טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentEgbaria Eisaam
SubjectOrganic Gelators in Solution and in the Gas Phase
DepartmentDepartment of Chemistry
Supervisor Dr. Chagit Denekamp


Abstract

Trans-4-tert-butyl-1-phenyl-cyclohexanol, so called 1t, is a known organic gelator, good enough to gelate no-polar organic solvents. However the cis isomer 1c is either soluble or crystallizes in these solvents, not forming a gel. 1t contains several functional groups that may be responsible for its gelation ability. Nevertheless, the comparison between the isomers leads to the conclusion that the spatial structure of 1t and related steric interactions are probably as important in the understanding of the gelation behavior. Cyclohexanol 1t is phenyl substituted and it appears that only the diastereoisomer with an axial phenyl group is an organogelator. Noteworthy is that the gelation ability of 1t is also a function of concentration, temperature and solvent type. The compounds we chose to prepare and study in the first part of this work are based on the structure of 1t with designed modifications. It was concluded that hydrogen bonding is the main interaction in the formation of these gels however p-interactions also contribute to the gelation process.



Cis, Trans-4-tert-butyl-1-phenyl-cyclohexanol


In the last part of this work supra-molecular interaction were studied using ESI-MS. Only a few systems were examined, however no correlation was found between gelation of organic systems and aggregation in the electrospray source. 4-tert-butyl-1-phenyl-cyclohexylamines 4 that was not active towards gelation in solution was found to form interesting clusters with trifluoroacetic acid with stereoselective characteristics. The trans isomer, which is analogous to the trans isomer 2t, gives rise to clusters as high as [M7TFA6+H+], where M is an amine molecule. On the other hand in the spectrum of the cis isomer 4c the largest cluster corresponds to [M4TFA3 + H+] (Figure 1). We developed a new method for the differentiation between isomeric amines according to their spatial structure.?


Figure 1:




Spectrum 1: ESI-MS measurement of 4t and 4c in a solution of MeOH/TFA.