0.1, respectively. The cubic unit volume of LiNi0.5Mn1.5−x Y x O4 also increased with increasing Y addition. The addition of Y is liable to the formation of more stable [Mn,Y]O6 and MnO6 octahedra and whole crystal structure. The result from charge/discharge analysis shows that the addition of Y resulted in decreasing discharge capacity from 123.56 mAh g−1 to 105.175 mAh g−1 and 104.369 for x = 0.05 and 0.1, respectively. However, capacity retention after the 25th cycle increased constantly from 77% to 88% and 92% with increasing Y addition. Doped Y, in general, improves the electrochemical performance of LiNi0.5Mn1.5−x Y x O4 as cathode material for LIBs.

Synthesis, crystal structure, Hirshfeld surface analysis, DFT studies and biological evaluation of bis(acetonitrile)bromido(η6-1-isopropyl-4-methylbenzene)osmium(II) hexafluoroantimonate

The complex bis(acetonitrile)bromido(η6-1-isopropyl-4-methylbenzene)osmium(II) hexafluoroantimonate, [OsBr(C10H14)(CH3CN)2]SbF6 (1) crystallizes as a triclinic system in space group P1 (no. 2), consisting of two cationic osmium(II) complex ions and two anionic hexafluoroantimonate counterions in each cell. Density Functional Theory (DFT) calculations were performed at the B3LYP/LanL2DZ and B3LYP/Def2 − SVP/Def2 − TZVP levels of theory. Reactivity descriptors and charge transfer properties were computed using frontier molecular orbital analysis. The DFT-optimized model systems from both basis sets were comparable to the experimentally determined X-ray diffraction results. Hirshfeld surface analysis shows significant non-covalent interactions including hydrogen bonds and halogen interactions. The MTT technique was utilized to conduct an in vitro cytotoxicity assay of 1 against cancerous cell lines (MCF-7 and A549) and normal cells (HEK293). Complex 1 is potent towards cancer cells as evidenced by the IC50 values of 5.02 ± 0.05 µM for MCF-7 cells and 13.36 ± 0.04 µM for A549 cells. Complex 1 demonstrated lower toxicity to normal cells with an IC50 value of 26.76 ± 0.08 µM for the HEK293 cell line compared to the doxorubicin standard with an IC50 value of 1.2 ± 0.1 µM.

Crystal structure of (1,4,7,10,13,16-hexa-oxa-cycloocta-decane-κ6 O)potassium-μ-oxalato-tri-phenylstannate(IV), the first reported 18-crown-6-stabilized potassium salt of tri-phenyl-oxalatostannate.

The title complex, (1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-1κ6 O)(μ-oxalato-1κ2 O 1,O 2:2κ2 O 1',O 2')triphenyl-2κ3 C-potassium(I)tin(IV), [KSn(C6H5)3(C2O4)(C12H24O6)] or K[18-Crown-6][(C6H5)3SnO4C2], was synthesized. The complex consists of a potassium cation coordinated to the six oxygen atoms of a crown ether mol-ecule and the two oxygen atoms of the oxalatotri-phenyl-stannate anion. It crystallizes in the monoclinic crystal system within the space group P21. The tin atom is coordinated by one chelating oxalate ligand and three phenyl groups, forming a cis-trigonal-bipyramidal geometry around the tin atom. The cations and anions form ion pairs, linked through carbonyl coordination to the potassium atoms. The crystal structure features C-H⋯O hydrogen bonds between the oxygen atoms of the oxalate group and the hydrogen atoms of the phenyl groups, resulting in an infinite chain structure extending along a-axis direction. The primary inter-chain inter-actions are van der Waals forces.

Investigation on Physicochemical Properties of Nonlinear Optical (NLO) Single Crystal: Rubidium Hydrogen Fumarate

A solvent evaporation method produced an optically high-quality semiorganic single crystal of Rubidium hydrogen fumarate (RbHF) at room temperature. The structural analysis reported that the RbHF crystallized in triclinic crystal system with centrosymmetric space group P1¯. The Powder XRD pattern indicates the grown crystal have good crystalline nature. FTIR spectroscopy examined the functional group and bonding in the grown molecule. A optical transparency of about 88% were observed in RbHF and having energy bandgap of 3.9 eV were calculated using Tauc’s plot. The grown crystals were thermally stable upto 170°C. Mechanical and dielectric analysis has been carried and their properties were discussed in detail. Intermolecular interactions were studied using Hirshfeld surface maps and 2D fingerprint plots. The grown crystal have positive photoconductivity nature. A Z-scan were used to study the third order NLO response in RbHF crystal. The third order nonlinear susceptibility of RbHF crystal was estimated as (χ3) = 1.60244 × 10-08 esu, nonlinear absorption coefficient (β) = 6.39395 × 10-5 cm2/W and nonlinear refractive index (n2) = 9.15822 × 10-12 cm/W. The observed results of the RbHF single crystal show, it has the potential application in optical and optoelectronic devices.

Occupational modulation in the (3+1)-dimensional incommensurate structure of (2S,3S)-2-amino-3-hydroxy-3-methyl-4-phenoxybutanoic acid dihydrate.

The incommensurately modulated structure of (2S,3S)-2-amino-3-hydroxy-3-methyl-4-phenoxybutanoic acid dihydrate (C11H15NO4·2H2O or I·2H2O) is described in the (3+1)-dimensional superspace group P212121(0β0)000 (β= 0.357). The loss of the three-dimensional periodicity is ascribed to the occupational modulation of one positionally disordered solvent water molecule, where the two positions are related by a small translation [ca 0.666 (9) Å] and ∼168 (5)° rotation about one of its O-H bonds, with an average 0.624 (3):0.376 (3) occupancy ratio. The occupational modulation of this molecule arises due to the competition between the different hydrogen-bonding motifs associated with each position. The structure can be very well refined in the average approximation (all satellite reflections disregarded) in the space group P212121, with the water molecule refined as disordered over two positions in a 0.625 (16):0.375 (16) ratio. The refinement in the commensurate threefold supercell approximation in the space group P1121 is also of high quality, with the six corresponding water molecules exhibiting three different occupancy ratios averaging 0.635:0.365.

Octocrylene carboxylate as an antenna in a luminescent Europium(III) complex: Experimental and theoretical insights

A new carboxylic acid, 2-cyano-3,3-diphenyl-2-propenoic acid, CLN, a chromophore ligand, was obtained by an alkaline hydrolysis reaction from the octocrylene, a commercial type B ultraviolet (UVB) radiation absorber. The CLN structure was elucidated by single-crystal X-ray diffraction (SCXRD) as being tetragonal with space group P4‾21/c and the presence of a carboxylic acid group was confirmed by mass, infrared (IR), and proton nuclear magnetic resonance (1H NMR) spectroscopy. In this way, coordination compounds were developed between CLN and Ln(III), Ln = being Gadolinium (Gd) and Europium (Eu), with a stoichiometry of 4:13 metal:ligand, confirmed by thermal and elemental analyses, corroborating with the metal cluster predicted by Sparkle/AM1 semi-empirical model. Photoluminescence data indicated that Eu(III) is efficiently sensitized by CLN due to its triplet excited state, determined using the emission spectrum of the Gd(III) mimic complex (T = 25,477 cm−1), being suitable for this purpose. Therefore, the emission spectrum of the Eu(III) complex exhibited a 5D0 → 7FJ transitions characteristic of the lanthanide ion. Furthermore, the Judd-Ofelt intensity parameters, the radiative and non-radiative decay rates, and the intrinsic quantum yield evaluated using the software LUMPAC software were in good agreement with the experimental values.

N,N-dibenzyl dithiocarbamato silver(I) as precursor for silver sulfide nanophotocatalysts for photocatalytic degradation of rhodamine 6G and trypan blue dyes

N,N-dibenzyl dithiocarbamate silver(I) was synthesized and characterized by spectroscopic techniques and single crystal X-ray crystallography. The complex crystallizes in the trigonal space group P31 to form a one-dimensional, chain-like polymeric structure connected by Ag-Ag argentophilic and Ag-S interactions. The complex was used as single source precursor and thermolyzed at 120, 160 and 200 °C in 1-dodecanethiol to prepare silver sulfide nanoparticles (AgS-120, AgS-160 and AgS-200). TEM images showed quasi-spherical nanoparticles with average particle sizes of 4.0, 5.4 and 5.5 nm for nanoparticles prepared at 120, 160 and 200 °C, respectively, with optical band gaps of 3.76, 3.81 and 3.71 eV. The as-prepared silver sulfide nanoparticles potential as photocatalysts were evaluated using rhodamine 6G and trypan blue under irradiation. The photocatalytic degradation efficiency of 42.4% (k = 3.03 × 10−3), 41.9% (k = 2.73 × 10−3) and 56.7% (k = 4.16 × 10−3) for rhodamine 6G dye and 35.4% (2.94 × 10−3), 49.7% (3.87 × 10−3) and 16.9% (9.0 × 10−4) for trypan blue dye were obtained in the presence of AgS-120, AgS-160 and AgS-200, respectively. The kinetics and mechanism of photocatalytic reaction show that the dye degradation in the presence of the as-prepared nanoparticles follow pseudo-first order kinetics.

Structural, spectroscopy, nonlinear optical, and laser damage threshold analyses of sodium guanidinium bis(4-methylbenzenesulfonate) hydrate (NGMBS) crystal

Sodium guanidinium bis(4-methylbenzenesulfonate) hydrate (NGMBS) crystallized in the monoclinic crystal system with non-centrosymmetric space group P21. The mixed ionic crystal assembly was stabilized by N H⋯O hydrogen bonding involving guanidinium ion and with Na+ ions surrounded by aqua ligands and S–O oxygen atoms completing six coordination involving with coordinate covalent and ion–dipole interactions. A supramolecular assembly in two dimensions (along the a and b-axis) is possible by H-bonding which brought the Na+ within a distance of 3.6493 Å. The two 4-methylbenzenesulfonate ligands in one formula unit were not identical and exhibited structural variations. Hirshfeld analyses indicated significant interaction due to N⋯H, O⋯H, and Na+ … O. The vibrational bands were ascertained using FTIR. A cut-off wavelength of 273 nm and bandgap of 4.50 eV were estimated from UV–visible spectroscopy. The compound excited at 260 showed emission at 291 nm. Colour purity up to 95.62 % was estimated from chromaticity calculations. Kurtz-Perry's method confirmed that NGMBS showed NLO properties 1.5 times than KDP. The NGMBS crystal demonstrated superior resistance to LASER induced damage as compared to urea.

Synthesis and crystal structure of new Mn (III) complex; a target catalyst for direct conversion of thiols after heterogenization

In this study, we are interested in the synthesizing of a new water-soluble complex of Mn (III) formulated as [Mn(pzo)(dipic)(H2O)2]2·3H2O; hereafter referred to as complex 1 where pzo− = pyrazonate and dipic2− = pyridine-2,6-dicarboxylate, under hydrothermal conditions. The molecular structure of complex 1 is primarily determined by single crystal X-ray diffraction (SC-XRD) which shows two mono-nuclear complexes of Mn (III) with three lattice water molecules. According to SC-XRD, complex 1 crystallizes in space group P1¯ of a triclinic system. The center of Mn (III) is seven-coordinated with a distorted pentagonal-bipyramidal geometry with three oxygen atoms and two nitrogen atoms in the equatorial plane. Two oxygen atoms of two water molecules are coordinated in the axial positions. In addition, the structure of complex 1 has been studied by elemental analysis (CHN), Fourier-transform infrared spectroscopy (FT-IR (, thermogravimetric analysis/differential thermal analysis/differential thermogravimetry (TGA/DTA/DTG). Complex 1 has been immobilized on the silica-coated Fe3O4 nanoparticles to produce an efficient and recyclable heterogeneous catalyst formulated as Fe3O4@SiO2@1; hereafter referred to as catalyst 1. Catalyst 1 was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), energy-dispersive X-ray spectrometer (EDS), FT-IR, scanning electron micrograph (SEM), powder X-ray diffraction pattern (PXRD), and Brunner-Emmet-Teller (BET). 1 was used as a new heterogeneous catalyst for the oxidative coupling of thiols to their corresponding disulfides using 30 % H2O2. Under optimum reaction conditions, catalyst 1 exhibited high catalytic activity. 1 can be recovered by a magnet and reused for at least 7 consecutive cycles without significant loss of catalytic performance.

(η6-Benzene)-chlorido-[(S)-2-(4-isopropyl-4,5-di-hydro-oxazol-2-yl)phenolato]ruthenium(II).

The title compound, [Ru(C12H14NO2)Cl(η6-C6H6)], exhibits a half-sandwich tripod stand structure and crystallizes in the ortho-rhom-bic space group P212121. The arene group is η6 π-coordinated to the Ru atom with a centroid-to-metal distance of 1.6590 (5) Å, with the (S)-2-(4-isopropyl-4,5-di-hydro-oxazol-2-yl)phenolate chelate ligand forming a bite angle of 86.88 (19)° through its N and phenolate O atoms. The pseudo-octa-hedral geometry assumed by the complex is completed by a chloride ligand. The coordination of the optically pure bidentate ligand induces metal centered chirality onto the complex with a Flack parameter of -0.056.

Variation of Cyclodextrin (CD) Complexation with Biogenic Amine Tyramine: Pseudopolymorphs of β-CD Inclusion vs. α-CD Exclusion, Deep Atomistic Insights.

Tyramine (TRM) is a biogenic catecholamine neurotransmitter, which can trigger migraines and hypertension. TRM accumulated in foods is reduced and detected using additive cyclodextrins (CDs) while their association characteristics remain unclear. Here, single-crystal X-ray diffraction and density functional theory (DFT) calculation have been performed, demonstrating the elusive pseudopolymorphs in β-CD inclusion complexes with TRM base/HCl, β-CD·0.5TRM·7.6H2O (1) and β-CD·TRM HCl·4H2O (2) and the rare α-CD·0.5(TRM HCl)·10H2O (3) exclusion complex. Both 1 and 2 share the common inclusion mode with similar TRM structures in the round and elliptical β-CD cavities, belong to the monoclinic space group P21, and have similar herringbone packing structures. Furthermore, 3 differs from 2, as the smaller twofold symmetry-related, round α-CD prefers an exclusion complex with the twofold disordered TRM-H+ sites. In the orthorhombic P21212 lattice, α-CDs are packed in a channel-type structure, where the column-like cavity is occupied by disordered water sites. DFT results indicate that β-CD remains elliptical to suitably accommodate TRM, yielding an energetically favorable inclusion complex, which is significantly contributed by the β-CD deformation, and the inclusion complex of α-CD with the TRM aminoethyl side chain is also energetically favorable compared to the exclusion mode. This study suggests the CD implications for food safety and drug/bioactive formulation and delivery.

Molecular structure, molecular docking, molecular dynamics simulation, and drug likeness evaluation of 3,7-dihydroxy-1,2-dimethoxyxanthone for its anticancer activity

A naturally occurring xanthone, named 3,7-dihydroxy-1,2-dimethoxyxanthone was experimentally and computationally investigated for its anticancer activity. Single crystal X-ray diffraction (XRD) analysis revealed that the compound crystallises in the triclinic space group P1. Vibrational frequencies, electronic properties, chemical reactivity descriptors, the molecular structure, and stability of the compound were investigated by DFT calculations using Gaussian 09 W program at the B3LYP/6–311+G(2d,p) level of theory. All calculations showed correlations to experimental data. Its thermodynamic parameters at various temperatures are presented. The title molecule was docked on the proteins of prostate, cervical, breast, and melanoma cancer cells, and the results showed comparable binding energies to the standard chemotherapeutic agent, doxorubicin with small differences in the range 0.2−0.7 kcal mol−1. Given that the compound showed significant potential on the proteins of prostate and cervical cancer cells, the dynamic properties of the bound state of title ligand with the two selected proteins were further examined through a 200 ns molecular dynamics simulation. The results showed relatively overall higher stability through the simulation time than the free target. All these findings were afterwards confirmed by the good in vitro inhibition activity of the compound against human prostate and cervical cancer cell lines with IC50 values of 9.55 and 9.19 µM, respectively in comparison to the standard drug, and additionally demonstrated innocuousness towards normal human kidney cancer cell lines. Moreover, the drug likeness properties indicated that the title compound has a high bioavailability, a good water solubility, a good gastrointestinal absorption, and can be easily synthesized.

Crystal structure and characterization of monascin from the extracts of Monascus purpureus-fermented rice.

We present a novel solid form of monascin, an azaphilonoid derivative extracted from Monascus purpureus-fermented rice. The crystal structure, C21H26O5, was characterized by single-crystal X-ray diffraction and belongs to the orthorhombic space group P212121. To gain insight into the electronic properties of the short contacts in the crystalline state of monascin, we utilized the Experimental Library of Multipolar Atom Model 2 (ELMAM2) database to transfer the electron density of monascin in its crystalline state. Hirshfeld surface analysis, fingerprint analysis, electronic properties and energetic characterization reveal that intermolecular C-H...O hydrogen bonds play a crucial role in the noncovalent bonding interactions by connecting molecules into two- and three-dimensional networks. The molecular electrostatic potential (MEP) map of the monascin molecule demonstrates that negatively charged regions located at four O atoms are favoured binding sites for more positively charged amino acid residues during molecular recognition. In addition, powder X-ray diffraction confirms that no transformation occurs during the crystallization of monascin.

Enhancement of superconductivity and structural phase transitions under pressure in FeTe0.89S0.11

The ternary iron chalcogenide, FeTe0.89S0.11 is a prominent member of the family of Fe-based superconductors with an ambient pressure Tc of around 8 K and a simple structure formed by layers of edge-sharing distorted tetrahedra separated by a van der Waals gap. Upon compression to 6 GPa, the Tc increases monotonically to 11 K. The superconductivity disappeared at about 6 GPa which was correlated to a softening of a Raman mode. High-resolution synchrotron X-ray diffraction shows that the FeTe0.89S0.11 started to transform from the monoclinic phase described by space group Cm to a disordered triclinic phase described by space group P1 at around 10 GPa (theoretical) - 14 GPa (experimental). Due to the phase transition the studied material transforms from a layered compound to a polymer, which is accompanied by a volume collapse of 4.65 %, indicating a discontinuous first-order phase transition. The disappearance of Raman modes, along with pressure independent resistivity, and ab initio calculations results support the structural and electronics phase transition. According to our results Fe(Te,S) may be useful for future high-field power applications being formed of relatively inexpensive and nontoxic elements.

Structural and Electrochemical Insights into Five Coordinate Cobalt bis(dithiolene) N-heterocyclic Carbene Complexes

Two new cobalt-bis(dithiolene)-IMes (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) complexes have been isolated, and a systematic solid-state structural characterization using single crystal X-ray diffraction studies was undertaken to confirm the identity of the complexes. (IMes)Co(S2C2Ph2)2 (1) crystallizes in a monoclinic space group I2/a, while (IMes)Co(S2C2(C6H4-p-OCH3)2)2 (2) crystallizes in a triclinic space group P1¯. A detailed solid-state structural analysis of 1 and 2 revealed that the extended structure is stabilized by a series of CH…S interactions. As validated using electrochemical studies, the binding of IMes to the cobalt atom may be electrochemically controlled by applying a suitable redox potential. These studies indicate that compounds 1 and 2 are expected to act as an effective electrochemical host, enabling them to be used as precursors to release IMes under environmentally benign conditions.

Crystal structure of the cytotoxic macrocyclic trichothecene Isororidin A.

The highly cytotoxic macrocyclic trichothecene Isororidin A (C29H40O9) was isolated from the fungus Myrothesium verrucaria endophytic on the wild medicinal plant `Datura' (Datura stramonium L.) and was characterized by one- (1D) and two-dimensional (2D) NMR spectroscopy. The three-dimensional structure of Isororidin A has been confirmed by X-ray crystallography at 0.81 Å resolution from crystals grown in the orthorhombic space group P212121, with one molecule per asymmetric unit. Isororidin A is the epimer of previously described (by X-ray crystallography) Roridin A at position C-13' of the macrocyclic ring.

Prediction of Novel Trigonal Chloride Superionic Conductors as Promising Solid Electrolytes for All-Solid-State Lithium Batteries.

Recently emerging lithium ternary chlorides have attracted increasing attention for solid-state electrolytes (SSEs) due to their favorable combination between ionic conductivity and electrochemical stability. However, a noticeable discrepancy in Li-ion conductivity persists between chloride SSEs and organic liquid electrolytes, underscoring the need for designing novel chloride SSEs with enhanced Li-ion conductivity. Herein, an intriguing trigonal structure (i.e., Li3SmCl6 with space group P3112) is identified using the global structure searching method in conjunction with first-principles calculations, and its potential for SSEs is systematically evaluated. Importantly, the structure of Li3SmCl6 exhibits a high ionic conductivity of 15.46 mS cm-1 at room temperature due to the 3D lithium percolation framework distinct from previous proposals, associated with the unique in-plane cation ordering and stacking sequences. Furthermore, it is unveiled that Li3SmCl6 possesses a wide electrochemical window of 0.73-4.30V vs Li+/Li and excellent chemical interface stability with high-voltage cathodes. Several other Li3MCl6 (M = Er, and In) materials with isomorphic structures to Li3SmCl6 are also found to be potential chloride SSEs, suggesting the broader applicability of this structure. This work reveals a new class of ternary chloride SSEs and sheds light on strategy for structure searching in the design of high-performance SSEs.

Golden ratio of the r+/r- for the structure-selectivity in the thermoelectric BaZn2-xCdxSb2 system

A total of five Zintl phase compounds in the solid-solution BaZn2-xCdxSb2 (0.10(2) ≤ x ≤ 2) system have been successfully synthesized by the molten Pb-flux method. Both powder X-ray and single-crystal X-ray diffraction analyses proved that the title compounds displayed the phase transition between the BaCu2S2-type phase (space group Pnma, Z = 4) and the CaAl2Si2-type phase (space group P3¯m1, Z = 1) depending on the Zn/Cd mixed ratio. Furthermore, this kind of structure selectivity was dictated by the radius ratio criterion between the cationic and the anionic elements (r+/r–): three Zn-rich compounds with the r+/r– > 1 (BaZn1.90(1)Cd0.10Sb2, BaZn1.75(2)Cd0.25Sb2, and BaZn1.62(2)Cd0.38Sb2) preferred to adopt the BaCu2S2-type phase, while two Cd-rich compounds with the r+/r– ≤ 1 (BaZn0.16(2)Cd1.84Sb2 and BaCd2Sb2) preferred to crystallize in the trigonal CaAl2Si2-type phase. A series of TB-LMTO calculations using the two hypothetical models: BaZn1.5Cd0.5Sb2 and BaZn0.5Cd1.5Sb2, proved that a resonance peak in the density of states of BaZn1.5Cd0.5Sb2 implied the enhanced Seebeck coefficient of the three Zn-rich compounds, and the reduction of band gap observed in a band structure of BaZn0.5Cd1.5Sb2 influenced the electrical conductivity of the Cd-rich BaZn0.16(2)Cd1.84Sb2. Temperature-dependent thermoelectric property measurements showed the maximum ZT of 0.54 for the quaternary BaZn1.62(2)Cd0.38Sb2, which should mainly be attributed to the reduced κtot due to the Zn and Cd disordering in the anionic frameworks.