The design and control of molecular self-assembly is of great interest in the development of new molecular architectures with multiple desired functions or properties. In this context, the gelling systems formed by low molecular weight gelators are particularly promising and are the subject of an ever increasing number of studies. Thus, owing to their non-conventional behaviour, low molecular weight gelators are very attractive for applications in various areas, including supramolecular templates or matrices, transport and drug release, art conservation, cosmetics, sensors, optoelectronics or actuators. However, despite numerous efforts to establish a structure-property relationship for the development of low molecular weight gelling agents, prediction of the gelling ability of a compound is not straightforward. A major challenge today is the rational design of small size molecular gelators coupled with an understanding of the mechanism of gelation.
Graphical Abstract
Scheme 1: Different types of 1-D and 2-D HBN forming supramolecular synthons.
Scheme 2: Salts studied in the present report.
Figure 1: Photomicrographs of the organogels (from left to right: nitrobenzene gel of DBUAMC 3; 1,2-dichlorob...
Figure 2: DSC of a 4.0 wt % 1,2-dichlorobenzene gel of DBAMC 6.
Figure 3: Left – Tgel vs [gelator] plot; right – semilog plot of mole fraction of the gelators against 1/T; 1...
Figure 4: SEM micrographs of the xerogels. (a) & (b) 0.5 wt % 1,2-dichlorobenzene gel of DBAMC 6; (c) 0.8 wt ...
Figure 5: Crystal structure illustration of DBUAMC 3; 3-D hydrogen bonded network; only one part of the disor...
Figure 6: Crystal structure illustrations of DBAMC 6; top – propagation 1-D network involving ammonium and ca...
Figure 7: Illustration of crystal structure of DCHADC 1; top – 1-D hydrogen bonded zigzag chain displaying SA...
Figure 8: PXRD patterns of salts 3, 6 and 1 under various conditions.
Graphical Abstract
Figure 1: Structure of amphiphiles 1–5.
Scheme 1: Synthetic procedure of the amphiphiles.
Figure 2: Variation of the Tgel with concentration of amphiphiles 1 and 2.
Figure 3: (a, b) FESEM images of the dried gels of 1 and 2, respectively at their MGC. (c, d) Two- and three-...
Figure 4: Luminescence spectra of 2 in water (λex = 330 nm) at various concentrations and room temperature.
Figure 5: FTIR spectra of (a) 1 and (b) 2 in CHCl3 solution (dashed line) and in D2O at the gel state (solid ...
Figure 6: 2D-NOESY spectra of 2 (2%, w/v) in DMSO-d6 with 70% water.
Figure 7: XRD diagram of the dried gel of 2.
Figure 8: Schematic representation of the possible arrangement of molecules during hydrogelation of 2.
Figure 9: MTT assay based percent NIH3T3 cell viability as a function of concentration of amphiphile 2.
Graphical Abstract
Figure 1: Structures of monomer EHUT and chain stoppers.
Figure 2: Substituted urea conformation. If R is alkyl, the most stable conformation is b); if R = H, the mos...
Figure 3: FTIR spectra, at 20 °C, for CDCl3 solutions of S4 (a) or EHUT (b), at several concentrations.
Figure 4: SANS intensity versus scattering vector for 12 mM solutions of EHUT or S4 in d8-toluene, at 22 °C. ...
Figure 5: Relative viscosity for solutions of EHUT (20 mM) in 1,3,5-trimethylbenzene at 25 °C, with increasin...
Figure 6: Relative viscosity for solutions of EHUT (1.1 mM) in toluene at 25 °C, with increasing molar fracti...
Graphical Abstract
Scheme 1: Oxalyl retro-dipetide gelators; each b to a, (a) LiOH/MeOH, H2O; (b) H+; each b to c: (c) NH3/MeOH.
Figure 1: Chiral bis(amino acid)-(I) and bis(amino alcohol)-(II)-oxalamide gelators.
Figure 2: TEM images (PWK staining) of: (S,S)-1a H2O/DMSO gel.
Figure 3: TEM images (PWK staining) of: (S,R)-1a H2O/DMSO gel.
Figure 4: TEM images (PWK staining) of: (S,R)-1b toluene gel showing the presence of short tape like aggregat...
Figure 5: The concentration dependence of NH and C*H chemical shifts in (S,R)-1b toluene-d8 gel samples (conc...
Figure 6: The concentration dependence of NH and C*H chemical shifts in (S,S)-1b and its racemate (S,S)-1b/(R...
Figure 7: Temperature dependence of: a) oxalamide NH protons (▲), Leu-NH protons (Δ) and b) oxalamide-α-Leu-C...
Figure 8: Temperature dependent CD spectra of: a) (S,R)-1b decalin gel (c = 3.4·10−2 M); b) (S,S)-1b decalin ...
Figure 9: X-ray powder diffractograms of (a) (S,R)-1b and (b) (S,S)-1b xerogels prepared from their toluene g...
Figure 10: (a) Fully minimized the lowest energy conformations of (S,S)-1b (top) and (S,R)-1b generated by sys...
Figure 11: Schematic presentation of the proposed (S,S)-1b and (S,R)-1b basic packing model based on XRPD, 1H ...
Figure 12: X-ray powder diffraction (XRPD) diagram of (S,R)-1a water/DMSO xerogel.
Graphical Abstract
Scheme 1: Synthesis of R-3 and S-3.
Figure 1: Concentration-dependent 1H NMR spectra of R-3 in chloroform (CDCl3). The red colours indicate the h...
Figure 2: a) R-3 gel in octane (5 mM); b) octane solution containing a mixture of R-3 (2.5 mM) and S-3 (2.5 m...
Figure 3: a) Concentration-dependent 1H NMR spectra of R-3 in cyclohexane-d12 and b) the shift of N–H signal ...
Figure 4: The evolution of ln(ee × 100) for the racemization of R-3 (1 mM) in the presence of 1 equivalent of...
Graphical Abstract
Figure 1: Molecular structures of β-Ala-His-EO2-C14 (a) and Gly-Gly-His-EO2-C14 (b).
Figure 2: ATR spectra of β-Ala-His-EO2-C14 in xerogel and D2O hydrogel, respectively.
Figure 3: SAXS profile of concentrated gel of β-Ala-His-EO2-C14 at different temperatures (where S = 2π/q and...
Figure 4: SEM micrographs of β-Ala-His-EO2-C14 hydrogels after drying.
Figure 5: 2D/3D self assembling of β-Ala-His-EO2-C14.
Graphical Abstract
Scheme 1: Reversible reaction of octadecylamine with carbon dioxide.
Figure 1: Flow curves of ODA-C/silicone oil gels at 25 °C and increasing stress.
Figure 2: η0 values as a function of ODA concentration.
Figure 3: Dependence of viscosity of ODA-C/silicone oil gels on temperature at a shear stress of 1 Pa. From t...
Figure 4: Optical micrographs of a 2 wt % ODA-C/silicone oil gel before (A) and after (B) the application of ...
Figure 5: Amplitude sweep test of a 2 wt % ODA-C/silicone oil gel showing G′ (■) and G″ (●). The vertical lin...
Figure 6: Frequency sweep tests and dynamic mechanical measurements of 2, 4, and 8 wt % ODA-C/silicone oil ge...
Figure 7: Damping factors of 2 (■), 4 (●) and 8 wt % (▲) gels at different frequencies.
Graphical Abstract
Figure 1: Amino acid based organogelators 1 and 2.
Scheme 1: Synthesis of organogelators 2.
Graphical Abstract
Scheme 1: Structure of the quarterthiophene derivative T1.
Scheme 2: Synthetic route to T1. Reagent and conditions: a) Boc anhydride, CH2Cl2, 6 h, 0 °C–rt, 97%; b) NBS,...
Figure 1: AFM height images of a film spin-coated from diluted gel solution of T1 in MCH (2 × 10−3 M) onto HO...
Figure 2: a) UV-vis spectra of T1 in chloroform (dashed line) and n-heptane (solid line); b) UV-vis spectra o...
Scheme 3: Proposed mode of self-assembly of T1.
Figure 3: UV-vis spectra of T1 (concentration 5 x 10−5 M) in cyclohexane (solid line) and 2.4% MeOH in cycloh...
Figure 4: AFM height images (A and B) of a film spin-coated from MCH solution (concentration 5 x 10−4 M) of a...
Figure 5: Variation of dose-normalized conductivity transients (Δσ/D) with time for T1.
Graphical Abstract
Figure 1: Schröder–van Laar analysis for the melting of toluene (open symbols) and ethanol/water (filled symb...
Figure 2: SANS from 50 mg ml−1 G6 in a range of solvents, 25 °C; d-acetone (circles), d-chloroform (triangles...
Figure 3: SANS from G6 25 °C in d-toluene as a function of G6 concentration; 5 mg ml−1 (circles), 10 mg ml−1 ...
Figure 4: SANS from a series of homologous gelators, G5 (circles), G6 (squares) and G8 (triangles) in d-tolue...
Figure 5: SANS from 50 mg ml−1 G6 in d-toluene, 25 °C; hydrogenous gelator (empty symbols) and partially deut...
Figure 6: SANS from 35 mg ml−1 G6 in 75% d-ethanol/25% D2O, 37 °C; hydrogenous gelator (empty symbols) and pa...
Figure 7: SESANS data for 50 mg ml−1 G6 in deuterated toluene, 25 °C.
Figure 8: Inelastic neutron spectroscopy from toluene gels (upper Figure): red deuterated toluene/hydrogenous...
Figure 9: Inelastic neutron spectroscopy from cyclohexane gels (upper Figure): red deuterated cyclohexane/hyd...
Scheme 1: Synthesis of hydrogenous gelators.
Scheme 2: Structure of partially deuterated gelators.
Graphical Abstract
Scheme 1: The chemical structures of the phenylalanine derivatives.
Figure 1: Optical images of (A) gel IV (1.5 wt %, pH = 4.6), (B) gel IV after UV irradiation (no aging), (C) ...
Figure 2: The optical images of (A) solution of 6 (2 wt %, pH = 9.0), (B) suspension of 6 (2 wt %, pH = 6.5),...
Figure 3: (A) Frequency dependence of dynamic storage modulus (G’) and loss modulus (G”) of gels I to IV at 1...
Figure 4: TEM images of the nanofibers that act as the matrices of gel I (A), gel II (B), gel III (C) and gel ...
Figure 5: The emission spectra (slit width = 3.0 nm) of the gels I–III and their solutions (I: λex= 265 nm; II...
Graphical Abstract
Figure 1: Structures of three ester derivatives of compound 1.
Figure 2: Structures of ester analogs 5–7 and headgroup 8.
Scheme 1: Synthesis of a series of esters 9A–18C.
Figure 3: Optical micrographs of the gels formed by compound 9A in hexane at 15 mg/mL (A, B), 9B in DMSO/wate...
Figure 4: An ethanol gel formed by compound 18A at <10 mg/mL. a) A clear solution when heated above 70 °C; b)...
Figure 5: Optical micrographs under bright field (a, b) and scanning electron micrograph (c) of the gel forme...
Figure 6: The UV–vis absorption spectra of the polymerized gel formed by compound 18A in ethanol (10 mg/mL): ...
Graphical Abstract
Scheme 1: Gelators 1 and 2.
Figure 1: Photographs of the gels: 1 in 1,2-dichlorobenzene (0.2% w/v, left); 2 in 1:1 DMSO/water (0.3% w/v, ...
Figure 2: Illustration of base-instability and acid-stability of the organogel of 1 in 1,2-dichlorobenzene.
Figure 3: Acid-instability and base-stability of the hydrogel of 2 in 1:1 DMSO/water.
Figure 4: (a) and (b) POM images of the gels of diethylaminolithocholyl iodide 1 in 1,2-dichlorobenzene (1.25...
Figure 5: (a) and (b) POM images of bis(2-hydroxyethyl)aminodeoxycholane 2 gel in 1:1 DMSO/water (normally-co...
Figure 6: Gel melting profile of diethylaminolithocholyl iodide 1 gel in 1,2-dichlorobenzene.
Figure 7: Gel melting profile of bis(2-hydroxyethyl)aminodeoxycholane 2 gel in 1:1 DMSO/water (normally coole...
Scheme 2: General method of synthesis of bile acid derived amines 1 and 2.
Graphical Abstract
Figure 1: Structures of the 2,3-dihydroxycholestane isomers studied in this work.
Figure 2: 3D plots for LMOG 1 and solvent parameters of the tested solvents a) Hansen solubility parameters (δ...
Figure 3: Tg-vs-concentration plots for gels of 1.
Figure 4: SEM images of xerogels from a,b) dichloromethane, and c,d) from dioxane.
Figure 5: Powder X-ray diffraction pattern of the xerogels of 1 from a) n-hexane and b) dichloromethane.
Figure 6: Self-assembly models proposed for LMOG 1, only the left handed helix is shown, head to head hydroge...
Figure 7: SEM images of nanostructured silica obtained from gels of LMOG 1 under the following conditions: 0....