Thermal properties of the gel made by low molecular weight gelator 1,2-O-(1-ethylpropylidene)-alpha-D-glucofuranose with toluene and molecular dynamics of solvent.
The studies of the gel-to-sol phase transition by the Raman, FT-IR, and 1H NMR methods of the gel made by low molecular weight organogelator 1,2-O-(1-ethylpropylidene)-alpha-D-glucofuranose with toluene as the solvent are reported. The FT-IR spectra revealed the existence of a hydrogen bond network formed by gelator molecules in the crystalline and gel phase. In both phases, the network formation is dominated by the gelator self-interaction. Upon gelation, only one stretching band of infrared absorption modes nualpha, assigned to the O(6)H hydroxyl protons of gelator, is shifted by Deltaupsilonalpha = 25 cm-1, which indicates the involvement of this proton in the interaction with the solvent molecules. The phase transition measurements performed as a function of gelator concentration allowed the calculation of the energy correlated with the transition from gel to solution phase. The obtained value of 72 kJ/mol is the largest one reported up until now for monosaccharide-based gels. The analysis of the temperature measurements of the toluene 1H NMR spectra provides evidence for a different chemical environment of toluene molecules in the gel. The toluene spin-lattice relaxation in bulk and gel indicate that the viscosity is most likely the main factor that influences the dynamics of toluene.
Tritt-Goc
Jadwiga
J
Institute of Molecular Physics, Polish Academy of Sciences, ul. M. Smoluchowskiego 17, 60-179 Poznań, Poland.
Bielejewski
Michał
M
Luboradzki
Roman
R
Lapiński
Andrzej
A
D005663:Furans / Q000737:chemistry*; D006860:Hydrogen Bonding; D008970:Molecular Weight; D012997:Solvents / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods; D014050:Toluene / Q000737:chemistry*
D005663:Furans; D012997:Solvents; D014050:Toluene