The key effect of the self-assembly mechanism of dendritic gelators: solubility parameters, generations and terminal effects

Abstract

The key effect of the self-assembly mechanism of dendritic gelators is researched by a comprehensive investigation of the gelation behavior of L-lysine dendritic gelators with different structures of three generations in 20 different solvents. The solvents investigation, 1 H NMR, tube inversion method, DSC, rheology, FTIR and rheological measurements show that the reported dendritic gelators self-assemble through the main driving force of hydrogen bonds and the second driving force of p-p stackings. So the key effect of the self-assembling mechanism is that these factors can influence the driving force of the self-assembly process. This is the reason that L-lysine dendritic gelators tend to gelate in solvents with low a and b parameter values, which have less influence on the formation of hydrogen bonds between the gelators. Higher generations provide a much greater hydrogen bond density in the gelators, which makes them have a higher gelation ability. The benzyl terminal groups provide the second driving force of p-p stacking, making the Bzl-Gly-Lys gelators have much stronger gelation ability. This research reports a comprehensive insight into the precise ways in which the solubility parameters of the solvents, the gelator generation and the terminal group effects can influence the self-assembly and gelation of dendritic gelators. Gaining this type of fundamental understanding is essential if the key effect of this important class of self-assembling soft materials is to be truly understood.

Functional organogelators formed by liquid-crystal carbazole-containing bis-MPA dendrimers

“…The critical gelation concentration (CGC) for these compounds ranges from 1 to 0.25% wt. These low CGCs, specially for dendrons (1 and 2) and codendrimers bearing one Cbz group (3 and 5), are consistent with a strong dendritic effect, 9,16 which in this case means that the presence of four mesogenic units together enhances the stabilisation of the interactions through p-p and van der Waals forces. Thermoreversibility of the gels was stated in cyclohexane by measuring the gel-sol transition temperature (T gel , in Table 2).…”

Self-Assembly of a Strong Polyhedral Oligomeric Silsesquioxane Core-Based Aspartate Derivative Dendrimer Supramolecular Gelator in Different Polarity Solvents

“…Supramolecular gels are colloidal soft materials consisting of self-assembled fiber networks that have attracted significant attention in recent years because of their all kinds of potential applications in various fields, − such as pollutant removal, drug delivery, biosensors, catalysis, optoelectronics, enzyme immobilization, solar cells, and so on. The well-defined supramolecules always achieve a reversible sol–gel phase transition by means of the noncovalent nature of the interactions including hydrogen bonding, π–π stacking, ion–ion, dipole–dipole, van der Waals force, host–guest, and ion coordination in the supramolecular network to form supramolecular gels. − …”

Topological structure influences on the gel formation process and mechanical properties of l-lysine based supramolecular gels

“…Supramolecules have well dened, three-dimensional branched architectures with different structures of molecular cores, and constitute a unique nanoscale toolkit, which achieves a reversible sol-gel phase transition by means of the noncovalent nature of the interactions including ion-ion, dipoledipole, hydrogen bonding, p-p stacking, van der Waals force, host-guest, and ion coordination, and in so doing trap solvent molecules in the supramolecular network to form supramolecular gels. 5,6 So the resultant material properties are generally determined by such non-covalent interactions, which are effective tools for constructing well-dened supramolecular structures driven by molecular self-assembly, controlled by the interplay of self-complementary and intermolecular supramolecular interactions that are further enforced through the generation of a multidimensional matrix structure. 7 This makes the design of new classes of small molecules that can give rise to gelation with targeted properties oen highly challenging as minor modications can greatly affect the macroscopic properties of the resulting material in an unexpected manner.…”