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Metal chalcogenides, as a new class of semiconductor materials, have a broad range of applications in synthetic chemistry due to their rich structures and excellent properties. We have synthesized two selenoantimonates A4Zn2Sb2Se7 [A = Rb(1), Cs(2)] under solvothermal conditions in the visible region using a band gap optimization strategy with alkali metals as structure-directing agents. Compounds 1 and 2 have a two-dimensional layered structure consisting of charge-balanced Rb+(1) or Cs+ (2) cations and [Zn2Sb2Se7]4- anions with novel 20-membered rings (20-MR) [Zn6Sb4Se10] with an aperture of 5.6949 × 13.7741 Ų formed in the middle. Furthermore, we have investigated the crystal structure, band gap, photoelectronic properties, and energy band structure. [ABSTRACT FROM AUTHOR]

A facile room-temperature synthetic method is presented to produce alkali metal salts of tert-butyl phosphonic acid. The reaction between equimolar amounts of alkali metal carbonates and tert-butyl phosphonic acid in methanol results in the formation of [(tBuPO3H)Li(H2O)3•(H2O)] (1), [(tBuPO3)Na2(H2O)4]n (2), and [(tBuPO3H)K(H2O)]n (3). Solid-state structures of these compounds have been confirmed by single-crystal X-ray diffraction studies and further validated using numerous spectroscopic and analytical techniques. Compounds 1--3 are polymeric solids that are predominantly made up of a 1-D polymeric metal phosphonate chain. This synthetic approach leads to the formation of network structures/polymers in the solid state that otherwise are absent in solution due to the ionic nature of the interaction between the alkali metal ions and phosphonate anions. Apart from the multidentate nature of the phosphonate ligands, additional hydrogen bonding interactions involving water molecules, free P--OH groups, and P O moieties allow these chains to be propagated into 2-D sheets. We have further utilized the completely metalated sodium phosphonate 2 to synthesize layered metal phosphonates [(tBuPO3)Ca(H2O)]n (4), [(tBuPO3)Mn(H2O)]n (5) and [(tBuPO3)Co(H2O)]n (6) via a simple metathesis reaction. [ABSTRACT FROM AUTHOR]

The exploration of nonlinear optical crystals with ultraviolet (UV) transparent ranges and easy-to-grow large-size crystals is one of the current research interests. Herein, by combining borate and phosphate groups, a novel congruently melting alkali-mixed metal borophosphate, Li3Na7B4P6O26 (LNBPO) with UV transparency was successfully designed and synthesized using a high-temperature flux method. LNBPO crystallizes in the non-centrosymmetric (NCS) and polar orthorhombic space group Pca21 (no. 29), showcasing interesting (B2P3O13)∞ chains along the c axis. Notably, LNBPO has a moderate second harmonic generation (SHG) response (∼0.38 × KDP) and displays a wide transmission ranging from 0.22 to 3.68 μm, as measured by a [001]-oriented crystal wafer. Furthermore, a high-quality single crystal of LNBPO with sizes up to 14 × 14 × 12 mm3 was grown using the top-seeded solution growth method. The refractive indices of LNBPO were determined by applying the minimum deviation angle method. These results show that LNBPO possesses a phase-matching wavelength as short as 483 nm, indicating its potential as a new UV NLO crystal. [ABSTRACT FROM AUTHOR]

By introducing the d0 metal cation Mo6+ into phosphates, two new molybdophosphates, K2MgMoP2O10 and K3Mg2MoP3O14, were synthesized by spontaneous crystallization, and their structures were determined by single-crystal X-ray diffraction. K2MgMoP2O10 shows a two-dimensional layer composed of the uncommon eight-membered ring [Mo2P2O16] formed by [MoO6] and [PO4], while K3Mg2MoP3O14 shows isolated [MoP3O14] clusters composed of [MoO5] and [PO4]. K2MgMoP2O10 and K3Mg2MoP3O14 have UV cut-off wavelengths of 277 and 271 nm, respectively, which are significantly shorter than those of most recently published molybdophosphates. To the best of our acknowledge, K2MgMoP2O10 exhibits the largest birefringence (a calculated value of 0.187 at 546 nm) among reported alkali metal or alkaline earth metal molybdophosphates, which provides a way to explore new birefringent materials. First-principles analysis of the electronic structure shows that the large birefringence of K2MgMoP2O10 mainly originates from the [MoO6] units. [ABSTRACT FROM AUTHOR]

Di-tert-butyldiphosphatetrahedrane (tBuCP)2 (A) is a reactive tetrahedral molecule which may serve as a source of new phosphaorganic molecules and ligands. However, the redox chemistry of this compound has not yet been investigated. Here, we show that the reduction of A with alkali metals (AM = Li, Na, K, Rb and Cs) affords 1,2,3-triphospholides [AM(crown ether)][1,2,3-P3C2tBu2] (1–5, [AM(crown ether)] = [Li([12]crown-4)2]+, [Na([15]crown-5)2]+, [K([18]crown-6)]+, [Rb([18]crown-6)]+, and Cs+) with 1,3-diphospholides [AM(crown ether)][1,3-P2C3tBu3] (6–10) formed as by-products. The potassium salt 3 was isolated on a preparative scale, allowing for reactivity studies. Transmetalation with iron(II) and ruthenium(II) chlorides yielded the sandwich complexes [Cp*M(η5-1,2,3-P3C2tBu2)] (11, M = Fe; 12, M = Ru, Cp* = C5Me5) featuring η5-coordinated triphospholide ligands. Treatment of 3 with [Cp2Fe][BAr4F] or [H(Et2O)2BAr4F] (BAr4F = B{C6H3(CF3)2}4) afforded the polyphosphorus compound tBu4C4P6 (13), which presumably results from the dimerisation of a 1,2,3-triphospholyl radical intermediate (1,2,3-P3C2tBu2)˙ (3˙). Tetracyclic 13 is closely structurally related to an isomer of the hydrocarbon hypostrophene (C10H10). [ABSTRACT FROM AUTHOR]

Alkali metal clusters with a single unpaired s-electron can be arranged three-dimensionally in a sodalite crystal by loading the guest alkali atoms. Na, K, and K-Rb alloy clusters are known to be Mott insulators and to exhibit antiferromagnetic ordering. The Néel temperature increases from about 50 K to about 100 K in this order. In this study, Li-Na alloy, Na-K alloy, and pure Rb samples were newly prepared and their magnetic, electrical conductivity, and optical properties were investigated, including those of previous samples. The Na-K alloy samples showed antiferromagnetic properties, which were intermediate between those of the Na and K samples. However, the Rb sample showed a non-magnetic metallic state. The shallower ionization potential in Rb is thought to cause an insulator-metal transition (Mott transition) due to weaker on-site Coulomb repulsion between electrons and larger electron transfer energy between neighboring clusters. On the other hand, the Li-Na alloy sample showed a non-magnetic insulating state. It is thought that the two electrons form a spin-singlet pair due to the strong electron-lattice interaction. In terms of electron correlations and polaron effects, the full picture of the element species dependence of the alkali metal-loaded sodalite is reviewed. [ABSTRACT FROM AUTHOR]

A new layered titanoniobate, Li3Ti5NbO14, a member of the AxM2nO4n+2 family, has been synthesized using a molten salt reaction between H3Ti5NbO14 and an eutectic mixture of LiOH and LiNO3. This compound crystallizes in the P21/m space group with a = 9.273(15) Å, b = 3.788(6) Å, c = 8.871(3) Å, and β = 114.33(1)°, as determined by 3D electron diffraction single crystal analysis. It exhibits [Ti5NbO14]3− layers similar to K3Ti5NbO14, but differs from the latter by a 'parallel configuration' of its [Ti5NbO5]3− ribbons between the two successive layers. The topotactic character of the reaction suggests that exfoliation plays a prominent role in the synthesis of this new form. This new phase intercalates reversibly 2 lithium through a first-order transformation leading to a capacity of 100 mA h g−1 at a potential of 1.67 V vs. Li/Li+. [ABSTRACT FROM AUTHOR]

The reactions of dimesitylphosphane oxide Mes2P(O)H with Lawessons reagent and dimesitylphoshane with selenium yield Mes2P(E)H with E = S (1a) and E = Se (1b), respectively, with moderate yields. Metalation of dimesitylphosphane sulfide 1a with n-butyllithium, sodium hydride or potassium hydride in THF allows the isolation of dinuclear dimesityl-thiophosphinites of the type [(thf)2A-S-PMes2]2 [A = Li (4), Na (5), K (2a)] with central four-membered A2S2 rings. The weaker base THP leads to the very similar aggregate [(thp)2K-S-PMes2]2 (3a) as has also been observed for the homologous potassium dimesityl-selenophosphinites of the type [(L)2K-Se-PMes2]2 [L = thf (2b), thp (3b)]. Addition of 18-crown-6 ether leads to deaggregation and expectedly to formation of mononuclear [(18C6)K-S-PMes2] (6). Moderate yields have been obtained due to dismutation reactions that yield the corresponding phosphinates AE2PMes2 and phosphanides APMes2, a degradation process which has been observed earlier also for Li-O-PMes2. This side reaction hampers the application of these thio- and selenophosphinites as catalysts in the addition of phosphane sulfides and selenides across alkynes. [ABSTRACT FROM AUTHOR]

A comprehensive study on the synthesis and characterization of NHC-ligated nickel(II) cyanoborates (CBs) is presented (NHC = N-heterocyclic carbene). Nickel(II) cyanoborates Ni[BH2(CN)2]2·H2O (Ib·H2O), Ni[BH(CN)3]2·0.5H2O (Ic·0.5H2O), Ni[B(CN)4]2·H2O (Id·H2O) were reacted with selected NHCs of different steric size. The reaction of the nickel cyanoborates with small to medium-sized NHCs Me2ImMe and iPr2Im (R2Im = 1,3-di-organyl-imidazolin-2-ylidene; R2ImMe = 1,3-di-organyl-4,5-dimethyl-imidazolin-2-ylidene) afforded cyanoborate salts containing the rare homoleptic fourfold NHC-ligated nickel(II) cations [Ni(NHC)4]2+ (NHC = Me2ImMe (1c–d), iPr2Im (2c–d)) and cyanoborate counter-anions. Bulkier NHCs such as Mes2Im and Dipp2Im afforded complexes trans-[Ni(NHC)2(CB)2] (trans-4b, trans-5c). For the combination of the cyanoborate anion [BH2(CN)2]− and iPr2ImMe the salt of the tris-NHC complex [Ni(iPr2ImMe)3(NC-BH2CN)][BH2(CN)2] (3b) was isolated. Salt metathesis of NHC-ligated nickel(II) halides (Ni(NHC)2X2) (X = Cl, Br) with silver(I) and alkali metal cyanoborates were used to synthesize mono- and disubstituted coordination compounds of the type cis- or trans-[Ni(NHC)2(CB)X] (cis-10c, cis-11c, trans-12b) and cis- or trans-[Ni(NHC)2(CB)2] (cis-13b, cis-14a–c, trans-14a–b, trans-15b, trans-5b). Further investigations reveal that NHC-ligated cyanoborate complexes can act as building blocks for coordination polymers, as observed for structurally characterized 1∞ {trans-[Ni(Mes2Im)2(μ2-[NC–BH2–CN])2]·2Ag(μ2-[BH2(CN)2])} (trans-5b·Ag). This study demonstrates the diverse character of cyanoborates in coordination chemistry as both, non-coordinating counter-anions, and weakly to medium coordinating anions forming novel transition metal complexes and salts. It provides evidence that a proper choice of cyanoborate and a proper choice of co-ligand can lead to a rich coordination chemistry of cyanoborate anions. [ABSTRACT FROM AUTHOR]

Reaction of [VO(OR)3] (R = Et, nPr) with 2,2′-diphenylglycine afforded the alkoxide-bridged dimers {[VO(OR)(μ-OR)][Ph2C(NH2)(CO2)]}2, whereas use of benzilic acid, in the presence of alkali metals, afforded 16-membered metallocycles {V8(O)4M(OR)8[Ph2C(OH)(CO2)]12} (M = <1 Na, K). For the ring systems, magnetic susceptibility data is consistent with mixed-valence vanadium with an average oxidation state of 3.5. The dimer and ring systems are capable of the ring opening polymerisation (ROP) of ε-caprolactone under N2, air, or as melts affording mostly low to medium molecular weight cyclic and linear products. [ABSTRACT FROM AUTHOR]

The reactions of dimesitylphosphane oxide Mes2P(O)H with Lawessons reagent and dimesitylphoshane with selenium yield Mes2P(E)H with E = S (1a) and E = Se (1b), respectively, with moderate yields. Metalation of dimesitylphosphane sulfide 1a with n-butyllithium, sodium hydride or potassium hydride in THF allows the isolation of dinuclear dimesityl-thiophosphinites of the type [(thf)2A-S-PMes2]2 [A = Li (4), Na (5), K (2a)] with central four-membered A2S2 rings. The weaker base THP leads to the very similar aggregate [(thp)2K-S-PMes2]2 (3a) as has also been observed for the homologous potassium dimesityl-selenophosphinites of the type [(L)2K-Se-PMes2]2 [L = thf (2b), thp (3b)]. Addition of 18-crown-6 ether leads to deaggregation and expectedly to formation of mononuclear [(18C6)K-S-PMes2] (6). Moderate yields have been obtained due to dismutation reactions that yield the corresponding phosphinates AE2PMes2 and phosphanides APMes2, a degradation process which has been observed earlier also for Li-O-PMes2. This side reaction hampers the application of these thio- and selenophosphinites as catalysts in the addition of phosphane sulfides and selenides across alkynes. [ABSTRACT FROM AUTHOR]

Liquid assisted ball milling of [NHC]HBr (NHC = N-heterocyclic carbene) salts with copper(I) chloride, and a range of alkali metal complexes was shown to efficiently produce (NHC)CuX (NHC = normal or RE-NHC, X = halide, alkoxide, amide, alkyl, aryl; RE-NHC = ring-expanded NHC). [ABSTRACT FROM AUTHOR]

Research into the use of sodium tetraalkoxyborate salts for different chemical applications including synthetic catalysis, hydrogen storage, or battery applications has been investigated, however, understanding of the structural, thermal and electrochemical properties of these salts has been lacking since the 1950s and 1960s. A review of the synthesis, as well as a thorough characterization using 1H NMR, 11B NMR, 13C{1H} NMR, FTIR, XRD, in situ XRD, DSC-TGA, RGA-MS, TPPA, and EIS has newly identified polymorphic phase changes for Na[B(OMe)4], K[B(OMe)4], Li[B(OMe)4], Na[B(OEt)4], Na[B(OBu)4], and Na[B(OiBu)4]. The crystal structure of K[B(OMe)4] was also solved in I41/a (a = 22.337(2) Å, c = 7.648(3) Å, V = 3815.6(4) Å3, ρ = 1.128(1) g cm−3). Ionic conductivity of the different salts was analyzed, however it was found that the compounds with longer alkyl chains had no measurable ionic conductivity compared to the shorter chained samples, Na[B(OMe)4] and K[B(OMe)4] with 9.6 × 10−8 S cm−1 and 1.6 × 10−7 S cm−1, at 114 °C respectively. [ABSTRACT FROM AUTHOR]

Exploring feasible tactics to induce the formation of non-centrosymmetric (NCS) structures, especially from centrosymmetric (CS) structures, is essential for the development of nonlinear optical crystals with more potential. An NCS alkali metal-containing molybdenum iodate hydrate, namely, NaMoO3(IO3)(H2O), was designed based on the CS matrix NaMoO3(IO3) via introducing a water molecule into the structure. The introduction of one crystalline water molecule results in the rearrangement of Λ-shaped cis-[MoO4(IO3)2] units, and the proper array of the cis-[MoO4(IO3)2] units in NaMoO3(IO3)(H2O) results in its strong SHG response of 4.6 × KH2PO4. In addition, NaMoO3(IO3)(H2O) exhibits a wider optical bandgap of 3.44 eV and a larger birefringence of 0.231 than its matrix. Furthermore, the framework of NaMoO3(IO3)(H2O) is highly similar to that of α-KMoO3(IO3), with water molecules assisting Na+ cations in occupying the position of K+. However, due to the extra hydrogen bond of water molecules, the [MoO3(IO3)]∞ layers in NaMoO3(IO3)(H2O) retain a parallel-stacking arrangement, different from the antiparallel arrangement of layers in α-KMoO3(IO3) with a centric structure. This study confirms the feasibility of applying a water molecule to adjust the orientation of basic building block units to assemble an NCS structure based on CS crystals. [ABSTRACT FROM AUTHOR]

Samples of the pseudo-binary system Na2−xLixGa7 (x ≤ 1) were synthesized from the elements at 300 °C in sealed Ta ampoules or by the reaction of Na2Ga7 with LiCl. The peritectic formation temperature decreases with increasing Li content from 501(2) °C (x = 0) to 489(2) °C (x = 1). The boundary compositions Na2Ga7 and Na1Li1Ga7 crystallize with different structure types related by a group–subgroup relation. While the Na-rich compositions (x ≤ 0.5) represent a substitutional solid solution (space group Pnma), the Li-rich compositions feature an unconventional replacement mechanism in which Li atoms occupying interstitial positions induce vancancies at the Na positions (space group Cmce). The crystal structure of Na1Li1Ga7 (a = 8.562(1) Å, b = 14.822(2) Å, c = 11.454(2) Å; Z = 8) was determined from X-ray single-crystal diffraction data, and reveals an anionic framework comprising 12-bonded Ga12 icosahedra and 4-bonded Ga atoms, with alkali–metal atoms occupying channels and cavities. The arrangement of cations makes NaLiGa7 a new structure type within the MgB12Si2 structure family. Band structure calculations for the composition NaLiGa7 predict semiconducting behavior consistent with the balance [Na+]2[Li+]2[(Ga12)2−][Ga–]2, considering closo Wade clusters [(12b)Ga12]2− and Zintl anions [(4b)Ga]−. Susceptibility measurements indicate temperature-independent diamagnetic behavior. [ABSTRACT FROM AUTHOR]

Borates are favored by materials scientists and chemists because of the significant electronegativity difference between B and O atoms and their flexible assembly modes resulting in abundant structures and excellent properties. For the design of deep-ultraviolet (DUV) optical crystals with excellent macroscopic performance, it is crucial to choose appropriate cations and anionic groups and microscopically reasonable assembly patterns. Herein, by introducing covalent tetrahedra ([MO4], M = Mg, Al), two new mixed alkali metal and alkaline earth metal borates, Rb3MgB5O10 and LiBaAl(BO3)2, were synthesized using the melt method and high-temperature solution method. They contain M–B–O two-dimensional (2D) layers (2∞ [MgB5O10] and 2∞ [Al(BO3)2], respectively) composed of isolated B–O groups ([B5O10]5− and [BO3]3−, respectively) and metal-centered tetrahedral connectors ([MgO4]6− and [AlO4]5−, respectively). Combining experiments and theoretical calculations shows that the two compounds have short cutoff edges (<200 nm) and moderate birefringences. Further analysis manifests that the isolated [MO4] covalent tetrahedra can optimize the arrangement of anion groups, guarantee the balanced optical properties of materials, and point out the direction for further exploration of novel borate structures. [ABSTRACT FROM AUTHOR]

Samples of the pseudo-binary system Na2−xLixGa7 (x ≤ 1) were synthesized from the elements at 300 °C in sealed Ta ampoules or by the reaction of Na2Ga7 with LiCl. The peritectic formation temperature decreases with increasing Li content from 501(2) °C (x = 0) to 489(2) °C (x = 1). The boundary compositions Na2Ga7 and Na1Li1Ga7 crystallize with different structure types related by a group–subgroup relation. While the Na-rich compositions (x ≤ 0.5) represent a substitutional solid solution (space group Pnma), the Li-rich compositions feature an unconventional replacement mechanism in which Li atoms occupying interstitial positions induce vancancies at the Na positions (space group Cmce). The crystal structure of Na1Li1Ga7 (a = 8.562(1) Å, b = 14.822(2) Å, c = 11.454(2) Å; Z = 8) was determined from X-ray single-crystal diffraction data, and reveals an anionic framework comprising 12-bonded Ga12 icosahedra and 4-bonded Ga atoms, with alkali–metal atoms occupying channels and cavities. The arrangement of cations makes NaLiGa7 a new structure type within the MgB12Si2 structure family. Band structure calculations for the composition NaLiGa7 predict semiconducting behavior consistent with the balance [Na+]2[Li+]2[(Ga12)2−][Ga–]2, considering closo Wade clusters [(12b)Ga12]2− and Zintl anions [(4b)Ga]−. Susceptibility measurements indicate temperature-independent diamagnetic behavior. [ABSTRACT FROM AUTHOR]

Three Mg-containing borates were obtained by high-temperature spontaneous crystallization. In the (A2O)- or (A2O-MO)-MgO-B2O3 system (A is alkali metal and M is alkaline-earth metal) reported in the ICSD, Li4Mg3SrB12O24 is the first compound that contains one-dimensional infinite anionic chains, and the two examples of the isostructural A2Mg3B16O28 (A = Rb, Cs) exhibit a two-dimensional infinite bilayer structure for the first time, which contributes to the enrichment of the structural chemistry of Mg-containing borates. Besides, the results of comparison and analysis in this system clearly show that Mg not only affects the anionic frameworks of borates to produce low-dimensional structures but, together with the ratio of Ncation/NB, is responsible for the dimensionalities of the anionic frameworks in borates. The optical properties of the three compounds also show that they all have short cutoff edges, and Cs2Mg3B16O28, in particular, could reach the deep-ultraviolet region (<200 nm). [ABSTRACT FROM AUTHOR]

In this study, we report a group of alkali metal aluminates bearing bis(organoamido)phosphane ligand. The starting complex {[PhP(NtBu)2]AlMe2}Li·OEt2 (1) was prepared by stepwise deprotonation of the parent PhP(NHtBu)2 by nBuLi and AlMe3. Further derivatization of aluminate 1 was performed by the virtual substitution of lithium -{[PhP(NtBu)2]AlMe2}K (2), methyl substituents – {[PhP(NtBu)2]AlH2}Li·THF (3), modification of steric bulk and induction effects on the phosphorus atom – {[tBuP(N-2,6-iPr2C6H3)2]AlMe2}Li·(OEt2)2 (4), and phosphorus atom oxidation state {[Ph(Y)P(NtBu)2]AlMe2}Li (Y = O (5), S (6), Se (7), Te (8)). The structure causing non-covalent interactions in 1–4 were evaluated with the help of theoretical calculations and topological analysis ranging from π-electron system-metal to agostic interactions of various types. The further reactions of 1 with various nucleophiles were found to be a versatile tool for the preparation of iminophosphonamides via the formation of P–E bond (E = Si, Ge, Sn, Pb, P, and C) and followed by P(III) → P(V) tautomeric shift. [ABSTRACT FROM AUTHOR]

Two new alkaline metal thioboratephosphates, RbB3P2S10 and CsB3P2S10, have been designed and fabricated by the flux method. The two compounds are composed of alkali metal polyhedral and [B6P4S20] T3-supertetrahedral units, and crystallize in I41/a and R3¯c space groups, respectively. The results enrich the chemical diversity of chalcogenides, and give insights for the exploration of new functional materials in thioboratephosphates. [ABSTRACT FROM AUTHOR]

Our density functional theory calculations show that silicon doping in g-CN (SiC3N3) can improve the electrochemical performance of g-CN as an anode of alkali metal-ion batteries and solve the problems of too high adsorption ability and migration energy barrier commonly found in porous carbon nitride. The stability of SiC3N3 was verified by molecular dynamics simulations and phonon spectroscopy. Elastic constant calculations revealed that the Si doping in g-CN can improve its mechanical properties. Specifically, Li/Na/K has a suitable adsorption capability (−0.71/−0.52/−0.98 eV) and a lower migration barrier (0.73/0.43/0.21 eV) on SiC3N3, where the barrier of a single Li-ion is the lowest among the doped porous carbon nitride materials studied so far. Moreover, SiC3N3 exhibits a high theoretical capacity (253/1512/1512 mA h g−1) and a low open-circuit voltage (0.48/0.18/0.31 V) for Li/Na/K ion batteries. Compared with B-doped g-CN previously studied, Si doping can more effectively improve the electronic conductivity of g-CN owing to greater charge transfer between Si and g-CN; the migration energy barrier of alkali metal ions on SiC3N3 is reduced more significantly due to its puckered structure instead of a planar structure; and the capacity of SiC3N3 is nearly doubled for alkali metal ion batteries because it has more feasible adsorption sites for alkali metals. These results suggest that Si-doped g-CN can be a universal anode material for alkali metal ion batteries. [ABSTRACT FROM AUTHOR]

Oxide semiconductors with mixed-valence states generally exhibit excellent optoelectronic and photochemical properties due to facile charge transfer in redox reactions. In this work, we investigate the effects of mixed alkali on the optical absorption, luminescence spectra and photocatalytic abilities of (Na1−xKx)Sb3O7 nanoparticles. All the samples are fabricated using a simple one-step hydrothermal method. The structural studies show that the largest substitution of K+ ions in (Na1−xKx)Sb3O7 is at x = 0.3. In hydrothermal synthesis, the mixed arrangement of K+ and Na+ in (Na1−xKx)Sb3O7 has an influence on the crystal shape of particles. NaSb3O7 develops into a regular cube shape. With the increase of K+ ions in (Na1−xKx)Sb3O7, the edges and corners of the cube are further ground off, resulting in irregularly spherical particles. This mixed-alkali antimonite belongs to a p-type indirect allowed transition semiconductor, and the optical band gap is 2.71 eV (x = 0.3). The intrinsic luminescence of NaSb3O7 is detected at 540 nm, which is nearly quenched in Na0.7K0.3Sb3O7. It is demonstrated that the substitution of K+ in NaSb3O7 significantly increases the photodegradation of RhB solutions. There are two types of Sb cations, i.e., Sb5+ and Sb3+ mixed in the structure. The improved photocatalysis is attributed to the charge mediators between Sb5+/Sb3+ couples. The experiment shows that co-doping cations in antimonite oxides may be one of the strategies to improve photochemical properties. [ABSTRACT FROM AUTHOR]

Oxide semiconductors with mixed-valence states generally exhibit excellent optoelectronic and photochemical properties due to facile charge transfer in redox reactions. In this work, we investigate the effects of mixed alkali on the optical absorption, luminescence spectra and photocatalytic abilities of (Na1−xKx)Sb3O7 nanoparticles. All the samples are fabricated using a simple one-step hydrothermal method. The structural studies show that the largest substitution of K+ ions in (Na1−xKx)Sb3O7 is at x = 0.3. In hydrothermal synthesis, the mixed arrangement of K+ and Na+ in (Na1−xKx)Sb3O7 has an influence on the crystal shape of particles. NaSb3O7 develops into a regular cube shape. With the increase of K+ ions in (Na1−xKx)Sb3O7, the edges and corners of the cube are further ground off, resulting in irregularly spherical particles. This mixed-alkali antimonite belongs to a p-type indirect allowed transition semiconductor, and the optical band gap is 2.71 eV (x = 0.3). The intrinsic luminescence of NaSb3O7 is detected at 540 nm, which is nearly quenched in Na0.7K0.3Sb3O7. It is demonstrated that the substitution of K+ in NaSb3O7 significantly increases the photodegradation of RhB solutions. There are two types of Sb cations, i.e., Sb5+ and Sb3+ mixed in the structure. The improved photocatalysis is attributed to the charge mediators between Sb5+/Sb3+ couples. The experiment shows that co-doping cations in antimonite oxides may be one of the strategies to improve photochemical properties. [ABSTRACT FROM AUTHOR]

Clathrate phases with crystal structures exhibiting complex disorder have been the subject of many prior studies. Here we report syntheses, crystal and electronic structure, and chemical bonding analysis of a Li-substituted Ge-based clathrate phase with the refined chemical formula Ba8Li5.0(1)Ge41.0, which is a rare example of ternary clathrate-I where alkali metal atoms substitute framework Ge atoms. Two different synthesis methods to grow single crystals of the new clathrate phase are presented, in addition to the classical approach towards polycrystalline materials by combining pure elements in desired stoichiometric ratios. Structure elucidations for samples from different batches were carried out by single-crystal and powder X-ray diffraction methods. The ternary Ba8Li5.0(1)Ge41.0 phase crystallizes in the cubic type-I clathrate structure (space group Pm3¯n no. 223, a ≈ 10.80 Å), with the unit cell being substantially larger compared to the binary phase Ba8Ge43 (Ba8□3Ge43, a ≈ 10.63 Å). The expansion of the unit cell is the result of the Li atoms filling vacancies and substituting atoms in the Ge framework, with Li and Ge co-occupying one crystallographic (6c) site. As such, the Li atoms are situated in four-fold coordination environment surrounded by equidistant Ge atoms. Analysis of chemical bonding applying the electron density/electron localizability approach reveals ionic interaction of barium with the Li–Ge framework, while the lithium–germanium bonds are strongly polar covalent. [ABSTRACT FROM AUTHOR]

Clathrate phases with crystal structures exhibiting complex disorder have been the subject of many prior studies. Here we report syntheses, crystal and electronic structure, and chemical bonding analysis of a Li-substituted Ge-based clathrate phase with the refined chemical formula Ba8Li5.0(1)Ge41.0, which is a rare example of ternary clathrate-I where alkali metal atoms substitute framework Ge atoms. Two different synthesis methods to grow single crystals of the new clathrate phase are presented, in addition to the classical approach towards polycrystalline materials by combining pure elements in desired stoichiometric ratios. Structure elucidations for samples from different batches were carried out by single-crystal and powder X-ray diffraction methods. The ternary Ba8Li5.0(1)Ge41.0 phase crystallizes in the cubic type-I clathrate structure (space group Pm3¯n no. 223, a ≈ 10.80 Å), with the unit cell being substantially larger compared to the binary phase Ba8Ge43 (Ba8□3Ge43, a ≈ 10.63 Å). The expansion of the unit cell is the result of the Li atoms filling vacancies and substituting atoms in the Ge framework, with Li and Ge co-occupying one crystallographic (6c) site. As such, the Li atoms are situated in four-fold coordination environment surrounded by equidistant Ge atoms. Analysis of chemical bonding applying the electron density/electron localizability approach reveals ionic interaction of barium with the Li–Ge framework, while the lithium–germanium bonds are strongly polar covalent. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbBr3 perovskite solar cells (PSCs) without hole-transport materials (HTMs) have attracted widespread attention because of their significant environmental stability. However, the poor quality of perovskite film and the energetics mismatch between CsPbBr3 and charge-transport layers limit the further improvement of the CsPbBr3 PSC performance. To solve this issue, the synergistic effect of alkali metal doping and thiocyanate passivation in NaSCN and KSCN dopants is utilized to improve the properties of the CsPbBr3 film. The Na+ and K+ with smaller ionic radii are doped at the A-site of CsPbBr3 to cause a lattice contraction, which contributes to the formation of CsPbBr3 film with enhanced grain size and crystallinity. The SCN− exerts the function of passivating the uncoordinated Pb2+ defects of CsPbBr3 film, leading to a reduction of trap state density. The incorporation of NaSCN and KSCN dopants also adjusts the band structure of CsPbBr3 film to improve the interfacial energetics match of the device. As a result, the charge recombination is suppressed, and the charge transfer and extraction are effectively promoted, delivering a highly enhanced power conversion efficiency of 10.38% for the champion KSCN doped CsPbBr3 PSCs without HTMs compared to 6.72% efficiency for the original device. Moreover, the stability of the unencapsulated PSCs under ambient conditions with high humidity (85% RH, 25 °C) is distinctly improved, retaining 91.1% of the initial efficiency after 30 days of aging. [ABSTRACT FROM AUTHOR]

Organo-alkali metal reagents are essential tools in synthetic chemistry. Alkali metal organometallics aggregate in solution and solid-state forming clusters and polymers. The structure of these aggregates and their structure–reactivity relationship have been of great interest for many decades. This Perspective will look at the strategies that have been employed to isolate low aggregates and, in particular, monomeric complexes of the most common alkali metal alkyls (M = Li–Cs, R = methyl, trimethylsilylmethyl, bis/tris(trimethylsilylmethyl), butyls and benzyl) and the relationship between level of aggregation, structure and reactivity. [ABSTRACT FROM AUTHOR]

Single crystals of A3MF6 (A = Rb, Cs; M = Al, Ga) were grown from mixed alkali chloride/fluoride fluxes in sealed silver tubes. For Cs3AlF6 and Cs3GaF6, two polymorphs were observed at room temperature: m-Cs3MF6 and o-Cs3MF6. For the two Rb containing compositions, only one room temperature polymorph was observed: o-Rb3AlF6 and t-Rb3GaF6, respectively. Simultaneous TGA/DSC and high temperature SCXRD/PXRD were used to study the high temperature behavior of A3MF6. The compounds of all four compositions were found to undergo structure transitions upon heating to the same cubic structure type, c-A3MF6. [ABSTRACT FROM AUTHOR]

Regulating the crystal structure by cations is one of the most effective methods to adjust the performances of optical materials and enrich the structural chemistry of solid-state inorganic crystals. In this work, only boron-thiophosphate BPS4 (BPS) was used as the template. By introducing alkali metal ions, Na+ and K+, the synthesis, structural revolution, and bandgap adjustment were studied. Namely, the first quaternary boron-thiophosphates, AB3P2S10 (A = Na, K) (ABPS) were obtained, whose anion skeleton decreased to zero dimension from one dimension (1D) in BPS. In addition, the bandgap showed obvious improvement from 3.30 (BPS) to 3.42 and 3.49 eV (ABPS). Structural studies and theoretical analyses indicated that the insert of cations separates the infinite chains to [B3P2S10] clusters, localizes the electrons around the S2− in [BS4] and [PS4] groups, and widens the bandgaps. This work could enrich the structural chemistry of boron-thiophosphates and reveal that ionic bonds can modulate the covalent skeleton and show the effect on the optical properties. [ABSTRACT FROM AUTHOR]

A crystal structure with a diamond-like anionic framework belongs to a non-centrosymmetric macrostructure due to the aligned arrangement of tetrahedral units, meeting the premise of second-order nonlinear optical (NLO) materials. Herein, two new Hg-based sulphides, namely RbHg4Ga5S12 (1) and CsHg4Ga5S12 (2), which are isostructural and crystallise in the trigonal space group R3, are successfully isolated in sealed silica tubes by a solid-state reaction. The features of their three-dimensional open honeycomb frameworks are attributed to the parallel alignment of tetrahedral MS4 (M is disordered by 0.444 Hg and 0.555 Ga) building motifs, accompanied by Rb+ (or Cs+) reseating in the cavities. Notably, although the band gap values of 1 and 2 are 2.30 and 2.36 eV, separately, their thermal expansion anisotropies (0.15 and 0.41, respectively) are favourable for achieving laser-induced damage thresholds (5.6 and 5.8 times that of AgGaS2 for 1 and 2, respectively). In addition, the strong polarisability of tetrahedral MS4 building motifs in the diamond-like anionic structures is responsible for the promising second-harmonic generation (SHG) intensities (1.1 and 1.8 times that of AgGaS2 for 1 and 2, respectively) in the particle size range of 50–75 μm with non-phase-matchable behaviour at 1910 nm. Furthermore, theoretical investigation elaborates that electron transitions in compounds 1 and 2 mainly occur from valence band S-3p to conduction band Hg-6s and Ga-4s states, demonstrating that the linear and nonlinear optical properties originate primarily from the synergy of tetrahedral MS4 units. [ABSTRACT FROM AUTHOR]

Rare earth borates, a subset of the essential nonlinear optical (NLO) materials, have sparked a significant amount of attention in recent years. In self-fluxing systems, two non-centrosymmetric scandium borates with classical B5O10 groups, namely Rb7SrSc2B15O30 (I) and Rb7CaSc2B15O30 (II), were successfully discovered. Both I and II exhibit a short ultraviolet (UV) cutoff edge (<200 nm) and appropriate second-harmonic generation efficiency (∼0.76 × KH2PO4, ∼0.88 × KH2PO4 at 1064 nm, respectively). According to theoretical calculations, it is speculated that the band gap and NLO characteristics of these two compounds are mostly derived from the B5O10 group and the ScO6 octahedron. Due to the short cutoff edges of I and II, they may be considered as potential NLO materials in the UV and even deep UV spectral ranges. Furthermore, the advent of I and II adds to the diversity of rare earth borates. [ABSTRACT FROM AUTHOR]

Whilst low-valent nickelates have recently been proposed as intermediates in Ni-catalysed reactions involving polar organometallics, their isolation and characterisation is often challenging due to their high sensitivity and reactivity. Advancing the synthetic, spectroscopic and structural insights of these heterobimetallic systems, here we report a new family of alkyne supported alkali-metal nickelates of the formula Li4(solv)n(Ar)4Ni2{μ2:η2,η2-Ph–C≡C–Ph} (where solv = Et2O, THF; Ar = Ph, o-Tol, naphthyl, 4-tBu-C6H4) which can be accessed through the combination of Ni(COD)2, Ph–C≡C–Ph and the relevant lithium aryl in a 2 : 1 : 4 ratio. Demonstrating the versatility of this approach, the sodium and potassium nickelates can also be accessed when using PhNa or via alkali-metal exchange with AMOtBu (AM = Na, K). When employing bulky or structurally constrained aryl-lithiums, mononickel complexes of the formula Li2(solv)n(Ar)2Ni{η2-Ph–C≡C–Ph} are instead obtained, highlighting the structural diversity of alkali-metal nickelates bearing alkyne ligands. Expanding the catalytic potential of these systems, their ability to promote the catalytic cyclotrimerisation of diphenylacetylene to hexaphenylbenzene was explored, with mononickel compounds bearing electron rich aryl-substituents displaying the best performance. [ABSTRACT FROM AUTHOR]

Heterobimetallic tert-butoxides of alkali metal cations with tetravalent actinide centers exhibit two distinctive structural motifs, [AnM2(OtBu)6] and [AnM3(OtBu)7] (AnIV = Th, U and MI = Li, Na, K, Rb, Cs), evidently governed by the size of the alkali metal ions. Both [AnM3(OtBu)7] AnM3 (AnIV = U, MI = Li; AnIV = Th, MI = Li, Na) and [AnM2(OtBu)6] AnM2 (AnIV = U, MI = Na–Cs; AnIV = Th, MI = K–Cs) compounds are obtained in nearly quantitative yields by reacting actinide and alkali metal silyl amides with an excess of tert-butyl alcohol. The AnM3 complexes form a cubane-type coordination motif, whereas the AnM2 complexes display a geometry resembling two face-shared bipyramids. The sodium derivatives of thorium and uranium (ThNa3 and UNa2) allow the determination of the structural transition threshold as a function of the ratio of the ionic radii ri(AnIV)/ri(MI). The AnM3 complexes are formed for ratios above 0.92 and the AnM2 type is formed for ratios below 0.87. All compounds are unambiguously characterized in both solution and solid states by NMR and IR spectroscopic studies and single crystal X-ray diffraction analyses, respectively. [ABSTRACT FROM AUTHOR]

The reactions between SnCl2 and three equivalents of the alkali metal phosphido-borane complexes [R2P(BH3)]M yield the corresponding tris(phosphido-borane)stannate complexes [LnM{R2P(BH3)}3Sn] [R2 = iPr2, LnM = (THF)3Li (2Li), (Et2O)Na (2Na), (Et2O)K (2K); R2 = Ph2, LnM = (THF)Li (3Li), (THF)(Et2O)Na (3Na), (THF)(Et2O)K (3K); R2 = iPrPh, LnM = (THF)4Li (4Li)]. In each case X-ray crystallography reveals an anion consisting of a trigonal pyramidal tin centre coordinated by the P atoms of the phosphido-borane ligands. These tris(phosphido-borane)stannate anions coordinate to the alkali metal cations via their BH3 hydrogen atoms in a variety of modes to give monomers, dimers, and polymers, depending on the alkali metal and the substituents at the phosphorus centres. In contrast, reactions between SnCl2 and three equivalents of [tBu2P(BH3)]M (M = Li, Na) gave the known hydride [M{tBu2P(BH3)}2SnH], according to multinuclear NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Ammonium borohydride, NH4BH4, has the highest gravimetric and volumetric hydrogen density among known inorganic compounds and a fascinating rock salt type crystal structure composed of H disordered tetrahedral complexes, NH4+ and BH4−, which are interlinked by a dense network of dihydrogen bonds. Here we report the synthesis, structure and properties of solid solutions in the binary systems, NH4BH4–MBH4 (M = K, Rb, Cs), which are investigated by in situ synchrotron radiation powder X-ray diffraction and thermal and photographic analysis. Full solubility and formation of (NH4)xM1−xBH4, is observed upon cryo-mechanochemical treatment. The solid solutions stabilize NH4BH4 from T ∼68 to ∼96 °C, alter the decomposition pathway and suppress the fierce decomposition of NH4BH4. However, for increased amounts of NH4BH4 in the solid solutions, the decomposition gradually shows more resemblance to that of pristine ammonium borohydride, and the thermal stability of the solid solutions appears to decrease down the group of the alkali metal ions, i.e. decreasing from K+, Rb+ and to Cs+. [ABSTRACT FROM AUTHOR]

C70 is the second most abundant fullerene next to C60. In this work, the exploration of C70 based electrides is proposed by theoretical encapsulation of group I/II trimetallic clusters into the C70 cage. Herein, we provide computational evidence that endohedral metallofullerenes M3@C70 (M = Li, Na, K, Be, Mg, Ca, Sr, Ba) can exist stably by calculating encapsulation energies and analyzing atom centered density matrix propagation molecular dynamics simulations. According to the results of the atoms in molecules analysis, electron localization functions and nonlinear optical properties, M3@C70 (M = Li, Be, Mg, Ca) fullerenes are identified as electrides. Interestingly, Li3@C70 and Be3@C70 are the systems with better electride performances among alkali metal and alkaline earth metal systems, respectively. It is worth noting that C70 can improve the polarizability and first hyperpolarizability of electrides compared with C60. Our work unearths the potential of M3@C70 electride systems and paves the way for the research of C70-based electrides. [ABSTRACT FROM AUTHOR]

The reaction of potassium (aza-15-crown-5)dithiocarbamate (KO4NCS2) and (Me2S)AuCl gave the dinuclear complex [Au(O4NCS2)]2, which underwent structural transformation upon heating to rearrange into the hexanuclear complex [Au(O4NCS2)]6. Under similar reaction conditions, KO4NCS2 reacted with AgNO3 or [Cu(CH3CN)4]ClO4 to give the 1-D coordination polymer [Ag(O4NCS2)]n (1) and the tetranuclear complex [Cu(O4NCS2)]4 (2), respectively. It is noted that upon heating a similar structural transformation process occurs from tetranuclear complex 2 to the octanuclear complex [Cu(O4NCS2)]8 (2′), connected by a weak Cu⋯S contact of 2.846 Å, and it has been isolated and corroborated by powder and single-crystal X-ray diffraction studies as well. Moreover, a variety of MO4NCS2 salts (M = Li+, Na+, K+ and Rb+) were used to react with AgNO3 to construct a series of coordination architectures: [LiAg(O4NCS2)2(μ-H2O)0.5]2 (3), {Na[Ag(O4NCS2)2]}n (4), {K[Ag(O4NCS2)2]}n (5) and {Rb[Ag(O4NCS2)2]}n (6). The smallest Li+ ion only coordinates with four oxygen atoms from the same azacrown ether ring and one H2O molecule, leading to a 1-D hydrogen-bonded chain with another azacrown ether ring for complex 3. The larger Na+ ion coordinates with seven oxygen atoms from two different crown ether rings, leading to a 1-D chain for complex 4. However, the largest K+ and Rb+ ions constitute a 1-D framework, except that each metal ion coordinates with eight oxygen atoms from two different crown ether rings, featuring a 1-D helical chain for complexes 5 and 6. Hence, the different sizes of alkaline metal ions exert a dramatic effect on the structural motifs of complexes 3–6. Remarkably, the dithiocarbamate moieties adopt μ2-bridging ([Au(O4NCS2)]2 and [Au(O4NCS2)]6), μ3- and μ4-bridging (1–2) and chelate forms (3–6) in the structural backbones. [ABSTRACT FROM AUTHOR]

In this work, a novel yellow-emitting phosphor SrLa2Sc2O7(SLSO):Bi3+ was synthesized by a high temperature solid-state method, with a wide coverage from 400 nm to 800 nm under near-ultraviolet (NUV) excitation and the full width at half maximum (FWHM) of up to 180 nm. The phosphor emits bright yellow light, which is observed using optical microscopy. Alkali metal (Li+, Na+, K+) ions were used as charge compensators to enhance the luminescence intensities of SrLa2Sc2O7:Bi3+. Finally, the yellow SrLa2Sc2O7:Bi3+,Li+ and blue Sr5(PO4)3Cl:Eu2+ phosphors were homogeneously mixed with silica gel and coated on a NUV light emitting diode (LED) at 370 nm to obtain white LEDs with a high color rendering index (Ra = 91.3), a low correlated color temperature (CCT = 4879 K) and color coordinates (0.34, 0.30). This work can provide a good candidate for making white LEDs. [ABSTRACT FROM AUTHOR]

Alkali metal chlorides have been used as molten salts for further preparing crystalline carbon nitride, but the effect of alkali metal types on the properties of crystalline carbon nitride has not been systematically studied. Therefore, in this paper, a series of crystalline carbon nitride samples doped with different alkali metals were successfully prepared using LiCl–KCl, KCl–NaCl, LiCl–KCl–NaCl and LiCl–NaCl as molten salts: LK-HTCN (Li–K co-doping), KN-HCN (K–Na co-doping), LKN-HTCN (Li–K–Na co-doping) and LN-HTCN (Li–Na co-doping). The experimental results show that KN-HCN contains only the heptazine unit structure, while the other samples contain heptazine and triazine unit structures. Meanwhile, the concentration of the cyano group in the KN-HCN sample structure is significantly higher than that of other samples, which may be related to the fact that there is only a heptazine unit in the structure of the KN-HCN sample. In addition, the loading mode of K and Na ions in the KN-HCN structure is favorable for the migration and separation of photogenerated charges. Thanks to these characteristics, KN-HCN showed excellent photocatalytic ammonia production activity. This study can provide theoretical insight for the development of crystallized carbon nitride. [ABSTRACT FROM AUTHOR]

Acid treatment of crystalline silicates is a facile method of creating pores for the preparation of crystalline silica-based microporous materials, but its success depends on the acid treatment conditions and both the composition and crystallinity of the starting silicates. Here, europium silicate Eu-AV-9 containing Na+, K+, and Eu3+ ions was treated with acetic acid for 1 d or 14 d to synthesize microporous silicate with high Eu loading by the selective leaching of K+ and Na+ from the silicate. The acid-treated Eu-AV-9 had both crystallinity and microporosity capable of adsorbing CO2, while the adsorption of Ar was very low. In addition, the values of both micropore volume and BET area of acid-treated samples increased when the time of acid treatment was increased. This result was attributed to the formation of structural defects caused by eliminating Eu in Eu-AV-9 over time of acid treatment. [ABSTRACT FROM AUTHOR]

Metal thiophosphates have aroused much research interest due to their structural chemistry and possible applications as infrared functional materials. In this study, five quaternary Sr-based alkali metal thiophosphates ASrPS4 (A = Li, Na, K, Rb, Cs) were obtained. Their structural comparison shows that their symmetry undergoes transformation from tetragonal (I41/acd) to monoclinic (P21/c) to orthorhombic (Pnma) system, which is induced by the cation size effects and coordination features of different alkali metal cations. The experimental and theoretical results demonstrate that the band gaps of all title compounds are large, namely 3.6–3.9 eV (experimental results) and 3.78–4.12 eV (HSE06). Theoretical analyses indicate that the [PS4] group could be regarded as a good unit for designing wide band gap compounds, and the birefringence of NaSrPS4 is 0.08 at the fundemental 1064 nm wavelength, which shows that it may be a potential infrared birefringent material. [ABSTRACT FROM AUTHOR]

Herein we detail the straightforward and scalable synthesis of sodium and potassium complexes of the 2,5-bis(tert-butyldimethylsilyl)-3,4-diphenylplumbolyl dianion (PblTBS,Ph). Their solid-state structures were found to comprise either monomeric solvates or coordination polymers depending on the alkali metal ion and crystallization medium. These complexes were readily prepared with high yields and purity compared to known routes to the dilithium congener of PblTBS,Ph and are well-positioned to serve as convenient precursors for salt metathesis-type reactions leading to metal complexes of the understudied PblTBS,Ph ligand. [ABSTRACT FROM AUTHOR]

In this work, a series of Cr3+-doped A2NaYF6 (denoted as ANYF:Cr; A = K, Rb, and Cs) fluoroyttrate double-perovskites with broad blue excitation and near-infrared (NIR) emission bands were prepared using a high-temperature solid-state reaction method. The physicochemical and spectroscopic properties of the as-prepared products, including crystal structure, bandgap, morphology, luminescence behaviour and optical performance, were studied in detail. The results show that the Cr3+ activators undergo a decreasing crystal field in ANYF in the direction from K to Cs, yielding a red shift of the emission peak position from 758 to 786 nm, whilst the full-width-at-half-maximum (FWHM) expands from 98 to 104 nm. By virtue of the broadband NIR emission, clear structural images of the tangerine section, mini LED flashlight and circuit board were obtained by merging the optimal RNYF:Cr phosphor on a blue InGaN chip, implying its potential use in light-emitting diodes for non-destructive testing. [ABSTRACT FROM AUTHOR]

The previously reported potassium aluminyl complex [(BDI-H)Al−K+]2 was converted in Li+ or Na+ salts by a salt metathesis reaction with Li(BPh4) or Na(BPh4), respectively; BDI-H = dianionic [(DIPP)N–C(Me)＝C(H)–C(＝CH2)–N(DIPP)2−] and DIPP = 2,6-diisopropylphenyl. The Rb and Cs aluminyl complexes were obtained by reaction of (BDI)Al with RbC8 or CsC8; BDI = HC[C(Me)N(DIPP)]2. Crystal structures of two monomers, (BDI-H)Al−Li+·(Et2O)2 and (BDI-H)Al−Na+·(Et2O)(TMEDA), and four dimers [(BDI-H)Al−M+]2 (M = Li, Na, Rb, Cs) are discussed. Lewis base-free dimers [(BDI-H)Al−M+]2 crystallize either as slipped dimers (Li+, Na+) in which each Al center features only one Al–M contact or as a symmetric dimer (K+, Rb+, Cs+) in which the cation bridges both Al centers. The dimer with the largest cation (Cs+) shows Cs⋯CH2＝C interactions between dimers, resulting in a coordination polymer. AIM and charge analysis reveal highly ionic Al–M bonds with strong polarization of the Al lone-pair towards the smaller cation Li+ and Na+. The Al–M bonds become weaker from Li to Cs. Calculated dimerization energies suggest that in apolar solvents only complexes with the heavier metals Rb and Cs may be in a monomer–dimer equilibrium. This is confirmed by DOSY measurements in benzene. Dimeric aluminyl complexes with heavier alkali metals (K-Cs) react with benzene to give a double C–H activation in para-positions. [ABSTRACT FROM AUTHOR]

A series of Rb1−yKyNa3(Li3SiO4)4:Eu2+(0 ≤ y ≤ 1) phosphors were successfully synthesized through a high-temperature solid-state reaction. The introduction of K+ into the RbNa3(Li3SiO4)4:Eu2+ phosphor to partially or completely replace Rb+ allows the emission spectrum to be modulated from blue (λ = 473 nm, FWHM = 22.5 nm) to a narrow cyan band (λ = 485 nm, FWHM = 21.1 nm). As the K+ ion content increases, the space group of the phosphor evolves from I4/M to I41/A. The complete replacement of Rb+ by K+ results in the KNa3(Li3SiO4)4:Eu2+ cyan phosphor, which shows excellent thermal stability (the comprehensive emission loss is only 8% at 150 °C) and can be used to fill the cyan light gap in white LED devices. By adding the KNa3(Li3SiO4)4:Eu2+ cyan phosphor in packaging with yellow and red phosphors, the color rendering index is increased from 90.2 to 97.1 and the correlated color temperature improved to 3658 K. These results indicate that the cyan phosphor has important application value in full-spectrum white LEDs. [ABSTRACT FROM AUTHOR]

The incorporation of Sc3+ can stabilize calcite-phase LuBO3:Ce3+ to grow large-sized single crystals but leads to the significant degradation of scintillation performance. In the present work, alkali metal ion (A+ = Li+, Na+, K+)-incorporated (Lu, A, Sc)BO3:Ce was rapidly synthesized in batches via a high-throughput sol–gel method. The aliovalent substitution of Lu3+ with A+ is balanced by the generation of oxygen vacancies by forming complexes. Thanks to the increased oxygen vacancies, the luminescence and XEL intensity of (Lu, Li, Sc)BO3:Ce are significantly enhanced by 2.2 times and 1.9 times, respectively. Further, the incorporation of A+ is attributed to the improved transition efficiency of charge carriers. The prepared scintillation screen fabricated with LASBO:Ce and PMMA shows that the spatial resolution can reach 8.6 lp mm−1, indicating its potential application in efficient and low-cost non-destructive X-ray detection. This work is of great significance in improving the luminescence and scintillation performance of (Lu, Sc)BO3:Ce single crystals and thin films and their application in the scintillation field. [ABSTRACT FROM AUTHOR]

Two new quaternary selenides AAg3Ga8Se14, (A = Rb, 1; Cs, 2) were synthesised via solid-state reaction in sealed silica tubes. Compounds 1 and 2 crystallised in the monoclinic space group Cm (no. 8) and their three-dimensional [Ag3Ga8Se14]− anionic frameworks were comprised of AgSe4 and GaSe4 tetrahedrons. Their UV-Vis-near infrared diffuse reflectance spectra showed that 1 and 2 possessed wide band gaps of 2.17 and 2.10 eV, respectively. Notably, under incident laser irradiation at 1910 nm, compounds 1 and 2 presented moderate second-harmonic generation responses of 0.6 and 0.7 × AgGaS2, respectively, with phase-matching behaviours due to the parallel arrangement of nonlinear optical (NLO) functional tetrahedral AgSe4 and GaSe4 units. The laser-induced damage thresholds of 1 and 2 were estimated to be 25.4 and 18.0 MW cm−2, respectively, which were 2.1 and 1.5 times the threshold of AgGaS2. This study revealed that the title selenides, which were constructed from tetrahedral units arranged in a parallel array, are promising infrared NLO materials. [ABSTRACT FROM AUTHOR]