Abstract:Unsaturated fatty acids play an important role in vivo not only as energy sources but also as main components of biomembranes (1-3). It is well known that fluidity of biomembrane is affected by its characteristic dynamic structure and is dependent on the unsaturated fatty acid, oleic acid (4-8). Oleic acid, which has a double bond at C9 position in its molecule and freely-rotating, adjacent methylene groups, is one of the representative cismonoene unsaturated fatty acids which are able to bend comparatively fr… Show more
“…Generally guanidiniumcarboxylate interaction proves to be a strong noncovalent bond, as reported for fatty acids and arginine. 24,25 The present NMR and XRD results strongly support this DDA-arginine interaction. At the pH, the amino acid forms a zwitterion of -NH 3 þ cation and -COO À anion at the amino acid a position.…”
supporting
confidence: 76%
“…Therefore, arginine becomes soluble, but DDA derivatives are insoluble. 24,25 Washing the hydrogel sample with hydrochloric acid (1 M) we successfully removed L-arginine from the photoirradiated DDA-arginine hydrogel. After filtration and evaporation of the solvent, the residue was dried in vacuo.…”
Section: Characterization Of the Hydrogel After Arginine Removalmentioning
confidence: 99%
“…At the pH, the amino acid forms a zwitterion of -NH 3 þ cation and -COO À anion at the amino acid a position. 24,25 It is very likely that the zwitterion forms salt bridges between the neighboring layers and stabilizes the layered structure in the nanofibers.
…”
mentioning
confidence: 99%
“…Inspired by the reports on gel-like systems of fatty acids and arginine, 24,25 we examined a salt of arginine and bola-type diacetylene diacid 10, 12-docosadiynedioic acid (DDA) for hydrogelation ( Figure 1). The salt gelator requires no multistep synthetic derivation.…”
A diacetylenic-acid arginine salt gelated water. The supramolecular structure and optical properties of the resultant hydrogel were examined by optical microscopy, electron microscopy, X-ray diffraction and ultraviolet (UV)-absorption and circular dichroism (CD) spectroscopies. Microscopic images showed that 10, 12-docosadiynedioic acid arginine salt formed a fibrous structure. X-ray diffraction and nuclear magnetic resonance measurements indicated guanidinium-carboxylate interaction. Upon UV irradiation, the gel polymerized to diacetylene oligomers, with a concomitant color change from white to orange. After the removal of arginine, CD spectra indicated that the diacetylene oligomers maintained chirality. Polymer Journal (2012) 44, 646-650; doi:10.1038/pj.2012.46; published online 4 April 2012Keywords: arginine; diacetylene; hydrogel; polymerization; self-assembly INTRODUCTION Low-molecular-weight gelators (LMWGs) have attracted much interest because of their unique features and potential applications as new soft materials. 1,2 The LMWGs construct supramolecular 3D networks consisting of nanofibrous assemblies of amphiphilic molecules. [3][4][5][6][7][8][9] Noncovalent interactions such as hydrogen-bonding, van der Waals, p-p and electrostatic interactions function as driving forces to stabilize these supramolecular nanostructures. 10,11 Polymerization of constituent molecules in supramolecular selfassemblies 12 will provide stable covalent assemblies. In particular, polymerization of the LWMGs with diacetylene groups has been actively investigated, [13][14][15][16] as simple photoirradiation induces polymerization or oligomerization if they arrange and align in a good order. The connection of amide, aromatic or ionic groups to diyne motives through synthetic derivation enables one to attain appropriate molecular arrangement to the polymerization. In most cases, however, the derivation requires several tedious steps. Moreover, a careful handling is necessary at every step to avoid photopolymerization of the synthetic intermediates under light.We have widely investigated the supramolecular nanostructures self-assembled from bola-amphiphiles. [16][17][18][19][20][21][22][23] For example, we previously reported that butadiyne 1-glucosamide connected bolaamphiphiles self-assemble to form nanofibers, and polymerization by photoirradiation causes the gelation of supramolecular networks in organic solvents. 16 In this synthesis, we always needed multistep derivation to attain the gelation.In the present work, we propose a new simple bola-type diacetylenic gelator. Inspired by the reports on gel-like systems of fatty acids and arginine, 24,25 we examined a salt of arginine and bola-type diacetylene diacid 10, 12-docosadiynedioic acid (DDA) for hydrogelation ( Figure 1). The salt gelator requires no multistep synthetic derivation. The hydrogel system showed formation of nanofibers and their stabilization by photo-oligomerization as well as chirality transfer to the nanofibers after the removal of the chiral amino acid.
...
“…Generally guanidiniumcarboxylate interaction proves to be a strong noncovalent bond, as reported for fatty acids and arginine. 24,25 The present NMR and XRD results strongly support this DDA-arginine interaction. At the pH, the amino acid forms a zwitterion of -NH 3 þ cation and -COO À anion at the amino acid a position.…”
supporting
confidence: 76%
“…Therefore, arginine becomes soluble, but DDA derivatives are insoluble. 24,25 Washing the hydrogel sample with hydrochloric acid (1 M) we successfully removed L-arginine from the photoirradiated DDA-arginine hydrogel. After filtration and evaporation of the solvent, the residue was dried in vacuo.…”
Section: Characterization Of the Hydrogel After Arginine Removalmentioning
confidence: 99%
“…At the pH, the amino acid forms a zwitterion of -NH 3 þ cation and -COO À anion at the amino acid a position. 24,25 It is very likely that the zwitterion forms salt bridges between the neighboring layers and stabilizes the layered structure in the nanofibers.
…”
mentioning
confidence: 99%
“…Inspired by the reports on gel-like systems of fatty acids and arginine, 24,25 we examined a salt of arginine and bola-type diacetylene diacid 10, 12-docosadiynedioic acid (DDA) for hydrogelation ( Figure 1). The salt gelator requires no multistep synthetic derivation.…”
A diacetylenic-acid arginine salt gelated water. The supramolecular structure and optical properties of the resultant hydrogel were examined by optical microscopy, electron microscopy, X-ray diffraction and ultraviolet (UV)-absorption and circular dichroism (CD) spectroscopies. Microscopic images showed that 10, 12-docosadiynedioic acid arginine salt formed a fibrous structure. X-ray diffraction and nuclear magnetic resonance measurements indicated guanidinium-carboxylate interaction. Upon UV irradiation, the gel polymerized to diacetylene oligomers, with a concomitant color change from white to orange. After the removal of arginine, CD spectra indicated that the diacetylene oligomers maintained chirality. Polymer Journal (2012) 44, 646-650; doi:10.1038/pj.2012.46; published online 4 April 2012Keywords: arginine; diacetylene; hydrogel; polymerization; self-assembly INTRODUCTION Low-molecular-weight gelators (LMWGs) have attracted much interest because of their unique features and potential applications as new soft materials. 1,2 The LMWGs construct supramolecular 3D networks consisting of nanofibrous assemblies of amphiphilic molecules. [3][4][5][6][7][8][9] Noncovalent interactions such as hydrogen-bonding, van der Waals, p-p and electrostatic interactions function as driving forces to stabilize these supramolecular nanostructures. 10,11 Polymerization of constituent molecules in supramolecular selfassemblies 12 will provide stable covalent assemblies. In particular, polymerization of the LWMGs with diacetylene groups has been actively investigated, [13][14][15][16] as simple photoirradiation induces polymerization or oligomerization if they arrange and align in a good order. The connection of amide, aromatic or ionic groups to diyne motives through synthetic derivation enables one to attain appropriate molecular arrangement to the polymerization. In most cases, however, the derivation requires several tedious steps. Moreover, a careful handling is necessary at every step to avoid photopolymerization of the synthetic intermediates under light.We have widely investigated the supramolecular nanostructures self-assembled from bola-amphiphiles. [16][17][18][19][20][21][22][23] For example, we previously reported that butadiyne 1-glucosamide connected bolaamphiphiles self-assemble to form nanofibers, and polymerization by photoirradiation causes the gelation of supramolecular networks in organic solvents. 16 In this synthesis, we always needed multistep derivation to attain the gelation.In the present work, we propose a new simple bola-type diacetylenic gelator. Inspired by the reports on gel-like systems of fatty acids and arginine, 24,25 we examined a salt of arginine and bola-type diacetylene diacid 10, 12-docosadiynedioic acid (DDA) for hydrogelation ( Figure 1). The salt gelator requires no multistep synthetic derivation. The hydrogel system showed formation of nanofibers and their stabilization by photo-oligomerization as well as chirality transfer to the nanofibers after the removal of the chiral amino acid.
...
“…As shown in Figure , anisotropic particles with sizes of several micrometers were observed, and they were identified as LC particles. The LC particles were also found to have a large dark cross part in the interiors thereof by microscopic observation, representing a kind of lamella LC. , 4 Polarized micrograph of precipitates in the 10FS(EO) 2 /water/scCO 2 mixture. …”
The effect of surfactant tail structure on the stability of a water/supercritical CO2 microemulsion (W/scCO2 muE) was examined for various fluorinated double-tail anionic surfactants of different fluorocarbon chain lengths, F(CF2)n (n = 4, 6, 8, and 10), and oxyethylene spacer lengths, (CH2CH2O)(m/2) (m = 2 and 4). The phase behavior of the water/surfactant/CO2 systems was studied over a wide range of CO2 densities from 0.70 to 0.85 g/cm(3) (temperatures from 35 to 75 degrees C and pressures up to 500 bar) and corrected water-to-surfactant molar ratios (W0c). All of the surfactants yielded a W/scCO2 muE phase, that is, a transparent homogeneous phase with a water content larger than that permitted by the solubility of water in pure CO2. With increasing W0c, a phase transition occurred from the muE phase to a macroemulsion or a lamella-like liquid crystal phase. The maximum W0c value was obtained at a tail length of 12-14 A, indicating the presence of an optimum surfactant tail length for W/scCO2 muE formation.
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