Full quantitative resource utilization of raw mustard waste through integrating a comprehensive approach for producing hydrogen and soil amendments

BACKGROUND

Pickled mustard, the largest cultivated vegetable in China, generates substantial waste annually, leading to significant environmental pollution due to challenges in timely disposal, leading to decomposition and sewage issues. Consequently, the imperative to address this concern centers on the reduction and comprehensive resource utilization of raw mustard waste (RMW). To achieve complete and quantitative resource utilization of RMW, this study employs novel technology integration for optimizing its higher-value applications.

RESULTS

Initially, subcritical hydrothermal technology was applied for rapid decomposition, with subsequent ammonia nitrogen removal via zeolite. Thereafter, photosynthetic bacteria, Rhodopseudomonas palustris, were employed to maximize hydrogen and methane gas production using various fermentation enhancement agents. Subsequent solid-liquid separation yielded liquid fertilizer from the fermented liquid and soil amendment from solid fermentation remnants. Results indicate that the highest glucose yield (29.6 ± 0.14) was achieved at 165-173℃, with a total sugar content of 50.2 g/L and 64% glucose proportion. Optimal ammonia nitrogen removal occurred with 8 g/L zeolite and strain stable growth at 32℃, with the highest OD600 reaching 2.7. Several fermentation promoters, including FeSO4, Neutral red, Na2S, flavin mononucleotide, Nickel titanate, Nickel oxide, and Mixture C, were evaluated for hydrogen production. Notably, Mixture C resulted in the maximum hydrogen production (756 mL), a production rate of 14 mL/h, and a 5-day stable hydrogen production period. Composting experiments enhanced humic acid content and organic matter (OM) by 17% and 15%, respectively.

CONCLUSIONS

This innovative technology not only expedites RMW treatment and hydrogen yield but also substantially enriches soil fertility. Consequently, it offers a novel approach for low-carbon, zero-pollution RMW management. The study's double outcomes extend to large-scale RMW treatment based on the aim of full quantitative resource utilization of RMW. Our method provides a valuable reference for waste management in similar perishable vegetable plantations.

Nanoarmor: cytoprotection for single living cells

Single cell modification or hybridization technology has become a popular direction in bioengineering in recent years, with applications in clean energy, environmental stewardship, and sustainable human development. Here, we draw attention to nanoarmor, a representative achievement of cytoprotection and functionalization technology. The fundamental principles of nanoarmor need to be studied with input from multiple disciplines, including biology, chemistry, and material science. In this review, we explain the role of nanoarmor and review progress in its applications. We also discuss three main challenges associated with its development: self-driving ability, heterojunction characteristics, and mineralization formation. Finally, we propose a preliminary classification system for nanoarmor.

Supracluster Assembly of Archimedean Cages with 72 Hydrogen Bonds for the Aldol Addition Reaction

Clusters that can be experimentally precisely characterized and theoretically accurately calculated are essential to understanding the relationship between material structure and function. Here, we propose the concept of "supraclusters", which aim to connect "supramolecules" and "suprananoparticles" as well as reveal the unique assembly behavior of "supraclusters" with nanoparticle size at the molecular level. The implementation of supraclusters is full of challenges due to the difficulty in satisfying the ordered connectivity of clusters due to their abundant and dispersed hydrogen bonding sites. By solvothermal synthesis under a high catechol (H2 CATs) content, we successfully isolated a series of triangular {Al6 M3 } cluster compounds possessing brucite-like structural features. Interestingly, eight {Al6 M3 } clusters form 72-fold strong hydrogen bonding truncatedhexahedron Archimedean {Al6 M3 }8 supracluster cage (abbreviated as H-tcu). Surprisingly, the solution stability of the H-tcu was further proved by electrospray ionization mass spectrometry (ESI-MS) characterization. Therefore, it is not difficult to explain the reason for assembly of H-tcu into edge-directed and vertex-directed isomers. These porous supraclusters can be obtained by scale-up synthesis and exhibit a noticeable catalysis effect towards the condensation of acetone and p-nitrobenzaldehyde. As an intermediate state of supramolecule and suprananoparticle, the supracluster assembly can enrich the cluster chemistry and bring new structural types.

Photochemical Synthesis of Atomically Precise Ag Nanoclusters

Photochemical methods are effective for controllable synthesis of silver nanoparticles with specific sizes and shapes. Whether they are capable of fabricating Ag nanoclusters (NCs) with atomic precision is yet to be proved. In this work, we synthesize an atomically precise Ag NC, [Ag₂₅(4-MePhC≡C)₂₀(Dpppe)₃](SbF₆)₃ (Ag₂₅), via a process mediated by visible light. Its total structure is determined by X-ray crystallography. The investigation of the mechanism reveals that the formation of Ag₂₅ is triggered by a photoinduced electron-transfer (PET) process. An electron of certain amines is excited by light with wavelength shorter than 455 nm and transferred to Ag⁺. The amine is oxidized to the corresponding amine N-oxide. Such a PET process is supported by experimental and density functional theory studies. To expand the application scope of the photochemical method, another three NCs, [Ag₁₉(4-^tBuPhC≡C)₁₄(Dpppe)₃](SbF₆)₃ (Ag₁₉), [Ag₃₂(4-^tBuPhC≡C)₂₂(Dppp)₄](SbF₆)₃ (Ag₃₂), and bimetallic [Ag₂₂Au₃(4-^tBuPhC≡C)₂₀(Dpppe)₃](SbF₆)₃ (Ag₂₂Au₃), are produced by replacing certain ingredients. Furthermore, since the formation of Ag₁₉ can be regarded as a photochromatic process, a facile amine visual detection method is also presented based on this mechanism.

Plasmon-Mediated Photoelectrochemical Hot-Hole Oxidation Coupling Reactions of Adenine on Nanostructured Silver Electrodes

Surface-enhanced Raman spectroscopy (SERS) has been widely applied in the identification and characterization of DNA structures with high efficiency. Especially, the SERS signals of the adenine group have exhibited high detection sensitivity in several biomolecular systems. However, there is still no unanimous conclusion regarding the interpretation of some special kinds of SERS signals of adenine and its derivatives on silver colloids and electrodes. This Letter presents a new photochemical azo coupling reaction for adenyl residues, in which the adenine is selectively oxidized to (E)-1,2-di(7H-purin-6-yl) diazene (azopurine) in the presence of silver ions, silver colloids, and electrodes of nanostructures under visible light irradiation. The product, azopurine, is first found to be responsible for the SERS signals. This photoelectrochemical oxidative coupling reaction of adenine and its derivatives is promoted by plasmon-mediated hot holes and is regulated by positive potentials and pH of solutions, which opens up new avenues for studying azo coupling in the photoelectrochemistry of adenine-containing biomolecules on electrode surfaces of plasmonic metal nanostructures.

Monocarboxylate-protected two-electron superatomic silver nanoclusters with high photothermal conversion performance

The first series of monocarboxylate-protected superatomic silver nanoclusters was synthesized and fully characterized by X-ray diffraction, fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and electrospray ionization mass spectrometry (ESI-MS). Specifically, compounds [Ag₁₆(L)₈(9-AnCO₂)₁₂]²⁺ (L = Ph₃P (I), (4-ClPh)₃P (II), (2-furyl)₃P (III), and Ph₃As (IV)) were prepared by a solvent-thermal method under alkaline conditions. These clusters exhibit a similar unprecedented structure containing a [Ag₈@Ag₈]⁶⁺ metal kernel, of which the 2-electron superatomic [Ag₈]⁶⁺ inner core shows a flattened and puckered hexagonal bipyramid of S₆ symmetry. Density functional theory calculations provide a rationalization of the structure and stability of these 2-electron superatoms. Results indicate that the 2 superatomic electrons occupy a superatomic molecular orbital 1S that has a substantial localization on the top and bottom vertices of the bipyramid. The π systems of the anthracenyl groups, as well as the 1S HOMO, are significantly involved in the optical and photothermal behavior of the clusters. The four characterized nanoclusters show high photothermal conversion performance in sunlight. These results show that the unprecedented use of mono-carboxylates in the stabilization of Ag nanoclusters is possible, opening the door for the introduction of various functional groups on their cluster surface.

Real-Time Sniffing Mass Spectrometry Aided by Venturi Self-Pumping Applicable to Gaseous and Solid Surface Analysis

Based on the Venturi self-pumping effect, real-time sniffing with mass spectrometry (R-sniffing MS) is developed as a tool for direct and real-time mass spectrometric analysis of both gaseous and solid samples. It is capable of dual-mode operation in either gaseous or solid phase, with the corresponding techniques termed as R_g-sniffing MS and R_s-sniffing MS, respectively. In its gaseous mode, R_g-sniffing MS is capable of analyzing a gaseous mixture with response time (0.8-2.1 s rise time and 7.3-9.6 s fall time), spatial resolution (<80 μm), three-dimensional diffusion imaging, and aroma distribution imaging of red pepper. In its solid mode, an appropriate solvent droplet desorbs the sample from a solid surface, followed by the aspiration of the mixture using the Venturi self-pumping effect into the mass spectrometer, wherein it is ionized by a standard ion source. Compared with the desorption electrospray ionization (DESI) technique, R_s-sniffing MS demonstrated considerably improved limit of detection (LOD) values for arginine (0.07 μg/cm² R_s-sniffing vs 1.47 μg/cm² DESI), thymopentin (0.10 μg/cm² vs 2.67 μg/cm²), and bacitracin (0.16 μg/cm² vs 2.28 μg/cm²). R_s-sniffing is applicable for the detection of C₆₀(OCH₃)₆Cl^-, an intermediate in the methoxylation reaction involving C₆₀Cl₆ (solid) and methanol (liquid). The convenient and highly sensitive R-sniffing MS has a characteristic separation of desorption from the ionization process, in which the matrix atmosphere of desorption can be interfaced by a pipe channel and self-pumped by the Venturi effect with consequent integration using a standard ion source. The R-sniffing MS operates in a voltage-, heat-, and vibration-free environment, wherein the analyte is ionized by a standard ion source. Consequently, a wide range of samples can be analyzed simultaneously by the R-sniffing MS technique, regardless of their physical state.

Toxic effect of fracturing flow-back fluid on Vibrio fischeri, Daphnia, and specific industry microorganisms Aspergillus niger and S. cerevisiae

Previous studies have shown that the soil microbial population and soil enzyme activity are seriously affected by fracturing flow-back fluid (FFBF) from the shale gas mining process. However, the toxic effect of FFBF on specific bacteria, fungi, and plankton has not been systematically confirmed in detail. In this paper, a toxic effect evaluation of FFBF was conducted using the representative toxicity test organisms Vibrio fischeri, Daphnia, Aspergillus niger, and S. cerevisiae, indicating that FFBF can significantly decrease the survival rate of these species. The results also showed that there was a significant negative correlation between the concentration of some inorganic toxicity factors and the survival rate when Daphnia was used as the test organism, indicating that the toxicity degree order for these inorganic toxicity factors is Ba²⁺ > Li⁺ > As³⁺ > Cl^- > Cu²⁺ > Rb²⁺ > Ga²⁺ > V²⁺ > Na⁺. In addition, other toxic factors, including polycyclic aromatic hydrocarbons (PAHs), were also determined, and the order of toxic effects with a negative correlation to the Daphnia survival rate was confirmed. These results showed that the biological toxicity of FFBF was caused not only by inorganic toxicity factors such as heavy metals but also by organic compounds such as PAHs. The results not only provide a significant reference value for the systematic assessment of biological toxicity by FFBF, but they also have great significance for developing approaches to appropriate FFBF treatment.

Stepwise Assembly of Ag42 Nanocalices Based on a MoVI-Anchored Thiacalix[4]arene Metalloligand

Metalloligand strategy has been well recognized in the syntheses of heterometallic coordination polymers; however, such a strategy used in the assembly of silver nanoclusters is not broadly available. Herein, we report the stepwise syntheses of a family of halogen-templated Ag₄₂ nanoclusters (Ag42c-Ag42f) based on Mo^VI-anchored p-tert-butylthiacalix[4]arene (H₄TC4A) as a metalloligand (hereafter named MoO₃-TC4A). X-ray crystallography demonstrates that they are similar C₃-symmetric silver-organic nanocalices capped by six MoO₃-TC4A metalloligands, which are evenly distributed up and down the base of 42 silver atoms. These nanoclusters can be disassembled to six bowl-shaped [Ag₁₁(MoO₃-TC4A)(RS)₃] secondary building units (SBUs, R = Et or ⁿPr), which are fused together in a face-sharing fashion surrounding Cl^- or Br^- as a central anion template. The electrospray mass spectrometry (ESI-MS) indicates their high stabilities in solution and verifies the formation of the MoO₃-TC4A metalloligand, thereby rationalizing the overall stepwise assembly process for them. Moreover, Ag42c shows lower cytotoxicity and better activity against the HepG-2 cell line than MCF-7 and BGC-823. These results not only exemplify the effectiveness of a thiacalix[4]arene-based metalloligand in the assembly of silver nanoclusters but also give us profound insight about the step-by-step assembly process in silver nanoclusters.

Employing gene chip technology for monitoring and assessing soil heavy metal pollution

Soil heavy metals pollution can cause many serious environment problems because of involving a very complex pollution process for soil health. Therefore, it is very important to explore methods that can effectively evaluate heavy metal pollution. Researchers were actively looking for new ideas and new methods for evaluating and predicting levels of soil heavy metal pollution. The study on microbial communities is one of the effective methods using gene chip technology. Gene chip technology, as a high-throughput metagenomics analysis technique, has been widely used for studying the structure and function of complex microbial communities in different polluted environments from different pollutants, including the soil polluted by heavy metals. However, there is still a lack of a systematic summarization for the polluted soil by heavy metals. This paper systematically analyzed soil heavy metals pollution via reviewing previous studies on applying gene chip technology, including single species, tolerance mechanisms, enrichment mechanisms, anticipation and evaluation of soil remediation, and multi-directional analysis. The latest gene chip technologies and corresponding application cases for discovering critical species and functional genes via analyzing microbial communities and evaluating heavy metal pollution of soil were also introduced in this paper. This article can provide scientific guidance for researchers actively investigating the soil polluted by heavy metals.

Hydrolysis-Promoted Building Block Assembly: Structure Transformation from Wheel and Ship to Cage

Accurately controlling the hydrolysis of metal ions can not only yield the desired structure of metal hydroxide clusters but also provide a deeper understanding of the formation process of natural hydroxide minerals. However, the capture of hydrolysis intermediates remains a significant challenge, and metal hydroxide clusters are mainly obtained by employing adventitious hydrolysis. In this study, we realized a hierarchical building block assembly from Y³⁺ ions to large Y₁₂, Y₃₄, and Y₆₀ clusters by controlling the hydrolysis process of lanthanide ions under different pH conditions. Single-crystal structural analysis showed that the Y₁₂ wheel, Y₃₄ ship, and Y₆₀ sodalite cage contain 4, 12, and 24 cubane-like [Y₄(μ₃-OH)₄]⁸⁺ units, respectively. The structure of the Y₆₀ cluster can be attributed to two Y₃₄ clusters or six Y₁₂ clusters linked by vertices. These clusters can be synthesized through the hydrolysis of Y³⁺ under different pH conditions, and Y₆₀ can be prepared from the obtained Y₁₂ or Y₃₄ crystals by the simple addition of Y³⁺ ions. The capture and conversion of the intermediates of lanthanide series hydroxide clusters, Y₁₂ or Y₃₄, during the assembly from Y³⁺ ions to Y₆₀ can facilitate an understanding of the formation process of high-nuclearity lanthanide clusters.

Toxic effects of shale gas fracturing flowback fluid on microbial communities in polluted soil

A large amount of shale gas fracturing flowback fluid (FFBF) from the process of shale gas exploitation causes obvious ecological harm to health of soil and water. However, biological hazard of soil microbial populations by fracturing flowback fluid remains rarely reported. In this study, the microbiological compositions were assessed via analyzing diversity of microbial populations. The results showed significant differences between polluted soil by fracturing flowback fluid and unpolluted soil in different pH and temperature conditions. And then, the microbe-index of biological integrity (M-IBI) was used to evaluate the toxicity of the fracturing flowback fluid based on analysis of microbial integrity. The results showed that polluted soil lacks key microbial species known to be beneficial to soil health, including denitrifying bacteria and cellulose-decomposing bacteria, and 35 °C is a critical value for estimating poor and sub-healthy level of damage to microbial integrity by fracturing flowback fluid. Our results provide a valuable reference for the evaluation of soil damage by fracturing flowback fluid.

Constructing π-Stacked Supramolecular Cage Based Hierarchical Self-Assemblies via π···π Stacking and Hydrogen Bonding

Constructing supramolecular cages with multiple subunits via weak intermolecular interactions is a long-standing challenge in chemistry. So far, π-stacked supramolecular cages still remain unexplored. Here, we report a series of π-stacked cage based hierarchical self-assemblies. The π-stacked cage (π-MX-cage) is assembled from 16 [MXL]⁺ ions (M = Mn²⁺, Co²⁺; X = Br^-, SCN^-, Cl^-; and L = tris(2-benzimidazolylmethyl)amine) via 18 intermolecular π-stacking interactions. The tetrahedral cage, consisting of four [MXL]⁺ ions as the vertexes and six pairs of [MXL]⁺ ions as the edges, features 48 exterior N-H hydrogen bond donors for hydrogen bond formation with guest molecules. By variation of the M²⁺/X^- pair, the π-MX-cage demonstrates unique versatility for incorporating a wide variety of species via different hydrogen-bonding modes during the assembly of hierarchical superstructures. In specific, the π-MnBr-cages encapsulate acetonitrile (CH₃CN) or cis-1,3,5-cyclohexanetricarbonitrile (cis-HTN) molecules in the central voids, while a core-shell tetrahedral inorganic cluster [Mn(H₂O)₆]@([Mn(H₂O)₄]₄[Br₄^2-]₆) (Mn@Mn₄-cage) is captured within the interstitial regions between cages. The π-CoSCN-cages are capable of stabilizing reactive sulfur-containing species, such as S₂O₄^2-, S₂O₆^2-, and HSO₃^- ions, in the hierarchical superstructure. Finally, H₂PO₄^- ions are incorporated between π-CoCl-cages, resulting in an inorganic mesoporous framework. These results provide insights into further exploring the chemistry and hierarchical assembly of supramolecular cages based on π-π stacking intermolecular interactions.

Production of a novel slow-release coal fly ash microbial fertilizer for restoration of mine vegetation

Driven by a need for economic development, a large number of mines have been exploited, resulting in the destruction of large areas of vegetation and a significant deterioration in local ecological environment. In order to restore vegetation of mines in a timely manner, a new type of organic fertilizer needs to be developed. However, until now, there has been a lack of organic fertilizer with slow-release suitable for mine virescence. As the largest amount of solid waste in coal-fired power plants, coal fly ash presents a promising basis as a bioresource for developing this type of organic fertilizer. In our study, for the first time, fly ash was demonstrated to be an effective carrier matrix via hydrothermal-alkali treatment sintering process for solving the problem of low efficiency of fly ash adsorption for microorganisms via sintering process. Then, a novel slow-release microbial fertilizer which can adsorb a variety of microorganisms was produced using ethyl cellulose as a solvent adhesive. Finally, the pot experiment showed that the soil fertility of abandoned mines can be improved after applying the fly ash microbial fertilizer, and demonstrated the regreening effects with Pseudodrynaria coronans and Buxus microphylla. Our study provides a green engineering approach to recycle fly ash for regreening mines, as well as a new development direction for high-value green recyclable pathway of fly ash.

A Giant 3d-4f Polyoxometalate Super-Tetrahedron with High Proton Conductivity

The assembly of gigantic heterometallic metal clusters remains a great challenge for synthetic chemistry. Herein, based on the slow release strategy of lanthanide ions and in situ formation of lacunary polyoxometalates, two giant 3d-4f polyoxometalate inorganic clusters [LaNi₁₂ W₃₅ Sb₃ P₃ O₁₃₉ (OH)₆ ]^23- (LaNi₁₂ ) and [La₁₀ Ni₄₈ W₁₄₀ Sb₁₆ P₁₂ O₅₆₈ (OH)₂₄ (H₂ O)₂₀ ]^86- (La₁₀ Ni₄₈ ) are obtained. The nanoscopic inorganic cluster La₁₀ Ni₄₈ possesses a super tetrahedron structure, which can be viewed as assembly from four LaNi₁₂ molecules encapsulating a central [La₆ (SbO₃ )₄ (H₂ O)₂₀ ]⁶⁺ octahedron core. This giant aesthetic La₁₀ Ni₄₈ tetrahedron containing 214 metal ions is the largest 3d-4f cluster reported thus far in polyoxometalate system. More interestingly, the LaNi₁₂ and La₁₀ Ni₄₈ display high stability in solution and La₁₀ Ni₄₈ displays excellent proton conductivity.

Elaborate Design of Ag8Au10 Cluster [2]Catenane Phosphors for High-Efficiency Light-Emitting Devices

In this work, rational design of highly soluble and phosphorescent Ag-Au cluster complexes with exceptional [2]catenane structures is conducted using 1,8-diethynyl-9H-carbazole (H₃decz) as a rigid U-shaped ligand with a distinguished hole-transport character. The self-assembly reaction of H₃decz, Au⁺, and Ag⁺ generated phosphorescent Ag₄Au₆ cluster 1 (Φ_em = 0.22 in CH₂Cl₂) with H₂decz^- having a free ethynyl (-C≡CH) group. When the four free C≡CH groups in the Ag₄Au₆ complex 1 are further bound to four (PPh₃)Au⁺ and four (PPh₃)Ag⁺ moieties through M-acetylide linkages, the formation of Ag₈Au₁₀ cluster 2 not only eliminates nonradiative ethynyl C-H vibrational deactivation process but also improves dramatically the molecular rigidity so that the phosphorescent efficiency of the Ag₈Au₁₀ cluster 2 (Φ_em = 0.63) is nearly 3 times that of the Ag₄Au₆ cluster 1. The Ag₈Au₁₀ cluster structure is further rigidified using diphsophine Ph₂P(CH₂)₄PPh₂ (dppb) in place of PPh₃ so that the phosphorescence of the Ag₈Au₁₀ cluster 3 (Φ_em = 0.77) is more efficient than that of 2. Making use of the Ag₈Au₁₀ clusters as phosphorescent dopants, high-efficiency solution-processed organic light-emitting diodes (OLEDs) were achieved with current efficiency (CE) and external quantum efficiency (EQE) of 47.2 cd A^-1 and 15.7% for complex 2 and 50.5 cd A^-1 and 14.9% for complex 3.

Synthesis, Structures, and Photoluminescence of Elongated Face-Centered-Cubic Ag14 Clusters Containing Lipoic Acid and Its Amide Analogue

Three face-centered-cubic (fcc) silver clusters-namely, [Ag₁₄(LA)₂(HLA)₄(PPh₃)₈]^2- (1), [Ag₁₄(HLA)₆(PPh₃)₈] (2), and [Ag₁₄(NLA)₆(PPh₃)₈] (3)-that are coprotected by lipoic acid (or its amide derivative) and phosphine ligands have been synthesized and structurally characterized (HLA = (±)-α-lipoic acid, LA = (±)-α-lipoate, and NLA = d,l-6,8-thioctamide). These clusters possess two superatomic electrons (the Jellium model), in harmony with a bonding octahedral Ag₆ core capped with 8 Ag atoms. Alternatively, the metal framework of 1-3 can be described as adopting a face-centered cubic (fcc) structure elongated along one of the 3-fold axes. The 12 S atoms from the six bioligands bridge the 12 edges of the (fcc) cube, forming a distorted icosahedron. The counterions, solvent or guest molecules play an important role in dictating the crystal lattices of the products. This is the first report of atom-precise structures of Ag-lipoic acid (or its derivatives) clusters, paving the way for further study of structure-property relationships of these bioligand protected metal nanoclusters. Photoluminescence was observed for cluster 3 with complex temperature-dependent emission patterns and efficiencies.

A Polyoxochromate Templated 56-Nuclei Silver Nanocluster

Most of polyoxometallates (POMs) templated silver nanoclusters recorded so far are polyoxomolybdates and polyoxotungstates; however, as congeneric polyoxochromates, they are rarely observed in silver nanoclusters. Herein, a high-nuclearity polyoxochromate, (Cr^III₄Cr^VI₈O₃₆)^12-, is uncovered in a novel silver nanocluster (SD/Ag56a) as an anion template. The mixed-valent (Cr^III₄Cr^VI₈O₃₆)^12- consists of four edge-sharing Cr^IIIO₆ octahedra and eight Cr^VIO₄ tetrahedra, which are fused together by sharing one or two vertexes. The (Cr^III₄Cr^VI₈O₃₆)^12- is the by far highest nuclearity polyoxochromate and is trapped by outer Ag₅₆ bracelet-like shell coprotected by quaternary ligands including ⁱPrS^-, NapCOO^- (2-naphthalenecarboxylate), CF₃COO^-, and CH₃CN. The antiferromagnetic property and solution behavior of SD/Ag56a are discussed in detail.

Hexadecanuclear MnII2MnIII14 Molecular Torus Built from in Situ Tandem Ligand Transformations

A mixed-valent hexadecanuclear manganese cluster, [Mn^II₂Mn^III₁₄(trz)₁₄(thetach)₄(μ₃-O)₈(H₂O)₁₀](ClO₄)₆ (Mn16), containing two Mn^II and 14 Mn^III ions, is constructed from mixed in situ generated ligands, 1,2,3-triazole (Htrz) and 1,3,5-tri(2-hydroxyethyl)-1,3,5-triazacyclohexane (H₃thetach). Remarkably, both ligands were not initially added into the reaction system, and their formations involve the in situ ligand decomposition and subsequent condensation reactions. The core of Mn16 is an elongated torus comprised of eight Mn atoms and four [Mn₂O₂] subunits bridged by oxo or alkoxide. The high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) of Mn16 dissolved in CH₃CN indicates its structure remains intact as +3 and +4 species. Temperature and field dependent magnetization revealed predominantly antiferromagnetic exchange interactions within the cluster. The work provides one-pot synthesis of high-nuclearity manganese clusters using the ligands generated by in situ reactions in a tandem fashion.

Enclosing classical polyoxometallates in silver nanoclusters

Due to the elusive nature of polyoxometallates (POMs) in the assembly of silver clusters, POMs trapped by silver clusters are usually different from the pristine form, which surely increases the novelty of the assembly results but makes the final structure predictability challenging. Herein, three novel high-nuclearity silver-thiolate clusters trapping two kinds of classical POMs, Lindqvist-Mo6O192- and V10O286-, are reported. They are identified to be [(V10O28)@Ag44] (SD/Ag44a), [(V10O28)@Ag46] (SD/Ag46), and [(Mo6O19)@Ag44] (SD/Ag44b) clusters, which are further extended to 1D chain, 2D sql layer, and 3D pcu framework, respectively. Of note, SD/Ag44b contains a regular cubic Mo6O19 core sealed by an Ag44(EtS)24 shell in a pseudo-sodalite unit and six SCl4 planar squares connecting the respective adjacent silver tetragonal faces. This structure is a novel zeolite closely related to the natural alumino-silicate 'sodalite' but exceptionally made of core-shell silver clusters. Moreover, the Oh symmetric Mo6O192- templates an Oh symmetric Ag44 cluster in SD/Ag44b, realizing authentic symmetry delivery from guest to host in this system. This is a rare silver cluster family with classical POMs encapsulated.

Space Craft-like Octanuclear Co(II)-Silsesquioxane Nanocages: Synthesis, Structure, Magnetic Properties, Solution Behavior, and Catalytic Activity for Hydroboration of Ketones

Two novel space craft-like octanuclear Co(II)-silsesquioxane nanocages, {Co₈[(MeSiO₂)₄]₂(dmpz)₈} (SD/Co8a) and {Co₈[(PhSiO₂)₄]₂(dmpz)₈} (SD/Co8b) (SD = SunDi; Hdmpz = 3,5-dimethylpyrazole), have been constructed from two similar multidentate silsesquioxane ligands assisted with a pyrazole ligand. The Co₈ skeleton consists of eight tetrahedral Co(II) ions arranged in a ring and is further capped by two (MeSiO₂)₄ ligands up and down. The auxiliary dmpz^- ligands seal the ring finally. Electrospray ionization mass spectrometry revealed SD/Co8a and SD/Co8b are highly stable in CH₂Cl₂. Magnetic analysis implies that SD/Co8a announces antiferromagnetic interactions between Co(II) ions. Moreover, both of them display good homogeneous catalytic activity for hydroboration of ketones in the presence of pinacolborane under mild conditions.

Self-Organization into Preferred Sites by MgII, MnII, and MnIII in Brucite-Structured M19 Cluster

The search for functional materials, for example those aiming at microelectronics, magnetic recording, and catalysis, often ventures into mixed metal systems to achieve optimization of the properties. Thus, understanding site preference and self-organization is crucial but hard to implement. Herein, we present a system whereby Mg^II, Mn^II, and Mn^III ions selectively locate exact positions within the Brucite-structured cluster, Mn₁₃Mg₆, [Mn^III⊂Mg^II₆⊂Mn^II₉Mn^III₃( L)₁₈(OH)₁₂(N₃)₆](ClO₄)₆·12CH₃CN, H L = 1-(hydroxymethyl)-3,5-dimethylpyrazolate). The Mn^III being small (78 pm) takes up the core position; while 6 Mg^II (86 pm) are located in the inner ring, and the 9 large Mn^II (97 pm) and 3 Mn^III occupy the outer ring. The factors (a) ionic radii, (b) regularity in coordination geometry, oxophilicity, and softness of Mg^II compared to Mn^II, and (c) Jahn-Teller distortion of Mn^III may all be implicated synergistically. Electrospray ionization mass spectrometry reveals the M₁₉ disc remains an integral unit when crystals are dissolved, and exchange between Mg and Mn occurs within the disc during its formation. Diamagnetic Mg^II doping insulates the magnetic exchange between the central Mn^III and those in the outer ring, thus giving an overall antiferromagnetic exchange interaction between nearest-neighbors of the outer ring. The work reveals the underlying rule for site-preference of main group metal versus transition metal in disc-like Brucite-structured cluster and provides an elegant new avenue to assemble heterometallic clusters in a stepwise fashion.

A 2D layer network assembled from an open dendritic silver cluster Cl@Ag11N24 and an N-donor ligand

A 2D layer network was synthesized from an N-donor ligand and a new silver cluster featuring an open dendritic structure with a high coordination ratio of N atom. Both the assembly process and luminescence properties of this complex was studied.

[Au18(dppm)6Cl4]4+: a phosphine-protected gold nanocluster with rich charge states

A diphosphine-protected 18-gold-atom nanocluster was isolated via a facile reduction of an Au^I precursor by NaBH₄.

Sniffing with mass spectrometry

Gaseous compounds are usually on-line detectable on sensors. The limitations of conventional sensors are suffering from incapability for exactly identifying multiple components as well as incompatibility to possible toxicants in every odor sample. Herein, we discuss an inlet modification to the laboratory standard mass spectrometer, inspired by the sensitive olfactory systems of animals, for direct sniffing, established by connecting a mini pump to the nebulizer gas tubing. The modified mass spectrometry method-sniffing-mass spectrometry (sniffing-MS)-can acquire detailed fingerprint spectra of mixed odors and shows high tolerance to toxicants. Furthermore, the method has a low limit of detection in the order of parts per trillion and is a 'sampling-free' technique for analyzing various gaseous compounds simultaneously, thus offering versatility for smelling daily commodities, tracking diffusion, and locating position of odors. Sniffing-MS can mimic or even surpass the olfaction of animals and is applicable for analyzing gaseous/volatile compounds, especially those polar compounds, in a simple manner depending on the intrinsic molecular mass-to-charge ratio.

Trapping an octahedral Ag6 kernel in a seven-fold symmetric Ag56 nanowheel

High-nuclearity silver clusters are appealing synthetic targets for their remarkable structures, but most are isolated serendipitously. We report here six giant silver-thiolate clusters mediated by solvents, which not only dictate the formation of an octahedral Ag₆⁴⁺ kernel, but also influence the in situ-generated Mo-based anion templates. The typical sevenfold symmetric silver nanowheels show a hierarchical cluster-in-cluster structure that comprises an outermost Ag₅₆ shell and an inner Ag₆⁴⁺ kernel in the centre with seven MoO₄^2- anion templates around it. Electrospray ionization mass spectrometry analyses reveal the underlying rule for the formation of such unique silver nanowheels. This work establishes a solvent-intervention approach to construct high-nuclearity silver clusters in which both the formation of octahedral Ag₆⁴⁺ kernel and in situ generation of various Mo-based anion templates can be simultaneously controlled.

Small size yet big action: a simple sulfate anion templated a discrete 78-nuclearity silver sulfur nanocluster with a multishell structure

A discrete 78-nuclearity Ag nanocluster with a sulfate-centered multishell structure was obtained, indicating that simple anions can induce the formation of high-nuclearity Ag clusters.

Solution behavior and magnetic properties of a novel nonanuclear copper(ii) cluster

A {Cu9} nanocluster was constructed from a new multidentate pyrazole–alcohol ligand and various small sterically-hindering anions. The ESI-MS was for the first time applied to Cu cluster chemistry to detect the solution behaviour and possible assembly mechanism of the {Cu9} cluster. The cluster also exhibited antiferromagnetic behaviour.

A giant 90-nucleus silver cluster templated by hetero-anions

A giant 90-nucleus silver cluster templated by hetero-anions was isolated and characterized.

A hexadecanuclear silver alkynyl cluster based NbO framework with triple emissions from the visible to near-infrared II region

A hexadecanuclear silver alkynyl cluster based NbO framework with triple emissions from visible to near-infrared II region.

Johnson Solids: Anion-Templated Silver Thiolate Clusters Capped by Sulfonate

Sulfonates were incorporated into six novel high-nuclearity silver(I) thiolate clusters under the guidance of anion templates varied from S^2- , SO₄^2- , α-[Mo₅ O₁₈ ]^6- , β-[Mo₅ O₁₈ ]^6- , [Mo₂ O₈ ]^4- , to [Mo₄ O₁₄ (SO₄ )]^6- . Single crystal X-ray analysis revealed that SD/Ag1, SD/Ag3, SD/Ag5, and SD/Ag6 are discrete [S@Ag₆₀ ], [α-Mo₅ O₁₈ @Ag₃₆ ], [Mo₂ O₈ @Ag₃₀ ]₂ , and [Mo₄ O₁₄ (SO₄ )@Ag₇₃ ] clusters, respectively, whereas SD/Ag2 and SD/Ag4 are one-dimensional (1D) chains based on the [SO₄ @Ag₂₀ ] and [β-Mo₅ O₁₈ @Ag₃₆ ] cluster subunits, respectively. Their silver skeletons are protected exteriorly by thiolates and sulfonates and interiorly supported by diverse anions as templates. Structurally, cluster SD/Ag1 is a typical core-shell structure comprised of an inner Ag₁₂ cuboctahedron and an outer Ag₄₈ shell. The sulfate-templated drum-like Ag₂₀ cluster subunits are bridged by PhSO₃^- to give a 1D chain of SD/Ag2. Complex SD/Ag3 and SD/Ag4 are spindle-like Ag₃₆ clusters with isomeric [Mo₅ O₁₈ ]^6- inside, and the latter is further extended to a 1D chain through PhSO₃^- bridges. A pair of [Mo₂ O₈ ]^4- templated gourd-like Ag₃₀ clusters are dimerized in a head-to-head fashion to form SD/Ag5. Complex SD/Ag6 is the largest cluster in this family and doubly templated by unprecedented [Mo₄ O₁₄ (SO₄ )]^6- anions. Geometrically, the silver shells of SD/Ag1-SD/Ag5 show the polyhedral features of Johnson solids, instead of the usual Platonic or Archimedean solids. Solution behaviors and luminescent properties were also investigated in detail.

High-efficiency bioconversion of kitchen garbage to biobutanol using an enzymatic cocktail procedure

Research on methods to produce biobutanol production from kitchen garbage (KG) as a potential substrate is thus far lacking. Here, the effect of various enzymatic hydrolysis procedures (EHP) was first tested using different enzyme cocktails, on the decomposition of KG. The efficiency of Clostridium acetobutylicum-mediated biobutanol production was then measured using two modes: separate hydrolysis and fermentation (SHF) and simultaneous saccharification fermentation (SSF) in the condition of adjusting pH. The optimal results were obtained using (1) an enzymatic hydrolysis cocktail procedure (EHC5), (2) use of the SSF approach and (3) pH control. This approach results in a biobutanol production of 16.37g/L and total solvent concentration of 32.96g/L. Compared to experiments that use pure glucose asa substrate, our results show that KG is a promising feedstock for biobutanol production. The results demonstrate the feasibility of this waste source for an industrial application via the EHP.

Assembly of silver Trigons into a buckyball-like Ag180 nanocage

Buckminsterfullerene (C60) represents a perfect combination of geometry and molecular structural chemistry. It has inspired many creative ideas for building fullerene-like nanopolyhedra. These include other fullerenes, virus capsids, polyhedra based on DNA, and synthetic polynuclear metal clusters and cages. Indeed, the regular organization of large numbers of metal atoms into one highly complex structure remains one of the foremost challenges in supramolecular chemistry. Here we describe the design, synthesis, and characterization of a Ag180 nanocage with 180 Ag atoms as 4-valent vertices (V), 360 edges (E), and 182 faces (F)--sixty 3-gons, ninety 4-gons, twelve 5-gons, and twenty 6-gons--in agreement with Euler's rule V - E + F = 2. If each 3-gon (or silver Trigon) were replaced with a carbon atom linked by edges along the 4-gons, the result would be like C60, topologically a truncated icosahedron, an Archimedean solid with icosahedral (Ih) point-group symmetry. If C60 can be described mathematically as a curling up of a 6.6.6 Platonic tiling, the Ag180 cage can be described as a curling up of a 3.4.6.4 Archimedean tiling. High-resolution electrospray ionization mass spectrometry reveals that {Ag3}n subunits coexist with the Ag180 species in the assembly system before the final crystallization of Ag180, suggesting that the silver Trigon is the smallest building block in assembly of the final cage. Thus, we assign the underlying growth mechanism of Ag180 to the Silver-Trigon Assembly Road (STAR), an assembly path that might be further employed to fabricate larger, elegant silver cages.

A Water-Stable Cl@Ag14 Cluster Based Metal-Organic Open Framework for Dichromate Trapping and Bacterial Inhibition

Decoding the principles of cluster-based framework assembly at the molecular level remains a persistent challenge. Herein, we isolated and characterized a novel water-stable three-dimensional (3D) metal-organic open framework [Cl@Ag₁₄(cPrC≡C)₁₀Cl₂·(p-TOS)·1/3H₂O]_n (SD/Ag14, cPrC≡CH = cyclopropylacetylene; p-TOS = p-toluenesulfonate), which contains a chloride-templated Ag₁₄ cluster as building block. For SD/Ag14, one chloride acts as the template to shape the Ag₁₄ cluster and the other bridges the clusters to a 3D pcu-h open framework. As revealed by high resolution electrospray mass spectrometry (HRESI-MS), the Ag₁₂-Ag₁₄ species are potential cluster-based intermediates to the 3D pcu-h framework, which authenticates a preconceived idea that the 3D framework is hierarchically assembled from the silver clusters as observed in solid state. Interestingly, SD/Ag14 can be used effectively to remove the environmental pollutant Cr₂O₇^2- from wastewater through anion exchange in a single-crystal-to-single-crystal (SC-SC) transformation fashion. Furthermore, SD/Ag14 exhibits excellent antibacterial activity against Staphylococcus aureus, thus making it a potential antibacterial agent.

Multifunctional Triple-Decker Inverse 12-Metallacrown-4 Sandwiching Halides

A family of six triple-decker complexes, {(MX)₂[(pz)₄]₃} (Hpz = 4-nitropyrazole, MX = NaCl, 1; NaBr, 2; NaI, 3; KCl, 4; KBr, 5, and KI, 6), exhibiting inclusion of halides into inverse 12-metallacrown-4 [inv-(12-MC_Cu(I),pz-4)] array has been realized. Single-crystal X-ray crystallography of each compound reveals a common structural feature consisting of four Cu^I ions bonded by four pz to form a square metallomacrocycle comprising four metal centers and eight N atoms, thus giving an inv-[12-MC_Cu(I),pz-4] motif. Two halides are sandwiched by three inv-[12-MC_Cu(I),pz-4] to form triple-deckers that are further extended in an offset stacking mode by ligand-unsupported cuprophilicity interactions to form a one-dimensional chain structure. Halides are attached to six Cu^I centers with weak Cu^I···halogen interaction, resembling anion templates. High-resolution electrospray ionization mass spectrometry reveals that the predominant fragments corresponding to a half of the triple-decker structures of 1-3 exist in solution. Compounds 4, 5, and 6 showed excellent electrocatalytic activities toward the reduction of nitrite and can also be used as selective "turn-off" sensors for Ag(I) in water. The present results will be helpful for the future design and synthesis of functional inverse metallacrowns and their multiple-decker complexes.

Structure, solution assembly, and electroconductivity of nanosized argento-organic-cluster/framework templated by chromate

In view of elucidating potential structures and assembly mechanism of silver clusters and silver cluster-based metal-organic frameworks, we prepared four argento-organic-clusters/frameworks where the structures were directed by chromate in the presence of different thiolates. All four structures with ^tBuC₆H₄S^-, SⁱBu^-, and SⁱPr^- consist of three core-shells, an inner CrO₄^2-, an intermediate Ag-S aggregate and finally the protective organic moieties. {(HNEt₃)₃[Ag(CrO₄)₄@Ag₄₆(SC₆H₄^tBu)₂₄(CF₃COO)₁₈(DMF)₄]} (1) is a supertetrahedron with an inner Ag(CrO₄)₄ tetrahedron shelled by four fused Ag_11.5S₆ lobes. [(CrO₄)₅@Ag₄₀(SⁱBu)₂₇(CF₃COO)₃]_n (2) is an undulated snake-like tube housing the infinite CrO₄^2- tetrahedra. [(CrO₄)₂@Ag₄₁(SⁱBu)₃₀(NO₃)₃(CN)₄]_n (3) forms an uncommon 7-connected kwh network incorporating hexagonal layers of Ag₁₉(SⁱBu)₁₅ balls with a single inner CrO₄^2- connected by another Ag atom. Both enantiomeric chiral qtz frameworks of [CrO₄@Ag₂₀(SⁱPr)₁₀(Cr₂O₇)₂(COOCF₃)₄(DMF)₄]_n (4) were structurally characterized. In 4, Cr₂O₇^2- connects the Ag₂₀(SⁱPr)₁₀ clusters with a trapped CrO₄^2- into a 3D quartz (qtz) structure, where the spherical cluster acts like oxygen and Cr₂O₇^2- takes the place of Si in SiO₂. Electrospray ionization mass spectrometry (ESI-MS) analysis of the reaction solutions of 1-4 clearly indicated that (i) the Ag(CrO₄)₄@Ag₄₆ core of 1 can retain its molecular structure in the solution and (ii) the chromate-templated polynuclear silver-thiolate species in solution are important building blocks to construct the 1D or 3D motif for 2-4. The electrochemistry in sulfuric acid and enhancement of the electrical conductivity upon I₂ doping have also been reported.

Anion-templated nanosized silver clusters protected by mixed thiolate and diphosphine

S^2-, MoO₄^2-, and Mo₆O₂₂^8- were successfully employed as templates in the formation of six high-symmetry polynuclear silver clusters as exemplified in the single-crystal X-ray structures of [S@Ag₁₈(^tBuC₆H₄S)₁₆(dppp)₄]·DMF·5CH₃CN·3CH₃OH (1), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppm)₆(MoO₄)₄]·2BF₄·C₂H₅NO (2), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppm)₆(MoO₄)₄]·2CF₃SO₃ (3), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppf)₆(MoO₄)₄]·2CF₃SO₃ (4), [MoO₄@Ag₂₄(MeC₆H₄S)₁₂(dppb)₆(MoO₄)₄]·2CF₃SO₃ (5) and [Mo₆O₂₂@Ag₄₆(^tBuC₆H₄S)₃₂(dppm)₄(CH₃CN)₈]·6CF₃SO₃ (6) (dppp = 1,3-bis(diphenylphosphino)propane, dppm = bis(diphenylphosphino)methane, dppf = 1,1'-bis(diphenylphosphino)ferrocene and dppb = 1,4-bis(diphenylphosphino)butane). Cluster 1 is a S^2--centered octadecanuclear banana-shaped molecule. Clusters 2-5 have similar structures consisting of a tetrahedron of a MoO₄^2- core and four MoO₄^2- where three silver atoms cap each face and a pair sits on each edge, giving tetraicosanuclear ball-shaped molecules. Although different diphosphine ligands and silver salts were used in the syntheses, 2-5 contain a common building cluster unit with similar geometry and nuclearity. With (Bu₄N)₂Mo₆O₁₉ as a template, a giant 46-silver-atom cluster encapsulates an in situ modified Mo₆O₂₂^8- unit. The nuclearity and geometry depend on the size and shape of the templates. High-resolution electrospray mass spectrometry (HR-ESI-MS) analyses of 4 indicate its exceptionally high stability in acetonitrile. The solid-state luminescence of 1 as a function of the temperature exhibits thermochromism from red to yellow due to the different intensities of the two bands. This work established a new strategy for the construction of polynuclear silver clusters using an anionic template and mixed S- and P-donor ligands where a promising approach for building novel dual emissive materials is unraveled.