scholarly journals Unraveling the Driving Forces in the Self-Assembly of Monodisperse Naphthalenediimide-Oligodimethylsiloxane Block Molecules

ACS Nano ◽  
2017 ◽  
Vol 11 (4) ◽  
pp. 3733-3741 ◽  
Author(s):  
José Augusto Berrocal ◽  
R. Helen Zha ◽  
Bas F. M. de Waal ◽  
Jody A. M. Lugger ◽  
Martin Lutz ◽  
...  
2015 ◽  
Vol 11 ◽  
pp. 2343-2349 ◽  
Author(s):  
Xiang Sun ◽  
Guoqiao Lai ◽  
Zhifang Li ◽  
Yuwen Ma ◽  
Xiao Yuan ◽  
...  

This paper reports the self-assembly of two new tetrathiafulvalene (TTF) derivatives that contain one or two urethane groups. The formation of nanoribbons was evidenced by scanning electron microscopy (SEM) and X-ray diffraction (XRD), which showed that the self-assembly ability of T 1 was better than that of T 2 . The results revealed that more urethane groups in a molecule did not necessarily instigate self-assembly. UV–vis and FTIR spectra were measured to explore noncovalent interactions. The driving forces for self-assembly of TTF derivatives were mainly hydrogen bond interactions and π–π stacking interactions. The electronic conductivity of the T 1 and T 2 films was tested by a four-probe method.


Nanoscale ◽  
2014 ◽  
Vol 6 (19) ◽  
pp. 11344-11350 ◽  
Author(s):  
Johannes Kirschner ◽  
Zhenxing Wang ◽  
Siegfried Eigler ◽  
Hans-Peter Steinrück ◽  
Christof M. Jäger ◽  
...  

2017 ◽  
Vol 70 (1) ◽  
pp. 52 ◽  
Author(s):  
Shuo Wang ◽  
Youguo Zhang ◽  
Qiang Li ◽  
Rongqin Sun ◽  
Lin Ma ◽  
...  

Amphiphilic peptides with or without oligoethylene glycol (OEG) chains based on 3,4-bis(benzyloxy)benzoic-linked glutamide were designed and their self-assembly was investigated. It was found that the amphiphilic peptide 3 with OEG chains could not only form stable gels in a wide range of solvents, but also showed better solubility in solvents than those without OEG chains. Fibrillar and nanotube structures were found in the gels formed and the width of the fibres could be tuned with added water content. The UV-vis and XRD results suggested that the driving forces for the peptide self-assembly were mainly intermolecular π–π and hydrogen-bonding interactions. These results provide a deeper understanding of the self-assembly mechanism and size control of nanofibrils formed by an OEG-based amphiphilic peptide.


2010 ◽  
Vol 82 (3) ◽  
pp. 523-533 ◽  
Author(s):  
Emilio M. Pérez ◽  
Nazario Martín

The search for molecular receptors capable of forming stable associates with fullerenes is a very active field of research in fullerene chemistry, with the purification from fullerite and the self-assembly of nanoscale electronic devices as driving forces. The construction of bivalent, tweezer-like receptors featuring two recognizing units connected through a spacer is one of the most successful design strategies employed in this field. Here, we present an overview of the most significant examples of these “molecular tweezers” for fullerenes.


Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3276 ◽  
Author(s):  
Samuele Rinaldi

Different classes of foldamers, which are synthetic oligomers that adopt well-defined conformations in solution, have been the subject of extensive studies devoted to the elucidation of the forces driving their secondary structures and their potential as bioactive molecules. Regardless of the backbone type (peptidic or abiotic), the most important features of foldamers are the high stability, easy predictability and tunability of their folding, as well as the possibility to endow them with enhanced biological functions, with respect to their natural counterparts, by the correct choice of monomers. Foldamers have also recently started playing a starring role in the self-assembly of higher-order structures. In this review, selected articles will be analyzed to show the striking number of self-assemblies obtained for foldamers with different backbones, which will be analyzed in order of increasing complexity. Starting from the simplest self-associations in solution (e.g., dimers of β-strands or helices, bundles, interpenetrating double and multiple helices), the formation of monolayers, vesicles, fibers, and eventually nanostructured solid tridimensional morphologies will be subsequently described. The experimental techniques used in the structural investigation, and in the determination of the driving forces and mechanisms underlying the self-assemblies, will be systematically reported. Where applicable, examples of biomimetic self-assembled foldamers and their interactions with biological components will be described.


2014 ◽  
Vol 1051 ◽  
pp. 278-282 ◽  
Author(s):  
Wei Song Hung ◽  
Kueir Rarn Lee ◽  
Juin Yih Lai

We utilized pressure-, vacuum-, and evaporation-assisted self-assembly techniques through which graphene oxide (GO) was deposited on modified polyacrylonitrile (mPAN). The fabricated composite GO/mPAN membranes were applied to dehydrate 1-butanol mixtures by pervaporation. Varying driving forces in the self-assembly techniques induced different GO assembly layer microstructures. XRD results indicated that the GO layer d-spacing varied from 8.3 Å to 11.5 Å. The self-assembly technique with evaporation resulted in a heterogeneous GO layer with loop structures; this layer was shown to be hydrophobic, in contrast to the hydrophilic layer formed from the other two techniques. From the pressure-assisted technique, the composite membrane exhibited exceptional pervaporation performance at 30 °C: concentration of water at the permeate side = 99.6 wt% and permeation flux = 2.54 kg m-2 h-1. This excellent separation performance stemmed from the dense, highly ordered laminate structure of GO.


2019 ◽  
Vol 10 ◽  
pp. 2094-2102 ◽  
Author(s):  
Stefania Carapezzi ◽  
Anna Cavallini

Background: Mechanisms of self-assembly/self-organization are fundamental for the emergence of nanoarchitectonic systems composed by elemental units, and it is important to build a theoretical framework for them. Additionally, because the enhanced functionalities of these systems are related to their spatial morphologies, it is necessary to quantify the self-organized design through suited statistical analysis tools. Results: We have investigated the self-assembly bundling process of nanowires fabricated by metal-assisted chemical etching (MACE). First, we have applied theoretical models in order to obtain a quantitative estimation of the driving forces leading to self-assembly. Then, we have studied the surfaces of the nanoarchitectures by means of multifractal analysis. We have found that these systems are not simple monofractals, but that the more complex paradigm of multifractality (different fractal dimensions across different scales) has to be applied to describe their morphology. Conclusion: The multifractal analysis approach has proven its ability to discriminate among different MACE nanoarchitectures. Additionally, it has demonstrated its capacity to measure the degree of homogeneity of these surfaces. Finally, a correlation between the growth conditions and the capacity dimension of the nanowires was obtained.


Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4544 ◽  
Author(s):  
Manuela Stefanelli ◽  
Federica Mandoj ◽  
Gabriele Magna ◽  
Raffaella Lettieri ◽  
Mariano Venanzi ◽  
...  

An overview of the solvent-driven aggregation of a series of chiral porphyrin derivatives studied by optical methods (UV/Vis, fluorescence, CD and RLS spectroscopies) is herein reported. The investigated porphyrins are characterized by the presence in the meso-positions of glycol-, steroidal- and glucosteroidal moieties, conferring amphiphilicity and solubility in aqueous media to the primarily hydrophobic porphyrin platform. Aggregation of the macrocycles is driven by a change in bulk solvent composition, forming architectures with supramolecular chirality, steered by the stereogenic centers on the porphyrin peripheral positions. The aggregation behavior and chiroptical properties of the final aggregated species strongly depend on the number and stereogenicity of the ancillary groups that dictate the mutual spatial arrangement of the porphyrin chromophores and their further organization in larger structures, usually detectable by different microscopies, such as AFM and SEM. Kinetic studies are fundamental to understand the aggregation mechanism, which is frequently found to be dependent on the substrate concentration. Additionally, Molecular Mechanics calculations can give insights into the intimate nature of the driving forces governing the self-assembly process. The critical use of these combined methods can shed light on the overall self-assembly process of chirally-functionalized macrocycles, with important implications on the development of chiral porphyrin-based materials.


Author(s):  
M. Kessel ◽  
R. MacColl

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.


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