Self-assembled fibrillar networks of a multifaceted chiral squaramide: supramolecular multistimuli-responsive alcogels

Abstract

Chiral N,N'-disubstituted squaramide has been found to undergo self-assembly in a variety of alcoholic solvents at low concentrations leading to the formation of novel nanostructured supramolecular alcogels. The gels responded to thermal, mechanical, optical and chemical stimuli. Solubility studies, gelation ability tests and computer modeling of a series of structurally related squaramides proved the existence of a unique combination of non-covalent molecular interactions and favorable hydrophobic/hydrophilic balance in that drive the anisotropic growth of alcogel networks. The results have also revealed a remarkable effect of ultrasound on both the gelation kinetics and the properties of the alcogels.

Synthesis and supramolecular self-assembly of glutamic acid-based squaramides

“…This is in good agreement with our previous observations made with a different squaramide, where we hypothesized that ultrasound could help to preserve only the thermodynamically more stable aggregates through a self-sorting mechanism, thus providing a more robust starting platform for rebuilding the gel network [21]. …”

“…Thus, compound 3 can be an alternative to compound 2 , and vice versa, depending on the solvent to be gelled (see below). Similarly to other amphiphilic gelators [21,29,31], the formation of a self-assembled network in organic solvents is likely driven by the formation of hydrogen bonds between different gelator molecules (polar head) as well as hydrophobic interactions between the long aliphatic chains.…”

“…In this work, and based on our previous experience with organogels based on squaramides [21], we decided to prepare and study an analogue of N -stearoyl-L-glutamic acid bearing the squaramide moiety instead of the amide group ( 4 , Fig. 1).…”

Sulfonamide as amide isostere for fine-tuning the gelation properties of physical gels

“…Thermal gel-to-sol transition temperature (T gel ) values were determined using a custom made set-up in which the sealed vial containing the gel was placed into a mold of an alumina block and heated up at approximately 5 C min À1 using an electric heating plate equipped with a temperature control couple. 37 The values obtained with this equipment were previously veried by DSC measurements. 31 Herein, the temperature at which the gel started to break was dened as T gel .…”

Glycoluril Clips for the Construction of Chemoresponsive Supramolecular Polymer Networks through Homodimer Cross‐Links

“…[12] Depending on the applied supramolecular motif, the formed network exhibits stimuliresponsiveness against a particular factor, such as temperature, [2] pH, [13] chemical agent, [8] etc. Moreover, some systems display multi-responsiveness, i. e., sensitivity against two or more factors, for example temperature and a certain chemical factor, [5][6]14] which substantially widens the range of such materials applications.…”