Tuning Rheological Behaviors of Supramolecular Aqueous Gels via Charge Transfer Interactions

Abstract

Rheological properties are critical for determining real applications of supramolecular gels in various fields. Correspondingly, the modulation of gel rheology will be very important for meeting real requirements. In this aspect, a few strategies were applied to tune the rheological behaviors of supramolecular gels, but some specific interactions like charge transfer (CT) interactions were less explored at the molecular level. Herein, we report a pyrene-containing derivative of diphenylalanine as a donor gelator and naphthalenediimide or 3,5dinitrobenzene as matching acceptor molecules. It was found that the viscoelastic properties and strength of the original gel could be tuned through addition of different acceptor molecules to the original gel with changing the ratios of the selected acceptor molecules. As a result, storage modulus was continuously adjusted over a wide range from 190,000 to 50,000 Pa by CT interactions. Furthermore, the mechanism of the CT-induced change in rheological properties was understood and clarified through relevant techniques (e.g., UV−Vis, fluorescence, and FT-IR spectroscopy and TEM). The findings in this work would provide a novel strategy to modulate the rheological properties of supramolecular gels for adaption to broader fields of real applications.

Self-Assembly of Amphiphilic PDI and NDI Derivatives with Opposite Thermoresponsive Fluorescent Behaviors in Aqueous Solution

“…The two molecules are very similar in essence except for the size of the aromatic core. The synthesis of NDI and PDI was carried out in a similar manner to previously reported compounds . (the synthetic method is shown in Scheme S1).…”

“…The synthesis of NDI and PDI was carried out in a similar manner to previously reported compounds. 40 (the synthetic method is shown in Scheme S1). The structures of PDI and NDI were characterized by 1 H NMR, 13 C NMR, and FT-IR, and all details of characterization data were reported (Scheme S1 and Figures S1−S7).…”

Differently N‐Capped Analogues of Fmoc‐FF

“…Recently, mechanical properties ( eg . Viscoelasticity and yield stress) of Py‐C4‐FF hydrogel were modulated through charge transfer interactions generated by the addition of different fluorescence acceptor molecules to the original gel [45] . Successively, FF building block was derivatized with a tetraphenylethylen‐group (TPE) and the aggregation induce emission (AIE) properties of TPE‐FF derivative (Figure 7C) were investigated upon molecular packaging caused by the aggregation [46] .…”

“…Viscoelasticity and yield stress) of Py-C4-FF hydrogel were modulated through charge transfer interactions generated by the addition of different fluorescence acceptor molecules to the original gel. [45] Successively, FF building block was derivatized with a tetraphenylethylen-group (TPE) and the aggregation induce emission (AIE) properties of TPE-FF derivative (Figure 7C) were investigated upon molecular packaging caused by the aggregation. [46] The TPE is a prototypical example of a molecule displaying AIE, [47] with a non-emissive behaviour in diluted solutions and a fluorescent one after aggregation or casting into solid films.…”

Self-assembled aggregates based on cationic amphiphilic peptides: structural insight

“…20 This latter feature can be modulated by peptide functionalization with polymeric or organic moieties. For instance, derivatization of a peptide with PEG (polyethylene glycol) 21,22 or with glycosyl groups 23 allows increasing its solubility; in contrast, the addition of alkyl chains 24,25 or aromatic moieties [26][27][28] causes a decrease in its solubility. Based on the evidence that peptide aggregation can be opportunely modified, many bioactive peptides have been functionalized and studied.…”