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Two zero-dimensional hybrid manganese bromide polymorphs ((DMAPH)2MnBr4) exhibit single-crystal to single-crystal phase transformation, accompanied by an increase in MnBr4 tetrahedral bond angle variance (σ2). This structural change leads to an emission redshift due to enhanced crystal field strength, achieving yellow emission with near-unity quantum yield, which highlights its potential for solid-state lighting applications. [ABSTRACT FROM AUTHOR]

The electrocatalytic splitting of water to produce hydrogen is regarded as an efficient and promising strategy but is limited by its large overpotential; thus, a highly efficient electrocatalyst is urgently needed. Mixed metal doping is an important strategy in defect engineering because the heteroatoms can change the intrinsic structure to form defects by affecting the atomic coordination mode and adjusting the electronic structure, which is often accompanied by morphological changes. Herein, two-dimensional layered bimetallic Co–pydc containing axially coordinated water molecules was selected by producing surface defects through Fe doping in Co centers as bifunctional electrocatalysts for OER and HER. The optimized Co0.59Fe0.41–pydc possesses outstanding OER performance with the lowest overpotential of 262 mV to reach j = 10 mA cm−2, and Co0.75Fe0.25–pydc possesses superior HER performance with the lowest overpotential of 96 mV at j = 10 mA cm−2. Furthermore, the overall water splitting device assembled with Co0.59Fe0.41–pydc@NF//Co0.59Fe0.41–pydc@NF affords a current density of 10 mA cm−2 at only 1.687 V. This work emphasizes the surface defects formed by tuning the electronic structure of metal centres accompanied with morphological changes of bimetallic dopants for efficient overall water splitting. [ABSTRACT FROM AUTHOR]

Zero-dimensional (0D) organic–inorganic metal halide hybrids have aroused heightened academic interest from the solid-state lighting field because of their abundant structural species and excellent photoluminescence properties. However, the synthesis of single-component white-light emitters with an ultra-broad emission band (>200 nm) remains a huge challenge. Here, we report on a 0D cadmium-based ultra-broadband solid white-light emitter using the luminescent active organic templates, namely (H2AMP)CdBr4·H2O (1, AMP = 2-piperidylmethylamine), containing isolated 0D CdBr4 tetrahedral anions separated by [H2AMP]2+ cations. Under 365 nm excitation, 1 shows an ultra-broadband "warm" white-light emission with a large bandwidth of 285 nm containing three emission bands at 451, 521, and 631 nm located in the blue, green, and red regions, respectively, which have a high color rendering index of 98 and a moderate photoluminescence quantum yield of 23.46%. Systematic investigations prove that the origin of white-light emission stems from the synergic work of singlet excitons bound in organic components as well as singlet and triplet excitons self-trapped into distorted tetrahedral substructures. To our knowledge, 1 should be the first observation of the coexistence of singlet and triplet self-trapped excitons in 0D tetrahedral CdX4-based metal halides at room temperature. Moreover, 1 is a direct bandgap semiconductor, as revealed by experimental results and theoretical calculations. Our work provides a novel approach for the development of single-component white-light emitters with more brilliant photophysical properties. [ABSTRACT FROM AUTHOR]

A close-packed superstructure consisting of Ti12 and Ti6 in one single crystal is prepared via a solvothermal synthesis. The closest twelve neighboring Ti6 clusters form a distorted cuboctahedron centered with a Ti12 cluster. Such a structure imitates the stacking sequence of a face-centered cubic (FCC) metal. By employing the cuboctahedron as a basic unit, the whole single crystal is re-rendered. [ABSTRACT FROM AUTHOR]

Low-dimensional metal halides with ns2 lone-pair electrons have been recognized as new generation luminescent emitters for various optoelectronic applications. However, 5s2 configuration tellurium halides have not received substantial attention despite their fascinating photoluminescence (PL) properties. Here, a hybrid tellurium-based double perovskite of (C20H20P)2TeCl6 is developed, in which the [TeCl6]2− octahedra are completely surrounded by [C20H20P]+ organic cations to form a unique zero-dimensional (0D) "host–guest" structure. An uncommon broadband yellow emission peaking at 570 nm with ultra-broad excitation from ultraviolet to blue light is excavated, which originates from the triplet self-trapped exciton (STE) emission of Te4+. Moreover, the 5s2 electronic transition mechanism of Te4+ is systematically revealed in depth, benefiting from the temperature-dependent fluorescence dynamic analysis and auxiliary theoretical calculations. It is concluded that the distortion degree of the [TeCl6]2− octahedron comprehensively affects the full width at half-maximum (FWHM) (positive correlation), Stokes shift (negative correlation) and PL intensity (negative correlation) with increasing temperatures. This work sheds new light on the PL behaviour of Te4+ and opens up a feasible avenue for blue-excitable broadband emissions in low-dimensional organic–inorganic hybrid double perovskites. [ABSTRACT FROM AUTHOR]

π-Conjugated-group systems are fascinating and have been pursued for nonlinear materials owing to their superior optical and electronic properties, but are so far quite limited. Here, we report a new ultraviolet (UV) nonlinear-optical (NLO) beryllium borate crystal PbBe2B2O6 that manifests an unprecedented π–π interacting BeBO5 group, constructed by interconnected π-conjugated BeO3 and BO3 units. The PbBe2B2O6 crystal has a short UV cutoff wavelength of 249 nm, phase-matching behavior in the whole transmission region from UV to IR light region (249–3166 nm), and remarkably the largest NLO effect (18.5 × KDP) among the π-conjugated UV NLO crystal materials. Theoretical calculation unravels that the highly NLO-active BeBO5 group has strong π–π interactions. This work offers an innovative source of BeO3-participating NLO materials and expands the frontier of NLO research. [ABSTRACT FROM AUTHOR]

Purple of Cassius is a pigment based on a gold colloid that has been known for hundreds of years. It has had a profound influence on modern nanoscience. But the origin of the small size of the Au nanoparticles (NPs) and their superior stability remains ambiguous. The experiments and characterization studies discussed here confirmed that SnCl2 functioned not only as a reducing agent but also as an effective surface capping agent through bimetallic Au–Sn bonding. This finding expands the types of Au NP stabilizer from traditional organic examples (e.g., thiolate or phosphine) to metallic examples. The formation of a Au–Sn interface also endows Au NPs with excellent activity and separability for the hydration of alkynes to ketones. [ABSTRACT FROM AUTHOR]

Dion–Jacobson (DJ) phase hybrid perovskites (HPs) have achieved impressive performance and high stability in optoelectronics devices. Despite that, research on the relationship between the structure and photoelectric properties of DJ HPs is still rare; particularly, the effect of diammonium cations with different conformations between the interlayers on the structure–activity relationship has not been reported. Herein, three kinds of DJ HP bulk crystals, BDAPbBr4 (1), 2AMPPbBr4 (2) and 2AMPYPbBr4 (3), have been constructed by interlayer cation engineering with the linear diammonium 1,4-butanediammonium (BDA), cyclic aliphatic diammonium 2-(aminomethyl)piperidinium (2AMP) and aromatic diammonium 2-(aminomethyl)pyridinium (2AMPY), respectively. These DJ HPs based on diammonium cations with different conformations exhibit diverse structures and optical and electronic properties. After an in-depth analysis, the photoelectric properties of these DJ HPs have been found to be significantly affected by the interlayer spacing, the insertion depth of the diammonium cations into the inorganic skeleton and the distortion degree of the inorganic layer. Finally, compound 3 constructed using the aromatic diammonium has been found to possess the shortest interlayer spacing (3.404 Å), the deepest insertion (1.147 Å) and the smallest distortion (173.7°), which afford it better photodetection performance (3.2 × 1011 Jones) than 1 (3.8 × 1010 Jones) and 2 (1.8 × 1011 Jones) under 405 nm irradiation. More importantly, it is precisely because of the rigidity and aromaticity of the 2AMPY cations that compound 3 has the best optical and photoelectric performance. These findings provide a foundation for designing optoelectronic devices with distinguished performance in the future. [ABSTRACT FROM AUTHOR]

Organic–inorganic metal halides have become a multifunctional platform for manipulating photoluminescence due to highly efficient and tunable emissions, especially for lead-free Mn2+-based halides. Herein, the zero-dimensional (0D) bromides of (C5H14N3)2MnBr4 and (CH6N3)2MnBr4 with different coordination environments were designed and synthesized by a solvent evaporation method. They exhibit green and red broadband emission peaks at 528 nm and 627 nm with high photoluminescence quantum yields of 86.83% and 61.91%, respectively, which are attributed to the d–d transition (4T1(G) → 6A1(S)) of [MnBr4]2− tetrahedral and [Mn3Br12]6− octahedral units. The cases emphasize the effect of organic ligands on the intrinsic emissions of Mn2+ ions, thereby revealing the luminescence mechanism of Mn2+ ions in 0D isolated structures through the Tanabe–Sugano (TS) energy diagram. Thanks to their bright and stable emissions, the fabricated white light-emitting diode (LED) based on (C5H14N3)2MnBr4 and (CH6N3)2MnBr4 provides an outstanding color rendering index (Ra) of 90.8 at a correlated color temperature (CCT) of 3709 K, along with the CIE chromaticity coordinates of (0.3985, 0.3979) and a luminous efficacy of 51.2 lm W−1. This work aims at clarifying the relationship between the coordination units of Mn2+ and tunable emissions, and in particular, proposes a new strategy to explore phosphors excited by blue light for white LEDs. [ABSTRACT FROM AUTHOR]

A new one-dimensional (1D) face-shared hybrid lead bromide of (2cepiH)PbBr3, which exhibits intrinsic broadband yellow-light emission with a quantum yield of 16.8% outperforming all previously reported 1D face-shared hybrid metal halides, is obtained. The origin of broadband emission and the coexistence of free excitons and self-trapped excitons are deeply investigated by variable-temperature photoluminescence spectra. Our work paves the way to discovering more wonderful light-emitting materials. [ABSTRACT FROM AUTHOR]

Low-dimensional-networked metal halides are attractive for the screening of emitters applied in solid-state lighting and displays, but the lead toxicity and poor stability are obstacles that must be overcome in industrial applications. Herein, we aim at the discovery of bright and stable photoluminescence in zero-dimensional (0D) Mn2+-based metal halides. By manipulation of Cl/Br transmutation, the nature of the halogen can be confirmed as a pivotal factor to tune the PL behaviors, and the optimum Mn2+ emission with a high PLQY of 99.8% and a short lifetime of 0.372 ms can be achieved in (C24H20P)2MnBr4. The thermal quenching behaviors have been discussed in depth, indicating that the synergistic effect of good chemical stability of organic groups, a long Mn⋯Mn distance of 10.447 Å and a relatively large activation energy (ΔE = 0.277 eV) provides a platform for achieving excellent thermal stability in (C24H20P)2MnBr4. Moreover, the as-fabricated white LED device with a high luminous efficacy of 118.9 lm W−1 and a wide color gamut of 105.3% National Television System Committee (NTSC) shows that (C24H20P)2MnBr4 can be employed as a desirable narrow-band green emitter for LED displays. This work provides a new understanding of fine tailoring halogens, and proposes a feasible approach to achieving high thermal stability emitters toward the targeted practical applications. [ABSTRACT FROM AUTHOR]

The design and utilization of dual sites for synergistic catalysts has been recognised as an efficient method towards high-efficiency catalysis in the cyanosilylation of aldehydes, which gives key intermediates for the synthesis of a number of valuable natural and pharmaceutical compounds. However, most of the reported dual-site catalysts for this reaction were homogeneous, accompanied by potential deactivation through internal complexation of the dual sites. Herein, by the rational selection of an uncoordinated tertiary nitrogen based tricarboxylic ligand (tris[(4-carboxyl)-phenylduryl]amine, H3TCBPA), a new three-dimensional calcium-based metal–organic framework (MOF), Ca3(TCBPA)2(DMA)2(H2O)2 (1, where TCBPA = ionized tris[(4-carboxyl)-phenylduryl]amine and DMA = N,N-dimethylacetamide), possessing accessible dual catalytic sites, Lewis-basic N and Lewis-acidic Ca, has been designed and constructed by a one-pot solvothermal reaction. As expected, 1 is capable of dually and heterogeneously catalysing the cyanosilylation of aldehydes at room temperature, and can be reused for at least 6 runs with a maximum turnover number (TON) of 1301, which is superior to most reported cases. Additionally, 1 shows CO2 adsorption ability and conversion with epoxides, which is beneficial for the establishment of a sustainable society. [ABSTRACT FROM AUTHOR]

Lanthanide metal–organic frameworks (Ln-MOFs) have demonstrated great potential in luminescence sensing and optical anti-counterfeiting. High-security anti-counterfeiting technology is of great importance and requires the development of universal luminescent materials with multiple modes of emission and adjustable photoluminescence. Herein, a 3D red light emission microporous europium(III) metal–organic framework [Eu3(OH)(1,3-db)2(H2O)4]·3H2O (1) (1,3-db = 1,3-di(3′,5′-dicarboxylpheny) benzene) was constructed from a zigzag [Eu3(COO)8] chain and π-electron-rich terphenyl-tetracarboxylate. Notably, the quenched fluorescence of 1 under hydrogen chloride vapor could be recovered upon fuming by a vapor of Et3N. Most strikingly, the strong blue light emission by nitrogen and sulfur co-doped carbon dots (N,S-CDs) could be encapsulated in 1 to generate a dual-emission composite, namely, N,S-CDs@Eu-MOF, which shows solvent-dependent photoluminescence: N,S-CD-related blue luminescence in water and Eu-MOF-related red emission in organic solvents. Taking advantage of the above unique reversible fluorescent behavior, Eu-MOF and N,S-CDs@Eu-MOF are prepared as fluorescent high-security inks to achieve data encryption and decryption on specific flower patterns. [ABSTRACT FROM AUTHOR]

One dimensional (1D) hybrid metal halides with core–shell quantum wire structures can display superior photoluminescence (PL) properties, e.g. high photoluminescence quantum yield and long lifetime; however, the single component white-light emissions in 1D hybrid systems composed of face-sharing octahedral chains have been only rarely reported. Herein, we report on a new 1D organic–inorganic hybrid cadmium chloride, (2cepiH)CdCl3 (2cepi = 1-(2-chloroethyl)piperidine), containing face-sharing CdCl6 octahedral chains. This incredible 1D Cd-based halide exhibited a bright white-light upon ultraviolet photoexcitation, which had an ultra-high color rendering index of 89 along with the CIE chromaticity coordinates of (0.27, 0.31). The fundamental mechanism of white-light emission was assigned to the synergistic emissions of free excitons and self-trapped excitons, as confirmed by the temperature-dependent PL spectra. To our knowledge, it is the first time that self-trapped exciton states are reported in 1D Cd-based hybrid materials with broadband white-light emission. Furthermore, both the experimental and the calculated results confirmed the semiconducting behavior of (2cepiH)CdCl3, and the band structure was determined by the inorganic frameworks. Our work provides a new idea to design novel single component white-light emitters. [ABSTRACT FROM AUTHOR]

An unprecedented CsPbBr3-based polar Dion–Jacobson type bilayered hybrid, (2meptH2)CsPb2Br7 (1, where 2mept = 2-methyl-1,5-diaminopentane), has been reported. Polarization could benefit the charge transport to induce low Ntrap. 1 exhibits a large on/off ratio (∼103), fast response time (∼200 μs) and high photodetectivity (∼109 Jones) for promising UV photodetection. [ABSTRACT FROM AUTHOR]

Discrete supertetrahedral clusters of metal chalcogenides are rare because of the difficulty involved in meeting global charge matching between the negative charge of the skeleton and counterion. We present herein the third type of a discrete chalcogenide cluster with a double T3 structure in the compound (HDBN)6[In20S33(DBN)6] (DBN = 1,5-diazabicyclo [4.3.0]-5-nonene), the anion of which features quasi-D3 symmetrical double-T3 In20S33 supertetrahedra with six cornered indium atoms coordinated by DBN molecules. DFT theory calculations of the interaction between host and guest show that this compound may have high kinetic stability and low photoelectric reactivity. [ABSTRACT FROM AUTHOR]

New paracelsian-like beryllophosphates M4LiBe4P7O24 and their tetrahedra-substituted phases M4Li(Li3P)P7O24 (MLiP2O6, M = Cs, Rb) were designed and synthesized. Interestingly, two types of phases undergo a structural transformation, resulting from the radius and valence charge number of tetrahedral cations. Four crystals demonstrate potential deep-UV NLO properties such as short absorption edges (<190 nm) and phase-matching SHG response. [ABSTRACT FROM AUTHOR]

Isostructural mixed alkali/alkaline-earth metal tellurite halides BaLiTe2O5X (X = Cl, Br) have been successfully synthesized by a mild hydrothermal method, which possess the [Te2O5]∞ chains formed by the corner-sharing connections of the TeO3 and TeO4 polyhedra. The [Te2O5]∞ chains are bridged via the LiO3 polyhedra to form the [LiTe2O5]∞ layers with 4- and 6-membered rings. The adjacent [LiTe2O5]∞ layers are linked via the BaO9 polyhedra to form the [BaLiTe2O5]∞ double layers, which are further connected via weak Ba–X–Li interactions to generate a 3D framework. Analysis of different lithium tellurites shows that the different arrangements of the Te–O and Li–O units in the lithium tellurites can be attributed to the cation–cation repulsion and lone-pair effect. Both compounds display good thermal stability, wide optical bandgaps (4.25 and 4.13 eV), and large birefringence. First-principles calculations indicate that the TeOn groups and X− determine the optical properties of BaLiTe2O5X (X = Cl, Br). [ABSTRACT FROM AUTHOR]

Herein two unprecedented octanuclear Co8 clusters are presented, [Cl@Co8 (TEOA)4(CH3CN)Cl3] (1) and [S@Co8(DEOA)6(NCS)2] (2) (H3TEOA = triethanolamine, H2DEOA = diethanolamine), in which tetrahedral μ4-chloride and in situ generated octahedral μ6-sulfide are used as templates. In spite of them being derivatives of cubes, eight Co atoms in 1 consist of two co-centered tetrahedra of different sizes, whereas in 2 they appear as a rhombohedron formed via elongating a cube along the C3-axis direction. Strong intra-cluster antiferromagnetic interactions were found. [ABSTRACT FROM AUTHOR]

Intriguing 1D single-walled metal–organic nanotubes (MONTs) Zn2(RR-CHCAIP)Py2(H2O) (HMOF-2) were successfully self-assembled using a semirigid homochiral ligand, 5,5′-((1R,2R)-cyclohexane dicarbonyl bis(azanediyl)) diisophthalic acid (RR-CHCAIP) with zinc salt, which was constructed from an organic ligand similar to the twin blades of a propeller with the Zn2(COO)4(H2O)(Py)2 cluster acted as the SBU, and the terminal pyridine auxiliary ligand capping at the Zn atoms played a key role in the formation of the 1D single nanotubes. The fluorescence of the HMOF-2 emulsion could be effectively quenched by D / L -lactic acid, D / L -tartaric acid enantiomers and D / L -alanine via hydrogen bonding interactions with the inwall of MONTs, which suggested this to be a remarkable chiral sensor for α-hydroxyl carboxylic acid and amino acid enantiomers with good sensitivity and enantioselectivity. Comparatively, HMOF-2 showed a negligible response towards D / L -mandelic acid and D / L -tyrosine, which chiefly arose from the confinement effect and the host–guest interaction of MONTs with the analytes. The construction strategy of MONTs based on the homochiral propeller-like ligand that bridges two metallic pillars will open new perspectives for developing self-assembling chiral MONTs with unique and practically useful enantioselective functions. [ABSTRACT FROM AUTHOR]

A pre-synthetic strategy was developed for the construction of single ion conductive covalent organic frameworks (COFs). A high Li+ conductivity of 1.6 × 10−3 S cm−1 at 273 K was achieved, and single Na+ and K+ COFs were also obtained by using Na+ and K+ salts as monomers according to this synthetic method. [ABSTRACT FROM AUTHOR]

Strategies for developing efficient energy conversion and storage devices that have been optimized by designing electrode materials is a critical challenge for researchers. Herein, we report the design and synthesis of a series of Co@NC trifunctional electrocatalysts derived from rationally designed cobalt-added anion MOF precursors and preliminarily reveal the relationship between the precursor and corresponding efficient electrocatalysts. Benefiting from the special composition of Co2+-doped anion MOFs involving Co2+ chelates as the Co2+ sources, the resulting CoT@NC electrocatalyst possesses abundant Co/Co–Nx/Co–Ox and multiple active nitrogen sites that are evenly distributed. As expected, the rich variety of active species and hierarchical pore structures endow CoT@NC with excellent performances toward ORR, HER, and OER, including a high half-wave potential value of 0.86 V for ORR and low overpotential values for OER (350 mV) and HER (209 mV) at 10 mA cm−2 in an alkaline solution. Moreover, we assembled a conventional Zn–air battery with CoT@NC as the air-cathode catalyst, which exhibited excellent rechargeable performance and ultrahigh durability. Moreover, CoT@NC coated on Ni foam was used as both anode and cathode for the overall water-splitting process, which needed a bias voltage of 1.70 V to achieve a current density of 10 mA cm−2. This study sheds light on the design, fabrication, and regulation of highly active cobalt-based electrocatalysts with abundant active sites and tunable pore structures for electrocatalysis and other applications. [ABSTRACT FROM AUTHOR]

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

Silver doped TiO2 (Ag–TiO2) materials show high activity and good stability in photocatalysis, but the mechanism could not be illustrated clearly due to their imprecise and inhomogeneous characteristics. Ag-doped titanium-oxo clusters (Ag-TOCs) with an exact crystal structure, which are rarely reported, are beneficial for further understanding structure–property relationships. Herein, six new Ag-TOCs with a butterfly-like Ti8Ag2 core have been synthesized through facile solvothermal reactions, in which two Ag ions are successfully linked to the surface of the Ti8 core. Of interest, the Ti6 unit of the Ti8Ag2 core is similar to that found in the anatase structure and may be a promising model for Ag–TiO2 materials. The band gaps of these Ag-TOCs show different values mainly affected by different ligands. DFT calculations revealed that the lowest energy bands of Ag-TOCs are attributed to the Ag-to-TiO core charge transfer bands. Additionally, all Ag-TOCs exhibit good photoelectric response and high photodegradation activity towards organic dyes. [ABSTRACT FROM AUTHOR]

Two new alkali–metal bismuth iodates KBi(IO3)3(OH) (1) and NaBi(IO3)4 (2) have been synthesized by a hydrothermal method via tuning of alkali–metal ions. Compound 1 crystallizes in the space group P1̅ and features a [Bi(IO3)3(OH)]n chain with eight-membered Bi–O–I–O–Bi–O–I–O rings. The [Bi(IO3)3(OH)]n chain consists of paddlewheel-like dimeric Bi2(OH)2(IO3)4 units linked by IO3 pairs. Compound 2 in the polar space group Cc features a [Bi(IO3)4]− double layer with Bi4I4 eight-membered rings (8-MRs). NaBi(IO3)4 exhibits a strong second harmonic generation (SHG) response of ∼5.0 × KDP (KH2PO4) and a wide transmittance window (0.4–12 μm), and structure analyses and theoretical calculations reveal that polarization results mainly from the proper alignment of the IO3 groups. The calculated electronic structure based on the DFT method indicates that the BiOn and IO3 groups dominate their optical properties. [ABSTRACT FROM AUTHOR]

A novel and thermally stable aluminum phosphate Li6Na3Sr14Al11P22O90 (1) has been achieved by using a solid-state molten method, which contains an oxo-centered trinuclear cluster and an anti-Lowenstein's rule Al–O–Al linkage and is constructed from two types of (3,6)-connected kgd layers [Al(Al3O)(PO4)7]25− and [Al(PO4)2]3−. The good optical transparency in the whole UV range and excellent thermal stability make the title compound a potential optical window material. [ABSTRACT FROM AUTHOR]

Density functional theory calculations combined with the energy and building-block decomposition analyses have been carried out to investigate the structures, stability orders, redox potentials and proton binding of the six Baker–Figgis isomers (α, β, γ, α*, β* and γ*) of [(SbO6)W18O54(OH)2]9− {H2SbW18} and [(NaF6)W18O54(OH)2]7− {H2NaW18} anions at the level of PBEsol-D3/TZP. Both bonding energy and Gibbs free energy analyses exhibit that the two non-classical Wells–Dawson (WD) species behave quite differently from each other. The pyroanimonate {H2SbW18}, with a stability order of γ* ＞ β* ＞ α ＞ α* ＞ β ＞ γ, is a non-classical WD species, while the hexafluoride {H2NaW18} (α ＞ β ＞ γ ＞ γ* ＞ β* ＞ α*) is a transition intermediate between classical and non-classical WD types, possessing both non-classical ([XW18O60(OH)2]n−, X = I, Te and W) and classical [Si2W18O62]8− properties. Energy decomposition analyses (EDA) reveal that spatial arrangement (Ehost), host–guest fragment interaction energy (FIE), and structural distortion energy (DE) are three key factors governing the relative stability of isomers; among these, DE is always dominant, while FIE and Ehost are subordinated but are still important. Building-block decomposition analyses (BDA) disclose that the octahedral {MO6} units of the equatorial belt, particularly the staggered belt, are always more distorted than those of the two polar caps inside each structure. The theoretical redox potentials demonstrate that the oxidizing power increases with a trend of α ＜ β ＜ γ and α* ＜ β* ＜ γ* for both species, and the first redox potential is closely related to the energy level of the LUMO of each anion. Evaluation of the proton inclusion energies suggests that {H2NaW18} can only embed two protons, while {H2SbW18} may encapsulate four; the number of embedded protons is controlled by both the charge of the heteroatom X and the volume of the tetrahedral {O4}/{OF3} cavity. [ABSTRACT FROM AUTHOR]

A series of alkali earth cadmium selenites including MgCd3(SeO3)4 (1), Ca0.7Cd2.3(SeO3)3 (2), SrCd(SeO3)2 (3) and BaCd(SeO3)2 (4) are synthesized by hydrothermal reaction and studied in detail by single crystal and powdered X-ray diffractions, thermal analyses, IR and UV spectral measurements and dipole moment calculation. 1 features a 3D anionic [Cd3(SeO3)4]2− framework constructed from isolated SeO3 trigonal pyramids and 2D [Cd3O12]n layers, in which the [Cd3O12]n layer is composed of edge-shared [Cd2O10]16− dimers and butterfly-like [Cd4O20]32− tetramers. 2 shows a smooth 2D [Cd2(SeO3)3]n layer composed of unique [Cd(SeO3)]n double chains. 3 exhibits a wavelike 2D [Cd(SeO3)2]n layer constructed from corner-shared CdO6 octahedra and isolated SeO3 trigonal pyramids. 4 displays a windmill-like 1D [Cd(SeO3)2]n chain built from zigzag [CdO4]n chain motifs and isolated SeO3 trigonal pyramids. The alkali earth oxide motifs demonstrate interesting and regular changes from isolated MgO6 octahedra, CaO7 polyhedra, and SrO9 tri-capped trigonal prisms based on a ribbon chain to BaO12 icosahedra based on a brucite-like layer, and meanwhile the SeO3 groups are observed from variable tetradentate to hexadentate coordination modes. These flexible motifs reveal that cadmium selenites are strongly affected by the size of the alkali earth cations, providing a feasible approach to modulating their space structure via selection of template cation. [ABSTRACT FROM AUTHOR]

Three genuine supramolecular isomers with an identical formula of [Co(cpna)(H2O)2] (1a, 1b and 1c) [H2cpna = 5-(4′-carboxyl-phenyl) nicotinic acid] have been synthesized by adjusting the relative molar ratio of Y-shaped ligand H2cpna : CoCl2 under solvothermal conditions. Isomer 1a possesses a two-dimensional (2D) 63-hcb layer, in which the central Co(ii) adopts trigonal bipyramidal geometry. 1b and 1c contain the same edge-shared dimeric SBUs, which are further ligated by cpna2− ligands to form 2D (3,6)-connected (43)2(46·66·83)-kgd layers and a 3D (3,6)-connected (4·62)2(42·610·83)-rtl net, respectively. The coordination modes of the cpna2− ligand in 1b and 1c are the same, indicating that only the difference in the dihedral angles of the pyridine and phenyl rings contributes to different isomers. Magnetic investigation indicates ferromagnetic interactions between Co(ii) ions in edge-shared dimeric SBUs. [ABSTRACT FROM AUTHOR]

The reversible crystal transformation between the mononuclear complex [Cu(tzbc)2(H2O)4] (1) and the 4-fold interpenetrated diamondoid MOF [Cu(tzbc)2] (2) was chemically implemented and structurally interpreted. Interestingly, despite 4-fold interpenetration, desolvated 2 with 1D channels and rich N-groups shows exclusive CO2 adsorption of up to 12.5 wt% at room temperature and low pressure, indicating potential application in the separation of industrial and automobile exhaust. [ABSTRACT FROM AUTHOR]

An expanded pyridyl-decorated MOF-505 analogue[Cu2(L)(H2O)2]·Gx (H4L = 5,5′-(pyridine-2,5-diyl)diisophthalic acid, G = solvent molecule) has been solvothermally synthesized and reported. It exhibited rare hierarchical meso- and microporosity. With exposed unsaturated CuII sites and Lewis basic pyridyl sites, the material shows both large CO2-uptake capacity (123.4 cm3 g−1 at 273 K, 1 bar) and high selectivity for CO2 over N2 (55.7) at 273 K. Furthermore, for the first time the compound has been exploited for its heterogeneous catalytic performance toward the cyanosilylation reaction under solvent-free conditions. The compound can be recycled up to five times with only a minor loss of activity. [ABSTRACT FROM AUTHOR]

The butterfly-like tetranuclear cobalt cluster based 3D MOF [Me2NH2][Co2(bptc)(μ3-OH)(H2O)2] (1) underwent a reversible thermally triggered single-crystal-to-single-crystal transformation via Co–Owater weakened intermediate 1a to produce a partly dehydrated phase [Me2NH2][Co2(bptc)(μ3-OH)(H2O)] (2), which was confirmed by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and IR spectroscopy. During the dehydration course, the local coordination environment of one Co2+ ion was changed from the saturated octahedron to a coordinately unsaturated square-pyramid, accompanied by a crystal color change from red to purple. Compared with pristine hydrated 1, dehydrated 2 exhibits highly efficient and recyclable catalytic activity for cyanosilylation of carbonyl compounds with a low catalyst loading of 0.1 mol% Co at room temperature under solvent-free conditions, which due to the open Co2+ sites as catalytically activated sites played a significant role in the heterogeneous catalytic process. [ABSTRACT FROM AUTHOR]