Based on the interfacial self-assembly of magnetite nanoparticles, we demonstrate the formation of colloidosomes with shells predominantly composed of monolayers of liquid-like, close-packed nanoparticles. The gelation of aqueous phase with agarose leads to robust and water-dispersible nanoparticle colloidosomes, allowing encapsulation of various water soluble materials. The cutoff of the nanoparticle colloidosomes obtained is primarily defined by the nanoparticle size. This controllable permeability should be of great importance for the encapsulation application.

This work presents several metallosupramolecular coordination polyelectrolytes (MEPEs) self-assembled from rigid, pi-conjugated, pyridine ring functionalized bisterpyridines and metal ions. The MEPEs are water-soluble and display different colors spanning the entire visible regions. Optical, electrochemical, and electrochromic properties of the obtained MEPEs are presented. The results show that the properties are profoundly affected by the nature of the substituents at the peripheral pyridine rings. Namely, MEPEs assembled from the electron-rich OMe group modified ligands exhibit high switching reversibility and stability and show a lower switching potential than the unsubstituted and electron-deficient Br-substituted analogues. The response times can be tuned either by the design of the ligands or by the choice of the metal ions to cover a broad time scale from under 1 s to several minutes. The optical memory is enhanced from 30 s to longer than 15 min as a comparison of unsubstituted and substituted MEPEs shows. Thus, the significantly enhanced stability and the ease of tuning the properties render this type of supramolecular assembly attractive as electrochromic materials for applications in a large variety of areas. Most importantly, we presented the structure-property relationships of MEPEs, which lays the groundwork for further design of new bisterpyridine-based metallosupramolecular functional materials.

Finding the right angle: The contact angle of nanoparticles at the water/oil interface can be engineered close to 90° by capping with ligands containing carboxylic ester terminal groups. This drives the nanoparticles to self‐assemble into close‐packed films (see picture), and thus provides the opportunity to create two‐ or three‐dimensional homo‐ or heterogeneous nanostructures for electronic, optoelectrical, and magnetic applications.

Since the first report on electrochromism, [1] rapidly growing interest has been paid to electrochromic materials (ECMs) as molecular switches for optical and electronic applications.[2]So far, conducting polymers (CPs), [3] molecular dyes, and metal oxides [2a,4] have been extensively investigated as three major classes of ECMs. Only few examples of metallo-supramolecular assemblies were reported, [5] however, these first researches indicate that the components are potential candidates for the next generation of single-layer, multi-color, lowvoltage ECMs. Metallo-supramolecular assemblies feature transition metal centered sites with redox dependent metalto-ligand charge transfer (MLCT), intervalence CT and intraligand transitions giving rise to strong optical contrast.[6] The electrochromic response is readily tuned by the choice of the metal ions as well as by the design of the ligands. [7] For the development of ECMs, ditopic bis-terpyridine based metallo-supramolecular coordination polyelectrolytes (MEPEs) are very attractive. Terpyridines have a rich coordination chemistry and generally high binding constants giving rise to macromolecular assemblies with distinct electrochemical properties.[8] The modularity of self-assembly permits introducing different metal ions and ligands as well as rapid fabrication of material libraries with a large range of properties. The resulting MEPEs are readily processed from aqueous media in various device architectures including thin films.[9] Additionally, MEPEs are also available as liquid crystalline phases that are readily processed as nanostructure, [10] thin films, [11] and mesophases.[12]In our research, we focus on pyridine-ring functionalized bis-terpyridines coupled with rigid, linear spacers, as contrasted to the unsubstituted analogues reported in previous reports.[ 8] We reasoned that a functional group at the pyridine periphery close to the metal ion will influence through steric or electronic effects the ligand field stabilization energy and, thus, affecting the properties of the MEPEs. A linear rigid-rod type structure affords a loose, uncongested polymer morphology facilitating unhindered counter ion transport, thereby leading to rapid response times. [3c,5d] Accordingly, four new MEPEs, Poly-FeL 2 ∼ Poly-FeL 5 , were self-assembled using Fe(II) and ligands L 2 ∼ L 5 , which have different substitutents and spacers (Fig. 1) in addition to the well-known Poly-FeL 1 as a reference. Here, we propose the first structure-property relationships for these materials, which are needed, but not available to date, to serve for the de novo design and fabrication of new materials. Most importantly, our results reveal that the substituents at the pyridine periphery of the ligands significantly affect the electrochromic properties of the resulting MEPEs. Consequently, MEPEs functionalized with electron-donating groups (OMe) display high stability, low switching potential, high reversibility, fast switching rates, and enhanced optical memory (defined here as the abil...

In various cultures, the Lotus plant has been considered to be a symbol of purity for a very long time because the leaves have a natural cleaning mechanism. Instead of wetting the surface, water droplets roll off the leaves' surfaces taking with them dirt and contamination.[1] This so-called Lotus effect is based on the superhydrophobic nature of the surface, realized by the fractal morphology of the two-tier roughness on both micro-and nanometer length scales. In order to artificially mimic water-repellent surfaces, it is necessary to prepare a surface composed of hydrophobic molecular or polymeric building blocks that exhibits a low surface energy and a rough fractal interfacial morphology. [2][3][4][5][6] However, when applying these principles to manufacturing of self-cleaning surfaces, the resulting biomimetic structures additionally have to be durable and stable, which is generally a difficult issue for self-organized supramolecular systems based on weak intermolecular forces. [7][8][9][10] Previously, superhydrophobic surfaces have been prepared using several techniques, such as sol-gel processing, [11,12] fabrication of structures from carbon nanotubes [13,14] and fluorinated polymers, [15] chemical vapor deposition, [16] and so forth. [17,18] To our knowledge fullerenes have not been employed as molecular components for superhydrophobic surfaces so far, even though they are at present one of the most fascinating carbon nanomaterials, [19] and are inexpensive compared to carbon nanotubes. To date, superhydrophobic materials have not been prepared by molecular self-organization in a convincing way. Here, we show for the first time that molecular self-organization of a fullerene derivative leads to macroscopic globular objects with a two-tier roughness on the micro-and nanoscopic length scale. Surfaces resulting from simple casting of these objects are superhydrophobic and surprisingly durable. The fullerene used in the present study is based on C 60 functionalized with three eicosyloxy aliphatic chains (1). Both parts of the molecule are hydrophobic and exhibit low free surface energies, which is one key requirement for the construction of superhydrophobic materials, with high surface roughness being the other criterion. Notably, the strength of the interactions between C 60 moieties and aliphatic chains depends on the environment and, therefore, allows us to control the self-assembly and aggregation behavior through the choice of the solvent. This gives us two independent parameters to manipulate the self-assembly of this class of fullerenes: [20][21][22][23][24][25] i) the design of the derivative, e.g., the number and length of aliphatic chains; and ii) the experimental conditions for self-assembly. Recently, we reported on the hierarchical self-assembly of a fullerene derivative bearing three hexadecyloxy groups furnishing various polymorphs depending on the experimental conditions such as solvent and temperature.[20]The fullerene derivative 1 (Fig. 1a) was prepared by refluxing the corresponding benza...

Using electrostatic layer-by-layer self-assembly (ELSA), the formation of multilayers with polyelectrolytes and nanoscopic polyoxometalate (POM) clusters of different sizes and charges is investigated. The multilayers are characterized by UV-vis absorption spectroscopy, optical ellipsometry, cyclic voltammetry, and atomic force microscopy. In all cases, it is possible to find experimental conditions to achieve irreversible adsorption and regular multilayer deposition. Most importantly, the surface coverage is directly related to the total charge of the POM anion and can be controlled from submonolayer to multilayer coverage by adjusting the ionic strength of the dipping solutions. Imaging the interfaces after POM deposition by atomic force microscopy reveals a granular surface texture with nanometer-sized features. The average interfacial roughness amounts to approximately 1 nm. Cyclic voltammetry indicates that the electrochemical properties of the POM clusters are fully maintained in the polyelectrolyte matrix, which opens a route toward practical applications such as sensors or heterogeneous catalysts. Moreover, the permeability toward electrochemically active probe molecules can be tailored through the multilayer architecture and deposition conditions. Finally, we note that despite the low total charge and comparably small size of the discrete POM anions, the multilayers are remarkably stable. This work provides basic guidelines for the assembly of POM-containing ELSA multilayers and provides detailed insight into characteristic surface coverage, permeability, and electrochemical properties.

We present a comprehensive study of the partially reduced polyoxomolybdate [H 3 Mo 57 V 6 (NO) 6 (2) was isolated as a dark violet solid, which readily dissolves in organic solvents. Slow evaporation of solutions of 2 on solid substrates forces the hydrophobic particles to aggregate into a cubic lattice. Annealing these so-formed films at elevated temperature causes de-wetting with terrace formation similar to liquid crystals and block copolymers. Compound 2 forms a stable Langmuir monolayer at the air ± water interface; Langmuir ± Blodgett multilayers are readily prepared by repeated transfer of monolayers on solid substrates. The films were characterized by optical ellipsometry, Brewster angle microscopy, transmission electron microscopy, and X-ray reflectance.

The reactivity of immobilized functional groups in thin layers of (3-aminopropy1)triethoxy~ilane (APS), (3-mercaptopropyl)trimethoxy~ilane, (3-bromopropyl)trimethoxysilane, and (8-bromoody1)trimethoxysilane on oxidized aluminum substrates was studied with reflection-adsorption infrared spectroscopy (RAIR), optical ellipsometry and contact-angle measurements. Mass changes on the surface associated with the surface-confined reactions were measured with the quartz crystal microbalance (QCM). Single layers of (3-a~ninopropy1)triethoxysilane on oxidized aluminum react with chlorodimethylsilane to give [(-0)3Si(CH2)3NH2+SiMe2HICl-and single layers of (3-mercaptopropy1)trimethoxysilane on oxidized aluminum react with phenylmercury hydroxide togive [(-0)fii(CHz)aSHgPh] , while no substitution reaction of (3-bromopropy1)trimethoxyailane and (8-bromoodyl)trimethoxyailaue monolayers occurred with cyanide.