Open-framework Chalcogenides Research Articles

All-Inorganic Open-Framework Chalcogenides, A3Ga5S9·xH2O (A = Rb and Cs), Exhibiting Ultrafast Uranyl Remediation and Illustrating a Novel Post-Synthetic Preparation of Open-Framework Oxychalcogenides

Fast and effective uranyl sequestration is of interest to the nuclear industry. Recently, layered chalcogenide materials have demonstrated fast, selective, and efficient sorption properties toward uranyl cations, and the development and investigation of new types of chalcogenide materials continues to be of interest and represents an intriguing option for uranyl remediation. Three new all-inorganic A3Ga5S9·xH2O (A = Rb, Rb/Cs, and Cs) open-framework chalcogenides were obtained via an in situ alkali carbonate to alkali sulfide conversion process achieved under mild hydrothermal conditions. The structures of the all-inorganic open-framework chalcogenides consist of a twofold interpenetrated diamond-like 3D framework containing pseudo-T3 [Ga10S20]10– supertetrahedra. Forty-eight percent of the structural volume is occupied by A+ cations and water species, as established by single-crystal X-ray diffraction (SCXRD), infrared (IR) spectroscopy, and energy-dispersive spectroscopy (EDS). The dynamic nature of the A+ cations and water molecules within the pores was investigated via SCXRD as well as by IR spectroscopy-monitored H2O-to-D2O exchange experiments. Framework stability was probed with post-synthetic treatment of A3Ga5S9·xH2O (A = Rb and Cs) samples in acidic solutions that resulted in the formation of the oxysulfide (A/H)3Ga5S9–yOy·xH2O (A = Rb and Cs; y = 0–1), as shown by SCXRD and IR. Ion-exchange studies on A3Ga5S9·xH2O (A = Rb and Cs) samples were carried out utilizing a uranyl acetate solution. The presence of the UO22+ species in the ion-exchange product was supported by IR spectroscopy and EDS. Batch method ion-exchange experiments on Cs3Ga5S9·xH2O powder demonstrated fast kinetics with 95% uranyl removal from the uranyl acetate solution during the first minute, a maximum uranyl uptake capacity of 15 mg/g, and the subsequent elution of uranyl species with KCl solution. The porous and dynamic nature of the A3Ga5S9·xH2O framework coupled with effective UO22+···S2– bonding interactions makes it a good potential sorbent for uranyl remediation from aqueous media.

A novel copper-rich open-framework chalcogenide with chiral topology constructed from distinctive bimetallic [Cu5SnSe10] clusters.

Reported here is the first chiral copper-rich open-framework chalcogenide with a quartz (qtz) topology built on distinctive [Cu5SnSe10] clusters connected by [SnSe4] bridging units. Through in situ sulfur doping, sulfurized compounds could be obtained that exhibit improved photocatalytic performance. This work expands the family of COCs with new building blocks and topologies and demonstrates the significance of chalcogen doping in COCs.

A Photoconductive X-ray Detector with a High Figure of Merit Based on an Open-Framework Chalcogenide Semiconductor.

A wide range of tunability in the physical parameters of a semiconductor used for X-ray detection is desirable to achieve targeted performance optimization. However, in a dense-phase semiconductor, fine-tuning one parameter often leads to unwanted changes in other parameters. Herein, the intrinsic openness in an open-framework semiconductor has been confirmed, for the first time, to be a key structural factor that weakens the mutual exclusivity of the adjustable physical parameters owing to a non-linear control mechanism. The controllable doping of S in a zeolitic In-Se host results in an optimal balance between resistivity, band gap, and carrier mobility, which finally results in an excellent X-ray detector with a high figure of merit for the mobility-lifetime product (7.12×10-4 cm2 V-1 ); this value is superior to that of a commercial α-Se detector. The current strategy of choosing open-framework semiconductor materials opens a new window for targeting high-performance X-ray detection.

Two Copper-Rich Open-Framework Chalcogenides Built from Unusual [Cu5(SnxM1-x)Se10] Clusters and [(SnxM1-x)2Se6] Dimeric Linkers (M = In and Ga).

Reported here are two unprecedented copper-rich open-framework chalcogenides constructed from unusual [Cu5(SnxM1-x)Se10] clusters and [(SnxM1-x)2Se6] dimeric linkers (M = In and Ga). The photoresponsive properties in the IR range and the photocatalytic activity for degradation of methylene blue dye of these two isostructural semiconductors were proved to be effectively adjusted by trivalent metal ions in a cluster.

Selectively Photocatalytic Activity of an Open-Framework Chalcogenide Built from Corner-Sharing T4 Supertetrahedral Clusters.

The photocatalysis process with high selectivity is a very important research forefront for the semiconductor photocatalytic decomposition of organic pollutants. However, the rational design of efficient photocatalysts with high selectivity is still a challenge. Here, we present an open-framework chalcogenide (Heta)8[In14Sn2Zn4Se33] (Heta = ethanolamine-H+) (compound 1) constructed from T4 supertetrahedral clusters [In14Sn2Zn4Se35]12- with visible-light-driven selectively photocatalytic degradation activity. Single-crystal XRD analysis shows that compound 1 crystallizes in I41/acd (no. 142) space group, with a = b = 24.3462(2) Å, c = 45.0062(9) Å, V = 26676.9(7) Å3, and Z = 8. Under visible-light irradiation, the selectively photocatalytic activities of 1 were evaluated by photodegradation of two kinds of cationic dye molecules, i.e., methylene blue (MB) and rhodamine B (RhB), against two anionic dyes, methyl orange (MO) and Kermes red (KR), with different sizes. We show that the adsorption capability and charge-matching between organic dyes and the supertetrahedral cluster together with a suitable band structure make it an excellent and selective photocatalyst. This is the first example of an open-framework chalcogenide based on supertetrahedral T4 for the selectively semiconductor photocatalytic decomposition of organic dyes.

An Open Framework Chalcogenide Supertetrahedral Cluster as Visible-Light Driven Photocatalysts for Selective Degradation

Selective photocatalytic decomposition of mixed pollutants is an effective approach to environmental remediation, yet it is still in its infancy. We present the syntheses and structural characterization of a crystalline open framework chalcogenide (Heta)6[In10S10Se8]·10H2O (Heta = ethanolamine-H+) (1) constructed from T3 supertetrahedral clusters. It is a 3D two-fold interpenetrated framework with protonated ethanolamine located in pores. This compound exhibits efficient and selective photocatalytic activities in the photodegradation of four kinds of organic dyes with a similar backbone but different charges and sizes. Compound 1 shows excellent photodegradation of Methylene Blue upon visible-light irradiation due to the strong oxidization of the superoxide radical (O2–•) generated in the photocatalytic process. The selective photocatalytic activities are related to the integration of appropriate band structures with distinct affinity and selectivity to organic dye molecules.

Two Penta-Supertetrahedral Cluster-Based Chalcogenide Open Frameworks: Effect of the Cluster Spatial Connectivity on the Electron-Transport Efficiency.

High-degree connectivity of clusters in open-framework chalcogenide semiconductors conceptually facilitates electron mobility between clusters; however, no direct evidence was obtained to prove the prediction because of the shortage of suitable structure models among such systems. Herein, two open-framework chalcogenides built from the same types of heterometallic P2-CuInSnS clusters but with different spatial connectivities of clusters were obtained, in which 3-connected clusters are assembled into a 3D framework with SrSi2 topology (MCOF-1) and 4-connected clusters (μ4-P2) are arranged into diamond topology (MCOF-2). Compared to MCOF-1, MCOF-2 exhibits a relatively rapid photocurrent response, good reproducibility, and high electrocatalytic oxygen reduction reaction activity. This work substantially demonstrates that cluster-based chalcogenide frameworks with higher-degree cluster connectivity possess faster electron-transport efficiency between adjacent clusters relative to low-connected ones with the same building units.

Unusual Flexibility of Microporous Sulfides during Ion Exchange.

Open-framework chalcogenides with ion-exchange capacity are promising materials for removing hazardous heavy-metal ions and for capturing radioactive Cs+. However, research on the exchange mechanism is limited, especially for the framework chalcogenides that have multiple bridging anions. Generally, open-framework chalcogenides that have multiple bridging anions at the window or wall of the channels are rigid during the ion-exchange process. We show here that microporous sulfides with μ3-S2- (where μ3 = triple bridging mode) at the windows exhibit framework flexibility upon ion exchange. Three new microporous sulfides Na4Cu8Ge3S12·2H2O (1), Na3(Hen)Cu8Sn3S12 (where en = ethylenediamine) (2) and (dap)2(Hdap)4Cu8Ge3S18 (where dap = 1,2-diaminopropane) (3) were synthesized under solvothermal conditions. Compounds 1 and 2 contain a copper-rich framework composed of icosahedral [Cu8S12]16- units linked via monomeric GeS44- or SnS44- tetrahedral units, whereas compound 3 features an expanded framework composed of icosahedral [Cu8S12]16- units interconnected with dimeric Ge2S64- units. These compounds exhibit unusual ion-exchange properties. Specifically, the frameworks of 1 and 2 (with μ3-S at the small windows) show "breathing action" upon ion exchange of K+ or Rb+, which have relative large sizes, and compound 3 exhibits framework flexibility upon Cs+ ion exchange with both space group and channels changed.

Assembly of Oxygen-Stuffed Supertetrahedral T3-SnOS Clusters into Open Frameworks with Single Sn2+ Ion as Linker

Here three new types of cluster-based tin oxysulfides are reported. Single-crystal X-ray diffraction analysis reveals that both compound 1 [Sn]2[Sn40O16S74](DMA)4(DEA)10(H+-DEA)12(H2O)20 (DMA = dimethylamine, DEA = diethylamine) and compound 3 [Sn][Sn40O16S74](H+-DMA)12(DEA)4(H22+-DACH)3(H2O)20 (DACH = 1,2-diaminocyclohexane) are built from oxygen-stuffed supertetrahedral T3-SnOS clusters with corner-sharing S2– and single Sn2+ ion as bridging linkers, and compound 2 [Sn40O16S73](DMA)(H+-TMA)18(H2O)14 (TMA = trimethylamine) is constructed by the interrupted supersupertetrahedral T3,2 clusters. Such variable and unique linkage modes are very useful for constructing other types of cluster-based crystalline open-framework chalcogenides. In addition, compound 2 is the first case that displays photoluminescence emission among T3-SnOS-based chalcogenides.

Open-Framework Chalcogenide Showing Both Intrinsic Anhydrous and Water-Assisted High Proton Conductivity.

Proton-conducting materials have attracted increasing interest because of the promising technological applications as key components in various electrochemical devices. It is of great significance for technique application to seek superior proton-conducting materials, operating under both anhydrous and humidified conditions in a wide temperature range. Herein we demonstrate the proton conductance of an open-framework chalcogenide, (CH3NH3)2Ag4Sn3S8 (1), and the postsynthesis product 2 achieved by doping hydrochloric acid into 1. Hybrid 2 displays both intrinsic anhydrous and water-assisted high proton conductance, with σ = 1.87 × 10-4 S·cm-1 at 463 K under N2 atmosphere and 1.14 × 10-3 S·cm-1 at 340 K and 99% relative humidity, and these conductivities are comparable to that in the efficient metal-organic frameworks-based proton-conducting materials. Moreover, hybrid 2 shows excellent thermal stability and long-term stability of proton conduction.

A unique non-interpenetrated open-framework chalcogenide with a large cavity.

Reported here is a unique non-interpenetrated open-framework metal chalcogenide built on a supertetrahedral [Fe4In16S35]14- cluster. The non-interpenetrated feature accompanied with the relatively large-sized cluster leads to a high extra-framework volume.

The First Observation on Dual Self-Closed and Extended Assembly Modes in Supertetrahedral T3 Cluster Based Open-Framework Chalcogenide

Reported here is a new open-framework metal chalcogenide semiconductor with omy topology built from typical supertetrahedral T3-InSnS cluster via dual self-closed and extended assembly modes. This represents the second case containing dual assembly modes in cluster based open-framework superlattices. Interestingly, the self-closed assembly of T3 clusters results in an unprecedented supersupertetrahedral T3,2 cluster, being a new member filling in the blank in the family of supersupertetrahedral clusters. In addition, the title compound also shows good photocatalytic activity for the degradation of methylene blue.

A Novel Open-Framework Cu-Ge-Based Chalcogenide Anode Material for Sodium-Ion Battery.

Open-framework chalcogenides are potential electrode materials for sodium-ion batteries (SIBs) due to their architectures with fast-ion conductivity. Herein, we report on the successful synthesis of open-framework Cu-Ge-based chalcogenides [Cu8Ge6Se19](C5H12N)6 (CGSe) and the research of their energy storage application as SIB anodes for the first time. As a result, the CGSe anode exhibited good electrochemical performances such as high reversible capacity (463.3 mAh g−1), excellent rate performance, and considerable cycling stability. Our exploration not only develops a promising electrode material for SIBs, but also extends the application of open-framework chalcogenides.

Assembly of supertetrahedral clusters into a Cu–In–S superlattice via an unprecedented vertex–edge connection mode

We demonstrated the first case of a vertex–edge inter-cluster connection mode in a three-dimensional open-framework chalcogenide built from the largest known T5 cluster.

PCU-type copper-rich open-framework chalcogenides: pushing up the length limit of the connection mode and the first mixed-metal [Cu7GeSe13] cluster

A pure dimeric connection mode and an unprecedented Cu7GeSe13 cluster were found in a series of pcu-type copper-rich open-framework chalcogenides.

ChemInform Abstract: A Novel Copper‐Rich Open‐Framework Chalcogenide Constructed from Octahedral Cu4Se6 and Icosahedral Cu8Se13 Nanoclusters.

AbstractThe Cu‐rich open‐framework chalcogenide (pipH)10 [Cu16Sn6Se19(Se2)6] (pip: piperidine) is prepared by solvothermal reaction of the elements and piperidine (Cu:Sn:Se = 1.8:4.3:25, autoclave, 180 °C, 12 d; 19% yield).

A novel copper-rich open-framework chalcogenide constructed from octahedral Cu4Se6 and icosahedral Cu8Se13 nanoclusters.

We demonstrated a unique copper-rich open-framework chalcogenide constructed from icosahedral Cu8Se13 and octahedral Cu4Se6 nanoclusters connected to each other through a SnSe3(Se2) bridging unit. The specific copper-rich composition gives rise to a narrow band gap and photoelectrical responsive properties in the infrared range.

Robust Crystalline Hybrid Solid with Multiple Channels Showing High Anhydrous Proton Conductivity and a Wide Performance Temperature Range.

A proton conductor displaying high anhydrous proton conductivity (≈10(-2) S cm(-1)) and good performance over a broad temperature range is presented. This hybrid material is produced via doping HCl into open-framework chalcogenide(C2N2H10)(C2N2H9)2 Cu8 Sn3S12, and has cubopolyhedral cavities and multiple channels.

Crystalline Open‐Framework Selenidostannates Synthesized in Ionic Liquids

Ready to direct: Crystalline selenidostannates were synthesized in imidazolium-based ionic liquids with a small amount of hydrazine monohydrate as additive (see scheme). They are the first open-framework chalcogenides structurally directed by imidazolium cations and are inaccessible by traditional methods.

Largest Molecular Clusters in the Supertetrahedral Tn Series

Supertetrahedral Tn clusters are exact fragments of cubic ZnS-type lattice and are often formed in situ as building units for the construction of 3-D open-framework chalcogenide materials. Small Tn clusters can also be synthesized in discrete forms, allowing them to exist as soluble species in solution. In addition to their tunable electronic and optical properties, these soluble clusters can be used as precursors for the synthesis of porous semiconducting and optical materials. However, the synthesis of large Tn clusters is a significant challenge, and for several decades prior to this work, the size of the discrete Tn cluster remained at T3, with only 10 metal sites (e.g., [Cd(10)S(4)(SPh)(16)](4-) and [M(5)Sn(5)S(20)](10-), M = Zn, Co). Here we report a family of discrete chalcogenide T4 clusters ([M(x)Ga(18-x)Sn(2)Q(35)](12-), x = 2 or 4; M = Mn, Cu, Zn; Q = S, Se) whose discovery resulted from an unusual phase transformation from a 3-D T4 covalent framework into 0-D T4 molecular clusters. The driving force for such a transformation is the perfect match in both charge density and geometry between chalcogenide clusters and protonated amine, leading to the higher stability of isolated clusters. The perfect match is achieved by using complex quaternary compositions to maximize charge tunability of the cluster. These T4 clusters are the largest molecular Tn clusters known to date and can be made in various compositions showing tunable band structures in both solution and solid state.