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Self-assembly Behavior (self-assembly + behavior)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Chemistry	50%

Selected Abstracts

Supramolecular Assembly of Perylene Bisimide with , -Cyclodextrin Grafts as a Solid-State Fluorescence Sensor for Vapor Detection

ADVANCED FUNCTIONAL MATERIALS, Issue 14 2009
Yu Liu
Abstract A nanoscopic supramolecular aggregate is constructed from perylene bisimide-bridged bis-(permethyl- , -cyclodextrins) 1 via ,,, stacking interactions. Its self-assembly behavior in organic and aqueous solutions is investigated by UV,Vis, fluorescence, and 1H NMR spectroscopy. Transmission electron microscopy and scanning electron microscopy images show the 1D nanorod aggregation of 1, which is birefringent under crossed polarizer conditions and strongly fluorescent as depicted in the fluorescence microscopy image. X-ray powder diffraction measurements indicate that 1 forms a well-ordered crystalline arrangement with a ,,, stacking distance of 4.02,Å. Furthermore, the solid-state fluorescence sensing is explored by utilizing the poly(vinylidene fluoride) membrane-embedded 1, giving that 1, as a novel vapor detecting material, can probe several kinds of volatile organic compounds and, especially, exhibits high sensitivity to organic amines. [source]

Synthesis of phenanthroline-terminated polymers and their Fe(II)-complexes

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2010
Miklós Nagy
Abstract Well-defined mono- and bifunctional, phenanthroline-terminated poly(ethylene glycol) and polyisobutylene capable of polymer network formation were synthesized. The starting materials mono- and bi-phenanthroline- (phen) terminated poly(ethylene glycols) (mPEG-phen, phen-PEG-phen) and polyisobutylenes (PIB-phen, phen-PIB-phen) were prepared by the Williamson synthesis and characterized by means of 1H NMR and MALDI-TOF mass spectrometry. According to UV,Vis spectrophotometry and ESI-TOF mass spectrometry, the phenanthroline-terminated polymers underwent quantitative complex formation with ferrous ions in solution. The aqueous solution of mPEG-phen shows self-assembly behavior. Important parameters, such as critical micelle concentration and hydrodynamic radius of the aggregates were also determined. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2709,2715, 2010 [source]

Photophysical and self-assembly behavior of poly(amidoamine) dendrons with chromophore as scaffold: The effect of dendritic architecture

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2008
Bing-Bing Wang
Abstract Two series of amphiphiles composed of hydrophilic poly(amidoamine) dendrons (from the first to the third generation) as the shell and hydrophobic aromatic chromophores (3,6-di(maleimidyl)-9-phenyl carbazole and 9-(4,-maleimidyl phenyl)-3-maleimidyl carbazole) as the central scaffold were synthesized. The effect of dendritic architecture on the photophysical properties and the self-assembly behavior of these amphiphiles were studied by UV,vis absorption spectroscopy, fluorescence spectroscopy, and transmission electron microscopy (TEM) measurements. Both the generation of dendritic shell and the location of dendrons at the chromophoric scaffold had great effect on the photophysical properties of these amphiphiles. In addition, different spherical aggregates were formed from these amphiphiles in the aqueous solution at different concentrations. Because of the combined effects of steric hindrance and architecture of dendritic shells, the amphiphiles from G2 dendron with central chromophore self-organized into ordered aggregates more readily than that from G1 and G3. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4584,4593, 2008 [source]

Reinforced Self-Assembly of Hexa- peri -hexabenzocoronenes by Hydrogen Bonds: From Microscopic Aggregates to Macroscopic Fluorescent Organogels

CHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2008
Xi Dou
Abstract Hexa- peri -hexabenzocoronene derivatives (HBCs) that have hydrogen-bonding functionalities (either amido or ureido groups) adjacent to the aromatic cores have been synthesized to study the effects of intracolumnar hydrogen bonds on the self-assembly behavior of HBCs. The hydrogen bonds effectively increased the aggregation tendency of these compounds in solution. In the bulk state, the typical columnar supramolecular arrangement of HBCs was either stabilized substantially (1,a, 1,b, 2,a, and 2,b), or suppressed by dominant hydrogen-bonding interactions (3). For some of the compounds (1,a, 2,a, and 2,b), the supramolecular arrangement adopted in the liquid-crystalline state was even retained after annealing, presumably owing to the reinforcement of the ,-stacking interactions by the hydrogen bonds. Additionally, the combined effect of the hydrogen bonds and ,-stacking of the aromatic moieties led to the formation of fluorescent organogels, whereby some derivatives were further investigated as novel low molecular-mass organic gelators (LMOGs). [source]

Self-Assembly of an Alkylated Guanosine Derivative into Ordered Supramolecular Nanoribbons in Solution and on Solid Surfaces

CHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2007
Stefano Lena Dr.
Abstract We report on the synthesis and self-assembly of a guanosine derivative bearing an alkyloxy side group under different environmental conditions. This derivative was found to spontaneously form ordered supramolecular nanoribbons in which the individual nucleobases are interacting through H-bonds. In toluene and chloroform solutions the formation of gel-like liquid-crystalline phases was observed. Sub-molecularly resolved scanning tunneling microscopic imaging of monolayers physisorbed at the graphite,solution interface revealed highly ordered two-dimensional networks. The recorded intramolecular contrast can be ascribed to the electronic properties of the different moieties composing the molecule, as proven by quantum-chemical calculations. This self-assembly behavior is in excellent agreement with that of 5,- O -acylated guanosines, which are also characterized by a self-assembled motif of guanosines that resembles parallel ribbons. Therefore, for guanosine derivatives (without sterically demanding groups on the guanine base) the formation of supramolecular nanoribbons in solution, in the solid state, and on flat surfaces is universal. This result is truly important in view of the electronic properties of these supramolecular anisotropic architectures and thus for potential applications in the fields of nano- and opto-electronics. [source]

Highly Ordered Mesoporous Carbonaceous Frameworks from a Template of a Mixed Amphiphilic Triblock-Copolymer System of PEO,PPO,PEO and Reverse PPO,PEO,PPO

CHEMISTRY - AN ASIAN JOURNAL, Issue 10 2007
Yan Huang
Abstract A series of highly ordered mesoporous carbonaceous frameworks with diverse symmetries have been successfully synthesized by using phenolic resols as a carbon precursor and mixed amphiphilic surfactants of poly(ethylene oxide)- b -poly(propylene oxide)- b -poly(ethylene oxide) (PEO,PPO,PEO) and reverse PPO,PEO,PPO as templates by the strategy of evaporation-induced organic,organic self-assembly (EISA). The transformation of the ordered mesostructures from face-centered (Fdm) to body-centered cubic (Imm), then 2D hexagonal (P6mm), and eventually to cubic bicontinuous (Iad) symmetry has been achieved by simply adjusting the ratio of triblock copolymers to resol precursor and the relative content of PEO,PPO,PEO copolymer F127, as confirmed by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and nitrogen-sorption measurements. The blends of block copolymers can interact with resol precursors and tend to self-assemble into cross-linking micellar structures during the solvent-evaporation process, which provides a suitable template for the construction of mesostructures. The assembly force comes from the hydrogen-bonding interactions between organic mixed micelles and the resol-precursor matrix. The BET surface area for the mesoporous carbonaceous samples calcined at 600,°C under nitrogen atmosphere is around 600,m2,g,1, and the pore size can be adjusted from 2.8 to 5.4,nm. An understanding of the organic,organic self-assembly behavior in the mixed amphiphilic surfactant system would pave the way for the synthesis of mesoporous materials with controllable structures. [source]

Two-Dimensional Self-Assembly of a Porphyrin,Polypyridyl Ruthenium(II) Hybrid on HOPG Surface through Metal,Ligand Interactions

CHEMPHYSCHEM, Issue 9 2010
Aimei Gao Dr.
Abstract The synthesis and self-assembly behavior of porphyrin,polypyridyl ruthenium(II) hybrid, which consists of a flexible alkyl chain attached with two conjugated moieties is described. The electronic absorption spectrum and emission spectra show that the [C8 -TPP-(ip)Ru(phen)2](ClO4)2, abbreviated as (C8ip)TPPC has optical properties. Scanning tunneling microscopy (STM) studies found that the ,,, interaction and metal,ligand interaction allow (C8ip)TPPC to form self-assembled structure and have an edge-on orientation on the highly oriented pyrolytic graphite (HOPG) surface. The multidentate structure in (C8ip)TPPC molecules act as linkers between the molecules and form metal,ligand coordination, which forces the assembly process in the direction of stable columnar arrays. In addition, although the sample was stored for two months in ambient conditions, STM experiments showed that the order of (C8ip)TPPC self-assembly only slightly decreased which indicates that the self-assembled monolayer is stable. This work demonstrates that introducing a metal-ligand in the porphyrin-polypyridyl compound is a useful strategy to obtain novel surface assemblies. [source]