Synthesis Of Nanoclusters Research Articles

Selective synthesis of fluorescent metal nanoclusters over metal nanoparticles.

Metal nanoparticles and nanoclusters are pivotal in nanomaterial science, each offering unique properties for diverse applications. Nanoclusters, typically smaller than 2nm, exhibit distinct optical and electronic characteristics due to quantum confinement, resulting in fluorescence emission. In contrast, metal nanoparticles, sized between 2 and 100nm, exhibit absorption spectra. Both are synthesized by reducing metal precursors in the presence of a suitable stabilizing agent. While nanoparticles have been the historical research focus, recent attention has shifted to nanoclusters for their exceptional properties and their synthesis has evolved significantly over the past few decades. This review discusses the selective synthesis of nanoclusters over nanoparticles, emphasizing the role of various factors such as ligand concentration(metal-to-ligand ratio), reducing agents, pH,reactiontime and temperature, solvents, and assistant reagents. Higher ligand concentrations stabilize smaller nanoclusters by preventing aggregation, while lower concentrations lead to larger nanoparticles. Stronger reducing agents produce smaller, more uniform particles, whereas weaker reducingagents yield larger ones. pH affects nanocluster size and emission properties. Solvents and assistant reagents influence reaction kinetics and material properties. Temperature and reaction time also play critical roles in controlling nanocluster size and properties. These insights guide the optimized synthesis of metal nanoclusters, for their specific applications.

Photosynthesis of Au8Cu6 nanocluster for photocatalysis in oxidative functionalization of alkynes

Ligand-protected metal nanoclusters provide an ideal platform for investigating photoredox catalysis. The central challenge is balancing their stability and catalytic activity. Here we show a photochemical reduction–oxidation cascade method for synthesizing an Au8Cu6 nanocluster, which features a robust structure and active surface. Photoredox catalytic activity of Au8Cu6 is developed for the functionalization of alkynes under oxidative conditions. Mechanism studies based on the precise structure reveal the catalytic process of the Au8Cu6 nanocluster. Oxidant-dependent selectivity of Au8Cu6 catalysis is developed for chemodivergent synthesis of mono- and di-functionalized products in high efficiency. The results will stimulate more research on metal nanocluster synthesis and catalysis.

Molecule-like synthesis of ligand-protected metal nanoclusters

Molecule-like synthesis of ligand-protected metal nanoclusters

Construction of an efficient microRNA sensing platform based on terminal deoxynucleotidyl transferase-mediated synthesis of copper nanoclusters

A conceptual innovative electrochemical sensing platform was constructed for microRNA (miRNA) detection based on terminal deoxynucleotidyl transferase (TdT)-mediated synthesis of copper nanoclusters. In principle, the substrate strand immobilized on working electrode acted as the template for the TdT-mediated DNA extension reaction, while the DNAzyme probe would be activated in the absence of miRNA 21, which led to the cleavage of the substrate strand to produce the 5’ phosphate terminus and inhibited the TdT-mediated DNA extension reaction. On the other hand, the presence of miRNA 21 initiated the toehold-mediated strand displacement reaction, causing the disassembly of the DNAzyme structure and preventing the substrate strand from being cleaved. This enabled the recycle amplification of target miRNA 21, and TdT catalyzed the DNA extension reaction on the 3’ hydroxyl terminus of the substrate strand, producing a large number of poly thymine (polyT) sequences. These sequences bound with copper ions for in-situ synthesis of copper nanoclusters on the sensing electrode, and the increased electrochemical signal of copper was recorded by differential pulse stripping voltammetry (DPSV), which paved the way for sensitive determination of miRNA 21 extracted from cancer cells with a detection limit of 36 aM. Due to its high sensitivity, user-friendly operation, and cost-effectiveness, this method is helpful for the fundamental research of sensing mechanism as well as the diagnosis of related diseases.

Short-Peptide-Modified Copper Nanoclusters as a Fluorescent Probe for the Specific Detection of Ascorbic Acid.

Metal nanoclusters assembled using short peptides as templates exhibit significant potential for development and application in the fields of catalysis and biomedicine, owing to their distinctive electronic structure, favorable optical properties, and biocompatibility. Among them, tripeptides exhibit a simpler structure and greater flexibility, enabling them to readily co-assemble with other functional components to create novel materials with significant application value. They can be assembled with copper ions to synthesize highly efficient luminescent nanoclusters, which can serve as an effective fluorescent probe. Here, we report a method for the synthesis of copper nanoclusters (Cu NCs) using tripeptides as templates, which also act as stabilizers and reducing agents. The synthesis conditions and properties were explored and optimized. Under optimal conditions, the Cu NCs exhibit excellent stability and are strongly fluorescent. The Cu NCs can detect 0.1-1.0 μmol/L of ascorbic acid with a low detection limit of 0.075 μmol/L, demonstrating high sensitivity and offering significant application potential for the trace of ascorbic acid in various substances. It also provides new ideas for the assembly of metal nanoclusters and the construction of fluorescent probe sensing platforms.

Dynamic Metal Exchange in Nanoclusters: Isotope Labeling Sheds Light on Cellular‐like Fusion Processes

AbstractGrasping the behavior of metal nanoclusters in solution at the atomic level is a pinnacle challenge in nanoscience. In addressing this, our work utilizes the Ag13@Ag16(BDT)12(TPP)4 (Ag29) nanocluster (where BDT represents 1,3‐benzenedithiol, and TPP is triphenylphosphine) as a template. We employ isotopic layering labeling, such as a109 Ag13@107 Ag16 core ‐shell structure, to mark the clusters. Subsequently, we conduct reactions with clusters featuring two different layering structures. Finally, we employ isotopic labeling to replace Ag in the shell, followed by analysis using ESI‐MS, enabling us to discern the process of intercluster reactions. We observed that the reactions primarily involve metal exchanges between the cores of different clusters and separately between their shells, highlighting distinct patterns of atomic‐level exchanges within these structures. This study thus offers pivotal insights into the molecular‐level mechanisms of metal exchange between clusters, significantly contributing to the development of metal nanocluster design and synthesis.

Ultra-facile synthesis of CuO nanoclusters with excellent antibacterial activity and their antimicrobial mechanism study

Ultra-facile synthesis of CuO nanoclusters with excellent antibacterial activity and their antimicrobial mechanism study

Gold nanoclusters stabilized with dopa-containing ligands: Catalyst-indicator integrated probe for tumor cell screening

Elevated hydrogen peroxide (H2O2) levels not only inflict cellular damage but also serve as a harbinger for various diseases. Tumor cells, in particular, often exhibit an abundance of H2O2. Hence, the detection of this pivotal molecule assumes paramount importance in monitoring physiological states and expediting cancer diagnosis. To this end, we have ingeniously devised an enzyme-free and monomeric system for intracellular H2O2 detection. Our astute selection of dopa-containing peptidomimetics, replete with ortho-bisphenol and amino acid moieties, has engendered the synthesis of distinctive fluorescent gold nanoclusters (AuNCs). These nanoclusters not only function as a peroxidase-like catalyst, catalyzing the decomposition of H2O2 into hydroxyl radicals (·OH), but also serve as an indicator, with their fluorescence quenched in response to varying H2O2 concentrations. Experimental results evince that our GDpE-AuNCs exhibit remarkable sensitivity, boasting a detection limit of 0.49 μM and a linear range of 5–1000 μM. Moreover, the amalgamation of catalyst and indicator within a single structure, facilitating efficient cellular uptake, engenders intracellular H2O2 detection and discernment of tumor cells. This pioneering approach bequeaths a valuable assay probe for monitoring physiological states and ushering in early disease diagnosis.

One-pot gram-scale synthesis of robust copper nanoclusters for photocatalytic difluoroalkylarylation of alkenes

One-pot gram-scale synthesis of robust copper nanoclusters for photocatalytic difluoroalkylarylation of alkenes

Structural Isomerism in Bimetallic Ag20Cu12 Nanoclusters.

Structural isomers of atomically precise metal nanoclusters are highly sought after for investigating structure-property relationships in nanostructured materials. However, they are extremely rare, particularly those of alloys, primarily due to the challenges in their synthesis and structural characterization. Herein, for the first time, a pair of bimetallic isomeric AgCu nanoclusters has been controllably synthesized and structurally characterized. These two isomers share an identical molecular formula, Ag20Cu12(C≡CR)24 (denoted as Ag20Cu12-1 and Ag20Cu12-2; HC≡CR is 3,5-bis(trifluoromethyl)phenylacetylene). Single-crystal X-ray diffraction data analysis revealed that Ag20Cu12-1 possesses an Ag17Cu4 core composed of two interpenetrating hollow Ag11Cu2 structures. This core is stabilized by four different types of surface motifs: eight -C≡CR, one Cu(C≡CR)2, one Ag3Cu3(C≡CR)6, and two Cu2(C≡CR)4 units. Ag20Cu12-2 features a bitetrahedron Ag14 core, which is stabilized by three Ag2Cu4(C≡CR)8 units. Interestingly, Ag20Cu12-2 undergoes spontaneous transformation to Ag20Cu12-1 in the solution-state. Density functional theory calculations explain the electronic and optical properties and confirm the higher relative stability of Ag20Cu12-1 compared to Ag20Cu12-2. The controlled synthesis and structural isomerism of alloy nanoclusters presented in this work will stimulate and broaden research on nanoscale isomerism.

Modulated assembly and structural diversity of heterometallic Sn-Ti oxo clusters from inorganic tin precursors.

Through modulating the multidentate ligands, solvent environments, and inorganic tin precursors during the synthesis processes, we have successfully prepared a series of unprecedented heterometallic Sn-Ti oxo clusters with structural diversity and different physiochemical attributes. Initially, two Sn6Ti10 clusters were synthesized using trimethylolpropane as a structure-oriented ligand and SnCl4·5H2O as a tin source. Then, when a larger pentadentate ligand di(trimethylolpropane) was used instead of trimethylolpropane and aprotic acetonitrile solvent was introduced into the reaction system, four low-nuclearity Sn-Ti oxo clusters were discovered, including two Sn1Ti1, one Sn2Ti2 and one Sn2Ti6. Finally, two mixed-valence state clusters, SnII4SnIV2TiIV14 and SnII4SnIV4TiIV20, were obtained by transforming the tin precursor from SnCl4·5H2O to SnCl2·2H2O and adjusting the acetonitrile solution with trace acetic acid/formic acid. Sn8Ti20 is the highest-nuclearity heterometallic Sn-Ti oxo cluster to date. Moreover, comparative electrocatalytic CO2 reduction experiments were carried out, and it was concluded that the Sn8Ti20-decorated electrode showed the most satisfactory performance due to the influence of mixed-valence states of the Sn atoms and the charging effects provided by 20 Ti4+ ions. This study presents important guiding significance for the design, synthesis and application optimization of functional heterometallic nanoclusters.

Biosynthesis of gold cluster nanozyme within the structure of TetX2 monooxygenase protein

The synthesis of gold nanoclusters within protein structures, such as TetX2 monooxygenase, presents a promising approach for obtaining nanostructures with enzyme-like activity. This is attributed to the presence of various amino acid groups that serve as biological templates for the formation and reduction of gold. The low toxicity, biocompatibility, solubility in aqueous systems, and specific fluorescence spectrum of these nanostructures enhance their utility in the detection of various analytes. The research involved expressing and purifying the recombinant enzyme TetX2, synthesizing gold on the TetX2 substrate, and investigating the effect of nanoclusters on the activity and structure of the TetX2 enzyme. The synthesis of gold nanoclusters(AuNCs) was carried out within the structure of TetX2. Finally, the accuracy of the AuNCs synthesis was verified by examining the morphology, size, spectroscopy, and catalytic activity. Results showed changes in the tertiary structure of the TetX2 enzyme in the presence of HAuCl4, loss of enzyme activity after the formation of gold nanoclusters, and successful incorporation of gold into the structure of TetX2. TetX2@AuNCs emitted blue light at 450 nm, and their catalytic properties were demonstrated through color changes in a chromogenic substrate (3,3′,5,5′-Tetramethylbenzidine-H2O2), indicating their authenticity. TetX2 is proposed as a new bio-template forthe synthesis of gold nanoclusters, with potential applications in biosensor design (Graphical abstract).

Synthesis of a Gold–Silver Alloy Nanocluster within a Ring‐Shaped Polyoxometalate and Its Photocatalytic Property

AbstractAlloying is an effective method for modulating metal nanoclusters to enrich their structural diversity and physicochemical properties. Recent investigations have demonstrated that polyoxometalates (POMs) can act as effective multidentate ligands for silver (Ag) nanoclusters to endow them with synergistic properties, reactivity, catalytic properties, and stability. However, the application of POMs as ligands has been confined predominantly to monometallic nanoclusters. Herein, we report a synthetic method for fabricating surface‐exposed gold (Au)−Ag alloy nanoclusters within a ring‐shaped POM ([P8W48O184]40−). Reacting an Ag nanocluster stabilized by the ring‐shaped POM with Au ions (Au+) was found to substitute several Ag atoms at the core of the nanocluster with Au atoms. The resultant {Au8Ag26} alloy nanocluster demonstrated superior photocatalytic activity and stability compared to the pristine Ag nanocluster in the aerobic oxidation of α‐terpinene under visible‐light irradiation. These findings provide fundamental insights into the formation and catalytic properties of POM‐stabilized alloy nanoclusters and advance exploration into the synthesis and applications of diverse metal nanoclusters.

Synthesis of a Gold-Silver Alloy Nanocluster within a Ring-Shaped Polyoxometalate and Its Photocatalytic Property.

Alloying is an effective method for modulating metal nanoclusters to enrich their structural diversity and physicochemical properties. Recent investigations have demonstrated that polyoxometalates (POMs) can act as effective multidentate ligands for silver (Ag) nanoclusters to endow them with synergistic properties, reactivity, catalytic properties, and stability. However, the application of POMs as ligands has been confined predominantly to monometallic nanoclusters. Herein, we report a synthetic method for fabricating surface-exposed gold (Au)-Ag alloy nanoclusters within a ring-shaped POM ([P8W48O184]40-). Reacting an Ag nanocluster stabilized by the ring-shaped POM with Au ions (Au+) was found to substitute several Ag atoms at the core of the nanocluster with Au atoms. The resultant {Au8Ag26} alloy nanocluster demonstrated superior photocatalytic activity and stability compared to the pristine Ag nanocluster in the aerobic oxidation of α-terpinene under visible-light irradiation. These findings provide fundamental insights into the formation and catalytic properties of POM-stabilized alloy nanoclusters and advance exploration into the synthesis and applications of diverse metal nanoclusters.

Conversion mechanism of the atomically precise group IB metal nanoclusters by theoretical calculations

The controllable synthesis and design of group IB metal (i.e., Au/Ag/Cu) and their alloy nanoclusters (IB-NCs) rely on an elucidation of the conversion mechanism, bonding preference, and structure–property relationships. In the past decades, the development of cluster-to-cluster transformation and spectroscopic tracking strategy have provided important mechanistic insights that greatly help researchers improve synthetic skills and explore the application of IB-NCs. Specifically, with the aid of DFT calculations, the structural information of cluster-to-cluster conversion, including the intermediates and active sites, can be deduced from the atomic level. In this review, the conversion mechanisms of IB-NCs in the past three years have been reviewed to summarize the key factors influencing structural transformation and reactivity. The three types of cluster-to-cluster conversion (i.e., foreign metal source, foreign ligand, and other reagents/condition-induced conversion) were highlighted for further synthesis and design of functional nanoclusters.

(Invited) Boosting Oxygen Evolution Reaction by Stabilization of Ultrasmall Ruthenium Nanoclusters on Thiol-Functionalized Metal-Organic Framework

Rational designing of efficient nanocatalysts plays a crucial role in catalyzing kinetically sluggish reactions like Oxygen Evolution Reaction (OER). However, the uncontrolled nucleation and growth of nanostructures poses major effectiveness and economic challenges in the implementation and commercialization of noble metal-based electrocatalysts. Functionalized Metal-Organic Frameworks (MOFs) have the properties to stabilize such unstable nanoclusters in extremely small sizes by compensating for their high surface energy and Ostwald’s ripening effect. Here, we have reported the synthesis of ultrasmall Ruthenium nanoclusters stabilized through thiol-functionalized Ni-MOF (Ru@Ni-M-SH). The stabilization of ruthenium under reduced conditions on the MOF surface was facilitated by the lower electronegativity and increased orbital overlapping effect of sulfur, resulting in an average size of 1.5 nm. A perturbed electronic structure confirmed from XPS as well as XAS studies revealed the fundamental understanding behind electronic redistribution. Backed with such a favorable electronic structure, the catalytic OER activity for Ru@Ni-M-SH outperformed the state-of-the-art RuO2 with three times higher current density (242 mA/cm2) and 143 mV reduced overpotential. With 95% Faradaic efficiency, the Turnover Frequency (TOF) and Mass activity of Ru@Ni-M-SH were found to be several orders higher as compared to RuO2. Unlike other Ru-based catalysts, Ru@Ni-M-SH showed extremely high stability with over 24 h of chronoamperometry study. With thorough in-situ analysis providing information regarding catalytically active sites and intermediates, Ru@Ni-M-SH established itself as an economically sustainable OER electrocatalyst.

Synthesis of novel polyethyleneimine-capped silver nanoclusters exhibiting ultraviolet-A fluorescence and their application in multiple sensing.

Cupric ions (Cu2+), pyrophosphate (PPi), and alkaline phosphatase (ALP) are involved in a variety of biochemical processes such as DNA replication, cellular metabolism and play an important role in human growth and development. It is of great significance to establish a method for the sensitive detection of Cu2+, PPi and ALP. In this work, polyethyleneimine-capped silver nanoclusters (PEI-AgNCs) were successfully synthesized by a one-pot method using hydrazine sulfate as reductant, exhibiting a unique strong fluorescence emission in the near-ultraviolet region at ∼339nm. Since the fluorescence of PEI-AgNCs can be quenched by Cu2+ through inner filtering effect (IFE), then recovered by competitive binding of pyrophosphate and Cu2+, and later weakened again by catalytic hydrolysis of alkaline phosphatase, a sensitive and selective strategy based on the changes of fluorescence "ON" or "OFF" was established to detect Cu2+, PPi and ALP. The LODs of these three analyteswere 36nM, 0.2μM, and 0.14 U L-1 at a S/N ratio of 3, respectively. A series of logic gate circuits for sensing cupric ions, pyrophosphate, and alkaline phosphatase were successfully constructed. The established methods have the potential for biosensing and environmental analysis and the specific UV-A fluorescence property of PEI-AgNCs may be helpful in photonic and optical areas.

Interactions of coinage metal nanoclusters with low-molecular-weight biocompounds.

Nowadays, coinage metal nanoclusters (NCs) are largely presented in diagnostics, bioimaging, and biocatalysis due to their high biocompatibility, chemical stability, and sensitivity to surrounding biomolecules. Silver and gold NCs are usually characterized by intense luminescence and photostability, which is in great demand in the detection of organic compounds, ions, pH, temperature, etc. The experimental synthesis of metal NCs often occurs on biopolymer templates, mostly DNA and proteins. However, this review mainly focuses on the interactions with small biomolecules (SBMs) of a molecular weight less than 1000 Da: amino acids, nucleobases, thiolates, oligopeptides, etc. Such molecules can serve as the templates for an eco-friendly facile one-pot synthesis of biocompatible luminescent NCs. The latter aspect makes NCs suitable for diagnostics and intracellular bioimaging. Another important aspect is the interaction of clusters with biomarkers, which is largely exploited by nanosensors: biomarker detection often occurs through either fluorescence emission "turn-on" or "turn-off" mechanisms. Moreover, as theoretical studies show, electronic absorption spectra and Raman spectra of the metal-organic complexes allow efficient detection of various analytes. In this regard, both theoretical and experimental studies of SBM complexes with metal NCs are in great demand. Therefore, this review aims to summarize up-to-date studies on the interaction of small biomolecules with coinage metal NCs from both theoretical and experimental viewpoints.

Photoresponse performance of Au (nanocluster and nanoparticle) TiO2: Photosynthesis, characterization and mechanism studies

In this study, gold (Au), nanoclusters (NC) and heterogeneous titanium dioxide (TiO2) were successfully synthesized by low-temperature photoelectron spectroscopy. The chemical structure of Au-TiO2 was characterized by XRD, EDX, XPS and HR-TEM. Optical properties were evaluated using PL and UV–Vis, and electrical properties were evaluated using CV, CP, UPS and EIS parameters. The results showed that Au nanocluster (NCs) were converted into Au nanoparticles (NPs) during high sunlight, and the transfer mechanism was examined. In addition, the produced nanoparticles can form a Schottky barrier with TiO2, which affects the band structure. Moreover, the simultaneous synthesis of nanoparticles and nanoclusters adds an extra dimension to the understanding of the photoelectronic behavior of structured photoelectrodes. Moreover, this research shows that good control of the photography process can result in more photos. This improvement is related to several factors, including the plasmonic field and coupling line bending.

Design of blue-emitting adenosine monophosphate-copper nanocluster: Detection of Vitamin B2 in real samples

We demonstrate a simple preparation protocol for the synthesis of novel adenosine monophosphate-stabilized copper nanoclusters (AMP-Cu NCs). Synthesis parameters are optimized to reach the best fluorometric signal. The prepared Cu NCs show characteristic blue emission at 430 nm, which is related to the presence of Cu13 metal cores. Three distinct lifetime components are identified and the metallic feature of the NCs is proven by X-ray photoelectron spectroscopy. The stability and the long-term storage of the AMP-Cu NCs were investigated by pH- and time-dependent measurements. Besides the synthesis and characterization, a possible liquid fluorescent assay method is also developed for the detection of the biologically important Vitamin B2 in complex real samples by with 2.01 ± 0.31 μM detection limit. For the real samples, the yeast and dietary supplements were selected, where the detected concentration of Riboflavin was in good agreement with the expected amount in these complex chemical systems.