Superbase route to supertetrahedral chalcogenide clusters

Pseudotetrahedral Organotin-Capped Chalcogenidometalate Supermolecules with Optical Limiting Performance

The rational design of crystalline clusters with adjustable compositions and dimensions is highly sought after but quite challenging as it is important to understand their structural evolution processes and to systematically establish structure-property relationships. Herein, a family of organotin-based sulfidometalate supertetrahedral clusters has been prepared via mixed metal and organotin strategies at low temperatures (60-120 °C). By engineering the metal composition, we can effectively control the size of the clusters, which ranges from 8 to 35, accompanied by variable configurations: P1-[(RSn)4M4S13], T3-[(RSn)4In4M2S16] (R = nbutyl-Bu and phenyl-Ph; M = Cd, Zn, and Mn), T4-[(BuSn)4In13Cu3S31], truncated P2, viz. TP2-[(BuSn)6In10Cu6S31], and even T5-[(BuSn)4In22Zn6Cu3S52], all of which are the largest organometallic supertetrahedral clusters known to date. Of note, the arylstannane approach plays a critical role in regulating the peripheral ligands and further enriching geometric structures of the supertetrahedral clusters. This is demonstrated by the formation of tin-oxysulfide clusters, such as T3-[(RSn)4Sn6O4S16] (R = Bu, Ph, and benzyl = Be) and its variants, truncated T3, viz., TT3-[(BuSn)6Sn3O4S13] and augmented T3, viz., T3-[(Bu3SnS)4Sn6O4S16]. Especially, two extraordinary truncated clusters break the tetrahedral symmetry observed in typical supertetrahedral clusters, further substantiating the advantages offered by the arylstannane approach in expanding cluster chemistry. These organometallic supertetrahedral clusters are highly soluble and stable in common solvents. Additionally, they have tunable third-order nonlinear optical behaviors by controlling the size, heterometallic combination, organic modification, and intercluster interaction.

Selective and benign alkylation of sulfido-oxo stannate clusters with propyl, pentyl, or hexyl substituents

Chalcogenido metalate compounds that are based on tetrahedral clusters have been extensively studied in recent years due to their rich structural chemistry and uncommon chemical and physical properties. Recently it was shown that partial butylation of the inorganic cluster core by ionothermal reactions allowed access to tetrahedral sulfido-oxo stannate clusters with reasonable solubility in conventional solvents at the retainment of their opto-electronic features. We have expanded this mild alkylation approach, and herein report success in receiving the first sulfido-oxo stannate clusters that are selectively propylated, pentylated, and hexylated. This was achieved in a unique way by preparing symmetrically 1,3-substituted imidazolium bromides in preparative scale and using them as both the reaction medium and alkylatoin reagent. We discuss the effect of the organic groups attached to the cluster and present in the counterions of the products on the compounds' structural and opto-electronic properties.

Diastereoselective Synthesis of Fused Tricyclic Pyridopyrimidines via Tandem Cyclization of Allenoates and Cyclic Amidines

The tandem cyclization of easily accessible allenoates and cyclic amidines for the synthesis of functionalized tricyclic pyridopyrimidines is reported herein. The annulation featured a broad substrate scope with good functional group tolerance under very mild conditions (35 examples, 32-85% yields). The pyridopyrimidines were obtained in a very short reaction time (1 min), at room temperature, under neat conditions, which offers an alternative way to the sustainable synthesis of functionalized pyridopyrimidines. The scalability of the developed protocol is further demonstrated by a gram-scale synthesis.

Bifunctional Supertetrahedral Chalcogenolate Cluster-Based Assembly Materials Constructed by a Photoactive Ligand

The assembly of supertetrahedral chalcogenolate clusters (SCCs) and multifunctional organic linkers could lead to the formation of tunable structures and synergistic properties. Two SCC-based assembled materials (SCCAM-1 and -2) constructed by a triangular chromophore ligand, tris(4-pyridylphenyl)amine, were successfully synthesized and characterized. The SCCAMs demonstrate unusually long-lived afterglow at low temperatures (83 K) and efficient activities for the photocatalytic degradation of organic dye in water.

Platonic and Archimedean solids in discrete metal-containing clusters

Metal-containing clusters have attracted increasing attention over the past 2-3 decades. This intense interest can be attributed to the fact that these discrete metal aggregates, whose atomically precise structures are resolved by single-crystal X-ray diffraction (SCXRD), often possess intriguing geometrical features (high symmetry, aesthetically pleasing shapes and architectures) and fascinating physical properties, providing invaluable opportunities for the intersection of different disciplines including chemistry, physics, mathematical geometry and materials science. In this review, we attempt to reinterpret and connect these fascinating clusters from the perspective of Platonic and Archimedean solid characteristics, focusing on highly symmetrical and complex metal-containing (metal = Al, Ti, V, Mo, W, U, Mn, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, lanthanoids (Ln), and actinoids) high-nuclearity clusters, including metal-oxo/hydroxide/chalcogenide clusters and metal clusters (with metal-metal binding) protected by surface organic ligands, such as thiolate, phosphine, alkynyl, carbonyl and nitrogen/oxygen donor ligands. Furthermore, we present the symmetrical beauty of metal cluster structures and the geometrical similarity of different types of clusters and provide a large number of examples to show how to accurately describe the metal clusters from the perspective of highly symmetrical polyhedra. Finally, knowledge and further insights into the design and synthesis of unknown metal clusters are put forward by summarizing these "star" molecules.

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.

Modification of metallic and non-metallic sites in pentasupertetrahedral chalcogenidometalate clusters for third-order nonlinear optical response

Four isomorphic P2 chalcogenide clusters named [Sn₁₁In₉Cu₆S₄₄]·11(H⁺DBU) (1) (DBU = 1,8-diazabicyclo[5.4.0] undec-7-ene), [Sn₁₀In₁₀Cu₆Se₄₄]·6(H₂²⁺DMAPA)·2(DMAPA)·9EG (2) (DMAPA = 3-dimethylaminopropylamine, EG = ethylene glycol), [Sn₁₀In₁₀Cu₆S₄₀O₄]·6[H₂²⁺PMDETA]·10EG (3) (PMDETA = pentamethyldiethylenetriamine), [Sn₁₀Ga₁₀Cu₆S₄₀O₄]·6(H₂²⁺DMAPA)·7EG (4) have been isolated via organotin precursor and mixed-metal strategy. These clusters exhibit excellent solubility in organic solvents. The continuous-regulation of optical band and optical limiting performance have been realized through precise controlled substituting engineering of cationic and anionic elements.

Atomically precise metal chalcogenide supertetrahedral clusters: frameworks to molecules, and structure to function

Metal chalcogenide supertetrahedral clusters (MCSCs) are of significance for developing crystalline porous framework materials and atomically precise cluster chemistry. Early research interest focused on the synthetic and structural chemistry of MCSC-based porous semiconductor materials with different cluster sizes/compositions and their applications in adsorption-based separation and optoelectronics. More recently, focus has shifted to the cluster chemistry of MCSCs to establish atomically precise structure-composition-property relationships, which are critical for regulating the properties and expanding the applications of MCSCs. Importantly, MCSCs are similar to II-VI or I-III-VI semiconductor nanocrystals (also called quantum dots, QDs) but avoid their inherent size polydispersity and structural ambiguity. Thus, discrete MCSCs, especially those that are solution-processable, could provide models for understanding various issues that cannot be easily clarified using QDs. This review covers three decades of efforts on MCSCs, including advancements in MCSC-based open frameworks (reticular chemistry), the precise structure-property relationships of MCSCs (cluster chemistry), and the functionalization and applications of MCSC-based microcrystals. An outlook on remaining problems to be solved and future trends is also presented.

Highly Soluble Supertetrahedra upon Selective Partial Butylation of Chalcogenido Metalate Clusters in Ionic Liquids

Supertetrahedral clusters have been reported in two generally different types so far: one type possessing an organic ligand shell, no or low charges, and high solubility, while the other cluster type is ligand-free with usually high charges and low or no solubility in common solvents. The latter is a tremendous disadvantage regarding further use of the clusters in solution. However, as organic substituents usually broaden the HOMO-LUMO gaps, which cannot be overcompensated by the (limited) cluster sizes, a full organic shielding comes along with drawbacks regarding opto-electronic properties. We therefore sought to find a way of generating soluble clusters with a minimum number of organic substituents. Here, we present the synthesis and full characterization of two salts of [Sn10 O4 S16 (SBu)4 ]4- that are high soluble in CH2 Cl2 or CH3 CN, which includes first NMR and mass spectra obtained from solutions of such salts with mostly inorganic supertetrahedral clusters. The optical absorption properties of this new class of compounds indicates nearly unaffected band gaps. The synthetic approach and the spectroscopic findings were rationalized and explained by means of high-level quantum chemical studies.

Structural Expansion of Chalcogenido Tetrelates in Ionic Liquids by Incorporation of Sulfido Antimonate Units

Multinary chalcogenido (semi)metalate salts exhibit finely tunable optical properties based on the combination of metal and chalcogenide ions in their polyanionic substructure. Here, we present the structural expansion of chalcogenido germanate(IV) or stannate(IV) architectures with SbIII , which clearly affects the vibrational and optical absorption properties of the solid compounds. For the synthesis of the title compounds, [K4 (H2 O)4 ][Ge4 S10 ] or [K4 (H2 O)4 ][SnS4 ] were reacted with SbCl3 under ionothermal conditions in imidazolium-based ionic liquids. Salt metathesis at relatively low temperatures (120 °C or 150 °C) enabled the incorporation of (formally) Sb3+ ions into the anionic substructure of the precursors, and their modification to form (Cat)16 [Ge2 Sb2 S7 ]6 [GeS4 ] (1) and (Cat)6 [Sn10 O4 S20 ][Sb3 S4 ]2 (2 a and 2 b), wherein Cat=(C4 C1 C1 Im)+ (1 and 2 a) or (C4 C1 C2 Im)+ (2 b). In 1, germanium and antimony atoms are combined to form a rare noradamantane-type ternary molecular anion, six of which surround an {GeS4 } unit in a highly symmetric secondary structure, and finally crystallize in a diamond-like superstructure. In 2, supertetrahedral oxo-sulfido stannate clusters are generated, as known from the ionothermal treatment of the stannate precursor alone, yet, linked here into unprecedented one-dimensional strands with {Sb3 S4 } units as linkers. We discuss the single-crystal structures of these uncommon salts of ternary and quaternary chalcogenido (semi)metalate anions, as well as their Raman and UV-visible spectra.

Discrete Supertetrahedral Tn Chalcogenido Clusters Synthesized in Ionic Liquids: Crystal Structures and Photocatalytic Activity

Discrete supertetrahedral Tn chalcogenido clusters, which can be regarded as the smallest semiconductor quantum dots with precise chemical composition, have attracted considerable attention due to their outstanding photoluminescent, photoelectric, and photo/electrocatalytic properties. Such discrete molecular clusters are suitable for solution processing towards functional materials and can be used as precursors for constructing open-framework chalcogenides. Traditionally they were synthesized hydro(solvo)thermally with molecular solvents (e. g. water or organic amines), while until recently imidazolium-based ionic liquids (ILs) were found suitable for their preparation acting as reactive solvent and stabilizer for molecular clusters. We discuss herein recent advances in the syntheses, crystal structures, and selected properties of discrete supertetrahedral Tn chalcogenido clusters obtained in ILs. In particular, the enhanced photocatalytic properties of monodispersed Tn clusters in solvents are highlighted.

Metal Chalcogenide Supertetrahedral Clusters: Synthetic Control over Assembly, Dispersibility, and Their Functional Applications

ConspectusMetal chalcogenide supertetrahedral clusters (MCSCs) bear the closest structural resemblance to II-VI or I-III-VI semiconductor nanocrystals and can be considered as well-defined ultrasmall "quantum dots" (QDs). Compared to traditional colloidal QDs that are typically associated with size dispersity, irregular surface atomic structures, poorly defined core-ligand interfaces, and random defect/dopant sites, the nano- or subnano-sized MCSCs feature precise structural properties such as atomically uniform size, precise structure, and ordered dopant distribution, all of which offer ample opportunities for a broad and in-depth understanding of the correlation between the precise local structure and site- or size-dependent properties, which are critical to the exploitation of their functional applications. Our previous Account in 2005 provided a narrative on the efforts to expand the structural diversity of open-framework materials using different-sized and compositionally tunable clusters as building blocks with a primary objective of integrating the semiconducting properties with porosity in zeolite-type solids. Over the past 15 years, significant progress has been made, particularly in the synthetic control of discrete clusters, allowing the establishment of the composition-structure-property correlation of the MCSCs to guide the optimization of their properties for various applications. In the present Account, the recent progress in MCSC-based chemistry is reviewed from three aspects: (1) controllable synthesis of new members and types of MCSC models and the development of organic-ligand-directed hybrid assembly modes for MCSC-based open frameworks; (2) new synthetic strategies for the discretization of MCSCs in crystal lattice and their dispersibility in solvents, affording practical applications of pure inorganic MCSCs as nanomaterials; and (3) functionality of MCSC-based materials including photochemical and electrochemical properties triggered by precise dopant/defect sites, open-framework-related functional expansion via host-guest chemistry, and dispersed cluster-based composite materials with synergy from functional multimetallic components. All these advances show that MCSCs with well-defined structures and atomically precise dopant/defect sites are powerful model systems for establishing the precise structure-composition-property correlation and understanding the photophysical dynamic behaviors, both of which are difficult or impossible to achieve in the traditional QD system. Perspectives on their potential applications are presented in terms of the amorphous assemblies of monodispersed MCSCs, MCSC-based two-dimensional layered materials, and optical/electronic devices.

[Bmmim]6[In10Se16Cl4]·(MIm)2: an organic-ligand free discrete T3 cluster for efficient hydrogen evolution under visible light irradiation

An indium selenide [Bmmim]6[In10Se16Cl4]·(MIm)2 (Bmmim = 1-butyl-2,3-dimethylimidazolium, MIm = 1-methylimidazole) cluster has been synthesized and characterized. The discrete T3 cluster could be stably dispersed in dimethyl sulfoxide, exhibiting photocatalytic hydrogen evolution activity at least six times that of the pristine in the solid state due to the exposure of more active sites.

Discrete Supertetrahedral T5 Selenide Clusters and Their Se/S Solid Solutions: Ionic-Liquid-Assisted Precursor Route Syntheses and Photocatalytic Properties

Although supertetrahedral Tn sulfide clusters (n=2-6) have been extensively explored, the synthesis of Tn selenide clusters with n>4 has not been achieved thus far. Reported here are ionic-liquid (IL)-assisted precursor route syntheses, characterizations, and the photocatalytic properties of six new M-In-Q (M=Cu or Cd; Q=Se or Se/S) chalcogenide compounds, namely [Bmmim]₁₂ Cu₅ In₃₀ Q₅₂ Cl₃ (Im) (Q=Se (T5-1), Se_48.5 S_3.5 (T5-2); Bmmim=1-butyl-2,3-dimethylimidazolium, Im=imidazole), [Bmmim]₁₁ Cd₆ In₂₈ Q₅₂ Cl₃ (MIm) (Q=Se (T5-3), Se_28.5 S_23.5 (T5-4), Se₁₆ S₃₆ (T5-5); MIm=1-methylimidazole), and [Bmmim]₉ Cd₆ In₂₈ Se₈ S₄₄ Cl(MIm)₃ (T5-6). The cluster compounds T5-1 and T5-3 represent the largest molecular supertetrahedral Tn selenide clusters to date. Under visible-light illumination, the Cu-In-Q compounds showed photocatalytic activity towards the decomposition of crystal violet, whereas the Cd-In-Q compounds exhibited good photocatalytic H₂ evolution activity. Interestingly, the experimental results show that the photocatalytic performances of the selenide/sulfide solid solutions were significantly better than those of their selenide analogues, for example, the degradation time of the organic dye with T5-2 was much shorter than that with T5-1, whereas the photocatalytic H₂ evolution efficiencies with T5-3-T5-6 improved significantly with increasing sulfur content. This work highlights the significance of IL-assisted precursor route synthesis and the tuning of photocatalytic properties through the formation of solid solutions.

A quasi-D3-symmetrical metal chalcogenide cluster constructed by the corner-sharing of two T3 supertetrahedra

The third type of a discrete cluster of metal chalcogenide was successfully prepared by selecting the organic base with strong alkaline and weak solvation. This work further enriches the structure chemistry of discrete supertetrahedral clusters.

A wide pH-range stable crystalline framework based on the largest tin-oxysulfide cluster [Sn20O10S34]

We report, herein, a diamond-like oxysulfide framework, 3D-T4-SnOS, based on the largest supertetrahedral cluster of Sn⁴⁺ ions, i.e. [Sn₂₀O₁₀S₃₄]. The framework remains intact in aqueous solution over a pH range between 1 and 14, and has a narrower optical bandgap, red-shifted fluorescence emission, and an enhanced photoelectric response compared to that of the smaller version, 2D-T3-SnOS, which has a building unit of supertetrahedral [Sn₁₀O₄S₂₀].

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

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

Ionothermal synthesis of discrete supertetrahedral Tn (n = 4, 5) clusters with tunable components, band gaps, and fluorescence properties

A series of discrete supertetrahedral Tn (n = 4, 5) clusters have been ionothermally synthesized.

A new class of hybrid super-supertetrahedral cluster and its assembly into a five-fold interpenetrating network

The first hybrid super-supertetrahedron, formed by five [Ga₁₀S₁₆L₄]²⁻ supertetrahedral clusters, is presented.

Structural transformation of selenidostannates from 1D to 0D and 2D via a stepwise amine-templated assembly strategy

An interesting structural transformation of multidimensional selenidostannates induced through a stepwise amine-templated assembly strategy.

Quantum Dot Surface Engineering: Toward Inert Fluorophores with Compact Size and Bright, Stable Emission

The surfaces of colloidal nanocrystals are complex interfaces between solid crystals, coordinating ligands, and liquid solutions. For fluorescent quantum dots, the properties of the surface vastly influence the efficiency of light emission, stability, and physical interactions, and thus determine their sensitivity and specificity when they are used to detect and image biological molecules. But after more than 30 years of study, the surfaces of quantum dots remain poorly understood and continue to be an important subject of both experimental and theoretical research. In this article, we review the physics and chemistry of quantum dot surfaces and describe approaches to engineer optimal fluorescent probes for applications in biomolecular imaging and sensing. We describe the structure and electronic properties of crystalline facets, the chemistry of ligand coordination, and the impact of ligands on optical properties. We further describe recent advances in compact coatings that have significantly improved their properties by providing small hydrodynamic size, high stability and fluorescence efficiency, and minimal nonspecific interactions with cells and biological molecules. While major progress has been made in both basic and applied research, many questions remain in the chemistry and physics of quantum dot surfaces that have hindered key breakthroughs to fully optimize their properties.

Open framework metal chalcogenides as efficient photocatalysts for reduction of CO2 into renewable hydrocarbon fuel

Open framework metal chalcogenides are a family of porous semiconducting materials with diverse chemical compositions. Here we show that these materials containing covalent three-dimensional superlattices of nanosized supertetrahedral clusters can function as efficient photocatalysts for the reduction of CO2 to CH4. Unlike dense semiconductors, metal cations are successfully incorporated into the channels of the porous semiconducting materials to further tune the physical properties of the materials such as electrical conductivity and band gaps. In terms of the photocatalytic properties, the metal-incorporated porous chalcogenides demonstrated enhanced solar energy absorption and higher electrical conductivity and improved photocatalytic activity.

Solvothermal synthesis, structure and physical properties of Cs[Cr(en)2MSe4] (M = Ge, Sn) with [MSe4](4-) tetrahedra as chelating ligand

Two chromium chalcogenide Cs[Cr(en)2GeSe4] () and Cs[Cr(en)2SnSe4] () have been synthesized by a solvothermal method. Both compounds crystallize in the monoclinic space group P21/n. The structures of the two compounds are characterized by isolated [Cr(en)2MSe4](-) clusters separated by Cs(+) ions. The optical properties of the two compounds were measured which indicate a similar band gap of 1.58 eV. DFT calculations demonstrated that the valance band maximum (VBM) consist of Cr 3d orbitals and Se 4p orbitals while the conductive band minimum (CBM) are composed of Cr 3d orbitals for both compounds, which explains their similar optical band gap energies. Both compounds possess paramagnetic behaviors with the effective magnetic moment of 3.97μB for Cs[Cr(en)2GeSe4] and 3.91μB for Cs[Cr(en)2SnSe4], respectively. Field-dependent magnetization measurements demonstrated their potential as magnetocaloric materials, with the magnetic entropy change of 11.6 J (kg K)(-1) for Cs[Cr(en)2GeSe4], and 14.2 J (kg K)(-1) for Cs[Cr(en)2SnSe4].

Tin sulfide and selenide clusters soluble in organic solvents with the core structures of Sn4S6 and Sn4Se6

Reactions of LSnCl (1) (L = N(2,6-iPr2C6H3)(SiMe3)) with sulfur and selenium, respectively under mild conditions yielded two tin chalcogenide clusters. Surprisingly the tin atoms of the L4Sn4S6 (2) and L4Sn4Se6 (3) clusters are oxidized from Sn(II) of the precursor to Sn(IV) of the products under concomitant reduction of elemental sulfur and selenium to sulfide and selenide, respectively. The released chlorine radicals from the precursor LSnCl (1) react under oxidative addition with another LSnCl molecule to yield the side product LSnCl3 (4). The soluble nature of clusters 2 and 3 in organic solvents is a unique property of this class of compounds and makes them suitable for reactions in organic solvents. Compounds 2 and 3 were characterized by single crystal X-ray diffraction and multinuclear NMR investigations. Furthermore in ROP polymerization, the two products show high catalytic activity. For the first time a tin selenide compound functions in ROP catalysis.

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

A unique open-framework chalcogenide was constructed from two kinds of cluster-based secondary building units (SBUs), namely, the icosahedral Cu₈Se₁₃ cluster and the octahedral Cu₄Se₆ cluster.

Water-soluble, heterometallic chalcogenide oligomers as building blocks for functional films

Highly water-soluble, discrete, heterometallic, chalcogenide oligomers displaying various valences in a single metal chalcogenide oligomer are proposed for functional films.

Synthesis of Crystalline Chalcogenides in Ionic Liquids

Crystalline chalcogenides belong to the most promising class of materials. In addition to dense solid-state structures, they may form molecular cluster arrangements and networks with high porosity, as in the so-called "zeotype" chalcogenidometalates. The high structural diversity comes along with interesting physical properties such as semi-/photoconductivity, ion transport capability, molecular trapping potential, as well as chemical and catalytic activity. The great interest in the development of new and tailored chalcogenides has provoked a continuous search for new and better synthesis strategies over the years. The trend has clearly been towards lower temperatures for both economic and ecological reasons as well as for better reaction control. This led to the application of ionic liquids as a designer-like medium for materials synthesis. In this Review, we summarize recent developments and present a survey of different chalcogenide families along with their properties.

Structural complexity in indium selenides prepared using bicyclic amines as structure-directing agents

The synthesis and characterization of five new indium selenides, [C9H17N2]3[In5Se(8+x)(Se2)(1-x)] (1-2), [C6H12N2]4[C6H14N2]3[In10Se15(Se2)3] (3), [C6H14N2][(C6H12N2)2NaIn5Se9] (4) and [enH2][NH4][In7Se12] (5), are described. These materials were prepared under solvothermal conditions, using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO) as structure-directing agents. Compounds 1-4 represent the first examples of ribbons in indium selenides, and 4 is the first example of incorporation of an alkali metal complex. Compounds 1, 2 and 4 contain closely related [In5Se(8+x)(Se2)(1-x)](3-) ribbons which differ only in their content of (Se2)(2-) anions. These ribbons are interspaced by organic countercations in 1 and 2, while in 4 they are linked by highly unusual [Na(DABCO)2](+) units into a three-dimensional framework. Compound 3 contains complex ribbons, with a long repeating sequence of ca. 36 Å, and 4 is a non-centrosymmetric three-dimensional framework, formed as a consequence of the decomposition of DABCO into ethylenediamine (en) and ammonia.

A nano-scale triangular ring cluster of indium–selenide: the structure and templating effect

The preparation and crystal structure of a novel nano-scale triangular In₃₃Se₆₀ ring cluster are reported. An inverse second-sphere coordination templating effect is responsible for the formation of the unusual triangular ring. The optical and electronic properties of the nanoring cluster are discussed.

[Mn2Ga4Sn4S20]8− T3 supertetrahedral nanocluster directed by a series of transition metal complexes

Three new manganese gallium tin sulfides based on T3 supertetrahedral nanocluster of [Mn₂Ga₄Sn₄S₂₀]⁸⁻ have been solvothermally synthesized and structurally characterized. The photocatalytic, second-order nonlinear optical and luminescence properties, as well as thermal stabilities of the title compounds were also studied.