Tn Clusters Research Articles

Mixed Solvothermal Synthesis of Tn Cluster-Based Indium and Gallium Sulfides Using Versatile Ammonia or Amine Structure-Directing Agents.

Metal chalcogenide supertetrahedral Tn clusters are of current interest for their unique compositions and structures, which rely highly on the structure-directing agents. Herein, we report four novel Tn cluster-based indium and gallium sulfides, namely, [NH(CH3)3]4In4S10H4 (1), (NH3)4Ga4S6 (2), [NH3CH2CH3]5(NH2CH2CH3)2Ga11S19 (3), and [NH3CH2CH2OH]6Ga10S18·2NH2CH2CH2OH (4). All four compounds were solvothermally synthesized in mixed amine-ethanol solutions or deep eutectic solvent (DES), where ammonia/amine molecules play significant structure-directing roles in the speciation and crystal growth. (1) Being protonated, the trimethylamine and ethanolamine molecules surround the T2-[In4S10H4]4- clusters (for 1) and [Ga10S18]n6n- open framework (for 4), respectively, compensating for the negative charge of the inorganic moieties. (2) With the lone pair of electrons, the ammonia molecules in 2 coordinate directly to corner Ga3+ ions of the {Ga4S6} cage to give a neutral T2-(NH3)4Ga4S6 cluster. (3) For compound 3, part of the ethylamine molecules act as terminating ligands for the T1 and T3 units in the [Ga11S19(NH2CH2CH3)2]n5n- layer, while the rest act as interlamellar countercations upon protonation. Theoretical studies reveal the contributions of N, C, and H to the density of states (DOS) for 2 and 3 because of their hybrid structures that combine the ammonia/amine ligands with sulfide moieties together.

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.

Heat stress modifies the lactational performances and the urinary metabolomic profile related to gastrointestinal microbiota of dairy goats.

The aim of the study is to identify the candidate biomarkers of heat stress (HS) in the urine of lactating dairy goats through the application of proton Nuclear Magnetic Resonance (1H NMR)-based metabolomic analysis. Dairy does (n = 16) in mid-lactation were submitted to thermal neutral (TN; indoors; 15 to 20°C; 40 to 45% humidity) or HS (climatic chamber; 37°C day, 30°C night; 40% humidity) conditions according to a crossover design (2 periods of 21 days). Thermophysiological traits and lactational performances were recorded and milk composition analyzed during each period. Urine samples were collected at day 15 of each period for 1H NMR spectroscopy analysis. Principal component analysis (PCA) and partial least square—discriminant analysis (PLS-DA) assessment with cross validation were used to identify the goat urinary metabolome from the Human Metabolome Data Base. HS increased rectal temperature (1.2°C), respiratory rate (3.5-fold) and water intake (74%), but decreased feed intake (35%) and body weight (5%) of the lactating does. No differences were detected in milk yield, but HS decreased the milk contents of fat (9%), protein (16%) and lactose (5%). Metabolomics allowed separating TN and HS urinary clusters by PLS-DA. Most discriminating metabolites were hippurate and other phenylalanine (Phe) derivative compounds, which increased in HS vs. TN does. The greater excretion of these gut-derived toxic compounds indicated that HS induced a harmful gastrointestinal microbiota overgrowth, which should have sequestered aromatic amino acids for their metabolism and decreased the synthesis of neurotransmitters and thyroid hormones, with a negative impact on milk yield and composition. In conclusion, HS markedly changed the thermophysiological traits and lactational performances of dairy goats, which were translated into their urinary metabolomic profile through the presence of gut-derived toxic compounds. Hippurate and other Phe-derivative compounds are suggested as urinary biomarkers to detect heat-stressed dairy animals in practice.

Supertetrahedral Cluster-Based In–Se Open Frameworks with Unique Polyselenide Ion as Linker

Reported here are three new In–Se open frameworks with unique polyselenide ion as linker. Single-crystal X-ray diffraction analyses demonstrate that supertetrahedral Tn (n = 2, 3) clusters serving as secondary building units in these compounds are connected via polyselenide ligands to form the interrupted or elongated diamond topologies. UV–vis absorption analysis and photoelectric response measurements indicate that these In–Se frameworks retain semiconductor properties, making them potential candidates in photocatalytic applications.

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

The preparation of crystalline molecularly supertetrahedral Tn clusters with variable sizes and components is of vital importance for the fundamental study of their physicochemical properties. However, setting up an efficient method to stabilize large discrete Tn clusters is a challenge due to their high negative charges and polymerization nature. In this work, we report on the ionothermal synthesis of three discrete T4 cluster compounds, namely [Bmmim]5[(CH3)2NH2]4[NH4][M4In16S31(SH)4]·6H2O (M = Mn (1), Zn (2), Cd (3), Bmmim = 1-buty-2,3-dimethyl-imidazolium), and four discrete T5 cluster compounds, namely [Bmmim]10[NH4]3[Cu5Ga30-xInxS52(SH)4] (x = 6.6 (5), 14.5 (6), 23.8 (7), and 30 (8)). The compound [Bmmim]10[NH4]3[Cu5Ga30S52(SH)4] (4) previously reported by us features a discrete T5 cluster. The steep UV-Vis absorption edges indicate band gaps of 2.20 eV for 1, 2.64 eV for 2, 2.69 eV for 3, 3.04 eV for 4, 2.65 eV for 5, 2.48 eV for 6, 2.32 eV for 7, and 2.30 eV for 8. The compositions of T5 clusters could be varied with the ratios of Ga : In in the starting reagents, providing an opportunity to systematically control the band gaps and fluorescence performances of T5 cluster-based compounds. This research might advance the understanding of the ionothermal preparation and functionality tuning of crystalline chalcogenides.

A Pd/Monolayer Titanate Nanosheet with Surface Synergetic Effects for Precise Synthesis of Cyclohexanones

A catalyst composed of monolayer nonstoichiometric titanate nanosheets (denoted as TN) and Pd clusters is constructed for precise synthesis of cyclohexanone from phenol hydrogenation with high conversion (>99%) and selectivity (>99%) in aqueous media under light irradiation. Experimental and DFT calculation results reveal that the surface exposed acid and basic sites on TN could interact with phenol molecules in a nonplanar fashion via a hexahydroxy hydrogen-bonding ring to form a surface coordination species. This greatly facilitates the adsorption and activation of phenol molecules and suppresses the further hydrogenation of cyclohexanone. Moreover, the surface Pd clusters serve as the active sites for the adsorption and dissociation of hydrogen molecules to provide active H atoms. The synergistic effect of the surface coordination species, TN and Pd clusters remarkably facilitate the high yield of cyclohexanone in photocatalysis. Finally, the possible thermo/photocatalytic mechanisms on Pd/TN are propo...

Silver-Sulfur Hybrid Supertetrahedral Clusters: The Hitherto Missing Members in the Metal-Chalcogenide Tetrahedral Clusters.

The synthesis of Group 11 metal chalcogenide supertetrahedral clusters (SCs) still remains a great challenge mainly due to the high tendency of metal aggregation through metallophilicity and global charge balance. Demonstrated herein are the preparation, crystallographic characterization, and optical properties of two stable silver-sulfur SCs through ligand-control; one as a discrete zero-dimensional (0D) V3,4-type cluster and the other as a one-dimensional (1D) zigzag chain extended by alternating V3,2-type clusters. The notation Vn,m (where n is the number of metal layers, and m is the number of vacant corners) is used to describe a new series of vacant-corner SCs, which can be derived from the regular Tn clusters. The existence of vacant-corner-type SCs may be ascribed to the low valence and tri-coordinated environment of silver ions. These are the first representatives of structurally determined silver-sulfur tetrahedral clusters thus far. This work enriches the coinage-metal chalcogenide tetrahedral cluster portfolio, discovers vacant-corner SCs present in silver-sulfur hybrid tetrahedral clusters, and provides effective means for further development of Group 11 coinage-metal chalcogenide SCs.

Co-assembled T4-Cu4In16S35 and Cubic Cu12S8 Clusters: A Crystal Precursor for Near-Infrared Absorption Material

Recently, discrete large Tn clusters have become particularly attractive because they can be used as starting materials not only for constructing porous chalcogenides but also for solution processing of semiconductor film materials with electronic and optical properties. However, the discrete large clusters of main-group metal chalcogenides are difficult to stabilize because of their high negative charge. We report herein a new crystal compound co-assembled by discrete T4 [Cu4In16S35H4]14–and cubic [Cu12S8]4– clusters. It is uncommon that the negatively charged CuS cluster acts as a template to sustain a hexagonal cavity formed by negatively charged T4 clusters. Its degeneration product shows an excellent near-infrared absorption property and photocurrent responsive properties.

Theoretical analysis of structures and electronic spectra in molecular cadmium chalcogenide clusters.

We present calculated structural and optical properties of molecular cadmium chalcogenide nonstoichiometric clusters with a size range of less than 1 nm to more than 2 nm with well-defined chemical compositions and structures in comparison to experimental characterization and previous theoretical work. A unified treatment of these clusters to obtain a fundamental understanding of the size, ligand, and solvation effects on their optical properties has not been heretofore presented. The clusters belong to three topological classes, specifically supertetrahedral (Tn), penta-supertetrahedral (Pn), and capped supertetrahedral (Cn), where n is the number of metal layers in each cluster. The tetrahedrally shaped Tn clusters examined in this work are Cd(ER)4(2-) (T1), Cd4(ER)10(2-) (T2), and Cd10E4 (')(ER)16(4-) (T3), where R is an organic group, E and E' are chalcogen atoms (sulfur or selenium). The first member of the Pn series considered is M8E'(ER)16(2-). For the Cn series, we consider the first three members, M17E4 (')(ER)28(2-), M32E14 (')(ER)36L4, and M54E32 (')(ER)48L4(4-) (L = neutral ligand). Mixed ligand clusters with capping ER groups replaced by halogen or neutral ligands were also considered. Ligands and solvent were found to have a large influence on the color and intensity of the electronic absorption spectra of small clusters. Their effects are generally reduced with increasing cluster sizes. Blueshifts were observed for the first electronic transition with reduced size for both cadmium sulfide and cadmium selenide series. Due to weakly absorbing and forbidden transitions underlying the one-photon spectra, more care is needed in interpreting the quantum confinement from the clusters' lowest-energy absorption bands.

Optical properties of Ga and in doped CdS nanocomposites: An experimental and first principles study

Present work deals with Ga and In doped CdS nanocomposites by experimental and theoretical means. For theoretical simulations, we considered Supertetrahedron (Tn) cluster models of substitutionally and interstially (Ga, In) doped CdS. To mimic experimental conditions polyvinyl alcohol (PVA) chain fragments were allowed to cap the clusters. Structural and electronic properties have been calculated using density functional theory (DFT). Frontier molecular orbital (FMO) plots indicate that transfer of charge occurs between organic (polymer) and inorganic (semiconducting nanoclusters) moieties. The transfer of charge leads to longevity of hybrid nanocomposites. Nanocomposites have been synthesized by the in situ chemical method at room temperature and characterized using XRD, TEM, FTIR and UV spectroscopy. DFT has been employed to simulate optical properties. There is a good agreement in optical band gap calculated from experimental method and theoretical approach.

Investigations of Al:CdS/PVA nanocomposites: A joint theoretical and experimental approach

In the present work we investigate the aluminium doped cadmium sulphide (Al:CdS) nanoparticles embedded in polyvinyl alcohol (PVA) matrix by chemical route and density functional theory (DFT) based simulations. Supertetrahedron (Tn) cluster models are considered for the simulation of CdS nanoparticles. Using DFT simulations on Tn clusters, we observe that band gap of ligated clusters is slightly more as compare to bare clusters. This indicates the ability of organic ligands (PVA) to open the band gap of inorganic CdS nanoclusters. Negative value of binding energy indicates the stability of the inorganic–organic hybrid system. Frontier molecular orbitals (FMOs) indicate the charge transfer between organic and inorganic moieties which provides stability and longevity to nanoparticles, a prime function of ligands in nanocomposites. Absorption spectra of pure and doped clusters are calculated using time dependent density functional theory (TDDFT). CdS/PVA and Al:CdS/PVA samples are synthesized at room temperature by chemical method. Their structure, size and band gap is characterized by XRD, TEM, FTIR and UV spectroscopy. Optical band gap values as observed experimentally are in agreement with simulated TDDFT results.

ChemInform Abstract: Magic Number Pt13 and Misshapen Pt12 Clusters: Which One is the Better Catalyst?

AbstractPtn (n = 12, 13) clusters are synthesized with atomic‐level precision by using a dendrimer ligand as the macromolecular template.

Polymeric supertetrahedral InS clusters assembled by new linkages

Four new indium chalcogenide compounds 1–4 were prepared by a similar solvothermal synthetic method in 1,2-diaminocyclohexane (dach) medium with or without the auxiliaries of germanium oxide or ionic liquid 1-butyl-3-methyl imidazolium bromide. Among them, two unusual polymeric structures assembled by Tn clusters were found. The anion of {H2dach·[Ni(dach)3]·[In12S20(dach)2]·3H2O}n (1) is a three-dimensional framework assembled by T3 clusters, in which the linkage is a unique In4(dach)4S6 cluster. The anion of {(Hdach)2·[Co(dach)3]4·[In16Co4S37]·dach·5H2O}n (3) is an unusual two-dimensional framework assembled by T4 clusters, in which the T4 clusters are linked by (S3)2− polysulfide ion. The structures of the other two new compounds are known, and they are {[Ni(dach)3]·[In2S4]·3H2O}n (2) and{(Hdach)4·[Co(dach)3]6·{[In16Co4S34]2[Co(dach)2]3}·6H2O}n (4). The auxiliaries play an important role in the structural assembly of the Tn clusters, mainly due to their effects on acidity of the reaction system and solubility of the reactants or products.

Superbase Route to Supertetrahedral Chalcogenide Clusters

Supertetrahedral Tn clusters are exact fragments of a cubic ZnS type lattice. Thus far, Tn clusters up to T4 with 20 metal sites can be synthesized in a discrete molecular form. Yet, synthesis of larger discrete supertetrahedral clusters still remains a great challenge, likely due to the rapidly increasing negative charge on the cluster as the size goes up. By using organic superbases (DBN and DBU) to help stabilize the negative charge, a family of discrete supertetrahedral chalcogenide clusters with sizes spanning from T3 (10 metal sites) to T5 (35 metal sites) have been made. The T5 cluster represents the largest molecular supertetrahedral Tn cluster known to date.

Transition Metal Complexes as Linkages for Assembly of Supertetrahedral T4 Clusters

Tn clusters are usually connected into frameworks by sulfur bridges. A new type of T4 compounds in which the clusters are linked by both sulfur bridges and transition metal complexes are described.

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.

Polyvalency of Tn (GalNAcα1→Ser/Thr) glycotope as a critical factor for Vicia villosa B4 and glycoprotein interactions

Vicia villosa B4 (VVL-B4) is an important lectin for detecting exposed Tn (GalNAcα1-Ser/Thr) determinants on cancer cells. In order to elucidate the binding factors involved in VVL-B4 and glycotope interaction, the binding properties of this lectin were analyzed by enzyme-linked lectinosorbent and inhibition assays. From the results, it is concluded that the most critical factor affecting VVL-B4 binding is polyvalency at the α anomer of Gal with –NH CH3CO at carbon-2 (Tn epitope), which enhances the reactivity by 3.3×105 times over monovalent Gal. The reactivities of glycotopes can be ranked as follows: high density Tn cluster≫Tn glycopeptides (MW<3.0×103)≫monomeric Tn to tri- Tn glycopeptides⋙other GalNAcα/β-related structural units>Gal and Galα- or β-linked ligands, demonstrating the essential role of the polyvalency of Tn glycotopes in the enhancement of the binding.

Binding profile of Artocarpus integrifolia agglutinin (Jacalin)

Artocarpus integrifolia agglutinin (Jacalin) from the seeds of jack fruits has attracted considerable attention for its diverse biological activities and has been recognized as a Galβ1→3GalNAc ( T) specific lectin. In previous studies, the information of its binding was limited to the inhibition results of monosaccharides and several T related disaccharides, but its interaction with other carbohydrate structural units occurring in natural glycans has not been characterized. For this reason, the binding profile of this lectin was studied by enzyme linked lectinosorbent assay (ELLSA) with our glycan/ligand collection. Among glycoproteins (gps) tested for binding, high density of multi-Galβ1→3GalNAcα1→ (m T α) and GalNAcα1→Ser/Thr (m Tn) containing gps reacted most avidly with Jacalin. As inhibitors expressed as nanograms yielding 50% inhibition, these m T α and m Tn containing glycans were about 7.1 × 10 3, 4.0 × 10 5, and 7.8 × 10 5 times more potent than monomeric T α, GalNAc, and Gal. Of the sugars tested and expressed as nanomoles for 50% inhibition, Tn containing peptides, T α, and the human P blood group active disaccharide ( P α, GalNAcβ1→3Galα1→) were the best and about 283 times more active than Gal. We conclude that the most potent ligands for this lectin are m Tn, m T, and possibly P α glycotopes, while GalNAcβ1→4Galβ1→, GalNAcα1→3Gal, GalNAcα1→3GalNAc, and Galα1→3Gal determinants were poor inhibitors. Thus, the overall binding profile of Jacalin can be defined in decreasing order as high density of m Tn, and m T α ⋙ simple Tn cluster > monomeric T α > monomeric P α > monomeric Tn > monomeric T > GalNAc > Gal > Methylα1→Man ≫ Man and Glc (inactive). Our finding should aid in the selection of this lectin for biological applications.

Fine specificity of domain-I of recombinant tandem-repeat-type galectin-4 from rat gastrointestinal tract (G4-N).

Galectins, a family of beta-galactoside-specific endogenous lectins, are involved in regulating diverse activities such as proliferation/apoptosis, cell-cell (matrix) interaction and cell migration. It is presently unclear to what extent the carbohydrate fine specificities of the combining sites of mammalian galectins overlap. To address this issue, we performed an analysis of the carbohydrate-recognition domain (CRD-I) near the N-terminus of recombinant rat galectin-4 (G4-N) by the biotin/avidin-mediated microtitre plate lectin-binding assay with natural glycoproteins (gps)/polysaccharide and by the inhibition of galectin-glycan interactions with a panel of glycosubstances. Among the 35 glycans tested for lectin binding, G4-N reacted best with human blood group ABH precursor gps, and asialo porcine salivary gps, which contain high densities of the blood group Ii determinants Galbeta1-3GalNAc (the mucin-type sugar sequence on the human erythrocyte membrane) and/or GalNAcalpha1-Ser/Thr ( Tn ), whereas this lectin domain reacted weakly or not at all with most sialylated gps. Among the oligosaccharides tested by the inhibition assay, Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc was the best. It was 666.7 and 33.3 times more potent than Gal and Galbeta1-3GlcNAc, respectively. G4-N has a preference for the beta-anomer of Gal at the non-reducing ends of oligosaccharides with a Galbeta1-3 linkage, over Galbeta1-4 and Galbeta1-6. The fraction of Tn glycopeptide from asialo ovine submandibular glycoprotein was 8.3 times more active than Galbeta1-3GlcNAc. The overall carbohydrate specificity of G4-N can be defined as Galbeta1-3GlcNAcbeta1-3Galbeta1-4Glc (lacto- N -tetraose)>Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc (lacto- N -neo-tetraose) and Tn clusters>Galbeta1-4Glc and GalNAcbeta1-3Gal>Galbeta1-3GalNAc>Galbeta1-3GlcNAc>Galbeta1-4GlcNAc>GalNAc>Gal. The definition of this binding profile provides the basis to detect differential binding properties relative to the other galectins with ensuing implications for functional analysis.

Forssman pentasaccharide and polyvalent Galβ1→4GlcNAc as major ligands with affinity for Caragana arborescens agglutinin

The binding properties of Caragana arborescens agglutinin (CAA, pea tree agglutinin) were studied by enzyme linked lectinosorbent assay (ELLSA) and by inhibition of CAA-glycan interaction. Among glycoproteins (gps) tested, CAA reacted strongly with asialo bird nest gp, asialo rat sublingual gp, human Tamm-Horsfall Sd(a +) urinary gp (THGP) and asialo THGP that are rich in GalNAcα1→, GalNAcβ1→ and/or Galβ1→4GlcNAc residues. CAA also bound tightly with multi-valent Galβ1→4GlcNAc (mII) containing glycoproteins (human blood group precursor gps, asialo fetuin) and asialo ovine salivary glycoprotein (Tn, GalNAcα1→Ser/Thr), but CAA reacted poorly or not at all with sialylated glycoproteins tested. Of the sugars tested for inhibition of binding, Forssman pentasaccharide (F p, GalNAcα1→3GalNAcβ1→3Galα1→4Galβ1→4Glc) was the best. It was about 2.3, 9.5 and 52.6 times more active than Galβ1→4GlcNAc, GalNAc and Gal, respectively, and about 1.9 times more active than tri-antennary Galβ1→4GlcNAc (Tri-II). These results suggest that this agglutinin is mainly specific for F p, mII and Tn clusters. This property can be used to detect human abnormal glycotopes related to F p and unmasked mII/Tn clusters and to study cell growth and differentiation given the lack of toxicity of this lectin toward mouse fibroblast cells.