Tailoring the Morphology and Fractal Dimension of 2D Mesh‐like Gold Gels

As there is a great demand of 2D metal networks, especially out of gold for a plethora of applications we show a universal synthetic method via phase boundary gelation which allows the fabrication of networks displaying areas of up to 2 cm². They are transferred to many different substrates: glass, glassy carbon, silicon, or polymers such as PDMS. In addition to the standardly used web thickness, the networks are parametrized by their fractal dimension. By variation of experimental conditions, we produced web thicknesses between 4.1 nm and 14.7 nm and fractal dimensions in the span of 1.56 to 1.76 which allows to tailor the structures to fit for various applications. Furthermore, the morphology can be tailored by stacking sheets of the networks. For each different metal network, we determined its optical transmission and sheet resistance. The obtained values of up to 97 % transparency and sheet resistances as low as 55.9 Ω/sq highlight the great potential of the obtained materials.     

Metal–Organic Coordination Strategy for Obtaining Metal-Decorated Mo-Based Complexes: Multi-dimensional Structural Evolution and High-Rate Lithium-Ion Battery Applications

Multi-dimensional metal oxides have attracted great attention in diverse applications due to their intriguing performances. However, their structural design remains challenging, particularly that based on organic chelation chemistry. Although metal–organic complexes with different architectures have been reported, their structure formation mechanisms are not well understood because of the complex chelation processes. Herein, we introduce a new metal–organic coordination strategy to construct metal-decorated (Ni, Co, Mn) Mo-based complexes ranging from 2D nanopetals to 3D microflowers. The chelating process of the metal–organic complex can be tuned by a surfactant, giving rise to different structures, and then a further metal can be appended. Thus, different metal (oxide)-decorated MoO₂/C-N structures were designed, enabling an extremely high lithium storage capability of 1018 mA h g⁻¹ and rate capacities of up to 10 A g⁻¹ over 1000 cycles. Relationships between electrochemical behavior and structure have been analyzed kinetically. A high-rate lithium-ion battery has been assembled from Ni-MoO₂/C-N and an Ni-rich layered oxide as the anode and cathode, respectively. We believe that this general metal–organic coordination strategy should be applicable to other multi-functional materials with superior capabilities.     

Two-Dimensional TeB Structures with Anisotropic Carrier Mobility and Tunable Bandgap

Two-dimensional (2D) semiconductors with desirable bandgaps and high carrier mobility have great potential in electronic and optoelectronic applications. In this work, we proposed α-TeB and β-TeB monolayers using density functional theory (DFT) combined with the particle swarm-intelligent global structure search method. The high dynamical and thermal stabilities of two TeB structures indicate high feasibility for experimental synthesis. The electronic structure calculations show that the two structures are indirect bandgap semiconductors with bandgaps of 2.3 and 2.1 eV, respectively. The hole mobility of the β-TeB sheet is up to 6.90 × 10² cm² V⁻¹ s⁻¹. By reconstructing the two structures, we identified two new horizontal and lateral heterostructures, and the lateral heterostructure presents a direct band gap, indicating more probable applications could be further explored for TeB sheets.     

Ruthenium(II) Photosensitizers of Tridentate Click‐Derived Cyclometalating Ligands: A Joint Experimental and Computational Study

A systematic series of heteroleptic bis(tridentate)ruthenium(II) complexes of click‐derived 1,3‐bis(1,2,3‐triazol‐4‐yl)benzene N^C^N‐coordinating ligands was synthesized, analyzed by single crystal X‐ray diffraction, investigated photophysically and electrochemically, and studied by computational methods. The presented comprehensive characterization allows a more detailed understanding of the radiationless deactivation mechanisms. Furthermore, we provide a fully optimized synthesis and systematic variations towards redox‐matched, broadly and intensely absorbing, cyclometalated ruthenium(II) complexes. Most of them show a weak room‐temperature emission and a prolonged excited‐state lifetime. They display a broad absorption up to 700 nm and high molar extinction coefficients up to 20 000 M ^?1 cm^?1 of the metal‐to‐ligand charge transfer bands, resulting in a black color. Thus, the complexes reveal great potential for dye‐sensitized solar‐cell applications.     

T4 virus-based toolkit for the direct synthesis and 3D organization of metal quantum particles

One of the challenges in building superstructures based on small metal particles is producing stable interparticle separation. Herein, we present a novel assembly method based on the use of the T4 bacteriophage capsid as a scaffold for the construction of 3D monodisperse metal–particle arrays. The highly regular and symmetrical protein surface of the T4 capsid allows the site‐directed adsorption and subsequent reduction of metal ions, thus permitting the growth of metal particles in situ to enable them to exist at a quantum size with a high degree of monodispersity. Both these characteristics contribute to a great improvement in the electrocatalytic activity of the patterned noble‐metal particles. Organized magnetic particles as small as 2–4 nm still maintain an observable ferromagnetic behavior, which makes them promising for a variety of possible biomedical applications.     

|(C6N4H21)2|[Ge7O14F6]: A New Germanate Compound Constructed from Alternately Stacked Pseudo Triple‐Sheet Layers

A novel layered germanate compound, |(C₆N₄H₂₁)₂|[Ge₇O₁₄F₆] (JU‐86, JU = Jilin University), was solvothermally synthesized. Its structure consists of 4.6‐net sheets built up from dissymmetric 8³ building units. Different from those found in several metal phosphate compounds, half of the 4.6‐net sheets in JU‐86 are constructed from right‐handed 8³ building units and the other half are constructed from left‐handed ones. Right‐handed and left‐handed 4.6‐net sheets are stacked alternately in JU‐86. Each 4.6‐net sheet is sandwiched by two layers of protonated tris(2‐aminoethyl)amine (tren) molecules to form an unusual pseudo triple‐sheet layer through hydrogen‐bonding interactions. No hydrogen bonds are found between different pseudo triple‐sheet layers.     

Amphiphilic block copolymers directed synthesis of mesoporous nickel-based oxides with bimodal mesopores and nanocrystal-assembled walls

Mesoporous late-transition metal oxides have great potential in applications of energy,catalysis and chemical sensing due to their unique physical and chemical properties.However,their synthesis via the flexible and scalable soft-template method remain a great challenge,due to the weak organic-inorganic interaction between the frequently used surfactants(e.g.,Pluronic-type block copolymers) and metal oxide precursors,and the low crystallization temperature of metal oxides.In this study,ordered mesoporous NiO with dual mesopores,high surface area and well-interconnected crystalline porous frameworks have been successfully synthesized via the facile solvent evaporation-induced co-assembly(EICA) method,by using lab-made amphiphilic diblock copolymer polystyrene-b-poly(4-vinylpyridine)(PS-b-P4 VP) as both the structure-directing agent(the soft template) and macromolecular chelating agents for nickel species,THF as the solvent,and nickel acetylacetonate(Ni(acac)2) as inorganic precursor.Similarly,by using Ni(acac)2 and Fe(acac)3 as the binary precursors,ordered mesoporous Fedoped NiO materials can be obtained,which have bimodal mesopores of large mesopores(32.5 nm) and secondary mesopores(4.0-11.5 nm) in the nanocrystal-assembled walls,high specific surface areas(～74.8 m~2/g) and large pore value(～0.167 cm~3/g).The obtained mesoporous Fe-doped NiO based gas sensor showed superior ethanol sensing performances with good sensitivity,high selectivity and fast response-recovery dynamics.     

Supramolecular adducts of mesocyclic diamines with various carboxylic acids: Charge-assisted hydrogen-bonding in molecular recognition

Aggregation of saturated mesocyclic diamine 1,4-diazacycloheptane (dach) or piperazine (pipz) and diversiform carboxylic acids with mono- or di-carboxyls yields a series of novel binary supramolecular adducts via two-point molecular recognition. All the supramolecular assemblies were obtained by solvent evaporation method from different media. X-ray single-crystal diffraction analyses reveal that these supramolecular moieties present 1D chain motif, 2D flat, corrugated sheet structures and 3D CdSO₄, pillar-layered networks through carboxylate-amide N–H⋯O, as well as its proton transfer form N⁺–H⋯O⁻, carboxyl head to tail O–H⋯O, and extended hydrogen-bonding interactions. Their compositions and structures were also confirmed by Fourier transform infrared (FT-IR) spectroscopy. Thermal stability of these binary crystalline adducts has been investigated by thermogravimetric analysis (TGA), suggesting similar thermal stabilities.     

The magnetic polaron modulated luminescence bands of organic-inorganic hybrid ferroelectric anti-perovskite (C3H9N)3Cd2Cl7 doped with Mn2+

Recently, the excellent optical properties of organic-inorganic hybrid metal halides have attracted much attention in the optoelectronic field. However, their complicated preparation processes seriously influence their properties and applications. In this work, we developed a series of organic-inorganic hybrid metal halides (C₃H₉N)₃Cd₂Cl₇:x%Mn²⁺ with an antiperovskite structure with ferroelectrics in an early report, giving tunable emissions contemporarily with different manganese (Mn)²⁺ concentrations via a simple mechanochemical method. Meanwhile, their single crystals were also grown by a slow thermal evaporation method. The as-grown products with Mn dopants exhibited diluted magnetic semiconductor behavior and varied emission profiles by different excitation wavelengths, which could be modified by the heat treatment. All the emission bands come from the different magnetic polarons with enhanced electron-phonon coupling or self-trapped exciton formation. Ferromagnetic coupling Mn–Mn pairs or clusters in the doped lattice favor the magnetic polaron and red emission at room temperature and even give much stronger emission above room temperature. The excitonic magnetic polaron and local excitonic magnetic polaron were detected at about 309 nm and 398 nm, respectively, with Mn doping. Without Mn²⁺ dopant, the weak emission band at about 398 nm can also be detected from an intrinsically bound exciton or confined exciton from the amine incorporated metal chlorides. This Mn-doped anti-perovskite Cd halides may find applications in the solid display and lighting, as well as the magneto-optical devices.     

Enhancement of Nonlinear Optical Scattering by Gold Nanoparticles through Aggregation-Induced Plasmon Coupling in the Near-Infrared

Gold nanoparticles (AuNPs) are regarded as promising building blocks in functional nanomaterials for sensing, drug delivery and catalysis. One remarkable property of these particles is the localized surface plasmon resonance (LSPR), which gives rise to augmented optical properties through local field enhancement. LSPR also influences the nonlinear optical properties of metal NPs (MNPs) making them potentially interesting candidates for fast, high resolution nonlinear optical imaging. In this work we characterize and discuss the wavelength dependence of the hyper-Rayleigh scattering (HRS) behavior of spherical gold nanoparticles (GNP) and gold nanorods (GNR) in solution, from 850 nm up to 1300 nm, covering the near-infrared (NIR) window relevant for deep tissue imaging. The high-resolution spectral data allows discriminating between HRS and two photon photoluminescence contributions. Upon particle aggregation, we measured very large enhancements (ca. 10⁴) of the HRS intensity in the NIR, which is explained by considering aggregation-induced plasmon coupling effects and local field enhancement. These results indicate that purposely designed coupled nanostructures could prove advantageous for nonlinear optical imaging and biosensing applications.     

Self-assembly of core-satellite gold nanoparticles for colorimetric detection of copper ions

Molecule-coated nanoparticles are hybrid materials which can be engineered with novel properties. The molecular coating of metal nanoparticles can provide chemical functionality, enabling assembly of the nanoparticles that are important for applications, such as biosensing devices. Herein, we report a new self-assembly of core-satellite gold nanoparticles linked by a simple amino acid l-Cysteine for biosensing of Cu²⁺. The plasmonic properties of core-satellite nano-assemblies were investigated, a new red shifted absorbance peak from about 600 to 800 nm was found, with specific wavelength depending on ratios with assembly of large and small gold nanoparticles. The spectral features obtained using surface-enhanced Raman spectroscopy (SERS) provided strong evidence for the assembly of the Cu²⁺ ions to the L-Cysteine molecules leading to the successful formation of the core-satellite Cu(l-Cysteine) complex on the gold surfaces. In addition, a linear relationship between the concentration of mediating Cu²⁺ and absorbance of self-assembled gold nanoparticles (GNPs) at 680 nm was obtained. These results strongly address the potential strategy for applying the functionalized GNPs as novel biosensing tools in trace detections of certain metal ions.     

Structuring Metal–Organic Framework Materials into Hierarchically Porous Composites through One-Pot Fabrication Strategy

Controlled synthesis of metal–organic framework (MOF)-based materials with multiple levels of porous structures across different length scales is of great interest in various applications but it still remains challenging. Most of the current strategies are time consuming and labor intensive, and not readily scaled-up. In this work, we introduce a straightforward one-pot fabrication strategy to prepare a robust and flexible hierarchically macro-meso-micro porous HKUST-1/polyvinylidene fluoride (PVDF) composite through solvent evaporation, in which MOF crystallization and polymer precipitation are combined together. The effect of the MOF precursor and the polymer initial amount on the morphology of the final composite was thoroughly studied. The interaction between the MOF and the polymer during the evaporation process is the key factor, which would limit the mobility of the polymer chains and cause instability in the MOF growth, thus endowing the composite with a hierarchically macro-meso-micro porous structure. This “all-in-one” porous structure could enhance the mass transport property of molecules within the composite. The obtained HKUST-1/PVDF composite showed an enhanced CO₂ adsorption rate constant of 0.821 min⁻¹ (298 K, 1 bar), which was 3.5 times higher than that of the pristine MOF. In addition, the composite showed an equivalent gas adsorption capacity under all tested pressures and greatly improved water stability.     

Simultaneous determination of Co, Ni, Cu and Zn ions in foodstuffs and vegetables with a new Schiff base using artificial neural networks

New complexes of Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ with a recently synthesized Schiff base derived from 3,6-bis((aminoethyl)thio)pyridazine were applied for their simultaneous determination with artificial neural networks. The analytical data show the ratio of metal to ligand in all metal complexes is 1:1. The absorption spectra were evaluated with respect to Schiff base concentration, pH and time of the color formation reactions. It was found that at pH 10.0 and 60 min after mixing, the complexation reactions are completed and the colored complexes exhibited absorption bands in the wavelength range 300-500 nm. Spectral data was reduced using principal component analysis and subjected to artificial neural networks. The data obtained from synthetic mixtures of four metal ions were processed by principal component-feed forward neural networks (PCFFNNs) and principal component-radial basis function networks (PCRBFNs). Performances of the proposed methods were tested with regard to root mean square errors of prediction (RMSEP%), using synthetic solutions. Under the working conditions, the proposed methods were successfully applied to simultaneous determination of Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ in different vegetable, foodstuff and pharmaceutical product samples.     

First successful design of semi-IPN hydrogel-silver nanocomposites: a facile approach for antibacterial application

Semi-IPN hydrogels in which poly(vinyl pyrrolidone) (PVP) chains were physically dispersed throughout poly(acrylamide) (PAM) gel networks were synthesized. These semi-IPN hydrogel networks can act as excellent nanoreactors for producing and stabilizing metal nanoparticles. The current methodology allows us to entrap metal nanoparticles throughout hydrogel networks via PVP chains. An optimized semi-IPN hydrogel formulation was found to produce silver nanoparticles, ca. 3-5 nm. The synthesized semi-IPN hydrogel-silver nanocomposites were fully characterized by using UV-vis, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The developed semi-IPN hydrogel-silver nanocomposite (SHSNC) was evaluated for preliminary antibacterial applications.     

Optical detection of Cu ion using a SQ-dye containing polymeric thin-film on Au surface

In this study, we have fabricated Cu²⁺ ion sensor using a squarylium dye (SQ-dye) containing polymeric thin-film. Surface Plasmon Resonance (SPR) was used as a signal amplifier to achieve high sensitivity and large linear dynamic range for detection of Cu²⁺ ion. High selectivity to Cu²⁺ ion was obtained by the effective electro-static interaction between SQ-dye and Cu²⁺ ion in the polymeric film. The optimal analytical condition of high selectivity and sensitivity in the wider linear dynamic range obtained in this study may be a result of the cooperative ‘hard-soft’ metal ion-ligand interaction and effective detection of refractive index changes by the complexation of Cu²⁺ ion and SQ-dye in SPR measurement. Among 10 different alkali metal, alkaline earth metal, and transition metal ions, SQ-dye in poly(vinylchloride)–poly(vinyl acetate)–poly(vinyl alcohol) (PVC–PVAc–PVA) copolymer film showed the highest selectivity to Cu²⁺ ion. Although the interaction between SQ-dye and metal ions has not been well understood, both cooperative ‘hard-soft’ metal ion-ligand interaction and size-selective recognition of Cu²⁺ ion to SQ-dye may contribute to high selectivity. Furthermore, additional sensitivity in the detection of Cu²⁺ ion by SPR was obtained by matching the wavelength of probing radiation of SPR and absorption maximum of SQ-dye at 675 nm, which allow to detect small changes in the refractive index by complex formation on the sensing surface. This result may apply in development of the Cu²⁺ ion selective sensor for medical, biochemical, and environmental applications.     

Low reflectivity and high flexibility of tin-doped indium oxide nanofiber transparent electrodes

Tin-doped indium oxide (ITO) has found widespread use in solar cells, displays, and touch screens as a transparent electrode; however, two major problems with ITO remain: high reflectivity (up to 10%) and insufficient flexibility. Together, these problems severely limit the applications of ITO films for future optoelectronic devices. In this communication, we report the fabrication of ITO nanofiber network transparent electrodes. The nanofiber networks show optical reflectivity as low as 5% and high flexibility; the nanofiber networks can be bent to a radius of 2 mm with negligible changes in the sheet resistance.     

Assembly of π‐Conjugated Phosphole Azahelicene Derivatives into Chiral Coordination Complexes: An Experimental and Theoretical Study

Aza[n]helicene phosphole derivatives have been prepared from aza[n]helicene diynes by the Fagan–Nugent route. Their photophysical properties (UV/Vis absorption and emission behavior) have been evaluated. Their behavior as P,N chelates towards coordination to Pd^II and Cu^I has been investigated: metal–bis(aza[n]helicene phosphole) assemblies are formed by a highly stereoselective coordination process, as demonstrated by X‐ray crystallography. An aza[6]helicene phosphole bearing an enantiopure helicene part has been obtained, which allows the preparation of enantiopure Pd^II and Cu^I complexes with original topologies and high molar rotation (MR) and circular dichroism (CD). The structure–property relationship established from the experimental data has been studied in detail by theoretical studies (TDDFT calculations of UV/Vis, CD, and MR). Aza[n]helicene phosphole derivatives show π conjugation extended over the entire molecule, and its influence on the MR of aza[6]helicene phosphole 5 c has been demonstrated. Finally, it has been shown that the nature of the metal (coordination geometry and electronic interaction) can have a great impact on the amplitude of the chiroptical properties in metal–bis(aza[n]helicene phosphole) assemblies.     

Structural Phase Transitions of a Molecular Metal Oxide

The structural phase of a metal oxide changes with temperature and pressure. During phase transitions, component ions move in multidimensional metal–oxygen networks. Such macroscopic structural events are robust to changes in particle size, even at scales of around 10 nm, and size effects limiting these transitions are particularly important in, for example, high-density memory applications of ferroelectrics. In this study, we examined structural transitions of the molecular metal oxide [Na@(SO₃)₂(n-BuPO₃)₄Mo^V₄Mo^VI₁₄O₄₉]⁵⁻ (Molecule 1 ) at approximately 2 nm by using single-crystal X-ray diffraction analysis. The Na⁺ encapsulated in the discrete metal-oxide anion exhibited a reversible order–disorder transition with distortion of the Mo–O molecular framework induced by temperature. Similar order–disorder transitions were also triggered by chemical pressure induced by removing crystalline solvent molecules in the single-crystal state or by substituting the countercation to change the molecular packing.     

MnII[MnII(CN)4]—A Magnetic Interpenetrating Three-Dimensional Diamondlike Solid

Three-dimensional extended diamondlike networks containing four-coordinate metal centers can be constructed from [Mn^II(CN)₄]²⁻ building blocks. Besides the title compound, which was prepared and its magnetic properties studied in detail, other novel magnetic solids might be able to be synthesized.     

Ultrastable Crystalline Semiconducting Hydrogenated Borophene

Borophene sheets have been synthesized in recent experiments, but the metallic nature and structural instability of the sheets seriously prevent emerging applications. Hydrogenated borophene has been predicted as an ideal material for nanoelectronic applications due to its high stability as well as excellent electronic and mechanical properties. However, the fabrication of hydrogenated borophene is still a great challenge. Here, we demonstrate that hydrogenated borophenes in large quantities can be prepared without any metal substrates by a stepwise in‐situ thermal decomposition of sodium borohydride under hydrogen as the carrier gas. The borophenes with good crystallinity exhibit superior stability in strong acid or base solvents. The structure of the grown borophene is in good agreement with the predicted semiconducting α‐boron sheet. A fabricated borophene‐based memory device shows a high ON/OFF‐current ratio of 3×10³ and a low operating voltage of less than 0.35 V as well as good stability.