1 research outputs found
The SolventāGelator Interaction as the Origin of Different Diffusivity Behavior of Diols in Gels Formed with Sugar-Based Low-Molecular-Mass Gelator
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.
4,6,4ā²,6ā²-<i>O</i>-terephthylidene-bisĀ(methyl-Ī±-d-glucopyranoside) (<b>1</b>) is found to be a new LMOG.
It gelatinizes only a limited number of solvents. Here, the gels of <b>1</b> with ethylene glycol (EG) and 1,3-propanediol (PG) are investigated
with FT-IR, Raman, and UVāvis 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 <b>1</b>/PG
gels are thermally more stable compared to <b>1</b>/EG gels.
The types of aggregates are most likely the H- and J-type in <b>1</b>/EG gels and the J-type in <b>1</b>/PG gels. Different
microstructures are observed: bundles of crossing fibers for <b>1</b>/EG and a honeycomb-like matrix for <b>1</b>/PG gels.
The diffusivity of the EG solvent in gels with <b>1</b> 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 solventāgelator interaction. The direct
proof of this interaction is given by the observed low frequency dispersion
of the spinālattice relaxation time of solvents in the gel
matrixes