945909-41-1Relevant academic research and scientific papers
Folding of a donor-containing ionene by intercalation with an acceptor
De, Swati,Ramakrishnan
, p. 149 - 156 (2011)
Cationic ionenes that bear electron-rich 1,5-dialkoxynaphthalene (DAN) units within the alkylene segment were allowed to interact with different types of electron-deficient, acceptor-containing molecules in an effort to realize intercalation-induced folding of the ionenes; the collapse of the chains was expected to occur in such a way that the donor and acceptor units become arranged in an alternating fashion. Several acceptor-bearing molecules were prepared by the derivatization of pyromellitic dianhydride and naphthalene tetracarboxylic dianhydride with two different oligoethylene glycol monomethyl ether monoamines. This yielded acceptor molecules with different water solubility and allowed the examination of solvophobic effects in the folding process. UV/Vis spectroscopic studies were carried out by using a 1:1 mixture of the DAN-ionenes and different acceptor molecules in water/DMSO solvent mixtures. The intensity of the charge-transfer (CT) band was seen to increase with the water content in the solvent mixture, thereby suggesting that the intercalation is indeed aided by solvophobic effects. The naphthalene diimide (NDI) bearing acceptor molecules consistently formed significantly stronger CT complexes when compared to the pyromellitic diimide (PDI) bearing acceptor molecules, which is a reflection of the stronger π-stacking tendency of the former. AFM studies of drop-cast films of different ionene-acceptor combinations revealed that compact folded structures are formed most effectively under conditions in which the strongest CT complex is formed. Know when to fold 'em: When coerced to collapse in a polar solvent in the presence of an electron-deficient amphiphilic folding agent, suitably modified ionenes with a symmetrically positioned electron-rich 1,5-dialkoxylnaphthalene (DAN) unit appear to form an accordion-type folded structure wherein the units are arranged in an alternating fashion (see picture). D=Donor; A=Acceptor. Copyright
Supramolecular ribbons from amphiphilic trisamides self-assembly
Garcia, Fatima,Buendia, Julia,Sanchez, Luis
supporting information; experimental part, p. 6271 - 6276 (2011/10/01)
Two amphiphilic C3-symmetric OPE-based trisamides have been synthesized and their self-assembling features investigated in solution and on surface. Variable-temperature UV-vis experiments demonstrate the cooperative supramolecular polymerization of these trisamides that self-assemble by the operation of triple C=O???H-N H-bonding arrays between the amide functional groups and π-π stacking between the aromatic units. The helical organization of the aggregates has been demonstrated by circular dichroism at a concentration as low as 1 × 10-4 M in acetonitrile. In the reported trisamides, the large hydrophobic aromatic core acts as a solvophobic module impeding the interaction between the polar TEG chains and the amide H-bonds. This strategy makes unnecessary the separation of the amide functional groups to the polar tri(ethylene glycol) chains by paraffinic fragments. Achiral trisamide 1 self-assembles into flat ribbon-like structures that experience an amplification of chirality by the addition of a small amount of chiral 2 that generates twisted stripes.
The self-assembly of six-petal microflowers by hydrogen-bonded shape-persistent triangular aromatic hydrazide derivatives
Lin, Jian-Bin,Wang, Gui-Tao,Jiang, Xi-Kui,Li, Zhan-Ting
scheme or table, p. 4221 - 4224 (2010/09/12)
Six-petal microflowers have been self-assembled in methanol from C 3-symmetric shape-persistent triangular aromatic hydrazide derivatives. Nine intramolecular hydrogen bonds are used to enhance the planarity of the aromatic backbone, while six 2-(2-(2-methoxyethoxy)ethoxy)- ethoxyl groups are appended to the rigid aromatic backbone. Scanning electron microscopy (SEM) images show that the molecules form unique six-petal flower-like aggregates in methanol. A self-assembling mechanism that is similar to the formation of snowflakes has been proposed.
Molecular structure of helical supramolecular dendrimers
Peterca, Mihai,Percec, Virgil,Imam, Mohammad R.,Leowanawat, Pawaret,Morimitsu, Kentaro,Heiney, Paul A.
supporting information; body text, p. 14840 - 14852 (2009/02/08)
The molecular structure of helical supramolecular dendrimers generated from self-assembling dendrons and dendrimers and from self-organizable dendronized polymers was elucidated for the first time by the simulation of the X-ray diffraction patterns of their oriented fibers. These simulations were based on helical diffraction theory applied to simplified atomic helical models, followed by Cerius2 calculations based on their complete molecular helical structures. Hundreds of samples were screened until a library containing 14 supramolecular dendrimers and dendronized polymers provided a sufficient number of helical features in the X-ray diffraction pattern of their oriented fibers. This combination of techniques provided examples of single-92 and -11 3 helices, triple-61, -81, -91, and -121 helices, and an octa-321 helix that were assembled from crownlike dendrimers, hollow and nonhollow supramolecular crownlike dendrimers, hollow and nonhollow supramolecular disklike dendrimers, and hollow and nonhollow supramolecular and macromolecular helicene-like architectures. The method elaborated here for the determination of the molecular helix structure was transplanted from the field of structural biology and will be applicable to other classes of synthetic helical assemblies. The determination of the molecular structure of helical supramolecular assemblies is expected to provide an additional level of precision in the design of helical functional assemblies resembling those from biological systems.
