Molecular Design of “Super” Hydrogelators:  Understanding the Gelation Process of Azobenzene-Based Sugar Derivatives in Water

Abstract

[structure: see text]. 1: R = beta-D-glucopyranoside. 2: R = alpha-D-glucopyranoside. 3: R = alpha-D-galactopyranoside. 4: R = alpha-D-mannopyranoside. As an attempt to rationally design aqueous organogelators, a bolaamphiphilic azobenzene derivative (1) bearing two sugar groups was synthesized. Compound 1 formed a gel in water even at concentrations as low as 0.05 wt % (0.65 mM). Spectroscopic studies and electron-micrographic observations have clarified the gel structure and the origin of the gelation ability for water.

Self‐Assembly of Octaaminoamido Derivatives of Resorcin[4]arene in Water − A “Cell‐Like” Submicron‐Scale Hydrogel Structure

“…[8a] Sugars, [10] bile acids, [11] azobenzenes, [12] and amino acids [13] have all been used successfully as hydrogelators.…”

“…Experimental Section 4,6,10,12,16,18,22,8,14,arene and 4, 6,10,12,16,18,22,24-octakis(ethoxycarbonylmethoxy)-2,8,14,20-tetraundecylcalix[4]arene were synthesized as described previously. [7b] 4, 6,10,12,16,18,22,24-Octakis{[N-(2-aminoethyl)amido]methoxy}-2,8,14,20-tetramethylcalix[4]arene (1): 4 ,6,10,12,16,18,22,8,14,arene (1.0 g, 0.81 mmol) was dissolved in ethylenediamine (30 mL) and the solution was stirred at room temperature for 7 days.…”

“…[7b] 4, 6,10,12,16,18,22,24-Octakis{[N-(2-aminoethyl)amido]methoxy}-2,8,14,20-tetramethylcalix[4]arene (1): 4 ,6,10,12,16,18,22,8,14,arene (1.0 g, 0.81 mmol) was dissolved in ethylenediamine (30 mL) and the solution was stirred at room temperature for 7 days. The precipitate obtained was filtered and washed with acetone (2 ϫ 50 mL).…”

“…The precipitate obtained was filtered and washed with acetone (2 ϫ 50 mL). The product, a white powder, was dried in vacuo (0.68 g, 6,10,12,16,18,22,8,14,arene (1.5 g, 1.2 mmol) was dissolved in dimethylethylenediamine (30 mL). The solution was stirred at room temperature for 4 h and then at 60°C for 6 days.…”

“…1 H NMR (300 MHz, D 2 O/CD 3 COOD, 25°C): δ ϭ 7.01 (s, 4 H), 6.50 (s, 4 H), 6.20 (s, 4 H), 5.74 (s, 4 H), 3.36Ϫ3.20 (m, 32 H), 2.97 (s, 16 H), 0.91 (s, 80 H), 0.53 (br. s, 12 H) 6,10,12,16,18,22,8,14,arene (2.8 g, 1.6 mmol) was dissolved in dimethylethylenediamine (50 mL). The solution was stirred at room temperature for 10 days and then at 60°C for 5 h. The solution was concentrated in vacuo and the precipitate obtained was washed with acetone (50 mL).…”