Steric‐Structure‐Dependent Gel Formation, Hierarchical Structures, Rheological Behavior, and Surface Wettability

Abstract

A series of bicholesteryl-based gelators with different central linker atoms C, N, and O (abbreviated to GC, GN, and GO, respectively) have been designed and synthesized. The self-assembly processes of these gelators were investigated by using gelation tests, field-emission scanning electron microscopy, field-emission transmission electron microscopy, UV/Vis absorption, IR spectroscopy, X-ray diffraction, rheology, and contact-angle experiments. The gelation ability, self-assembly morphology, rheological, and surface-wettability properties of these gelators strongly depend on the central linker atom of the gelator molecule. Specifically, GC and GN can form gels in three different solvents, whereas GO can only form a gel in N,N-dimethylformamide (DMF). Morphologies from nanofibers and nanosheets to nanospheres and nanotubes can be obtained with different central atoms. Gels of GC, GN, and GO formed in the same solvent (DMF) have different tolerances to external forces. All xerogels gave a hydrophobic surface with contact angles that ranged from 121 to 152°. Quantum-chemical calculations indicate that the GC, GN, and GO molecules have very different steric structures. The results demonstrate that the central linker atom can efficiently modulate the molecular steric structure and thus regulate the supramolecular self-assembly process and properties of gelators.

Strong Blue Emissive Supramolecular Self-Assembly System Based on Naphthalimide Derivatives and Its Ability of Detection and Removal of 2,4,6-Trinitrophenol

“…The G ′ and G ″ values of gels G-P and G-B were about 100 and 700 and 10 and 90 Pa, respectively. These results indicated that an energy-storage process occurred without energy dissipation, which also confirmed that the three gels had a good elastic character …”

“…These results indicated that an energy-storage process occurred without energy dissipation, which also confirmed that the three gels had a good elastic character. 53 UV−vis absorption and fluorescence spectra can provide important information about the self-assembly process. 54−57 The UV−vis absorption and fluorescence spectra of G-P and G-B in solution (10 −5 M) and gel states (0.69 and 0.45 w/v %) were investigated (Figure 3).…”

Self-assembly of the monohydroxy triterpenoid lupeol yielding nano-fibers, sheets and gel: environmental and drug delivery applications

“…XRD peaks observed at 1.35, 0.65, 0.46 nm for both the xerogels prepared from the gels in DMF and n-heptane are close to the ratio 1 : 1/2 : 1/3 indicating a lamellar pattern of self-assembled microstructures like brillar network/crystalline bers, sheets which are consistent with our microscopic observations by SEM, HRTEM, AFM discussed earlier. [65][66][67] A few peaks at 0.57, 0.46, 0.43, 0.34 nm found in the powder diffraction pattern generated from its single crystal structure were also observed in the xerogels of 1 from n-heptane and DMF as well as the neat powder indicating that ordered arrangement of molecules are also present in the gel morphology. The peaks at 0.95, 0.85, 0.67, 0.63, 0.60, 0.49, 0.39 nm observed in the single crystal did not match with the diffraction pattern from the xerogels of 1 in DMF and n-heptane indicating the uniqueness of the gel morphologies different from the single crystal (Fig.…”

Naphthalimide-based fluorescent gelator for construction of both organogels and stimuli-responsive metallogels

“…In the past two decades, design and synthesis of low molecular weight gelators is of increasing interest due to their potential applications in catalysis, biochemistry, tissue engineering, pollutant removal and sensing materials. [1][2][3][4][5][6][7][8][9] Organic compounds are found efficient gelators in organic solvents or water due to the dedicate and synergetic intermolecular interactions including hydrogen bonding, hydrophobic and p-p stacking interaction. For example, Ajayaghosh et al report many kinds of p organogelators with distinct optical properties; 10 D. K. Smith demonstrates a series of 1,3:2,4-dibenzylidene-D-sorbitol (DBS) organolator with varies applications such as pollutant removal and gel electrolytes; 11 Lu and Xue synthesize the carbazole-based pconjugated gelator for vapor sensing.…”