# Synthesis, Characterization, and Self-Assembly of a Tetrathiafulvalene (TTF)-Triglycyl Derivative
## 4 Conclusions  
In conclusion, TTF-triglycyl derivative **14** was synthesized and fully characterized by standard techniques. This compound was found to act as a LMW gelator for a series of organic solvents after a heating-cooling cycle. Therefore, the presence of aromatic rings on the peptide linked to the TTF unit is not a requirement for the formation of supramolecular gels using TTF-peptide conjugates. The critical gelation concentrations ranged from \(\sim\)5 to 50 g/L, and the thermal _gel_-to-_sol_ transition temperatures varied from \(\sim\)36 to 51 \({}^{\circ}\)C. FE-SEM imaging of the xerogels, prepared by freeze-drying the organogels, showed fibrillar microstructures with distinctive features depending on the solvent used to prepare the gels. Moreover, the viscoelastic and brittle nature of a model gel system was also supported by dynamic rheological experiments. Finally, UV-vis-NIR analysis of a model xerogel confirmed the oxidation of the TTF unit upon exposure to I\({}_{2}\) vapor. Nevertheless, FT-IR spectroscopy showed that the oxidation was accompanied with concurrent alteration of the intermolecular hydrogen-bonded network.  
The following are available online at [[http://www.mdpi.com/2076-3417/8/5/671/s1](http://www.mdpi.com/2076-3417/8/5/671/s1)]([http://www.mdpi.com/2076-3417/8/5/671/s1](http://www.mdpi.com/2076-3417/8/5/671/s1)), NMR spectra, FT-IR spectra, Figure S1: Thermolock used for \(T_{gel}\) determinations. (A) Front view of the set-up. (B) Top view of the set-up during a typical experiment. The set-up was previously calibrated with literature data for known compounds, Figure S2: FT-IR spectra of solid **14**, **14** dissolved in DCM, and xerogel, i.e., prepared by freeze-drying the organogel made of **14** in DCM (29 g/L), Figure S3: FT-IR spectra of the xerogel, obtained from the corresponding organogel made of **14** in DCM (29 g/L), before and after iodine-doping.  
[PERSON] carried out the synthesis and characterization of all compounds, and observed for the first time the aggregation tendency of the gelator. [PERSON], [PERSON], and [PERSON] carried out the rest of the experiments. [PERSON] and [PERSON] directed the project. All authors participated in writing the manuscript.  
This work was supported by the Ministerio de Economia, Industria y Competitividad (CTQ2014-52588-R, CTQ2017-84415-R), Generalitat de Catalunya (2014/SGR/624), the Instituto de Salud Carlos III (ISCIII) (Cb06.01_0019), and Universitat Regensburg, CIBER-BBN is an initiative funded by the VI National R+D+i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER actions and financed by ISCIII with  
Figure 6: UV-vis-NIR spectra before and after doping with I\({}_{2}\) the xerogel prepared from the organogel made of **14** in DCM (29 g/L).  
assistance from the European Regional Development Fund. We thank [PERSON], [PERSON], [PERSON], and [PERSON] (IOCB, Academy of Sciences of the Czech Republic) for their help in the synthesis of the TTF derivative; [PERSON] (Universitat Regensburg) for preliminary gelation tests; and [PERSON] (Universitat Regensburg) for assistance with UV / IR measurements. [PERSON] thanks Deutsche Forschungsgemeinschaft (DFG) for the Heisenberg Professorship Award.  
The authors declare no conflict of interest.