title: The solvent-gelator interaction as the origin of different diffusivity behavior of diols in gels formed with sugar-based low-molecular-mass gelator.
abstract: Organogels are soft materials consisting of low-molecular-mass gelators (LMOGs) self-assembled through noncovalent interactions into 3D structures, in which free spaces are filled by organic solvents. 4,6,4',6'-O-terephthylidene-bis(methyl-α-d-glucopyranoside) (1) is found to be a new LMOG. It gelatinizes only a limited number of solvents. Here, the gels of 1 with ethylene glycol (EG) and 1,3-propanediol (PG) are investigated with FT-IR, Raman, and UV-vis spectroscopies, the NMR relaxometry and diffusometry methods, and microscopic observation. The chemical structures of both solvents are closely related, but the variety of physical characteristics of the gels is large. The 1/PG gels are thermally more stable compared to 1/EG gels. The types of aggregates are most likely the H- and J-type in 1/EG gels and the J-type in 1/PG gels. Different microstructures are observed: bundles of crossing fibers for 1/EG and a honeycomb-like matrix for 1/PG gels. The diffusivity of the EG solvent in gels with 1 behaves as expected, decreasing with increasing gelator concentration, whereas the opposite behavior is observed for the PG solvent. This is a most fascinating result. To explain the diffusion enhancement, we suggest that a dynamic hydrogen bonding network of PG solvent in gel matrixes is disrupted due to solvent-gelator interaction. The direct proof of this interaction is given by the observed low frequency dispersion of the spin-lattice relaxation time of solvents in the gel matrixes.
authors.affiliation: Institute of Molecular Physics, Polish Academy of Sciences , ul. M. Smoluchowskiego 17, 60-179 Poznań, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kowalczuk
authors.forename: Michał
authors.initials: M
authors.lastname: Bielejewski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Lapiński
authors.forename: Roman
authors.initials: R
authors.lastname: Luboradzki
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Tritt-Goc
mesh_terms: D002241:Carbohydrates / Q000737:chemistry*; D004058:Diffusion; D019855:Ethylene Glycol / Q000737:chemistry; D005782:Gels / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009005:Monosaccharides / Q000737:chemistry*; D044367:Phase Transition; D011409:Propylene Glycols / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D044366:Transition Temperature
chemical_list: C000597131:4,6,4',6'-O-terephthylidene-bis(methyl-alpha-D-glucopyranoside); D002241:Carbohydrates; D005782:Gels; D009005:Monosaccharides; D011409:Propylene Glycols; D012997:Solvents; C041787:1,3-propanediol; D019855:Ethylene Glycol