# Synthesis, Characterization, and Self-Assembly of a Tetrathiafulvalene (TTF)-Triglycyl Derivative
## 3 Results and Discussion
### Characterization of Organogels  
In general, relatively low _gel_-to-_sol_ transition temperatures (\(T_{\text{gel}}\)) were determined for all gels ranging from 36 to 51 \({}^{\circ}\)C (\(\pm\)3) (Table 1). As typically observed with most supramolecular gels, \(T_{\text{gel}}\) gradually increased with increasing gelator concentration due to the generation of denser networks (Figure 3). Taking the gels prepared in toluene and ethyl acetate as representative systems, a plateau region was reached before the gels collapsed into partial and inhomogeneous gels that constantly lose solvent over time. The increment of the \(T_{\text{gel}}\) until the plateau region was \(\sim\)39 \({}^{\circ}\)C for toluene and \(\sim\)25 \({}^{\circ}\)C for ethyl acetate with respect to the initial values obtained at their CGC. Linear Ln-Ln plot (Figure 3, inset) using the percentage increases of \(T_{\text{gel}}\) showed that the percentage increment of \(T_{\text{gel}}\) was \(\sim\)1.1-fold higher for the gel made in ethyl acetate. Further research is necessary to understand the reasons behind such differences. Figure 3: Variation of \(T_{\text{gel}}\) with increasing gelator concentration for the gels made in toluene and ethyl acetate. Inset: Normalized Ln-Ln plot of \(T_{\text{gel}}\) percentage increases. Figure 2: (**a**) Photographs of upside-down vials having selected gels made of **14** in toluene, benzene, chlorobenzene (PhCl), and dichloromethane (DCM) at the CGC (see Table 1); (**b**) illustration of the thermal _sol-gel_ transition of the gel made of **14** in toluene at the CGC. Dynamic rheological experiments (Figure 4) for the model gel made of **14** in toluene confirmed its viscoelastic nature. Within the linear regime established by dynamic frequency sweep (DFS) and dynamic strain sweep (DFS) measurements, the storage modulus \(G^{\prime\prime}\) was found to be one order of magnitude higher than the loss modulus \(G^{\prime\prime}\) with low frequency dependency (i.e., \(G^{\prime}\approx\) 8.9 \(\pm\) 0.5 kPa, \(G^{\prime\prime}\approx\) 0.75 \(\pm\) 0.1 kPa) (Figure 3a). Moreover, the gels were brittle in nature, which was confirmed by its destruction at low frequency and \(\sim\)7% of strain (Figure 4a). Finally, dynamic time sweep (DTS) measurements at 0.1% strain and 1 Hz frequency confirmed the stability of the gel over time at RT (Figure 4b). Morphological studies of selected organogels were conducted by field emission scanning electron microscopy (FE-SEM) of the corresponding xerogels (Figure 5). In general, fibrillar networks with high aspect ratio were observed for several organogels made of **14**. As observed with other supramolecular self-assembled gels, interactions between solvent-aggregate, solvent-gelator, and gelator-gelator molecules are also regulated by the solvent nature and have a major effect on the microstructure of  
Figure 4: (**a**) Dynamic frequency sweep (DFS), dynamic strain sweep (DSS), and (**b**) dynamic time sweep (DTS) measurements for the model gel made of **14** in toluene (9 g/L). The tan \(\delta\) (i.e., \(G^{\prime\prime}/G^{\prime}\), damping coefficient) was reproducible in random experiments. the materials. For instance, dense and entangled leaf-like structures were observed for the material obtained in ethyl acetate (Figure 5a), whereas the samples prepared in benzonitrile showed a smooth surface with fibrillar structures of \(\sim\)0.5-1 \(\upmu\)m in diameter (Figure 5b). A highly dense and porous network made of fibers up to \(\sim\)1 \(\upmu\)m in diameter was observed for the gel made in 1,4-dioxane (Figure 5c). Surfaces made of smaller fibers of \(\sim\)50-100 nm in diameter resembling a mountainous valley were observed for the specimens prepared in toluene (Figure 5d). However, fibrillar-globular structures with diameters between \(\sim\)100 and 500 nm were distinguished when the solvent used for the preparation of the gel was dichloromethane (Figure 5e).