Search results for "Self-assembly"
showing 10 items of 438 documents
The functionalization of nanodiamonds (diamondoids) as a key parameter of their easily controlled self-assembly in micro- and nanocrystals from the v…
2014
We detail herein readily accessible processes to control previously unobserved robust self-assemblies of nanodiamonds (diamondoids) in micro- and nanocrystals from their mild vapor deposition. The chemical functionalization of uniform and discernible nanodiamonds was found to be a key parameter, and depending on the type of functional group (hydroxy, fluorine, etc.) and its position on the diamondoid, the structure of the discrete deposits can vary dramatically. Thus, well-defined anisotropic structures such as rod, needle, triangle or truncated octahedron shapes can be obtained, and self-assembled edifices of sizes ranging from 20 nm to several hundred micrometers formed with conservation …
Supramolecular self-assembly on the B-Si(111)-(√3x√3) R30° surface: From single molecules to multicomponent networks
2017
Abstract Understanding the physical and chemical processes in which local interactions lead to ordered structures is of particular relevance to the realization of supramolecular architectures on surfaces. While spectacular patterns have been demonstrated on metal surfaces, there have been fewer studies of the spontaneous organization of supramolecular networks on semiconductor surfaces, where the formation of covalent bonds between organics and adatoms usually hamper the diffusion of molecules and their subsequent interactions with each other. However, the saturation of the dangling bonds at a semiconductor surface is known to make them inert and offers a unique way for the engineering of m…
Sulfate-Templated 2D Anion-Layered Supramolecular Self-Assemblies
2019
Summary Using solution and solid-state analyses, we demonstrate that the tripodal N-methylated(1,3,5-benzene-tricarboxamide)-tris(phenylurea) BTA ligands, possessing urea functionalities in the meta position, are able to form extended self-assembly 2D networks via hydrogen bonding templated by sulfate (SO42–). The divergence of the urea binding sites confers a propeller-like conformation to the ligands and is key to formation of the self-assemblies. Studies in solution and in the solid state as well as scanning electron microscopy (SEM) on the self-assembly properties of the ligands showed that the convergence also leads to the formation of hierarchical structures, including porous films an…
Thermodynamical aspects regarding the formation of self-assembly decylpolyglucoside structures
2005
In this study, we used a generalized form of a recently reported parametrization based on the differential geometry and the thermodynamics of dispersed systems to ascertain the capability of decylpolyglucoside alone or in association with cholesterol to form vesicle structures (niosomes). The theoretical calculation of the energy balance involved in the vesicles formation was carried out using values of the critical concentration of formation (ccf), surface tension and the molar surface area of the non-ionic surfactant. Furthermore, in order to confirm the theoretical results found in this work, we prepared and characterized vesicles made with decylpolyglucoside and cholesterol. The vesicle…
Size control of InAs∕InP(001) quantum wires by tailoring P∕As exchange
2004
The size and emission wavelength of self-assembled InAs∕InP(001) quantum wires (QWrs) is affected by the P∕As exchange process. In this work, we demonstrate by in situ stress measurements that P∕As exchange at the InAs∕InP interface depends on the surface reconstruction of the InAs starting surface and its immediate evolution when the arsenic cell is closed. Accordingly, the amount of InP grown on InAs by P∕As exchange increases with substrate temperature in a steplike way. These results allow us to engineer the size of the QWr for emission at 1.3 and 1.55 μm at room temperature by selecting the range of substrate temperatures in which the InP cap layer is grown.
From Mannose to Small Amphiphilic Polyol: Perfect Linearity Leads To Spontaneous Aggregation
2016
Terminally unsaturated and diastereochemically pure polyol derived from d-mannose shows spontaneous aggregation behavior in water solution. In order to study and clarify this unforeseen phenomenon, a conformational study based on NMR spectroscopy combined with ab initio structure analysis using the COSMO-solvation model was pursued. The results, together with X-ray diffraction studies, suggest a low energy linear conformation for this particular substrate both in solid states and in solution. For such small-sized acyclic carbohydrate derivatives, the linear conformation appears to be a key prerequisite for the unusual molecular self-assembly reported herein. peerReviewed
Structural characterization of 2,2-di-n-butyl-4-methyl-1,3,2-dioxastannolane isolated from supercritical CO2 conditions
2009
The title compound has been isolated as single crystals from the synthesis of propylene carbonate from racemic 1,2-propanediol and carbon dioxide using n-Bu2SnO as a catalyst precursor. The X-ray crystallographic structure analysis revealed the self-assembly of di-n-butyltin(IV) 1,2-propanediolate units, linked together through long-distance Sn-O interactions leading to a one-dimensional polymeric architecture organized in a syndiotactic arrangement. The coordination geometry around the tin atoms can be described as an unusual faced-capped trigonal bipyramidal environment.
Magnetic Control over the Fractal Dimension of Supramolecular Rod Networks
2021
<p>Controlling supramolecular polymerization is of fundamental importance to create advanced materials and devices. Here we show that the thermodynamic equilibrium of Gd<sup>3+</sup>-bearing supramolecular rod networks is shifted reversibly at room temperature in a static magnetic field of up to 2 T. Our approach opens opportunities to control the structure formation of other supramolecular or coordination polymers that contain paramagnetic ions.</p>
Alkylated Aromatic Thioethers with Aggregation‐Induced Emission Properties—Assembly and Photophysics
2019
In this contribution, we present the synthesis and self-assembly of alkylated thioethers with interesting photophysical properties. To this end, the emission, absorption and excitation spectra in organic solvents and as aggregates in water were measured as well as the corresponding photoluminescence quantum yields and lifetimes. The aggregates in aqueous media were visualized and measured using transmission electron microscopy. Besides that, crystal structures of selected compounds allowed a detailed discussion of the structure–property relationship. Furthermore, the mesomorphic behavior was investigated using polarized optical microscopy (POM) as well as differential scanning calorimetry (…