Polymerization of Bolaform Butadiyne 1-Glucosamide in Self-Assembled Nanoscale-Fiber Morphology

Abstract

Polymerization of constituent molecules in supramolecular self-assemblies 1 will provide stable covalent assemblies. In contrast to a number of studies on bilayer-membrane(BLM)-templated polymerization of diacetylenes, 2 only few studies have been reported for the polymerization in monolayer lipid membranes (MLMs) such as liposomes 3 or multi sheets. 4 Furthermore, the characteristics of the polymerized entity have been uncertain, owing to the fairly poor solubility of the products. Bolaamphiphiles, 5 unlike one-headed amphiphiles, are characteristic of forming MLMs such as supramolecular tubes 6a and rods. 6b-d We have recently reported the supramolecular fiber formation from 1-glucosamide bolaamphiphiles. 7 Packing parameters of the alkylene chains in their crystals 8 are in good accord with those of reactive diacetylene monomers. 9 Thus, butadiynes were incorporated into the bolaamphiphile bridge to provide a potential candidate for the topochemical polymerization within the fiber MLMs, as represented by 1 and 2. Here, we first describe nanoscale fiber (nanofiber) formation from the bolaform butadiyne 1-glucosamide 1 and its partial polymerization leading to oligodiacetylene-containing fibers.The polymerizable bolaform (1-aldosamide)s 1 and 2 have been synthesized 10 by condensation of octa-acetylated 1-glucosamine and 1-galactosamine with 5,7-dodecadiynedioic acid, respectively, according to the method previously reported. 11 Upon slow cooling to room temperature, the solutions of 1 (7 g) in an ethyl acetate/ n-hexane (300/700 mL) mixture solidified to a gel. Similar gelation also occurs for bolaform (1-aldosamide)s 11 and (urethane amide)s 12 with saturated oligomethylene chains. The gel from 1 is a little resistant to mechanical stress. No gels of 1 were produced from common organic solvents such as MeOH, CHCl 3 , and DMF. Energy-filtering transmission electron microscopy (EF-TEM) 13 for the unstained specimens revealed that the gel from the ethyl acetate/n-hexane solution was composed of nanofibers with widths of 6-20 nm ( Figure 1, parts a and b). In contrast to helical ribbons formed from the 1-glucosamide bolaamphiphiles, 7 the present fibers form ribbons without remarkable twisting or spirals. The nanofibers of 1 were robust during the EF-TEM observation, presumably because of the polymerization of the butadiynes by an electron beam of the EF-TEM. The formation of linear amide hydrogen bond chains can be confirmed by the appearance of the amide N-H and CdO stretching bands at 3343, 3060, and 1680 cm -1 , and the N-H deformation band at 1535 cm -1 in FT-IR spectra. 14 These findings are consistent with a layered structure of 1 within the fibers, stabilized by a one-dimensional hydrogen-bonded network ( Figure 2a). 15 However, the 1-galactosamide homologue 2, an epimer of 1, formed no fibers but amorphous solids in the same solvent. It was due to steric hindrance between adjacent pyranose rings in a stacked conformation similar to that in Figure 2a.Upon exposure to 254-nm light 16 or γ-ray 17 under an ...

Liquid-crystalline gels exhibiting electrooptical light scattering properties: fibrous polymerized network of a lysine-based gelator having acrylate moieties

“…Photopolymerization of selfassembled fibers is an effective method to produce stable gels. [22][23][24][25][26][27][28][29] The enhancement of the thermal stability and durability of the self-assembled LC gels is essential for practical applications.…”

Supramolecular nanofiber formation from commercially available arginine and a bola-type diacetylenic diacid via hydrogelation

“…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.…”

“…[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).…”

“…[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.…”

Molecular Self-Assembly into One-Dimensional Nanotube Architectures and Exploitation of Their Functions

“…Possible molecular shapes and spatial arrangement of each functional group, and the local environment of solvophilic and solvophobic moieties allow us to produce a variety of discrete organic nanotubes, together with different types of self-assembly strategy. 2,11 We have been investigating the self-assembly behavior of synthetic amphiphilic molecules that append sugar, [12][13][14][15][16][17][18] peptide, [19][20][21] and nucleic acid moieties [22][23][24][25][26] as hydrophilic headgroups. 27 Those structural components in nature are wellknown to form diverse and multiple hydrogen-bond networks.…”