The Solvent鈥揋elator Interaction as the Origin of Different Diffusivity Behavior of Diols in Gels Formed with Sugar-Based Low-Molecular-Mass Gelator

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• 作者：Joanna Kowalczuk ; Micha艂 Bielejewski ; Andrzej 艁api艅ski ; Roman Luboradzki ; Jadwiga Tritt-Goc
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：April 10, 2014
• 年：2014
• 卷：118
• 期：14
• 页码：4005-4015
• 全文大小：494K
• 年卷期：v.118,no.14(April 10, 2014)
• ISSN：1520-5207

文摘

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鈥?6鈥?O-terephthylidene-bis(methyl-伪-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鈥搗is 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鈥揼elator interaction. The direct proof of this interaction is given by the observed low frequency dispersion of the spin鈥搇attice relaxation time of solvents in the gel matrixes.