Search results for "Stack"
showing 10 items of 392 documents
Introduction to the microsymposium and on the modulation of thermodynamic parameters relative to biomolecule-solvent interactions
1980
Abstract As a result of introducing a macromolecule in a solvent, changes in the structures of both solute and solvent are generally found. In this specific meaning we refer here to ‘relaxation phenomena’. The discussion will either concern or keep in a view the case of biomolecules and to which extent these changes are involved in their thermodynamic stability or functional structure: Dr. Ben-Naim will discuss hydrophobic interactions and structural changes in the solvent; Dr. Wen will focus on thermodynamic properties of aqueous solutions on hydrophobic solutes; Dr. Cordone, Dr. Fornili and myself shall discuss results of experiments concerning solutes on several types(proteins, polynucle…
Non-Centrosymmetric Homochiral Supramolecular Polymers of Tetrahedral Subphthalocyanine Molecules
2015
This is the peer reviewed version of the following article: Angewandte Chemie - International Edition 54.8 (2015): 2543-2547, which has been published in final form at http://dx.doi.org/10.1002/anie.201411272. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving
Melt processing of hexa-peri-hexabenzocoronene on the water surface
2011
A discotic polycyclic aromatic hydrocarbon, hexa-peri-hexabenzocoronene, was oriented by slow cooling from the isotropic phase on a water surface as a film. For melt processing at low temperatures, an HBC derivative with long swallow-tailed alkyl side chains was chosen. The supramolecular organization in the resulting thin layer was investigated by electron microscopy. In high-resolution mode, the structural study showed large domains in which the columnar structures were oriented uniaxially with an edge-on arrangement of the hydrophobic molecules. The length of the stacks exceeded several hundred nanometers without obvious defects. The small-area analysis by TEM allowed the direct visualiz…
(Z)-Ethyl 2-oxo-3-(1,2-dihydroquinolin-2-ylidene)propanoate
2010
Both independent molecules in the asymmetric unit of the tautomeric title compound, C14H13NO3, a synthetic product obtained from 2-lithiomethylquinoline and diethyl oxalate, crystallize in the enaminone form with a Z configuration around the double bond. Intramolecular N—H...O hydrogen bonds occur, generating an S(6) graph-set motif. In the crystal, weak intermolecular C—H...O and π–π stacking interactions [centroid–centroid distances = 3.7020 (14)–3.7429 (13)Å] define a three-dimensional supramolecular network.
Pyrene-Derived Novel One- and Two-Component Organogelators
2003
A new class of alkyl-chain-appended pyrene derivatives 4-14 were synthesized and evaluated for their gelation abilities. Depending on the nature of the linking group, these compounds gelated a number of organic solvents, either in the presence or in the absence of the acceptor molecule 2,4,7-trinitrofluorenone (TNF). Compounds with ester, ether, or alkyl linkages gelated a number of hydroxylic and hydrocarbon solvents by means of a charge-transfer interaction with TNF, while compounds with amide, urethane and urea linkers formed gels on their own in a variety of solvents by means of pi-pi stacking and hydrogen-bonding interactions. The Xray crystal structure of urethane (S)-12 showed hydrog…
One-dimensional coordination polymers constructed from di- and trinuclear {3d–4f} tectons. A new useful spacer in crystal engineering: 1,3-bis(4-pyri…
2014
Four new heterometallic 3d–4f complexes have been obtained using bi- and trinuclear building blocks: 1∞[Ni(L1)Gd(NO3)3(azbbpy)]·CH3CN (1), [Zn(L1)Eu(NO3)3(azbbpy)]·H2O (2), 1∞[(CuL2)2Gd(NO3)2(dca)] 3 and 1∞[(NiL2)2Dy(H2O)4(oxy-bbz)]NO3·3H2O (4), [H2L1 = 1,3-propanediyl-bis(2-iminomethylene-6-methoxyphenol), H2L2 = 2,6-di(acetoacetyl)pyridine, azbbpy = 1,3-bis(4-pyridyl)azulene, dca− = dicyanamide anion, and oxy-bbz = the dianion of the 4,4′-oxy-bis(benzoic) acid]. 1 and 2 represent the first complexes containing 1,3-bis(4-pyridyl)azulene as a ligand. 1, 3, and 4 are one-dimensional coordination polymers constructed from heterometallic nodes connected by the exo-dentate ligands. Helical chai…
Dynamics of entangled supramolecular polymer networks in presence of high-order associations of strong hydrogen bonding groups
2017
Dynamics of entangled polymer chains in the melt state are deliberately excluded in most of the studies on supramolecular polymer networks by utilizing nonentangled precursor chains. Relaxation of the system mainly depends on the dissociation of the associative groups in latter case and nonentangled chains deliver nothing to resist afterward. Conversely, in an entangled system, relaxation of polymer chains and dissociation of associative groups can occurred parallel. Supramolecular networks based on an entangled precursor polymer with different levels of strong associating ureidopyrimidinone (UPy) groups are synthesized to screen the corresponding effects on the dynamics of the system. Bina…
Correlation between polymer architecture, mesoscale structure and photovoltaic performance in side-chain-modified poly(p-arylene-ethynylene)-alt-poly…
2011
Abstract Recent investigations have shown that an anthracene containing poly( p -arylene-ethynylene)-alt-poly( p -arylene-vinylene) statistical copolymer consisting of a well defined conjugated backbone, along which linear and branched alkoxy side chains are attached in a random manner, yields, compared to its counterparts with regular side chain substitution, an improved performance in polymer [6,6]:-phenyl-C 61 -butyric acid methyl ester (PCBM) bulk-heterojunction solar cells. The microscopic origin for the improved power conversion efficiency ( η ≈ 3.8%) of the statistical copolymer – which is the best in its material class – has not been resolved. We conducted grazing incidence wide-an…
Thermal and viscoelastic properties of entangled supramolecular polymer networks as a powerful tool for prediction of their microstructure
2018
Abstract Thermal and viscoelastic properties of entangled supramolecular polymer networks, SPNs, depend strongly on binary and collective assembly of associative groups. The collective assemblies can phase separate from polymer matrix chains and form domains with different sizes and shapes, which have different melting point transitions. By increasing content of associative groups along the polymer chains, their high-order association leads to formation of domains, which have higher melting temperatures than other ones. We prepared a SPN system that contains three networks. All networks have similar precursor polymer backbone, but different content of ureidopyrimidinone, UPy, moiety as stro…
Theoretical Design of Organic Metals Based on the Phthalocyanine Macrocycle
1990
Phthalocyanine molecular crystals and cofacially linked polymers are well documented as low-dimensional materials that may attain high electrical conductivities. Air-stable conductivities on the order of 1 to 1000 S/cm after partial oxidation by iodine have been reported.1–3 These conductivity studies indicate that the electrical conductivity has very little dependence on the identity of the atom complexed in the cavity, but is strongly dependent on the orientation and spacing of the phthalocyanine rings. A columnar stacking with minimum spacing leads to a maximum interaction between π-molecular orbitals on adjacent rings and promotes the highest conductivity. More effective π-interactions …