## 3 Results and Discussion
### 3.2. Gelation in Organic Solvents  
The majority of these newly synthesized amide and urea-amide derivatives showed gelation properties in organic solvents during their work-up or isolation. A systematic study was then performed to examine the gelation behavior of these partially fluorinated amide or urea-amide derivatives in various organic solvents. A methodology was developed where gelation was attempted with varying amounts of organogelator with a matching a solvent system. A suitable solvent system selection is based on initial solubility experiments. In general, a gelator that is too soluble in an organic solvent will stay dissolved without forming a gel, even at high concentrations. If the gelator is not soluble in an organic solvent, and partially or fully dissolves at high temperature, it may precipitate again as the temperature is lowered. Ideally, the organogelators should dissolve in a solvent at a temperature close to its boiling point and assemble into a network upon cooling, leading to a single gel phase that does not move upon shaking or inverting the vial. In a typical screening experiment, 0.5-4 mg/mL slurries of the organogelators in various organic solvents were prepared and heated with stirring at a temperature 5 \({}^{\circ}\)C below the boiling point of the solvent to induce full dissolution. Gelation occurred upon cooling, as was evident by significant increase in viscosity and/or the formation of a translucent-to-opaque appearance, without the formation of precipitate. The majority of the partially fluorinated amide and urea-amide derivatives showed gelation properties in a variety of organic solvents at remarkably low concentrations, ranging from 0.5 to 4 mg/mL. The partially fluorinated amide derivative **5a** showed gelation properties in acetone (2-3 mg/mL) and _n_-butanol (3-4 mg/mL) leading to partial gels. The corresponding perfluorobutyl derivative (**5b**) showed gelation in acetone at 3-4 mg/mL and was a clear solution in _n_-butanol at various concentrations. Both **5a** and **5b** existed either as clear solutions or slurries in THF, dichloromethane, methanol and toluene at various concentrations (0.5-4 mg/mL), and did not show any signs of gelation. Compound **5c** did not gel under any conditions tested, indicating that a long-chain perfluoroalkyl group is probably needed to induce gelation of these bis-amide systems. We then examined the tris-amide systems **6a-c** for their gelation abilities at various concentrations in a variety of organic solvents. Compound **6a** gelled in acetone (2 mg/mL) and in _n_-butanol (4 mg/mL) to form opaque gels which were stable for several weeks at room temperature. Similarly, compound **6b** formed stable hazy gels in acetone at (3 mg/mL) and in dichloromethane (2 mg/mL). Compound **6c** formed gels in acetone at (1-2 mg/mL) and in methanol (2 mg/mL), indicating gelation could be induced on this tris-amide system even though it comprises a pentafluorophenyl group. Gelation of urea-amide derivatives (**7a-c** and **8a-c**) was then attempted in a variety of organic solvents under varying concentrations. Compound **7a** gelled in THF (2 mg/mL) and acetone (2 mg/mL) forming stable gels, and partially gelled in _n_-butanol (3 mg/mL). Compound **7b** gelled in acetone and THF (3 mg/mL), leading to stable gels. The pentafluorophenyl urea-amide derivative **7c** remained as slurry or solution in many organic solvents, although partial gel formation was observed in dichloromethane (2 mg/mL). The urea-bis-amide derivatives **8a-c** showed excellent gelation properties in a variety of organic solvents. Compound **8a** gelled in both acetone and dichloromethane at 2-3 mg/mL concentrations. Compound **8a** also showed partial gelation in THF and _n_-butanol at 2-4 mg/mL concentrations. Compound **8b** gelled in dichloromethane (2 mg/mL) and acetone (3 mg/mL), leading to stable gels.