Search

This mini-review focuses on the recent understanding of the impacts of ligands on the photoluminescence properties of atomically precise silver nanoclusters.

A ligand exchange strategy has been employed to understand the role of ligands on the structural and optical properties of atomically precise 29 atom silver nanoclusters (NCs). By ligand optimization, ∼44-fold quantum yield (QY) enhancement of Ag29(BDT)12-x(DHLA)x NCs (x = 1-6) was achieved, where BDT and DHLA refer to 1,3-benzene-dithiol and dihydrolipoic acid, respectively. High-resolution mass spectrometry was used to monitor ligand exchange, and structures of the different NCs were obtained through density functional theory (DFT). The DFT results from Ag29(BDT)11(DHLA) NCs were further experimentally verified through collisional cross-section (CCS) analysis using ion mobility mass spectrometry (IM MS). An excellent match in predicted CCS values and optical properties with the respective experimental data led to a likely structure of Ag29(DHLA)12 NCs consisting of an icosahedral core with an Ag16S24 shell. Combining the experimental observation with DFT structural analysis of a series of atomically precise NCs, Ag29-yAuy(BDT)12-x(DHLA)x (where y, x = 0,0; 0,1; 0,12 and 1,12; respectively), it was found that while the metal core is responsible for the origin of photoluminescence (PL), ligands play vital roles in determining their resultant PLQY.

During the last few decades, noble metal nanoclusters (NCs) have become an exciting building block in the field of nanoscience. With their ultrasmall size that ranges between 1 and 2 nm, NCs fill the gap between atoms and nanoparticles (NPs), and they show significantly different physicochemical properties compared to their bulk counterparts, such as molecule‐like HOMO‐LUMO discrete electronic transitions, photoluminescence, etc. These properties made NCs potential candidates in various applications, including catalysis, chemical/bioimaging, biomedicine, sensing, and energy conversion. Controlling the size of NPs, which usually exhibit a degree of polydispersity, has been a significant challenge for nano‐scientists. However, metal NCs with atomic precision pave the way to accurately fabricate NPs based on an atom‐by‐atom assembly. This Perspective is directed to the community of nano‐scientists interested in the field of NCs and summarizes the most commonly used synthetic routes of atomically precise metal NCs. Moreover, this Perspective provides an understanding of the different techniques used to control the size of metal NCs with insights on switching the surface ligands from phosphine to thiol. This Perspective also explains the role of physicochemical parameters in different synthetic routes such as high‐temperature route, CO‐directed route, solid‐state route, ligand‐exchange‐induced size/structure transformation (LEIST), etc. We finally give a brief outlook on future challenges of currently used synthetic routes with some suggestions to improve them.

Food-grade titanium dioxide (E171) contains variable percentages of TiO2 nanoparticles (NPs) posing awareness about its potential effects on human and animal health. Despite many studies, the actual relationship between the physicochemical properties of E171 NPs and their interaction with biological targets is still far from clear. We evaluated the acute toxicity of E171 in invertebrate and vertebrate animals. In the nematode C. elegans, E171 up to 1.0 mg/mL did not affect worm’s viability and lifespan but significantly impaired pharyngeal function, reproduction, and development. We also focused our attention on the fate of E171 after its penetration inside the circulatory tree, investigating whether its intravenous administration to mice could result in an acute over-absorption to filter organs. A significant increase of hepatic Ti concentration and the formation of microgranulomas were observed. Interstitial inflammation and parenchymal modification were found in lung coupled with Ti accumulation, probably due to the propensity of TiO2 NPs to agglomerate, as demonstrated by transmission electron microscopy experiments showing that the incubation of E171 with serum promoted the formation of compact clusters. Overall, these data emphasize, once again, the actual risk for human and animal exposure to E171.

The design of ligand‐free platinum nanoclusters (PtNCs) for the field of renewable energy is still challenging. Herein, we reported a fast synthesis of ligand‐free Pt nanoclusters (NCs) by utilizing the outer defect of a representative type of zeolitic imidazolate framework (ZIF). Structural investigation suggests a homogenous distribution of the PtNCs on the outer layer of the ZIF‐8 structure. The as‐prepared PtNCs@ZIF‐8 exhibits high catalytic activity for the hydrogen evolution reaction (HER). The extremely low overpotential with 1.4 mV, high kinetic current (specific and mass activity at 50 mV), and larger exchange current density were achieved in acidic solution, better than those of the commercial 20% Pt/C catalysts under the same condition. Furthermore, the PtNCs can be extracted from the ZIF‐8 structure to both aqueous and non‐aqueous solvent, which could be further used for other systems. These findings allow for a simple route of template‐guided NC synthesis and their release.

There are only a few examples of atomically precise, ligand protected, bimetallic coinage metal clusters in which molecular structure remains essentially unchanged over a wide composition range starting from the corresponding homometallic species. Such model systems are particularly useful to study the dynamics of alloy formation on the nanoscale. Here we demonstrate the unusual reactivity of solvated metalloid-superatom Ag29(BDT)12(PPh3)4 (BDT = 1,3 benzenedithiol) clusters toward semiconducting Cu12S6(DPPPT)4 (DPPPT = bis(diphenylphosphino)pentane) clusters as an efficient way to exchange multiple copper atoms into the atomically precise silver clusters without changing overall the structure type. Concentration-dependent UV-vis absorption and online mass spectrometry shows that 14 Cu atoms can be exchanged into the silver cluster. Beyond the 14 Cu atom exchange, the cluster degrades to smaller thiolates. Information on cluster structures is obtained from high-resolution ion mobility mass spectrometry, which shows a linear decrease in collision cross section (CCS) with each Ag/Cu exchanged. Several isomeric structures are calculated by density functional theory (DFT), and their calculated collision cross sections are used to identify the most stable isomers for each Ag/Cu exchange product. Ag/Cu exchange is essentially limited to the cluster surface/shell. The core appears not to be involved.

16 pags., 7 figs., 1 tab., Goldnanostars are among the most efficient plasmonic nano-materials for optical sensing with surface enhanced Ramans cattering. In recent years,goldnanostars have increased relevance in physics,analytical chemistry, environmental science,biology and medicine,and in particularin sensing and therapy. These colloid scan sustain ultra strong electromagnetic fields which allow their use as single particles optical enhancers;are colloidally stable and may have a marked catalytical activity. Due to their exotic shape,these colloids present characteristic optical and reactive behaviors. Here,we briefly discuss the optical properties, the synthetic routes and the analytical applications of these nanoparticles., This work is supportedby the Ministeriode Ciencia Innovacion/AEI and the European Union Next Generation /PRTR(PID2020-120306RB-I00 and PDC2021-121787-I00),the AGAUR (2017SGR883),the Universitat Rovira i Virgili (2021PFR-URV-B2-02), the Cluster of Excellence’ Advanced Imaging of Matter’of the Deutsche Forschungsgemeinschaft (DFG)– EXC 2056 – project ID390715994and the ENSEMBLE3 project(GA No. MAB/2020/14) Foundation for Polish Science-European Union (GA.No.857543)

Most studies about the interaction of nanoparticles (NPs) with cells have focused on how the physicochemical properties of NPs will influence their uptake by cells. However, much less is known about their potential excretion from cells. However, to control and manipulate the number of NPs in a cell, both cellular uptake and excretion must be studied quantitatively. Monitoring the intracellular and extracellular amount of NPs over time (after residual noninternalized NPs have been removed) enables one to disentangle the influences of cell proliferation and exocytosis, the major pathways for the reduction of NPs per cell. Proliferation depends on the type of cells, while exocytosis depends in addition on properties of the NPs, such as their size. Examples are given herein on the role of these two different processes for different cells and NPs.

The fate of polymer-coated Eu- and Bi-doped GdVO4 nanoparticles (NPs) of cubic shape upon cellular internalization was investigated. After having been endocytosed by cells, the cubic Eu- and Bi-dop...

The development of novel prostate-specific membrane antigen (PSMA)-targeted radioactive theranostic agents is currently limited to facilities capable of working with high-energy radioisotopes. Even preselection of lead structures in vitro relies mostly on radioactive assays with PSMA(+) LNCaP and PSMA(-) PC-3 cells. Assays utilizing radioisotopes are time consuming, costly, and limit discovery to a small group of scientists with special facilities. Nonradioactive alternatives are therefore needed in the field. In this paper, we describe an inductively coupled plasma mass spectrometry (ICP-MS)-based method for the evaluation of PSMA-targeting ligands conjugated to DOTA-chelates of Europium. This method is based on LNCaP and PC-3 cells and has been validated with the well-established targeting ligand PSMA-617.

In solution, nanoparticles may be conceptually compartmentalized into cores and engineered surface coatings. Recent advances allow for simple and accurate characterization of nanoparticle cores and surface shells. After introduction into a complex biological environment, adsorption of biological molecules to the nanoparticle surface as well as a loss of original surface components occur. Thus, colloidal nanoparticles in the context of the biological environment are hybrid materials with complex structure, which may result in different chemical, physical, and biological outcomes as compared to the original engineered nanoparticles. In this review, we will discuss building up an engineered inorganic nanoparticle from its inside core to its outside surface and following its degradation in a biological environment from its outside to its inside. This will involve the way to synthesize selected inorganic nanoparticles. Then, we will discuss the environmental changes upon exposure of these nanoparticles to biological media and their uptake by cells. Next, the intracellular fate of nanoparticles and their degradation will be discussed. Based on these examples, the need to see nanoparticles in the context of the biological environment as dynamic hybrid materials will be highlighted.

Bovine serum albumin (BSA)-protected AgPt bimetallic nanoparticles have been synthesized through a galvanic replacement reaction, using a silver nanoprism as a template. Synthesis was performed without the use of synthetic chemical surfactants, using proteins as a surface coating. Structural and compositional characterizations were performed using several spectroscopic and microscopic techniques. The protein-protected AgPt nanoparticles show effective pH-switchable enzyme mimicking (“nanozyme”) activity similar to catalase and peroxidase. The platinum content in the AgPt nanoparticles is playing an important role in determining the enzymatic catalysis rate of the nanoparticles. Because of their porous structure, molecular payloads such as calcein also can be incorporated into the AgPt nanoparticles, which can be released on demand by chemical triggers, such as hydrogen peroxide.

Nanoparticle (NP)-based cell imaging offers good potential for future diagnosis tools in medicine. Gold and iron oxide NPs can be used as contrast agents for imaging by computed tomography (CT) and magnetic resonance imaging (MRI), respectively. Thus, also cells which have been labeled with these NPs may be tracked. This may be important for in vivo tracking of administered or transplanted cells. In this work, we optimized the conditions to label stem cells and macrophages with a library of gold and iron oxide NPs of different sizes (5–100 nm core diameter) and shapes. We investigated the amount of NPs which can be delivered to different cells, as well as their related toxic effects, in relation to the physicochemical properties of the NPs. Our study revealed that in general, when cells are exposed to NPs at similar elemental concentration (e.g., Au or Fe), bigger NPs lead to higher internalized elemental amounts as compared to exposure with smaller sized NPs. While the exposure concentrations are limited concerning the onset of toxicity, bigger NPs lead to better labeling than small NPs, resulting in improved contrast for imaging with enhanced biocompatibility.

Anisotropic popcorn-shaped gold nanoparticles (GNPCs) were synthesized through a sustainable route. Proteins were used as ligands, and among several proteins, bovine serum albumin (BSA) produced hi...

A ligand exchange strategy has been employed to understand the role of ligands on the structural and optical properties of atomically precise 29 atom silver nanoclusters (NCs). By ligand optimization, ∼44-fold quantum yield (QY) enhancement of Ag

Optical spectroscopic measurements are conducted on luminescent silver nanocluster (AgNC) decorated ZnO tetrapods (ZnO Tp), AgNC@ZnO Tp, synthesized via a colloidal route. Their properties are compared with those of the corresponding AgNC and ZnO Tp to understand their impact on the photoluminescence (PL). Raman spectroscopy reveals the high structural integrity of the ZnO structure in the AgNC@ZnO Tp. PL analysis of the ZnO Tp shows a well-resolved near band edge emission and a green band comprised by the overlapping of at least three emitting optical centres. The addition of AgNC to ZnO Tp in the hybrid material enhances the emission from ZnO surface states. The recombination of the AgNC in water solution is dominated by a red emission band peaking at ∼1.9 eV and the PL excitation spectra monitored at the band maximum reveal that the red PL of AgNC is preferentially populated by well-defined excitation bands corresponding to discrete electronic transitions of the NCs. Yet, a shift to lower energies of the AgNC emission occurs in the AgNC@ZnO Tp hybrid when excited with energies below the ZnO bandgap, while for energies above this value no emission from the AgNC was observed, with the ZnO-related recombination dominating the spectra. A gradual loss in the PL intensity of the AgNC is observed in the hybrid with increasing time, which is consistent with their coalescence to transform into larger Ag nanoparticles (NPs) on the tetrapod surface, as revealed by confocal microscopy. published

11-Mercaptoundecanoic acid-protected gold nanoclusters (Au@MUA NCs) were synthesized and investigated as a model to understand the photoluminescence (PL) properties of water-soluble, structurally u...

Advanced materials 33(31), 2101549 (2021). doi:10.1002/adma.202101549, Published by Wiley-VCH, Weinheim

Protein corona formation on the surface of nanoparticles (NPs) is observed in situ by measuring diffusion coefficients of the NPs under the presence of proteins with a F-19 nuclear magnetic resonance (NMR) based methodology. Formation of a protein corona reduces the diffusion coefficient of the NPs, based on an increase in their effective hydrodynamic radii. With this methodology it is demonstrated that the apparent dissociation constant of protein-NP complexes may vary over at least nine orders of magnitude for different types of proteins, in line with the Vroman effect. Using this methodology, the interaction between one type of protein and one type of nanoparticle can be studied quantitatively. Due to the NMR-based detection, this methodology has no interference by absorption/scattering effects, by which optical detection schemes are affected. By using the potential of the NMR chemical shift, the detection of multiple F-19 signals simultaneously opens the possibility to study the diffusion of several NPs at the same time. The F-19 labeling of the NPs has negligible effect on their acute toxicity and moderate effect on NPs uptake by cells. This work was supported by the Cluster of Excellence "Advanced Imaging of Matter" of the Deutsche Forschungsgemeinschaft (DFG) EXC 2056 - project ID 390715994, by the Basque Government (project IT1196-19) and by the Fundacion Biofisica Bizkaia and the Basque Excellence Research Centre (BERC) program of the Basque Government. This work was performed under the Maria de Maeztu Units of Excellence Programme-Grant No. MDM-2017-0720 Ministry of Science, Innovation and Universities. The help of Marta Gallego in the surface tension and TEM measurements is acknowledged. Parts of the ICP-MS measurements were done at the ICP-MS facility of CIC biomaGUNE by Javier Calvo.

Laser fragmentation in liquids (LFL) allows the synthesis of fully inorganic, ultrasmall gold nanoparticles, usAu NPs (

A laboratory class was developed and evaluated to illustrate the synthesis of metal nanoclusters (NCs) and to explain their photoluminescence properties for the case of silver. The described experi...

Colloidal nano- and micro-particles can introduce new properties and functionalities to existing materials and thus are a valuable building block for the construction of novel materials. This is discussed for the case of ion-selective ligands, hence molecules that can bind specifically ions of one type. First, in case ion-selective fluorescent ligands are attached to the surface of particles, these fluorophores sense the local ion concentration at the particle surface and not the bulk ion concentration. Thus, the ion-response of the ligands can be tuned by attaching them to the surface of particles. Second, in case ligands specific for particular ions are bound to the surface of particles, these ions can provide contrast and thus the particles can be imaged. This involves for example Gd-ions, which provide contrast for magnetic resonance imaging (MRI), and 111In-ions, which provide contrast for imaging of radioactivity. By attaching the ligands to the surface of particles, their physicochemical properties (as for example size and solubility) are changed, which affects their interaction with cells and, consequently, biodistribution. Attachment of ion-chelators for imaging to particles thus allows for tuning their biodistribution. Third, ion-specific ligands can be also attached to the surface of magnetic particles. In this case ions bound to the ligands can be extracted with magnetic field gradients and magnetic separation becomes possible. Therefore, magnetic particles provide a handle to the ligands, which enables the extraction of ions from solution. These examples demonstrate how the attachment of different types of colloidal particles to one existing class of molecules, ion-selective ligands, can open new fields of applications of these molecules.

Silver nanoparticles were grown in aqueous solution, without the presence of typical surfactant molecules, but under the presence of different proteins. The shape of the resulting silver nanoparticles could be tuned by the selection of the types of proteins. The amount of accessible lysine groups was found to be mainly responsible for the anisotropy in nanoparticle formation. Viability measurements of cells exposed to protein capped spherical or prism-shaped NPs did not reveal differences between both geometries. Thus, in the case of protein-only coated Ag NPs, no shape-induced toxicity was found under the investigated exposure conditions.

Nanoparticles rival pharmaceuticals in synthetic inefficiency, in particular as measured by process mass intensity, with by far the largest contribution to waste being from solvents. We have therefore developed a greener method of synthesizing silver nanoparticles using a paste format instead of a metal salt solution. The paste-based synthesis requires 87% less solvent yet still produces exclusively Na4Ag44(p-MBA)30 nanoparticles, without size sorting, with 89% yield. By using a stoichiometric silver-thiolate polymer as a precursor to intimately mix the metal atoms and ligands, and by using a small amount of liquid to form a paste to promote mass transport, the heterogeneity and kinetics problems that are associated with entirely solid-state syntheses were avoided. Because the nanoparticle product was also a paste, solvent use for postprocessing was minimized. Use of the silver-thiolate polymer can also reduce health risks associated with hazardous free thiols in conventional solution-phase syntheses. Usi...

Atomically precise gold and silver clusters are a new class of sensitizers which can be used as substitutes for dyes in the classical dye-sensitized solar cells (DSCs). Here noble metal clusters protected by proteins and thiols (Au30@BSA, Au25SBB18, and Ag44MBA30) have been used for photovoltaic studies. These metal clusters were used as sensitizers for the photoanodes fabricated using TiO2 nanotubes (NTs) and the commercial P25 TiO2 nanoparticles. The TiO2, clusters and the solar cells were characterized by spectroscopy, microscopy, current-voltage (I-V) and incident photon-to-current conversion efficiency (IPCE) measurements. A systematic I-V study revealed a conversion efficiency of 0.35 % for the Au30@BSA sensitized solar cell made from TiO2 NTs which showed an IPCE maximum of 3 % at ∼ 400 nm.

The design of nanoparticles is critical for their efficient use in many applications ranging from biomedicine to sensing and energy. While shape and size are responsible for the properties of the inorganic nanoparticle core, the choice of ligands is of utmost importance for the colloidal stability and function of the nanoparticles. Moreover, the selection of ligands employed in nanoparticle synthesis can determine their final size and shape. Ligands added after nanoparticle synthesis infer both new properties as well as provide enhanced colloidal stability. In this article, we provide a comprehensive review on the role of the ligands with respect to the nanoparticle morphology, stability, and function. We analyze the interaction of nanoparticle surface and ligands with different chemical groups, the types of bonding, the final dispersibility of ligand-coated nanoparticles in complex media, their reactivity, and their performance in biomedicine, photodetectors, photovoltaic devices, light-emitting devices, sensors, memory devices, thermoelectric applications, and catalysis.

Inorganic iron oxide nanoparticle cores as model systems for inorganic nanoparticles were coated with shells of amphiphilic polymers, to which organic fluorophores were linked with different conjugation chemistries, including 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) chemistry and two types of &ldquo, click chemistry&rdquo, The nanoparticle-dye conjugates were exposed to different enzymes/enzyme mixtures in order to investigate potential enzymatic degradation of the fluorophore-modified polymer shell. The release of the dyes and polymer fragments upon enzymatic digestion was quantified by using fluorescence spectroscopy. The data indicate that enzymatic cleavage of the fluorophore-modified organic surface coating around the inorganic nanoparticles in fact depends on the used conjugation chemistry, together with the types of enzymes to which the nanoparticle-dye conjugates are exposed.

Ultrasmall semiconductor clusters are exciting materials because of their molecularly precise structures and their unique optical spectra. “Magic-sized” CdSe clusters are transformed into their Cu2Se counterparts by means of ion exchange. We leverage the molecularly precise structure and high sensitivity of these clusters to investigate the mechanism of cation exchange. We optically identify a metastable intermediate in the solid-state transformation. Isolation and characterization of this intermediate provide insight into the dynamic structural rearrangement of the cationic sublattice in the course of cation exchange and the role of ligand passivation. Such understanding of the dynamics of ion exchange at the solid–liquid interface could help engineer improved materials for solid-state electrolytes and energy storage devices.

Highly organized crossed bilayer assemblies of nanowires (NWs) are made using directed hydrogen bonding between the protecting ligand shells of atomically precise cluster molecules anchored on NWs. Layers of quantum clusters remain sandwiched between two neighboring NWs at a defined distance, dictated by the core-size of the cluster, while the orientation of the ligands in space dictates the interlayer geometry.

A highly luminescent (quantum yield 21%) mixed chalcogenide silver cluster, Ag56Se13S15 cluster of Ag2X stoichiometry, protected with a 4-tert-butylbenzyl mercaptan ligand has been synthesized and characterized. Investigation using diverse tools of analysis such as mass spectrometry, elemental analysis, thermogravimetry and X-ray diffraction confirmed this composition. The cluster emits in solution and in the solid state and has been deposited on oxide supports to get red emitting films. The specificity of cluster emission to the mercuric ion Hg(II), among a range of heavy metal ions, was used to develop a sensor, which shows sensitivity down to 1 ppb. A pH paper like visual detector was developed by combining the Hg(II)-sensitive emission of the cluster and the insensitive emission of fluorescein isothiocyanate. The test strip showed visual detection down to 1 ppb in real water samples.

The first atomically precise and monolayer protected iridium cluster in solution, Ir9(PET)6 (PET – 2-phenyethanethiol) was synthesized via a solid state method. The absence of a plasmonic band at ∼350 nm, expected in the UV/Vis spectra for spherical Ir particles of 10 nm size indicated that the synthesized cluster is smaller than this dimension. Small angle X-ray scattering (SAXS) showed that the cluster has a particle size of ∼2 nm in solution which was confirmed by transmission electron microscopy (TEM). The blue emission of the cluster is much weaker than many noble metal clusters investigated so far. X-ray photoelectron spectroscopy (XPS) measurements showed that all Ir atoms of the cluster are close to the zero oxidation state. The characteristic S–H vibrational peak of PET at 2560 cm−1 was absent in the FT-IR spectrum of the cluster indicating RS–Ir bond formation. The molecular formula of the cluster, Ir9(PET)6 was assigned based on the most significant peak at m/z 2553 in the matrix assisted laser desorption ionization mass spectrum (MALDI MS), measured at the threshold laser intensity. Density functional theory calculations on small Ir@SCH3 and Ir@PET clusters and comparison of the predictions with the IR and 1H-NMR spectra of Ir9(PET)6 suggested that the PET ligands have two distinct structural arrangements and are likely to be present as bridging thiolates –(Ir–SR–Ir)– and singly attached thiolates –(Ir–SR).

Luminescent molecules attached to resonant colloidal particles are an important tool to study light-matter interaction. A traditional approach to enhance the photoluminescence intensity of the luminescent molecules in such conjugates is to incorporate spacer-coated plasmonic nanoantennas, where the spacer prevents intense non-radiative decay of the luminescent molecules. Here, we explore the capabilities of an alternative platform for photoluminescence enhancement, which is based on low-loss Mie-resonant colloidal silicon particles. We demonstrate that resonant silicon particles of spherical shape are more efficient for photoluminescence enhancement than their plasmonic counterparts in spacer-free configuration. Our theoretical calculations show that significant enhancement originates from larger quantum yields supported by silicon particles and their resonant features. Our results prove the potential of high-index dielectric particles for spacer-free enhancement of photoluminescence, which potentially could be a future platform for bioimaging and nanolasers

This paper describes an unusual chemical reaction that takes place on a graphene composite in a concerted fashion. The reaction shows the conversion of a persistent organochlorine pesticide, lindane (C6H6Cl6), present in water, to different isomers of trichlorobenzenes (TCBs, C6H3Cl3) on the surface of reduced graphene oxide-silver composites (RGO@Ag). The reaction is unique to the composite and does not occur on RGO and nanoparticles of Ag separately. The products of the reaction were isolated and extensively characterized using analytical techniques such as gas chromatography-mass spectrometry, electrospray ionization mass spectrometry, infrared and NMR, which unequivocally confirmed their identity. The as-formed TCBs were removed from the aqueous medium by adsorption on the same composite. Adsorption of lindane is physical in nature, but that of TCBs is through - interactions. The study reveals the unusual chemical reactivity of graphene-metal composites and their potential for water treatment. The uniqueness of the reaction on RGO@Ag is due to the simultaneous removal of three HCl molecules, leading to the formation of aromatic compounds and concomitant formation of silver chloride. Recycling capacity and effect of diverse species present in natural waters were tested for potential applications in sustainable water treatment. � 2015 American Chemical Society.

Synthesis, characterization, and applications of colloidal nanoparticles have been a prominent topic of current research interests within the last two decades. Available reports in the literature that describe the synthesis of colloidal nanoparticles are abundant with various degrees of reproducibility and simplicity. Moreover, different methods for the characterization of colloidal nanoparticle's basic properties are employed, resulting in conflicting results in many cases. Herein, we describe >in detail> selected standard protocols for the synthesis, purification, and characterization of various types of colloidal inorganic nanoparticles including gold nanoparticles, silver nanoparticles, iron oxide nanoparticles, and quantum dots. This report consists of five main parts: The first and the second parts are dedicated to describing the synthesis of various types of hydrophobic and hydrophilic nanoparticles in organic solvents and in aqueous solutions, respectively. The third part describes surface modification of nanoparticles with a focus on ligand exchange reactions, to allow phase transfer of nanoparticles from aqueous to organic solvents and vice versa. The fourth and the fifth parts describe various general purification and characterization techniques used to purify and characterize nanoparticles, respectively. Collectively, this contribution does not aim to cover all available protocols in the literature to prepare inorganic nanoparticles but rather provides detailed synthetic procedures for important inorganic nanocrystals with a full description of their purification and characterization process., This work was supported by the German Research Foundation (DFG Grant PA 794/25-1) and by the European Commission (Project FutureNanoNeeds). C.C.-C. acknowledges the Spanish Ministerio de Economía y Competitividad for a Juan de la Cierva—Incorporación contract. A.E. acknowledges Junta de Andalucı́a (Spain) for a Talentia Postdoc Fellowship, cofinanced by the European Union Seventh Framework Programme, Grant Agreement No. 267226. M.C. acknowledges Ikerbasque for a Research Fellow position. N.F. acknowledges support funding from the Swedish Governmental Agency for Innovation Systems (Vinnova). I.C. acknowledges the Alexander Von Humboldt Foundation for postdoctoral fellowship. M.G.S. acknowledges funding from Fazit Stiftung. L.Z. acknowledges funding from Chinese Scholarship Council (CSC).

A selenolate-protected Ag-Pd alloy cluster was synthesized using a one-pot solution-phase route. The crude product upon chromatographic analyses under optimized conditions gave three distinct clusters with unique optical features. One of these exhibits a molecular peak centered at m/z 2839, in its negative ion mass spectrum assigned to Ag5Pd4(SePh)12 -, having an exact match with the corresponding calculated spectrum. Tandem mass spectrometry of the molecular ion peak up to MS9 was performed. Complex isotope distributions in each of the mass peaks confirmed the alloy composition. We find the Ag3Pd3 - core to be highly stable. The composition was further supported by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. (Graph Presented). � 2014 American Chemical Society.