Three-Dimensional Chiral Microporous Germanium Antimony Sulfide with Ion-Exchange Properties

Rapid and Selective Uptake of Radioactive Cesium from Water by a Microporous Zeolitic-like Sulfide

The fast and efficient removal of 137Cs+ ions from water is of great significance for the further treatment and disposal of highly active nuclear waste. Hitherto, although many layered metal sulfides have been proven to be very effective in capturing aqueous cesium, three-dimensional (3D) microporous examples have rarely been explored, especially compounds that are systematically used to study cesium ion exchange behaviors. In this paper, we present detailed Cs+ ion exchange properties of a 3D, microporous, zeolitic-like sulfide, namely K@GaSnS-1, in different conditions. Isotherm studies indicate that K@GaSnS-1 has a high cesium saturation capacity of 249.3 mg/g. In addition, it exhibits rapid sorption kinetics, with an equilibrium time of only 2 min. Further studies show that K@GaSnS-1 also displays a strong preference and good selectivity for cesium, with the highest distribution coefficient Kd value up to 3.53 × 104 mL/g. Also noteworthy is that the excellent cesium ion exchange properties are well-maintained despite acidic, basic, and competitive multiple-component environments. More importantly, the Cs+-exchanged products can be easily eluted and regenerated by a low-cost and eco-friendly method. These merits demonstrated by K@GaSnS-1 render it very promising in the effective and efficient separation of radioactive cesium from nuclear waste.

Novel Zr-Doped Thiostannate Spinning Fiber (Fiber-KZrTS) for Highly Efficient and Renewable Recovery of Cesium and Strontium from Geothermal Water

The efficient and renewable recovery of cesium and strontium by absorption from a new type of geothermal water liquid mineral resource is highly desirable but still challenging. In this work, a new Zr-doped layered potassium thiostannate adsorbent (KZrTS) was first synthesized and used for Cs⁺ and Sr²⁺ green and efficient adsorption. It was found that KZrTS had very fast adsorption kinetics toward both Cs⁺ and Sr²⁺ with an equilibrium reached within 1 min, and the theoretical maximum adsorption capacities for Cs⁺ and Sr²⁺ were 402.84 and 84.88 mg/g, respectively. Moreover, to solve the loss problem of the engineering application of the powdered adsorbent KZrTS, KZrTS was uniformly coated with polysulfone by wet spinning technology to form micrometer-level filament-like absorbents (Fiber-KZrTS), whose adsorption equilibrium rates and capacities toward Cs⁺ and Sr²⁺ are almost the same as that of powder. Furthermore, Fiber-KZrTS showed excellent reusability, and the adsorption performance remained virtually unchanged after 20 cycles. Therefore, Fiber-KZrTS has potential application for green and efficient cesium and strontium recovery from geothermal water.

Crystalline chalcogenidometalate-based compounds from uncommon reaction media

Chalcogenides are one of the most versatile inorganic materials families, further subdivided into a large variety of specific groups of compounds, ranging from neat binary or multinary solids and nanoparticles of the same formal compositions, both in crystalline or non-crystalline form, to complicated open-framework structures and cluster compounds, also including organ(ometall)ic derivates of the latter. The large variety regarding both the compositions and the structures is associated with an enormous variety of properties, ranging from simple or high-tech pigments through a multitude of opto-electronic devices and electrolytes to materials for ion separation or high-sophisticated catalysts. Naturally, this also goes hand in hand with a corrosponding breadth of synthesis strategies. Traditionally, chalcogenides have been accessed via high-temperature methods, which continuously have been replaced by lower-temperature approaches for economical and ecological reasons. Moreover, more recent methods also showed that new types of chalcogenide materials can be obtained under such milder conditions that are not accessible via traditional routes. To shed light onto one of the numerous families of chalcogenides, this feature article summarizes current achievements in the generation of multinary chalcogenidometallate-based clusters and networks via non-classical routes, using ionic liquids, surfactants, or hydrazine as reaction media at moderately elevated termperature.

High-capacity recovery of Cs+ ions by facilely synthesized layered vanadyl oxalatophosphates with the clear insight into remediation mechanism

Radiocesium remediation is of great significance for the sustainable development of nuclear energy and ecological protection. It is very challenging for the effective recovery of ¹³⁷Cs from aqueous solutions due to its strong radioactivity, solubility and mobility. Herein, the efficient recovery of Cs⁺ ions has been achieved by three layered vanadyl oxalatophosphates, namely (NH₄)₂[(VO)₂(HPO₄)₂C₂O₄]·5 H₂O (NVPC), Na₂[(VO)₂(HPO₄)₂C₂O₄]·2 H₂O (SVPC), and K_2.5[(VO)₂(HPO₄)_1.5(PO₄)_0.5(C₂O₄)]·4.5 H₂O (KVPC). NVPC exhibits the ultra-fast kinetics (within 5 min) and high adsorption capacity for Cs⁺ (q_m^Cs = 471.58 mg/g). It also holds broad pH durability and excellent radiation stability. Impressively, the entry of Cs⁺ can be directly visualized by the single-crystal structural analysis, and thus the underlying mechanism of Cs⁺ capture by NVPC from aqueous solutions has been illuminated at the molecular level. This is a pioneering work in the removal of radioactive ions by metal oxalatophosphate materials which highlights the great potential of metal oxalatophosphates for radionuclide remediation.

Two new metal-chalcogenide-cluster-based frameworks with single metal ions of Zn2+(/Sb3+) serving as inter-cluster linkers

Two new metal-chalcogenide-cluster-based frameworks, in which P1-ZnSnS clusters are linked to each other by both corner-shared S^2- ions and single metal ions of Zn²⁺ (or Sb³⁺) to form one new 3D (3,4)-connected network (MCCF-22) and one 2D-layered framework (MCCF-23), respectively, are reported. Notably, MCCF-22 exhibits good performance toward photodegradation of methylene blue compared with its analogue framework with only S^2- ions as the linker.

Highly Efficient Uptake of Cs+ by Robust Layered Metal-Organic Frameworks with a Distinctive Ion Exchange Mechanism

¹³⁷Cs with strong radioactivity and a long half-life is highly hazardous to human health and the environment. The efficient removal of ¹³⁷Cs from complex solutions is still challenging because of its high solubility and easy mobility and the influence of interfering ions. It is highly desirable to develop effective scavengers for radiocesium remediation. Here, the highly efficient uptake of Cs⁺ has been realized by two robust layered metal-organic frameworks (MOFs), namely [(CH₃)₂NH₂]In(L)₂·DMF·H₂O (DMF = N,N'-dimethylformamide, H₂L= H₂aip (5-aminoisophthalic acid) for 1 and H₂hip (5-hydroxyisophthalic acid) for 2). Remarkably, 1 and 2 hold excellent acid and alkali resistance and radiation stabilities. They exhibit fast kinetics, high capacities (q _m ^Cs = 270.86 and 297.67 mg/g for 1 and 2, respectively), excellent selectivity for Cs⁺ uptake, and facile elution for the regeneration of materials. Particularly, 1 and 2 can achieve efficient Cs⁺/Sr²⁺ separation in a wide range of Sr/Cs molar ratios. For example, the separation factor (SF _Cs/Sr) is up to ∼320 for 1. Moreover, the Cs⁺ uptake and elution mechanisms have been directly elucidated at the molecular level by an unprecedented single-crystal to single-crystal (SC-SC) structural transformation, which is attributed to the strong interactions between COO^- functional groups and Cs⁺ ions, easily exchangeable [(CH₃)₂NH₂]⁺, and flexible and robust anionic layer frameworks with open windows as "pockets". This work highlights layered MOFs for the highly efficient uptake of Cs⁺ ions in the field of radionuclide remediation.

Highly selective cesium(I) capture under acidic conditions by a layered sulfide

Radiocesium remediation is desirable for ecological protection, human health and sustainable development of nuclear energy. Effective capture of Cs⁺ from acidic solutions is still challenging, mainly due to the low stability of the adsorbing materials and the competitive adsorption of protons. Herein, the rapid and highly selective capture of Cs⁺ from strongly acidic solutions is achieved by a robust K⁺-directed layered metal sulfide KInSnS₄ (InSnS-1) that exhibits excellent acid and radiation resistance. InSnS-1 possesses high adsorption capacity for Cs⁺ and can serve as the stationary phase in ion exchange columns to effectively remove Cs⁺ from neutral and acidic solutions. The adsorption of Cs⁺ and H₃O⁺ is monitored by single-crystal structure analysis, and thus the underlying mechanism of selective Cs⁺ capture from acidic solutions is elucidated at the molecular level.

The removal of radiocesium from acidic solutions is challenging. Here, the authors report the rapid and highly selective capture of cesium(I) from strongly acidic solutions by a robust layered metal sulfide.

Novel One-Pot Solvothermal Synthesis of High-Performance Copper Hexacyanoferrate for Cs+ Removal from Wastewater

Efficient removal of radioactive cesium from complex wastewater is a challenge. Unlike traditional precipitation and hydrothermal synthesis, a novel vast specific surface area adsorbent of copper hexacyanoferrates named EA-CuHCF was synthesized using a one-pot solvothermal method under the moderate ethanol media characterized by XRD, SEM, EDS, BET, and FTIR. It was found that the maximum adsorption capacity towards Cs+ was 452.5 mg/g, which is far higher than most of the reported Prussian blue analogues so far. Moreover, EA-CuHCF could effectively adsorb Cs+ at a wide pH range and low concentration of Cs+ in geothermal water within 30 minutes, and the removal rate of Cs+ was 92.1%. Finally, the separation factors between Cs+ and other competitive ions were higher than 553, and the distribution coefficient of Cs+ reached up to 2.343 × 104 mL/g. These properties suggest that EA-CuHCF synthesized by the solvothermal method has high capacity and selectivity and can be used as a candidate for Cs+ removal from wastewater.

Efficient Removal of Cs+ and Sr2+ Ions by Granulous (Me2NH2)4/3(Me3NH)2/3Sn3S7·1.25H2O/Polyacrylonitrile Composite

The need to effectively and selectively remove radioactive ¹³⁷Cs and ⁹⁰Sr from nuclear waste solutions persists to mitigate their environmental mobility and high radiotoxicity. Because it is difficult to effectively remove them from acidic environments that degrade most sorbents, new sorbent materials are highly desirable. Here, efficient removal of Cs⁺ and Sr²⁺ is achieved by the composite of layered tin sulfide (Me₂NH₂)_4/3(Me₃NH)_2/3Sn₃S₇·1.25H₂O (FJSM-SnS) and polyacrylonitrile (PAN) (FJSM-SnS/PAN). The granulous composite possesses regular particle morphology and good mechanical strength as an engineered form. It shows excellent acid-base and γ-irradiation resistance, high maximum adsorption capacities (q_m) of 296.12 and 62.88 mg/g for Cs⁺ and Sr²⁺ ions, respectively, and high selectivity even in the presence of excess Na⁺ ions or using lake water. Impressively, q_m^Cs of FJSM-SnS/PAN reaches 89.29 mg/g under even acidic conditions (pH = 2.5). The column loaded with FJSM-SnS/PAN granules exhibits high removal rates (R) toward low-concentration Cs⁺ and Sr²⁺ ions under both neutral and acidic conditions. Moreover, the composite can be recycled and reused with high R^Cs and R^Sr. This work highlights the great potential of metal sulfide ion-exchangers in engineered form for the efficient removal of Cs⁺ or Sr²⁺ ions, especially under acidic conditions, for radionuclide remediation.

Layered Thiostannates with Distinct Arrangements of Mixed Cations for the Selective Capture of Cs+, Sr2+, and Eu3+ Ions

The selective capture of radioactive cesium, strontium, and lanthanides from liquid nuclear waste is of great significance to environmental remediation and human health. Herein, the rapid and selective removal of Cs⁺, Sr²⁺, and Eu³⁺ ions is achieved by two metal sulfides (FJSM-SnS-2 and FJSM-SnS-3). Both structures feature [Sn₃S₇]_n^2n- layers with the mixed cations of [CH₃NH₃]⁺ and [Bmmim]⁺ (1-butyl-2,3-dimethylimidazolium) as templates. However, the ratios and arrangements of mixed cations in the interlayered spaces are distinct. It is unprecedented that [CH₃NH₃]⁺ and [Bmmim]⁺ in FJSM-SnS-2 are alternatingly arranged in different interlayered spaces, whereas they in FJSM-SnS-3 are located in the same interlayered spaces. It is the first time that the ionic liquid cation and protonated organic amine have been simultaneously incorporated into metal sulfides. Both compounds show high capacities, rapid kinetics, and a wide pH active range for Cs⁺, Sr²⁺, and Eu³⁺. Even under excess Na⁺ ions, both show excellent selectivity in capturing trace Sr²⁺ and Eu³⁺ ions. FJSM-SnS-3 presents the highest K_d^Eu to date. They still retain high removal efficiency even after intense β and γ radiation. Moreover, it is first confirmed by the in situ tracking method of mass spectrometry that the large-sized [Bmmim]⁺ ions are exchangeable. It is found that the arrangement of cations between interlayered spaces is a crucial factor affecting ion exchange performance. This work will likely change the consensus that large-sized organic cations are difficult to be exchanged and thus further highlight the great potential of metal sulfide ion exchangers for radionuclide remediation.

Structural diversities in centrosymmetric La8S4Cl8La12S8Cl4[SbS3]8 and non-centrosymmetric Ln12S8Cl8[SbS3]4 (Ln = La and Ce): syntheses, crystal and electronic structures, and optical properties

Three thioantimonides charge compensated by Ln/S/Cl cationic layers, namely, La8S4Cl8La12S8Cl4[SbS3]8 and Ln12S8Cl8[SbS3]4 (Ln = La and Ce), have been discovered by conventional solid-state reactions. The former crystallizes in the centrosymmetric space group Pbcm (no. 57), while the latter adopts the polar non-centrosymmetric space group Cc (no. 9). Both of them contain isolated SbS3 trigonal-pyramidal units, which are connected either with the alternating centric [La8S4Cl8]8+ and mirror-symmetric [La12S8Cl4]16+ cationic layers perpendicular to the [001] direction in La8S4Cl8La12S8Cl4[SbS3]8 or with the acentric [Ln12S8Cl8]12+ cationic layers perpendicular to the [100] direction in Ln12S8Cl8[SbS3]4. Interestingly, the discrete SbS3 trigonal pyramids pack in a centrosymmetric and non-centrosymmetric fashion in La8S4Cl8La12S8Cl4[SbS3]8 and La12S8Cl8[SbS3]4, respectively, which can be ascribed to the different compositions and packing fashions in Ln/S/Cl cationic layers. In addition, optical gaps of 2.31 and 2.60 eV for La12S8Cl8[SbS3]4 and La8S4Cl8La12S8Cl4[SbS3]8, respectively, were determined by UV/vis reflectance spectroscopy, showing a blue shift with respect to La7Sb9S24, which can be attributed to the greater contributions of La to the bottom of the CB as confirmed by the DFT study.

Robust and Flexible Thioantimonate Materials for Cs+ Remediation with Distinctive Structural Transformation: A Clear Insight into the Ion-Exchange Mechanism

It is imperative yet challenging to efficiently sequester the ¹³⁷Cs⁺ ion from aqueous solutions because of its highly environmental mobility and extremely high radiotoxicity. The systematical clarification for underlying mechanism of Cs⁺ removal and elution at the molecular level is rare. Here, efficient Cs⁺ capture is achieved by a thioantimonate [MeNH₃]₃Sb₉S₁₅ (FJSM-SbS) with high capacity, fast kinetics, wide pH durability, excellent β and γ radiation resistances, and facile elution. The Cs⁺ removal is not significantly impacted by coexisting Na⁺, K⁺, Ca²⁺, Mg²⁺, and Sr²⁺ ions which is beneficial to the remediation of Cs⁺-contaminated real waters. Importantly, the mechanism is directly illuminated by revealing an unprecedented single-crystal to single-crystal structural transformation upon Cs⁺ uptake and elution processes. The superior Cs⁺ removal results from an unusual synergy from strong affinity of soft S^2- with Cs⁺, easily exchangeable [MeNH₃]⁺ cations, and the flexible and robust framework of FJSM-SbS with open windows as trappers.

Fast and Selective Removal of Aqueous Uranium by a K+-Activated Robust Zeolitic Sulfide with Wide pH Resistance

For the nuclear industry, uranium is not only an important strategic resource but also a serious global contaminant with radiotoxicity and high chemotoxicity. It is very important to efficiently capture uranium from complex aqueous solutions for further treatment and disposal of nuclear wastes. Herein, we first demonstrate the suitability of a three-dimensional (3D) water-stable K⁺-exchanged zeolitic sulfide, namely K@GaSnS-1, for the remediation of radioactive and toxic uranium by ion exchange. In comparison to the pristine compound GaSnS-1, the K⁺-activated porous sulfide K@GaSnS-1 exhibits faster [UO₂]²⁺ ion uptake kinetics, following the pseudo-second-order adsorption model. Further studies indicate that K@GaSnS-1 shows high exchange capacity (q_m^U = 147.6 mg/g) and wide pH resistance (pH 2.75-10.87). In particular, it can efficiently capture [UO₂]²⁺ ion even when excessive amounts of Na⁺, K⁺, Mg²⁺, and Ca²⁺ ions are present. The highest distribution coefficient value K_d, signifying the affinity and selectivity for [UO₂]²⁺ ion, reaches as high as 1.24 × 10⁴ mL/g. More importantly, the uranium in corresponding exchanged samples can be facilely and effectively eluted by a low-cost and eco-friendly method. These merits of K@GaSnS-1 make it promising for the effective and selective removal of uranium from complex contaminated water.

Ionic liquid cations as methylation agent for extremely weak chalcogenido metalate nucleophiles

Selective in situ methylation of terminal chalcogenide ligands of molecular chalcogenido metalate anions in ionothermal reactions with alkylimidazolium-based ionic liquids yields a series of organo-functionalized chalcogenido metalate compounds. We present the syntheses and crystal structures of (C₄C₁C₁Im)_4+x [Sn₁₀S₁₆O₄(SMe)₄][An] _x (1a-1f), (dmmpH)₆[Mn₄Sn₄Se₁₃(SeMe)₄] (2), and (C _n C₁Im)₆[Hg₆Te₁₀(TeMe)₂] (3a, 3b). The methylation was confirmed by Raman spectroscopy, and the optical absorption properties of the methylated compounds were determined and compared to purely inorganic analogs.

A series of new vanadium(iii) chalcogenido-antimonates: an unusual seven-coordinate nitro-selenidovanadium(iii) complex

A series of new vanadium(iii) chalcogenidoantimonates [VIII(dap)2SbQ3] (Q = S (1), Se (2); dap = 1,2-diaminopropane), [H2dien][VIII2(en)2(dien)2(μ2-O)][SbSe4]2 (3, en = ethylenediamine; dien = diethylenetriamine) and [VIII(dien)2SbSe4] (4) have been solvothermally synthesized and structurally characterized. Both 1 and 2 contain neutral vanadium(iii)-centered complexes [VIII(dap)2SbQ3], where the [SbQ3]3- anion acts as a chelating ligand to complex [VIII(dap)2]3+, but they exhibit different molecular conformations. 3 consists of selenidoantimonate anions [SbSe4]3-, the protonated H2dien2+ cation, and the dinuclear complex [VIII2(en)2(dien)2(μ2-O)]4+ based on two [VIII(en)(dien)]3+ units bridged by one μ2-O group. 4 contains neutral [VIII(dien)2SbSe4] moieties with seven coordinated vanadium centres, which offers a rare example of high coordination of a nitro-selenidovanadium(iii) complex, mainly because the vanadium(iii) ion has a regular octahedral configuration based on the structures in the solid state. The optical, magnetic and photoelectronic properties of all compounds have been investigated, and the density functional theory calculation of 4 has also been studied.

A stable anionic metal–organic framework with open coordinated sites: selective separation toward cationic dyes and sensing properties

A multifunctional anionic metal–organic framework was successfully synthesized using a new pyridyl–tricarboxylate ligand. It could be applied as a luminescent sensor for Fe³⁺ ions and TNP and it showed selective adsorption of cationic dyes.

Alkylammonium thiostannate inorganic/organic hybrids as high-performance photocatalysts with a decoupled adsorption–photodegradation mechanism

For traditional photocatalysts, the adsorption and successive surface reaction constitute a coupled and integrated process, owing to the limited number of catalytic active centres available. An attempt to boost the photocatalytic performance to optimize the adsorption and surface reaction process may be performed by exploring various photocatalyst infrastructures. Herein, we use a facile solvothermal method to synthesize a series of layered alkylammonium thiostannate hybrids, namely (baH)₂Sn₃S₇, (haH)₂Sn₃S₇ and (oaH)₂Sn₃S₇ (ba = butylamine, ha = hexylamine, oa = octylamine). The hybrids showed broad UV-visible light absorption with appropriate band gaps. The inorganic/organic amphiphilic infrastructure of these hybrids enables them to exhibit prominent ion-exchange properties for Rhodamine B, with a large capacity over a wide pH range (1–11). And the adsorbed Rhodamine B is photodegraded within 30 minutes. A mechanistic study indicates that the adsorption and photodegradation steps are performed at the organic and inorganic layers within these hybrids, respectively, which are decoupled and independent. We conclude that the high-performance integrated adsorption–photodegradation ability is a consequence of the lipophilicity of intercalated alkylammonium and the photocatalysis performance of the 2D [Sn₃S₇]_n²ⁿ⁻ monolayers.

For traditional photocatalysts, the adsorption and successive surface reaction constitute a coupled and integrated process, owing to the limited number of catalytic active centres available.

Hydrazine-solvothermal methods to synthesize polymeric thioarsenates from one-dimensional chains to a three-dimensional framework

A series of polymeric Mn(ii)-thioarsenates [Mn(en)₃]_n[(N₂H₄)₂Mn₆(μ₆-S)(μ-N₂H₄)₂(μ₃-AsS₃)₄]_n (1), [N₂H₅]_n[{Mn(μ-N₂H₄)₂(μ-AsS₄)}·0.5en]_n (2), [Mn(μ-trien){Mn(μ-N₂H₄)(μ-AsS₃)}₂]_n (3), [{Mn(N₂H₄)}₂(μ-N₂H₄)₂{Mn(μ-N₂H₄)₂(μ-AsS₃)₂}]_n (4), [Mn₃(μ-N₂H₄)₆(μ₃-AsS₄)(μ₂-AsS₄)]_n (5), and [Mn(NH₃)₆]_n[{Mn(NH₃)(μ-AsS₄)}₂]_n (6) were synthesized using a hydrazine-solvothermal method. The thioarsenate units AsS₃ and AsS₄ coordinate to Mn(ii) ions with variable coordination modes, forming a Mn–As–S ternary cluster (1), chains (2, 4–6), and layers (3), respectively. The hydrazine molecules act as inter-cluster, intra-chain and intra-layer bridging ligands to join the Mn(ii) ions, resulting in hydrazine hybrid 1-D, 2-D, and 3-D Mn(ii)-thioarsenate moieties in 1–5. Compounds 1–6 exhibit tunable semiconducting band gaps varying in the range of 2.19–2.47 eV. Compound 1 displays stronger antiferromagnetic coupling interactions than that of compound 2.

Mn(ii)-thioarsenates [Mn(en)₃]_n[Mn₆S(N₂H₄)₄(AsS₃)₄]_n (1), [N₂H₅]_n[{Mn(N₂H₄)₂(AsS₄)}·0.5en]_n (2), [Mn(trien){Mn(N₂H₄)(AsS₃)}₂]_n (3), [Mn₃(N₂H₄)₆(AsS₃)₂]_n (4), [Mn₃(N₂H₄)₆(AsS₄)₂]_n (5), and [Mn(NH₃)₆]_n[{Mn(NH₃)(AsS₄)}₂]_n (6) were prepared in N₂H₄ by solvothermal methods.

[CH3 NH3 ]4 Ga4 SbS9 S0.28 O0.72 H: A Three-Dimensionally Open-Framework Heterometallic Chalcogenidoantimonate Exhibiting Ni2+ Ion-Exchange Property

An open-framework chalcogenidoantimonate, namely, [CH₃ NH₃ ]₄ Ga₄ SbS₉ S_0.28 O_0.72 H (1), has been solvothermally synthesized and structurally characterized. Interestingly, 1 showed Ni²⁺ ion-exchange properties and wide pH resistance, with a maximum exchange capacity of 76.9 mg g^-1 . To the best of our knowledge, this is the first example of amine-directed three-dimensional (3D) heterometallic chalcogenidometalates for highly selective Ni²⁺ ion capture with a high distribution coefficient (K_d =1.65×10⁵  mL g^-1 ).

A Series of Lanthanide Selenidogermanates: The First Coexistence of Three Types of Selenidogermanate Units in the Same Architecture

A series of lanthanide selenidogermanates, (H₂peha)[Ln₂(μ-OH)₂(tepa)₂Cl₂]{[Ln₂(μ-OH)₂(tepa)₂Cl]₂(μ-Ge₂Se₆)}[Ge₂Se₆]Cl₂ [Ln = Y (1a) and Er (1b); peha = pentaethylenexamine, tepa = tetraethylenepentamine], [Sm₂(μ-OH)₂(tepa)₂(μ-Ge₂Se₆)]_n (2), [Ho₂(μ-OH)₂(tepa)₂(μ-Ge₂Se₆)]_n (3), and [Ce₄(tepa)₄(μ-GeSe₄)(μ-GeSe₅)(μ-Ge₂Se₆)]_n (4), were made under solvothermal conditions. Compounds 1a and 1b contain a protonated H₂peha²⁺ ion, the complex cation [Ln₂(μ-OH)₂(tepa)₂Cl₂]²⁺, a [Ge₂Se₆]^4- anion, free Cl^- ions, and a {[Ln₂(μ-OH)₂(tepa)₂Cl]₂(μ-Ge₂Se₆)}²⁺ cation constructed by two unsaturated [Ln₂(μ-OH)₂(tepa)₂Cl]³⁺ groups connecting via the trans terminal Se atoms of the [Ge₂Se₆]^4- anion, which provides the first example of an organic decorated lanthanide selenidogermanate cation. Both compounds 2 and 3 contain one-dimensional chains [Ln₂(μ-OH)₂(tepa)₂(μ-Ge₂Se₆)]_n constructed by a combination of unsaturated complex cations [Ln₂(μ-OH)₂(tepa)₂]⁴⁺ and [Ge₂Se₆]^4- anions, but their stacking patterns of neutral chains are different. Compound 4 contains one-dimensional chain [Ce₄(tepa)₄(μ-GeSe₄)(μ-GeSe₅)(μ-Ge₂Se₆)]_n, where three different selenidogermanate units acting as bridging ligands connect unsaturated [Ce(tepa)]³⁺ ions. Compound 4 represents the first example of the coexistence of three different selenidogermanate anions in the same architecture. Their optical properties are studied, and the magnetic properties of compounds 1b and 2-4 are also investigated.

A novel 2-D Mn selenidostannate(iv) incorporating high-nuclear Mn clusters with spin canting behavior

A solvothermal reaction of SnCl₄·5H₂O, Mn and Se in ethanolamine (Hea) yielded a novel 2-D Mn selenidostannate(iv) [Mn₇(ea)₆(SnSe₄)₂]_n (1), which not only provides the first example of the incorporation of a hepta-nuclear Mn cluster [Mn₇(ea)₆]⁸⁺ into a selenidostannate(iv) framework, but also shows unusual spin canting behavior.

Lanthanide(III) complexes with μ-SnSe4 and μ-Sn2Se6 linkers: solvothermal syntheses and properties of new Ln(III) selenidostannates decorated with linear polyamine

New lanthanide-selenidostannate complexes [{La(peha)(Cl)}{La(peha)(NO3)}(μ-1κ2:2κ2-SnSe4)] (1), [H2trien][{La(trien)2}2(μ-1κ:2κ-Sn2Se6)][Sn2Se6]·H2O (2) and [{Ln(tepa)(μ-OH)}2(μ-1κ:2κ-Sn2Se6)] n ·nH2O (Ln=Sm(3), Eu(4)) were prepared by solvothermal methods in pentaethylenehexamine (peha), triethylenetetramine (trien) and tetraethylenepentamine (tepa), respectively. Acting as a tetradentate chelating and bridging ligand, μ-1κ2:2κ2-SnSe4, the tetrahedral SnSe4 unit joins {La(peha)(Cl)}2+ and {La(peha)(NO3)}2+ complex fragments to generate the neutral coordination compound 1. The tetradentate μ-1κ2:2κ2 bridge in 1 represents a new coordination mode for the SnSe4 tetrahedron. In 2, dinuclear [Sn2Se6]4− anions are formed of SnSe4 tetrahedra via edge-sharing. One [Sn2Se6]4− anion acts as a bidentate bridging ligand in a μ-1κ:2κ coordination mode to join two {La(trien)2}3+ units, and the other [Sn2Se6]4− anion exists as a free charge compensating ion. In 3 and 4, the [Sn2Se6]4− anion connects binuclear [{Ln(tepa)(μ-OH)}2]2+ (Ln=Sm, Eu) units with a bidentate μ-1κ:2κ mode, giving neutral coordination polymers [{Ln(tepa)(μ-OH)}2(μ-1κ:2κ-Sn2Se6)] n . The La(2)3+ ion in 1 is in a 10-fold coordination environment of LaN6O2Se2, whereas the La(1)3+ ions in 1 and 2 are in 9-fold coordinated environments forming polyhedra LaN6ClSe2 and LaN8Se, respectively. The Sm3+ and Eu3+ ions in 3 and 4 are both in an 8-fold coordination environment of LnN5O2Se. Compounds 1−4 exhibit optical band gaps between 2.21 and 2.42 eV. Their thermal stabilities were investigated by thermogravimetric analyses.

Multitopic ligand directed assembly of low-dimensional metal-chalcogenide organic frameworks

Despite tremendous progress in metal-organic frameworks, only limited success has been achieved with metal-chalcogenide organic frameworks. Metal-chalcogenide organic frameworks are desirable because they offer a promising route towards tunable semiconducting porous frameworks. Here, four novel semiconducting chalcogenide-organic hybrid compounds have been synthesized through a solvothermal method. Multitopic organic molecules, i.e., 1,2-di-(4-pyridyl)ethylene (L¹), 1,3,5-tris(4-pyridyl-trans-ethenyl)benzene (L²) and tetrakis(4-pyridyloxymethylene)methane (L³), have been used as linkers to assemble Zn(SAr)₂ or Zn₂(SAr)₄ units to generate different patterns of spatial organizations. Single-crystal structural analyses indicate that compounds NTU-2, NTU-3 and NTU-4 possess two-dimensional layer structures, while compound NTU-1 adopts a one-dimensional coordination framework (NTU-n, where n is the number related to a specific structure). The diffuse-reflectance spectra demonstrate that these four compounds possess indirect bandgaps and their tunable bandgaps are correlated with their compositions and crystal structures.

Post-synthetic ion-exchange process in nanoporous metal–organic frameworks; an effective way for modulating their structures and properties

In this review paper, we considered all of the reports on the ion-exchange process which occur in the pores of MOFs. A comparison between MOFs before and after-exchange process and their applications were addressed.

Syntheses, structures, and properties of sulfides constructed by SbS4teeter-totter polyhedra: Ba3La4Ga2Sb2S15and BaLa3GaSb2S10

Two new pentanary sulfides Ba₃La₄Ga₂Sb₂S₁₅(1) and BaLa₃GaSb₂S₁₀(2) have been discovered.

Facile Hydrazine-Hydrothermal Syntheses and Characterizations of Two Quaternary Thioarsenates(III): Two-Dimensional SrAg4 As2 S6 ⋅2 H2 O and One-Dimensional BaAgAsS3

Two new quaternary thioarsenates(III), SrAg4 As2 S6 ⋅2 H2 O (1) and BaAgAsS3 (2), have been prepared through a hydrazine-hydrothermal method at low temperature. Compound 1 possesses a two-dimensional (2D) layer network, while compound 2 features a one-dimensional (1D) column structure. The detailed structure analysis indicates that Sr(2+) and Ba(2+) cations have different directing effects on the structures of thioarsenates(III). Both experimental and theoretical studies demonstrate that compounds 1 and 2 are narrow-gap semiconductors. Our success in synthesizing these two quaternary thioarsenates(III) proves that the hydrazine-hydrothermal technique is a powerful yet facile synthetic method for exploring new complex chalcogenides with diverse crystal structures and interesting physical properties.

Synthesis, Structure, Band Gap, and Near-Infrared Photosensitivity of a New Chalcogenide Crystal, (NH4)4Ag12Sn7Se22

A new chalcogenide crystal, (NH4)4Ag12Sn7Se22 (FJSM-STS), has been solvothermally synthesized. The crystal structure, which is composed of arrays of [Sn3Se9]n(6n-) chains interconnecting [SnAg6Se10]n(10n-) and [Ag3Se4]n(5n-) layers, is unprecedented among the reported A/Ag/Sn/Q (A = cation; Q = S, Se, and Te) compounds. Optical absorption together with theoretical calculations of the band structure indicate a direct band gap of 1.21 eV for FJSM-STS, which is close to the ideal band gap to maximize the photoconversion efficiency proposed by Shockley and Queisser. The toxic-metal-free crystal of FJSM-STS exhibits obvious photosensitivity in the near-infrared range. The variates of power and temperature on the photosensitivity have been studied.

Metal sulfide ion exchangers: superior sorbents for the capture of toxic and nuclear waste-related metal ions

Metal sulfide ion-exchangers (MSIEs) have emerged as a new class of promising sorbents for the removal of toxic and radioactive metals from wastewater.

Metal sulfide ion-exchangers (MSIEs) represent a new addition to the field of ion exchange materials. This is a growing class of materials that display exceptional selectivity and rapid sorption kinetics for soft or relatively soft metal ions as a result of their soft basic frameworks. Without requiring functionalization, they outperform the most efficient sulfur-functionalized materials. This is the first review focusing on this class of materials; it covers the most important MSIEs, focusing on their synthesis, structural features and ion-exchange chemistry. Furthermore, recent developments in the engineered and composite forms of MSIEs are described. Future research opportunities are also discussed in the hope of inspiring additional scientists to engage in this new area of research on sulfidic ion-exchange materials.